US Pat. No. 9,795,066

INVERTER

SUNGROW POWER SUPPLY CO.,...

1. An inverter comprising: an electronic device, a magnetic element, a heat radiator, a cooling fan, a first enclosure and
a second enclosure connected with the first enclosure via a mounting plate, wherein
the mounting plate is located between the first enclosure and the second enclosure;
the electronic device is disposed inside the first enclosure;
the heat radiator and the cooling fan are disposed inside the second enclosure;
the magnetic element is disposed outside the first enclosure and the second enclosure;
the magnetic element is disposed on a top plate of the second enclosure;
the cooling fan is disposed on a side plate of the second enclosure inside the second enclosure, the side plate being perpendicular
to gaps between fins of the heat radiator; and

the side plate is perpendicular the top plate.

US Pat. No. 10,056,781

POWER CARRIER SIGNAL COUPLING CIRCUIT AND COMMUNICATION SYSTEM

SUNGROW POWER SUPPLY CO.,...

1. A power carrier signal coupling circuit, connected to a three-phase alternating current (AC) power line, comprising:a first power carrier signal coupling channel, comprising a first capacitor;
a second power carrier signal coupling channel, comprising a second capacitor;
a signal transceiver; and
a coupling transformer, comprising a primary winding, a first secondary winding and a second secondary winding, wherein a first terminal of the first secondary winding is connected to the signal transceiver, a second terminal of the first secondary winding is connected to a first terminal of the second secondary winding, and a second terminal of the second secondary winding is connected to the signal transceiver, wherein
a phase of the three-phase AC power line serves as a common channel,
the first power carrier signal coupling channel is arranged between the common channel and one of two phases of the three-phase AC power line other than the phase of the three-phase AC power line serving as the common channel,
the second power carrier signal coupling channel is arranged between the common channel and the other of the two phases of the three-phase AC power line other than the phase of the three-phase AC power line serving as the common channel, and
a first terminal of the first capacitor is connected to one of the two phases of the three-phase AC power line other than the phase of the three-phase AC power line serving as the common channel, a second terminal of the first capacitor is connected to a first terminal of the primary winding, a first terminal of the second capacitor is connected to the other of the two phases of the three-phase AC power line other than the phase of the three-phase AC power line serving as the common channel, a second terminal of the second capacitor is connected to the first terminal of the primary winding, and a second terminal of the primary winding is connected to the common channel.

US Pat. No. 9,923,481

PHOTOVOLTAIC SYSTEM AND METHOD FOR CONTROLLING THE SAME

SUNGROW POWER SUPPLY CO.,...

1. A method for controlling a photovoltaic system, the photovoltaic system comprising a photovoltaic output device, an inverter
device, an AC interface device, a control device and an AC load, wherein a supply terminal of the AC load is connected to
an AC output side of the inverter device, and a control terminal of the AC load is connected to the control device, and the
method for controlling the photovoltaic system is applied to the control device and comprises:
controlling the AC interface device to maintain the inverter device being disconnected from an electrical grid;
starting the inverter device and then starting the AC load;
determining whether a grid connection condition is met for the photovoltaic system; and
controlling the AC interface device to connect the inverter device to the electrical grid, in a case that it is determined
that the grid connection condition is met for the photovoltaic system, wherein the grid connection condition is used to determine
whether power output by the photovoltaic output device is capable of maintaining a stable operation of the inverter device
and the AC load,

wherein the AC load comprises any one or more of a fan and a dehumidifier.

US Pat. No. 9,385,701

METHOD AND DEVICE FOR GENERATING PWM PULSES FOR MULTI-LEVEL INVERTER

SUNGROW POWER SUPPLY CO.,...

1. A method for generating PWM pulses for a multi-level inverter, wherein the method is applied to a device for generating
the PWM pulses for the inverter, wherein the device comprises a DSP control unit and a detection control unit connected to
the DSP control unit, and wherein the method comprises:
outputting PWM high frequency signals by three PWM peripheral units of the DSP control unit;
sending the PWM high frequency signals to the detection control unit;
detecting level signals outputted by a preset number of GPIO interfaces of the DSP control unit, by the detection control
unit;

determining, for each phase, two high frequency complementary switches of the inverter, according to state of the level signals;
sending, for each phase, the PWM high frequency signal outputted by one of the PWM peripheral units to a first switch of the
two switches;

inversing, for each phase, the PWM high frequency signal outputted by the one of the PWM peripheral units;
sending, for each phase, the inversed PWM high frequency signal to a second switch of the two switches; and
maintaining, for each phase, state of other switches of the inverter except the two switches unchanged in a power frequency
period, wherein the state of the other switches are determined according to a correspondence stored for each phase between
the level signals outputted by the GPIO interfaces and the states of the switches.

US Pat. No. 9,923,517

PHOTOVOLTAIC INVERTER SYSTEM, POTENTIAL INDUCED DEGRADATION EFFECT COMPENSATION METHOD AND DEVICE FOR THE SAME

SUNGROW POWER SUPPLY CO.,...

1. A potential induced degradation (PID) effect compensation method for a photovoltaic inverter system, applied to a PID effect
compensation device for the photovoltaic inverter system, wherein the PID effect compensation device for the photovoltaic
inverter system comprises a direct current voltage sampling unit, a processing control unit, an isolation alternating-current/direct-current
(AC/DC) conversion unit and a switching protection unit, and the PID effect compensation method comprises:
outputting, by the direct current voltage sampling unit, a direct current voltage signal to the processing control unit;
determining, by the processing control unit, whether a PID effect compensation condition is met based on the direct current
voltage signal;

calculating, by the processing control unit, a compensation voltage to be outputted by the isolation AC/DC conversion unit
based on the direct current voltage signal, if the PID effect compensation condition is met; and

controlling, by the processing control unit, the isolation AC/DC conversion unit to apply the compensation voltage between
positive electrode terminals of photovoltaic modules and ground via the switching protection unit, to perform PID effect compensation
on the photovoltaic modules.

US Pat. No. 10,003,198

METHOD AND DEVICE FOR MONITORING AND SUPPRESSING RESONANCE

SUNGROW POWER SUPPLY CO.,...

7. A device for monitoring and suppressing a resonance applied to a grid-connection generation system, wherein the device comprises:a sample conditioning circuit connected to a preset sample point of the grid-connected generation system and configured to monitor a current sample voltage of the preset sample point;
a controller connected to the sample conditioning circuit and configured to acquire amplitudes of harmonics of the current sample voltage using a preset algorithm, verify whether a resonance occurs in the grid-connected generation system based on the acquired amplitudes of the harmonics, and acquire current corrections of parameters of inverters in the grid-connected generation system according to a preset rule in a case that the resonance occurs in the grid-connected generation system;
a communication bus connected to the controller and the inverters in the grid-connected generation system and configured to transmit the current corrections acquired by the controller to the inverters respectively; and
an adjusting module connected to the controller and the inverters and configured to adjust the parameters of the inverters using the current corrections and a preset resonance suppressing algorithm until the resonance disappears in the grid-connected generation system, wherein the adjusting module comprises a first adjusting unit configured to adjust bandwidths of the inverters using the current corrections and a preset adjustment formula, wherein the preset adjustment formula is:
where Kp indicates a proportion control parameter, ?Uout indicates the current corrections and Kpmin indicates minimum allowable adjustment values of the bandwidths of the inverters;a second adjusting unit configured to adjust active damping coefficients of the inverters using a preset active damping algorithm and the current corrections; and
a third adjusting unit configured to transmit respectively the current corrections to the inverters to control an inactive damping resistor to be connected to a respective one of the inverters.

US Pat. No. 10,075,127

PHOTOVOLTAIC RAPID SHUTDOWN DEVICE AND PHOTOVOLTAIC SYSTEM

SUNGROW POWER SUPPLY CO.,...

1. A photovoltaic rapid shutdown device, applied to a photovoltaic system, wherein the photovoltaic system comprises a plurality of photovoltaic modules connected in series with each other, and the photovoltaic rapid shutdown device comprises:a first switch,
a second switch,
a bypass diode,
an auxiliary power supply,
a control circuit, and
a communication circuit, wherein
one of the plurality of photovoltaic modules serves as a power supplying photovoltaic module, and an output terminal of the power supplying photovoltaic module is connected to an input terminal of the auxiliary power supply;
the first switch is connected in series between the power supplying photovoltaic module and an adjacent photovoltaic module of the power supplying photovoltaic module;
two terminals of the second switch are connected to a positive output terminal and a negative output terminal of a branch formed by the plurality of photovoltaic modules connected in series with each other, respectively;
a cathode of the bypass diode is connected to a low voltage terminal of the adjacent photovoltaic module of the power supplying photovoltaic module, and an anode of the bypass diode is connected to a low voltage terminal of the power supplying photovoltaic module;
the communication circuit is configured to receive a shutdown instruction transmitted from outside and transmit the shutdown instruction to the control circuit; and
the control circuit is configured to control the first switch to be turned off and the second switch to be turned on when receiving the shutdown instruction.

US Pat. No. 10,038,391

CENTRAL-STRING INVERTER DEVICE

SUNGROW POWER SUPPLY CO.,...

1. A central-string inverter device, comprisinga container, and
a plurality of string inverters installed in the container, wherein
the plurality of string inverters are arranged in two rows located respectively on two opposite sides of the container;
an intermediate duct is formed between the two rows of string inverters;
an air outlet is arranged on each of side walls of the two opposite sides of the container,
an air inlet is arranged on each of side walls of the other two opposite sides of the container or on a bottom wall of the container;
pulling structures corresponding to the plurality of string inverters are arranged on a string inverter bracket which is installed on a bottom wall of the container, each of the string inverters is installed or removed through the corresponding pulling structure.

US Pat. No. 10,027,125

CONTROL METHOD AND SYSTEM FOR PHOTOVOLTAIC INVERTERS WHOSE AC SIDES ARE CONNECTED IN PARALLEL

SUNGROW POWER SUPPLY CO.,...

1. A control method for photovoltaic inverters whose AC sides are connected in parallel, applied to a system in which AC sides of inverters are connected in parallel and DC sides of the inverters are independent from each other, wherein the system comprises at least two inverters which are a first inverter and a second inverter, wherein an input terminal of the first inverter is connected with a first PV array, an input terminal of the second inverter is connected with a second PV array, the first PV array and the second PV array each have a parasitic capacitance to ground, and the first inverter is coupled with the second PV array through the parasitic capacitances to form a common-mode loop; wherein the method comprises:detecting a first direct voltage of the first inverter and a second direct voltage of the second inverter;
obtaining a difference between the first direct voltage and the second direct voltage; and
adjusting the direct voltages of the inverters to control the difference to be within a predetermined range and to control a common-mode voltage in the common-mode loop to be within a predetermined common-mode voltage range.

US Pat. No. 9,843,274

THREE-LEVEL PHOTOVOLTAIC INVERTER PULSE WIDTH MODULATION METHOD AND MODULATOR

SUNGROW POWER SUPPLY CO.,...

1. A pulse width modulation method for a three-level photovoltaic inverter, comprising:
switching a pulse width modulation mode of the three-level photovoltaic inverter to a 13-vector space vector pulse width modulation
SVPWM mode in a case of detecting that potential safety hazards exist in the three-level photovoltaic inverter,

wherein the 13-vector SVPWM mode is a SVPWM mode in which 12 short ones of 27 on-off state vectors of the three-level photovoltaic
inverter are discarded and only 6 long vectors, 6 middle vectors and 3 zero vectors are reserved.

US Pat. No. 9,553,503

METHOD FOR STARTUP CONTROL OF PHOTOVOLTAIC INVERTER, SYSTEM THEREOF, AND PHOTOVOLTAIC POWER GENERATION SYSTEM

SUNGROW POWER SUPPLY CO.,...

10. A photovoltaic power generation system, comprising a photovoltaic panel, a controller, a speed regulation device connected
to both the photovoltaic panel and the controller, a photovoltaic inverter connected to the speed regulation device, and a
load connected to the photovoltaic inverter, wherein
the photovoltaic panel is configured to absorb solar energy, convert the solar energy into direct current, and send the direct
current to the photovoltaic inverter;

the controller is configured to control startup and shutdown of the photovoltaic inverter;
the speed regulation device is configured to regulate the rotation speed of a fan of the photovoltaic inverter;
the photovoltaic inverter is configured to convert the direct current from the photovoltaic panel into alternating current
for the use of the load through maximum power tracking; and

the controller comprises a first obtaining unit, a control unit connected to the first obtaining unit, a second obtaining
unit connected to the control unit, and a determining unit connected to the second obtaining unit,

the first obtaining unit is configured to obtain a value of an input voltage of the photovoltaic inverter;
the control unit is configured to start a fan of the photovoltaic inverter in a case that the value of the input voltage of
the photovoltaic inverter is greater than a startup threshold, and the fan is powered by an input side of the photovoltaic
inverter;

the second obtaining unit is configured to obtain a further value of the input voltage of the photovoltaic inverter after
the startup of the fan, and obtain a voltage drop of the input voltage based on the value of the input voltage of the photovoltaic
inverter and the further value of the input voltage of the photovoltaic inverter after the startup of the fan; and

the determining unit is configured to initiate grid-connected operation of the photovoltaic inverter in a case that the voltage
drop of the input voltage is less than or equal to a voltage determination threshold, and the determining unit changes the
voltage determination threshold based on a power determination threshold of the photovoltaic inverter.

US Pat. No. 10,103,544

MEDIUM AND HIGH VOLTAGE GRID-CONNECTED POWER GENERATION SYSTEM, MEDIUM AND HIGH VOLTAGE GRID-CONNECTED SYSTEM AND CONTROL UNIT THEREOF

SUNGROW POWER SUPPLY CO.,...

1. A control circuitry of a medium and high voltage grid-connected system, which is applied to the medium and high voltage grid-connected system, wherein the medium and high voltage grid-connected system comprises at least one inverter unit and the control circuitry of the medium and high voltage grid-connected system, wherein,the control circuitry of the medium and high voltage grid-connected system has a first terminal connected with the at least one inverter unit through a communication line, a second terminal connected with a controlling terminal of a switch, a third terminal connected with a connection point of a transformer and the switch, and a fourth terminal connected with a connection point of the switch and a medium and high voltage power grid; and
the control circuitry of the medium and high voltage grid-connected system is configured to:
collect a voltage of the medium and high voltage power grid, obtain a power grid amplitude and a power grid phase synchronization signal based on the voltage of the medium and high voltage power grid, send the power grid amplitude and the power grid phase synchronization signal to the at least one inverter unit through the communication line, whereby the at least one inverter unit performs an excitation on the transformer based on the power grid amplitude and the power grid phase synchronization signal and sends a switch closing command to the control circuitry of the medium and high voltage grid-connected system after the excitation is successful, close the switch in response to the switch closing command, and send a status signal of the switch to the at least one inverter unit in a real-time manner, when the switch is open; and
open the switch in response to a switch opening command from the at least one inverter unit, when the switch is closed and a system standby condition is satisfied.

US Pat. No. 9,912,252

PRE-CHARGE CIRCUIT AND PHOTOVOLTAIC INVERTER

SUNGROW POWER SUPPLY CO.,...

1. A pre-charge circuit, comprising an alternating current power source, a half-bridge rectifier, an auxiliary charging capacitor,
a current limiting device and a controllable switch, and the pre-charge circuit being connected to a target charging capacitor
to form a voltage doubling rectifier circuit; wherein
a direct current side of the half-bridge rectifier is connected in parallel to the target charging capacitor, and an alternating
current side of the half-bridge rectifier is connected to one end of the alternating current power source;

one end of the auxiliary charging capacitor is connected to any one end of the target charging capacitor, and the other end
of the auxiliary charging capacitor is connected to the other end of the alternating current power source; and

the current limiting device and the controllable switch are connected in series in each charging path of the pre-charge circuit.

US Pat. No. 9,712,083

METHOD AND DEVICE FOR SWITCHING OPERATION MODE OF A FIVE-LEVEL INVERTER

SUNGROW POWER SUPPLY CO.,...

7. A device for switching an operation mode of a five-level inverter, comprising:
a first processing unit configured to determine a first three-level operation mode as a three-level operation mode of the
five-level inverter to be switched to from a five-level operation mode in a case that a PV input voltage is higher than a
bridge line-line voltage command value of the five-level inverter required when the five-level inverter is connected to a
power grid, wherein the five-level inverter has two three-level operation modes;

a second processing unit configured to switch, after the operation mode of the five-level inverter is switched to the first
three-level operation mode, the operation mode of the five-level inverter from the first three-level operation mode to a second
three-level operation mode in a case that a junction temperature of a switching device operating in the first three-level
operation mode exceeds a first preset value; and

a third processing unit configured to switch the operation mode of the five-level inverter from the second three-level operation
mode to the first three-level operation mode in a case that the junction temperature of a switching device operating in the
second three-level operation mode exceeds a second preset value.

US Pat. No. 9,692,321

FIVE LEVEL INVERTER

SUNGROW POWER SUPPLY CO.,...

1. A five-level inverter, comprising: a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a
sixth switch, a first capacitor unit, a second capacitor unit, a third capacitor unit, a fourth capacitor unit, a first inductor,
a second inductor, a first reverse flow preventive element and a second reverse flow preventive element; wherein
a positive pole of a direct-current power supply is connected to a first terminal of the first switch and a first terminal
of the first capacitor unit; a negative pole of the direct-current power supply is connected to a first terminal of the second
switch and a second terminal of the second capacitor unit;

a second terminal of the first switch is connected to a first terminal of the first reverse flow preventive element, a first
terminal of the third switch and a first terminal of the fifth switch;

a second terminal of the first reverse flow preventive element is connected to a second terminal of the first capacitor unit,
a first terminal of the second capacitor unit and a first terminal of the second reverse flow preventive element;

a second terminal of the second reverse flow preventive element is connected to a second terminal of the second switch, a
first terminal of the fourth switch and a first terminal of the sixth switch;

a second terminal of the third switch is connected to a first terminal of the first inductor and a second terminal of the
fourth switch; a second terminal of the fifth switch is connected to a first terminal of the second inductor and a second
terminal of the sixth switch;

a second terminal of the first inductor is connected to a first terminal of the third capacitor unit; a second terminal of
the second inductor is connected to a second terminal of the fourth capacitor unit;

a second terminal of the third capacitor unit and a first terminal of the fourth capacitor unit are connected to the second
terminal of the first capacitor unit;

the first reverse flow preventive element is configured to prevent a current from flowing from the first terminal of the first
reverse flow preventive element to the second terminal of the first reverse flow preventive element in a case that the first
switch is turned on;

the second reverse flow preventive element is configured to prevent a current from flowing from the first terminal of the
second reverse flow preventive element to the second terminal of the second reverse flow preventive element in a case that
the second switch is turned on; and

the second terminal of the first inductor and the second terminal of the second inductor are alternate-current output terminals
of the inverter,

wherein the inverter is configured to operate in six active operation modes which comprises a first operation mode, a second
operation mode, a third operation mode, a fourth operation mode, a fifth operation mode and a sixth operation mode, wherein:

the first switch, the second switch, the third switch and the sixth switch are turned on, and the fourth switch and the fifth
switch are turned off, in a case that the inverter is in the first operation mode;

the inverter is configured to operate in a first operation sub-mode or a second operation sub-mode in a case that the inverter
is in the second operation mode; the first switch, the third switch and the sixth switch are turned on, the second switch,
the fourth switch and the fifth switch are turned off, the second terminal of the first capacitor unit is in a charging state,
in a case that the inverter is in the first operation sub-mode; and the second switch, the third switch and the sixth switch
are turned on, the first switch, the fourth switch and the fifth switch are turned off, and the second terminal of the first
capacitor unit is in a discharging state, in a case that the inverter is in the second operation sub-mode;

the third switch and the sixth switch are turned on, and the first switch, the second switch, the fourth switch and the fifth
switch are turned off, in a case that the inverter is in the third operation mode;

the first switch, the second switch, the fourth switch and the fifth switch are turned on, and the third switch and the sixth
switch are turned off, in a case that the inverter is in the fourth operation mode;

the inverter is configured to operate in a third operation sub-mode or a fourth operation sub-mode in a case that the inverter
is in the fifth operation mode; the first switch, the fourth switch and the fifth switch are turned on, the second switch,
the third switch and the sixth switch are turned off, and the second terminal of the first capacitor unit is in the charging
state, in a case that the inverter is in the third operation sub-mode; and the second switch, the fourth switch and the fifth
switch are turned on, the first switch, the third switch and the sixth switch are turned off, and the second terminal of the
first capacitor unit is in the discharging state, in a case that the inverter is in the fourth operation sub-mode; and

the fourth switch and the fifth switch are turned on, and the first switch, the second switch, the third switch and the sixth
switch are turned off, in a case that the inverter is in the sixth operation mode.

US Pat. No. 10,044,288

COMBINED INVERTER

SUNGROW POWER SUPPLY CO.,...

1. A combined inverter, comprising: at least two separate box bodies connected detachably, whereinall components of the combined inverter are placed into the box bodies separately,
at least one electrical connection terminal is arranged outside each of the box bodies, and the electrical connection terminal of one of the box bodies is capable of being connected to the electrical connection terminal of another of the box bodies; and
a connector, wherein the box bodies are connected detachably via the connector;
wherein a plurality of fixing holes are arranged onto a back surface of the connector facing toward a wall surface or a supporter, to fix the connector onto the wall surface or the supporter.

US Pat. No. 10,044,291

METHOD AND DEVICE FOR MODULATING A FIVE-LEVEL INVERTER, AND PHOTOVOLTAIC SYSTEM

SUNGROW POWER SUPPLY CO.,...

1. A method for modulating a five-level inverter, comprising:acquiring a voltage command value Vcmd of a phase bridge of the five-level inverter;
controlling a first switching device and a fourth switching device to be switched on alternately in a case that Vcmd?V1Pos+Vthrs1;
controlling the first switching device and a third switching device to be switched on alternately in a case that V1Pos?Vthrs2?Vcmd controlling the fourth switching device and the third switching device to be switched on alternately in a case that 0?Vcmd controlling the third switching device and a fifth switching device to be switched on alternately in a case that ?V1Neg+Vthrs3?Vcmd<0;
controlling the third switching device and a second switching device to be switched on alternately in a case that ?V1Neg?Vthrs4?Vcmd controlling the fifth switching device and the second switching device to be switched on alternately in a case that Vcmd wherein Vthrs1 represents a voltage value greater than or equal to Dthrs*(V2Pos?V1Pos), Vthrs2 represents a voltage value greater than or equal to Dthrs*V1Pos, Vthrs3 represents a voltage value greater than or equal to Dthrs*V1Neg, and Vthrs4 represents a voltage value greater than or equal to Dthrs*(V2Neg?V1Neg); and Dthrs indicates a duty ratio corresponding to a sum of narrow pulse time and dead-band time of the five-level inverter; and
the five-level inverter alternately outputs five voltage levels +1, ?1, +2, ?2 and 0 in different combinations of switching states of the switching devices, V1Pos represents magnitude of a voltage outputted by the five-level inverter when the five-level inverter outputs the level +1, V1Neg represents magnitude of a voltage outputted by the five-level inverter when the five-level inverter outputs the level ?1, V2Pos represents magnitude of a voltage outputted by the five-level inverter when the five-level inverter outputs the level +2, and V2Neg represents magnitude of a voltage outputted by the five-level inverter when the five-level inverter outputs the level ?2; the level +1 is outputted when the fourth switching device is switched on; the level ?1 is outputted when the fifth switching device is switched on; the level +2 is outputted when the first switching device is switched on; the level ?2 is outputted when the second switching device is switched on; and the level 0 is outputted when the third switching device is switched on.

US Pat. No. 10,045,097

METHOD FOR UPLOADING DATA OF CELL PANEL MONITORING SYSTEM AND CELL PANEL MONITORING SYSTEM

SUNGROW POWER SUPPLY CO.,...

6. A data uploading system comprising a plurality of cell panel monitoring systems and a server, wherein each cell panel of a photovoltaic system is provided with one of the cell panel monitoring systems, and wherein each cell panel monitoring system comprises:a plurality of voltage collection circuits,
a controller, and
a transmission circuit;
wherein each string of photovoltaic cells of each of the cell panels is connected in parallel with one of the plurality of voltage collection circuits, and each of the plurality of voltage collection circuits is configured to collect parameter information of the corresponding string of photovoltaic cells and stores the parameter information into the controller;
wherein the transmission circuit is configured to transmit the collected corresponding parameter information to a busbar in a form of a pulse carrier signal;
wherein the server is configured to obtain parameter information of the cell panels through demodulation of the pulse carrier signal, data uploaded in a preset time difference ?T is determined by the server as valid data, and remaining data is discarded;
wherein the server is connected in series in the busbar; and
wherein real-time performance of the data improves as a value of the preset time difference ?T decreases.

US Pat. No. 9,906,166

METHOD AND DEVICE FOR CONTROLLING OPERATION OF INVERTER

SUNGROW POWER SUPPLY CO.,...

1. A method for controlling an operation of an inverter, comprising:
determining whether a direct current side voltage of the inverter is greater than an operation voltage setting threshold;
and

in a case that the direct current side voltage of the inverter is not greater than the operation voltage setting threshold,
controlling the inverter to operate according to a five level control strategy; and

in a case that the direct current side voltage of the inverter is greater than the operation voltage setting threshold:
adjusting the direct current side voltage by using a maximum power tracking algorithm;
adjusting linearly a floating capacitor voltage of the inverter based on the adjusted direct current side voltage;
determining whether the adjusted floating capacitor voltage is in a preset range, wherein the preset range ranges from a quarter
of the operation voltage setting threshold minus a preset threshold to a quarter of the operation voltage setting threshold
plus the preset threshold; and

controlling the inverter to operate according to a five level control strategy in a case that the adjusted floating capacitor
voltage is in the preset range; and

controlling the inverter to operate according to a seven level control strategy in a case that the adjusted floating capacitor
voltage is not in the preset range.

US Pat. No. 9,673,731

PARALLEL INVERTER SYSTEM, AND SHUTDOWN CONTROL METHOD AND SHUTDOWN CONTROL DEVICE FOR PARALLEL INVERTER SYSTEM

SUNGROW POWER SUPPLY CO.,...

1. A shutdown control method for a parallel inverter system, wherein the parallel inverter system comprises at least two inverter
apparatuses, alternating-current terminals of each of the at least two inverter apparatuses are connected to alternating-current
switches and then the at least two inverter apparatuses are connected in parallel, parallel connection points are connected
to an alternating-current load or an alternating-current power grid; and the shutdown control method comprises:
obtaining a shutdown instruction;
determining a level of the shutdown instruction based on the shutdown instruction;
controlling an inverter apparatus to be shut down of the at least two inverter apparatuses and the alternating-current switches
connected to the inverter apparatus to be shut down according to the level of the shutdown instruction,

wherein the controlling the inverter apparatus to be shut down and the alternating-current switches connected to the inverter
apparatus to be shut down according to the level of the shutdown instruction comprises:

locking out instantly a driving signal for power switch devices of the inverter apparatus to be shut down in a case that the
level of the shutdown instruction is determined to be an emergency level; and

transmitting a switch-off signal to the alternating-current switches connected to the inverter apparatus to be shut down to
lock out the driving signal for the power switch devices of the inverter apparatus to be shut down, in a case that the level
of the shutdown instruction is determined to be a normal level.

US Pat. No. 9,997,941

CHARGING AND DISCHARGING SYSTEM AND METHOD, AND PHOTOVOLTAIC POWER GENERATION SYSTEM

SUNGROW POWER SUPPLY CO.,...

11. A charging and discharging method applied to a charging and discharging system comprising: a unidirectional converter, a unidirectional switch, an energy storage device and a controller, whereinan input terminal of the unidirectional converter is connected to an output terminal of a photovoltaic device of a photovoltaic power generation system to which the charging and discharging system is applied, and an output terminal of the unidirectional converter is connected to an input terminal of the energy storage device;
the unidirectional switch is connected between an output terminal of the energy storage device and an input terminal of a bidirectional inverter of the photovoltaic power generation system to which the charging and discharging system is applied; and
the controller is connected to the unidirectional converter, the unidirectional switch, the energy storage device and the bidirectional inverter;
and the method comprising:
in a case that output power of the photovoltaic device is greater than preset maximum output power of the bidirectional inverter, the controller controls the unidirectional converter to charge the energy storage device with first charging power, wherein the first charging power is a difference between the output power of the photovoltaic device and the preset maximum output power of the bidirectional inverter; wherein the controller controls unidirectional converter to charge the energy storage device with first charging power, comprises:
comparing a voltage of the input terminal of the unidirectional converter with the open-circuit voltage of the energy storage device; and
in a case that the voltage of the input terminal of the unidirectional converter is higher than the open-circuit voltage of the energy storage device, controlling the unidirectional converter to reduce the voltage of the input terminal of the unidirectional converter to be equal to the open-circuit voltage of the energy storage device, and in a case that the voltage of the input terminal of the unidirectional converter is equal to the open-circuit voltage of the energy storage device, controlling the unidirectional converter to charge the energy storage device with the first charging power; or
in a case that the voltage of the input terminal of the unidirectional converter is lower than the open-circuit voltage of the energy storage device, controlling the unidirectional converter to raise the voltage of the input terminal of the unidirectional converter to be equal to the open-circuit voltage of the energy storage device, and in a case that the voltage of the input terminal of the unidirectional converter is equal to the open-circuit voltage of the energy storage device, controlling the unidirectional converter to charge the energy storage device with the first charging power; or
in a case that the voltage of the input terminal of the unidirectional converter is equal to the open-circuit voltage of the energy storage device, controlling the unidirectional converter to charge the energy storage device with the first charging power; or
in a case that output power of the photovoltaic device is less than preset minimum output power of the bidirectional inverter, the controller sends a voltage-reducing-signal to the bidirectional inverter, and in a case that a voltage of the input terminal of the bidirectional inverter is detected to be lower than or equal to an open-circuit voltage of the energy storage device, the controller controls the unidirectional switch to close, wherein the voltage-reducing-signal is used to instruct the bidirectional inverter to reduce the voltage of the input terminal of the bidirectional inverter to be lower than or equal to the open-circuit voltage of the energy storage device.

US Pat. No. 9,906,022

CASCADED MULTILEVEL CONVERTER SELF-TEST SYSTEM AND SELF-TEST METHOD FOR THE SAME

SUNGROW POWER SUPPLY CO.,...

1. A cascaded multilevel converter self-test system comprising a cascaded multilevel converter and a self-test device, wherein
the cascaded multilevel converter comprises at least two converting circuits which are cascaded, and the self-test device
comprises at least one current detecting circuit, a voltage acquiring module and a calculating module, and wherein:
the at least two converting circuits each have a first output terminal and a second output terminal and are electrically connected
in sequence with the first output terminal and the second output terminal, and each of the at least two converting circuits
is provided with and electrically connected to an external direct current source in a one-to-one manner, the direct current
source is configured to supply a direct current to the converting circuit corresponding to the direct current source;

a first terminal of the at least one current detecting circuit is electrically connected to the first output terminal of the
first one of the at least two converting circuits and/or the second output terminal of the last one of the at least two converting
circuits, a second terminal of the at least one current detecting circuit is grounded; the at least one current detecting
circuit is configured to detect a first detected current in a case that the cascaded multilevel converter is in a first conducting
state and a second detected current in a case that the cascaded multilevel converter is in a second conducting state;

the voltage acquiring module is configured to acquire first bus voltages of the at least two converting circuits in a case
that the cascaded multilevel converter is in the first conducting state and second bus voltages of the at least two converting
circuits in a case that the cascaded multilevel converter is in the second conducting state; and

the calculating module is configured to calculate an insulation resistance value of the cascaded multilevel converter based
on the first detected current, the second detected current, the first bus voltages of the at least two converting circuits
and the second bus voltages of the at least two converting circuits.

US Pat. No. 10,084,392

FIVE-LEVEL INVERTER AND APPLICATION CIRCUIT OF THE SAME

SUNGROW POWER SUPPLY CO.,...

1. A five-level inverter, connected between a positive terminal and a negative terminal of a direct-current power supply, and connected in parallel to a branch in which a first capacitor is connected in series to a second capacitor, wherein the five-level inverter comprises:a first switch branch comprising a first unidirectional element and a first switch transistor, wherein a common terminal of the first unidirectional element and the first switch transistor is connected to a first terminal of the first capacitor;
a second switch branch comprising a second unidirectional element and a second switch transistor, wherein a common terminal of the second unidirectional element and the second switch transistor is connected to a first terminal of the first switch branch;
a third switch branch comprising a third unidirectional element and a third switch transistor, wherein a first terminal of the third switch branch is connected to a first terminal of the second switch branch, a second terminal of the first capacitor and a first terminal of the second capacitor;
a fourth switch branch comprising a fourth unidirectional element and a fourth switch transistor, wherein a first terminal of the fourth switch branch is connected to the first terminal of the third switch branch;
a fifth switch branch comprising a fifth unidirectional element and a fifth switch transistor, wherein a first terminal of the fifth switch branch is connected to the first terminal of the fourth switch branch;
a sixth switch branch comprising a sixth unidirectional element and a sixth switch transistor, wherein a first terminal of the sixth switch branch is connected to a common terminal of the fifth unidirectional element and the fifth switch transistor, a common terminal of the sixth unidirectional element and the sixth switch transistor is connected to a second terminal of the second capacitor;
a seventh switch transistor;
an eighth switch transistor; and
a clamping capacitor,
wherein a first terminal of the clamping capacitor is connected to a second terminal of the first switch branch, a second terminal of the second switch branch, a second terminal of the third switch branch and a first terminal of the seventh switch transistor;
wherein a second terminal of the clamping capacitor is connected to a second terminal of the fourth switch branch, a second terminal of the fifth switch branch, a second terminal of the sixth switch branch and a second terminal of the eighth switch transistor;
wherein a first terminal of the eighth switch transistor is connected to a second terminal of the seventh switch transistor at a connection point connected to an output terminal of the five-level inverter; and
wherein each of the seventh switch transistor and the eighth switch transistor is a switch transistor providing a bidirectional power path.

US Pat. No. 10,205,403

CASCADED H-BRIDGE INVERTER AND METHOD FOR HANDLING FAULT THEREOF

SUNGROW POWER SUPPLY CO.,...

1. A method for handling a fault of a cascaded H-bridge inverter, comprising:in the cascaded H-bridge inverter connected to N solar panels and comprising N capacitors, N H-bridge modules, N switching devices and a controller, with N being a positive integer,
detecting, by the controller, an output voltage or an output power of each of the N solar panels;
determining, by the controller, whether the output voltage of at least one of the N solar panels is lower than a preset voltage, or whether the output power of at least one of the N solar panels is lower than a preset power;
controlling a corresponding one of the N switching devices to be switched off and changing a set value of a voltage across a corresponding one of the N capacitors in a direct current side by the controller, in a case that the output voltage of at least one of the N solar panels is lower than the preset voltage, or that the output power of at least one of the N solar panels is lower than the preset power; and
controlling, by the controller, a corresponding one of the N H-bridge modules to perform inverting by taking the set value of the voltage across the capacitor in the direct current side as an input value, so that a total output modulation voltage of the cascaded H-bridge inverter meets a preset condition;
wherein a process of the controlling the corresponding switching device to be switched off and changing the set value of the voltage across the corresponding capacitor in the direct current side by the controller comprises:
controlling, by the controller, the corresponding switching device to be switched off;
calculating the set value of the voltage across the corresponding capacitor in the direct current side, based on the total output modulation voltage needed by the cascaded H-bridge inverter meeting the preset condition; and
controlling, by the controller, the set value of the voltage across the corresponding capacitor in the direct current side to be raised.

US Pat. No. 10,205,444

PWM CONTROL METHOD FOR FIVE-LEVEL INVERTING CIRCUIT, CONTROL CIRCUIT AND INVERTER

SUNGROW POWER SUPPLY CO.,...

1. A pulse width modulation (PWM) control method for a five-level inverting circuit, applied to a five-level inverting circuit comprising a first capacitor, a second capacitor, a third capacitor, a first switch branch, a second switch branch, a third switch branch, a fourth switch branch, a fifth switch branch, a sixth switch branch, a seventh switch branch and an eighth switch branch,a branch forming by connecting the first capacitor and the second capacitor in series being connected between a positive output terminal and a negative output terminal of a direct current (DC) power supply,
the first switch branch being connected between a first terminal of the third capacitor and the positive output terminal of the DC power supply,
the second switch branch and the third switch branch being connected between a second terminal of the first capacitor and the first terminal of the third capacitor,
the fourth switch branch and the fifth switch branch being connected between a first terminal of the second capacitor and a second terminal of the third capacitor,
the sixth switch branch being connected between the second terminal of the third capacitor and the negative output terminal of the DC power supply,
the seventh switch branch being connected between the first terminal of the third capacitor and an output terminal of the five-level inverting circuit, and
the eighth switch branch being connected between the second terminal of the third capacitor and the output terminal of the five-level inverting circuit; and
the PWM control method comprising:
performing a complementary processing to enable a first control signal and a fourth control signal to be complementary to each other, the first control signal controlling to turn on or turn off the first switch branch, and the fourth control signal controlling to turn on or turn off the fourth switch branch;
performing a complementary processing to enable a fifth control signal and a second control signal to be complementary to each other, the fifth control signal controlling to turn on or turn off the fifth switch branch, and the second control signal controlling to turn on or turn off the second switch branch;
performing a complementary processing to enable a third control signal and a sixth control signal to be complementary to each other, the third control signal controlling to turn on or turn off the third switch branch, and the sixth control signal controlling to turn on or turn off the sixth switch branch;
performing a complementary processing to enable a seventh control signal and an eighth control signal to be complementary to each other, the seventh control signal controlling to turn on or turn off the seventh switch branch, and the eighth control signal controlling to turn on or turn off the eighth switch branch; and
performing an interlocking processing to enable the first control signal and the second control signal to be interlocked with each other, and performing an interlocking processing to enable the sixth control signal and the fifth control signal to be interlocked with each other.

US Pat. No. 10,128,756

DC-DC CONVERTER WITH HIGH TRANSFORMER RATIO

SUNGROW POWER SUPPLY CO.,...

1. A direct current to direct current converter with high transformer ratio, comprising two direct current to direct current converter bodies,wherein inputs of the two direct current to direct current converter bodies are connected in parallel and outputs of the two direct current to direct current converter bodies are connected in series, and the inputs of the two direct current to direct current converter bodies are connected to a positive electrode and a negative electrode of a direct current source respectively;
wherein each of the two direct current to direct current converter bodies is a boost-buck direct current to direct current converter;
wherein one of the boost-buck direct current to direct current converters comprises a first inductor, a first power switch and a first series branch, the first inductor and the first power switch are connected in series to a direct-current source, the first series branch is connected in parallel to the first power switch, and the first series branch comprises a second power switch, a first capacitor and a second capacitor which are connected in series; and
the other one of the boost-buck direct current to direct current converters comprises a second inductor, a third power switch and a second series branch, the second inductor and the third power switch are connected in series to the direct-current source, the second series branch is connected in parallel to the third power switch, and the second series branch comprises a fourth power switch, the second capacitor and a third capacitor which are connected in series.

US Pat. No. 10,298,019

COMMUNICATION HOST AND PHOTOVOLTAIC POWER GENERATION SYSTEM

SUNGROW POWER SUPPLY CO.,...

1. A communication host applied to a photovoltaic power generation system, wherein the photovoltaic power generation system comprises photovoltaic strings and optimizers, each of the photovoltaic strings comprises at least one photovoltaic module, each of the optimizers is connected in parallel with at least one of the photovoltaic strings, output terminals of a plurality of optimizers in the optimizers are connected in series to form an optimizer set, an output terminal of the optimizer set is connected to a direct current input terminal of a grid-connected inverter, and the communication host comprises:an acquiring module configured to acquire an operating state parameter of the photovoltaic power generation system, wherein the operating state parameter comprises at least one or more of the following parameters: an output voltage of the optimizer, an operating state of the optimizer, an input current of the grid-connected inverter and an input power of the grid-connected inverter;
a determining module configured to determine, based on the operating state parameter, whether the optimizer meets a first preset triggering condition; and
a control module configured to perform at least one of the following operations:
transmitting, in a case where the optimizer meets the first preset triggering condition, a first triggering instruction for decreasing a direct current bus voltage, to instruct the photovoltaic power generation system to decrease, in response to the first triggering instruction, the direct current bus voltage of the grid-connected inverter in the photovoltaic power generation system, and
transmitting, in a case where the optimizer meets the first preset triggering condition, a second triggering instruction for adjusting an output voltage limiting value of the optimizer, to instruct the photovoltaic power generation system to increase, in response to the second triggering instruction, an output voltage limiting value of at least one of the optimizers meeting the first preset triggering condition.

US Pat. No. 10,462,938

INVERTER POWER CABINET

SUNGROW POWER SUPPLY CO.,...

1. An inverter power cabinet, comprising a cabinet body and power devices arranged in the cabinet body, wherein the cabinet body has a low-protection grade installation cavity and a high-protection grade installation cavity, the high-protection grade installation cavity is an airtight cavity;the power devices comprise high protection grade power devices arranged in the low-protection grade installation cavity and low-protection grade power devices arranged in the high-protection grade installation cavity, wherein:
the low-protection grade installation cavity has an outer cold air inlet and an inner hot air outlet which are in communication with outside world, and a first fan is further provided in the low-protection grade installation cavity; and
the inverter power cabinet further comprises a heat exchanger configured to dissipate heat of the high-protection grade installation cavity; and
wherein at least one second fan is further arranged in the high-protection grade installation cavity; and
the cabinet body comprises a DC cabinet and an AC cabinet, wherein:
the DC cabinet has the low-protection grade installation cavity and a first high-protection grade installation cavity, and the low-protection grade installation cavity is hermetically separated from the first high-protection grade installation cavity;
the AC cabinet has a second high-protection grade installation cavity; and
the high-protection grade installation cavity comprises the first high-protection grade installation cavity and the second high-protection grade installation cavity.

US Pat. No. 10,348,217

DISTRIBUTED VOLTAGE SOURCE INVERTERS

Sungrow Power Supply Co.,...

1. A method to supply power to an alternating current (AC) power system, comprising:providing a plurality of full bridge inverter stages, each of said full bridge inverter stages having a primary node and a secondary node, each of said full bridge inverter stages having a positive and a negative node, each of said full bridge inverter stages having a voltage supporting device electrically connected in a parallel relationship between said positive node and said negative node and a direct current (DC) source connected between the positive node and negative node;
providing at least one stacked inverter phase, each of the at least one stacked inverter phase having a plurality of said full bridge inverter stages, each of said full bridge inverter stages in each of the at least one stacked inverter phase interconnected in a series relationship with said secondary node of one of said full bridge inverter stages connected to said primary node of another full bridge inverter stage, said series interconnection defining a first full bridge inverter stage and a last full bridge inverter stage, each of the at least one stacked inverter phase having an input node at said primary node of said first full bridge inverter stage and an output node at said secondary node of said last full bridge inverter stage;
providing a local controller coupled to each full bridge inverter stage providing the control signals to each full bridge inverter stage to output a sinusoidal voltage waveform, each local controller coupled to a communication transceiver;
providing one or more switches or relays connected in series between the primary and secondary conductor of each said stacked inverter phase and the power grid; and
providing a system controller communicating with each local controller communication transceiver, the system controller generating system control signals for configuration, synchronization, activation, deactivation and operating mode selection of said local controller, and said system controller providing on and off control signals to said switches or relays to prevent reverse power flow from the power grid across said full bridge inverter stages when the output voltage of said stacked inverter phase is or falls below the power grid voltage.

US Pat. No. 10,320,294

DISCHARGING METHOD OF BUS CAPACITOR, CONTROLLER, DC-DC CONVERTER AND INVERTER

SUNGROW POWER SUPPLY CO.,...

1. A discharging method of a bus capacitor, applied to a controller of a DC-DC converter, wherein the DC-DC converter comprises the bus capacitor, a switch and a reactor, and the discharging method of the bus capacitor comprises:detecting a voltage across the bus capacitor;
determining whether the voltage across the bus capacitor meets a preset condition, after the DC-DC converter is powered off; and
controlling, in a case that the voltage across the bus capacitor meets the preset condition, the switch to be turned on or turned off to cause the bus capacitor, the switch and the reactor to form a current loop for consuming residual power of the bus capacitor, until the voltage across the bus capacitor does not meet the preset condition;
wherein the DC-DC converter is a bi-directional DC-DC converter, the bus capacitor comprises a first bus capacitor and a second bus capacitor, the switch comprises a first switch and a second switch connected in series, and a third switch and a fourth switch connected in series, and two series connection points are respectively connected to two terminals of the reactor; and
wherein the controlling, in a case that the voltage across the bus capacitor meets the preset condition, the switch to be turned on or turned off to cause the bus capacitor, the switch and the reactor to form a current loop for consuming residual power of the bus capacitor, until the voltage across the bus capacitor does not meet the preset condition comprises:
controlling, in a case that a voltage across the first bus capacitor meets the preset condition, the fourth switch to be turned on, and controlling the first switch to be turned on in response to a first preset periodic pulse, until the voltage across the first bus capacitor does not meet the preset condition, wherein in each period of the first preset periodic pulse, a current in the reactor decays to zero in a turn-off time of the first switch; and
controlling, in a case that a voltage across the second bus capacitor meets the preset condition, the second switch to be turned on, and controlling the third switch to be turned on in response to the first preset periodic pulse, until the voltage across the second bus capacitor does not meet the preset condition, wherein in each period of the first preset periodic pulse, a current in the reactor decays to zero in a turn-off time of the third switch.

US Pat. No. 10,367,355

CASCADED MULTI-LEVEL INVERTER SYSTEM AND MODULATION METHOD THEREOF, AND CONTROLLER

SUNGROW POWER SUPPLY CO.,...

1. A modulation method for a cascaded multi-level inverter system, applied to a controller for the cascaded multi-level inverter system, the cascaded multi-level inverter system comprising a reactive compensation device and a plurality of inverter units, the reactive compensation device and the plurality of inverter units being connected with the controller, the reactive compensation device being connected with a power grid, the plurality of inverter units being connected with a plurality of DC sources respectively, the modulation method comprising:performing a maximum power point tracking control based on a voltage signal and a current signal of each of the plurality of DC sources and a voltage signal and a current signal of the power grid obtained by sampling, calculating a first modulation signal for suppressing power imbalance, and outputting the first modulation signal to each of the plurality of inverter units;
calculating a reactive compensation current component based on the voltage signal and the current signal of each of the plurality of DC sources and the voltage signal of the power grid obtained by sampling;
calculating a reactive current instruction value which is equal in size and opposite in direction to the reactive compensation current component based on the reactive compensation current component;
calculating an active current instruction value based on a DC-side voltage set value signal of the reactive compensation device, and a DC-side voltage signal of the reactive compensation device obtained by sampling; and
calculating, based on the reactive current instruction value, the active current instruction value, and a current signal of the reactive compensation device obtained by sampling, a second modulation signal for causing an output power factor of the cascaded multi-level inverter system to be 1, and outputting the second modulation signal to the reactive compensation device.

US Pat. No. 10,389,132

AC-DC PHOTOVOLTAIC DEVICE

SUNGROW POWER SUPPLY CO.,...

1. An alternating-current direct-current (AC-DC) photovoltaic device, comprising:a photovoltaic module,
a direct current side capacitor,
a direct current pulse width modulation (DC-PWM) power switching circuit, and
a controller, wherein
the direct current side capacitor is connected in parallel with an output terminal of the photovoltaic module;
an input terminal of the DC-PWM power switching circuit is connected with the output terminal of the photovoltaic module;
the DC-PWM power switching circuit comprises a controllable switch transistor;
the controller is configured to output a switch control signal to control a switching state of the controllable switch transistor in the DC-PWM power switching circuit, comprising: outputting a direct current modulation signal as the switch control signal to control the DC-PWM power switching circuit to output a direct current PWM wave and outputting an alternating current modulation signal as the switch control signal to control the DC-PWM power switching circuit to output an alternating current PWM wave.

US Pat. No. 10,505,370

SAFETY DETECTION DEVICE AND METHOD OF GRID-CONNECTED INVERTER

SUNGROW POWER SUPPLY CO.,...

1. A grid-connected inverter safety detection device applied in a photovoltaic inverter system, wherein the photovoltaic inverter system comprises a PV array, an inverter, a switch, a power grid, and resistors comprising a phase resistor and a N-wire resistor, wherein output terminals of the PV array are connected to input terminals of the inverter, an output terminal of the inverter are connected to a first terminal of the power grid via the switch, the switch is in an off state, a second terminal of the power grid functions as a point N which is connected to a negative output terminal of the PV array via the N-wire resistor, and the first terminal of the power grid are connected to the negative output terminal of the PV array via the phase resistor; andthe device comprises a voltage detection circuit, a filter circuit, a comparison circuit and a controller, wherein
the voltage detection circuit is configured to detect a voltage between the point N and the ground, or a voltage between the first terminal of the power grid and the ground;
the filter circuit is configured to filter out an alternating current component of the voltage detected by the voltage detection circuit and to retain a direct current component of the voltage;
the comparison circuit is configured to compare the direct current component of the voltage with a preset voltage value and transmit a comparison result to the controller; and
the controller is configured to determine, according to the comparison result, whether an alternating current side at the output terminals of the inverter has normal insulation.

US Pat. No. 10,574,059

CONTROL APPARATUS AND COMBINER BOX

SUNGROW POWER SUPPLY CO.,...

1. A control apparatus, applied to a photovoltaic power generation system, wherein the photovoltaic power generation system comprises an inverter and a plurality of combiner boxes, an input terminal of each of the combiner boxes is connected to at least one string comprising an optimizer, output terminals of the plurality of combiner boxes are connected in parallel and connected to a direct current side of the inverter, and the control apparatus comprises:a controller configured to transmit, in response to a received maintenance signal, a safe mode switching instruction to the optimizer connected to the combiner box, to control the optimizer to operate in a safe mode; or transmit, in response to a received restart signal, a safe mode exit instruction to the optimizer connected to the combiner box, to control the optimizer to operate in a maximum power point tracking (MPPT) mode; and
a parameter detection module configured to detect an input voltage, an output voltage and an output current of the combiner box, and output the detected input voltage, output voltage and output current to the controller, wherein in a case that the optimizer operates in the safe mode and the output current is smaller than a threshold, the controller outputs a switch-off signal for disconnecting the combiner box from the inverter, and wherein in a case that the optimizer operates in the MPPT mode and the input voltage is greater than the output voltage, the controller outputs a switch-on signal for connecting the combiner box with the inverter.

US Pat. No. 10,361,640

CASCADED PHOTOVOLTAIC GRID-CONNECTED INVERTER, CONTROL METHOD AND CONTROL DEVICE FOR THE SAME

SUNGROW POWER SUPPLY CO.,...

9. A control device for a cascaded photovoltaic grid-connected inverter, comprising:a first determining unit, configured to determine whether at least one of inverter units of the cascaded photovoltaic grid-connected inverter is over-modulated;
a calculating unit, configured to calculate a maximum reactive power and a minimum reactive power permitted to be injected to a power grid in a situation that a power factor of a system is not less than a minimum permitted value, in a case that the first determining unit determines that at least one of the inverter units of the cascaded photovoltaic grid-connected inverter is over-modulated;
a second determining unit, configured to simulate an operation state of the cascaded photovoltaic grid-connected inverter after the maximum reactive power is injected to the power grid and determine whether each of the inverter units in the operation state is in a modulating region;
a first processing unit, configured to inject a reactive power to the power grid in a case that the second determining unit determines that each of the inverter units is in the modulating region after the maximum reactive power is injected to the power grid, wherein a value of the reactive power is not less than the minimum reactive power and not greater than the maximum reactive power; and
a second processing unit, configured to control the cascaded photovoltaic grid-connected inverter to exit an operation mode of independently performing a maximum power point tracking control on each of photovoltaic panels, in a case that the second determining unit determines that not all the inverter units are in the modulating region after the maximum reactive power is injected to the power grid,
wherein the first determining unit is further configured to:
acquire a direct current side current maximum value and a grid side current effective value of the cascaded photovoltaic grid-connected inverter;
determine whether the grid side current effective value is less than M times of the direct current side current maximum value, wherein

 ? is a maximum permitted value of a modulation degree in a current modulation strategy; and
determine that at least one of the inverter units of the cascaded photovoltaic grid-connected inverter is over-modulated in a case that the grid side current effective value is less than M times of the direct current side current maximum value.

US Pat. No. 10,574,064

OFF-GRID ENERGY STORAGE SYSTEM AND CONTROL METHOD FOR OFF-GRID ENERGY STORAGE SYSTEM

SUNGROW POWER SUPPLY CO.,...

1. An off-grid energy storage system, comprising n energy storage inverters identified by P1, P2, . . . , Pn sequentially, wherein a direct current side of each of the energy storage inverters is connected to an independent storage battery, and alternate current sides of the energy storage inverters are connected in parallel, wherein the storage battery connected to the direct current side of Pj is identified by Bj, where j=2, 3, . . . , n, whereina control system for an output waveform of P1 has a voltage-current double loop control structure; and
a control system for an output waveform of pj has a current loop control structure, wherein a current loop given value of pj is equal to a value obtained by adding a current correction value of Pj to a current loop given value of P1, wherein the current correction value of Pj is an output quantity of an automatic control system for causing Bj to have the same operating parameter as B1.

US Pat. No. 10,503,126

ACCESS CONTROL METHOD FOR PARALLEL DIRECT CURRENT POWER SUPPLIES AND DEVICE THEREOF

SUNGROW POWER SUPPLY CO.,...

1. An access control method for parallel direct current power supplies, performed by an access control device for parallel direct current power supplies which is applied to a grid-connected inverter, wherein,a direct current side of the grid-connected inverter is connected with n direct current power supplies in parallel via 2n switches; and
the access control device for the parallel direct current power supplies comprises: a control unit and an insulation resistance detection circuit, and n is a positive integer greater than 1; wherein,
one ends of n of the 2n switches are connected with positive output terminals of the n direct current power supplies in a one-to-one correspondence, and the other ends are connected with a positive input terminal of the insulation resistance detection circuit and a positive input terminal of the grid-connected inverter;
one ends of the other n of the 2n switches are connected with negative output terminals of the n direct current power supplies in a one-to-one correspondence, and the other ends are connected with a negative input terminal of the insulation resistance detection circuit and a negative input terminal of the grid-connected inverter;
wherein the method comprises:
S101, detecting, by the insulation resistance detection circuit, values of single insulation resistances to ground of the n direct current power supplies;
S102, determining, by the control unit, whether values of the single insulation resistances to ground each are greater than a first threshold;
S103, controlling, by the control unit, each switch connected with a direct current power supply, a value of a single insulation resistance to ground of which is not greater than the first threshold, to be open, and controlling each switch connected with a direct current power supply, a value of a single insulation resistance to ground of which is greater than the first threshold, to be closed, in response to determining that the values of the single insulation resistances to ground are not all greater than the first threshold;
S104, detecting, by the insulation resistance detection circuit, a value of a total insulation resistance to ground of direct current power supplies currently in parallel, after step S103 is performed or in a case that in step S102 all the values of the single insulation resistances to ground is greater than the first threshold;
S105, determining, by the control unit, whether the value of the total insulation resistance to ground is greater than a second threshold different than the first threshold;
S106, controlling, by the control unit, a switch connected with a direct current power supply, a value of a single insulation resistance to ground of which is smallest of the direct current power supplies that are currently in parallel and have the values of the single insulation resistances to ground all greater than the first threshold, to be open, in response to determining that the value of the total insulation resistance to ground is not greater than the second threshold; and
repeatedly performing steps S104, S105 and S106 till the value of the total insulation resistance to ground of direct current power supplies currently in parallel is greater than the second threshold.

US Pat. No. 10,355,618

ACTIVE NEUTRAL POINT CLAMPED INVERTER, ZERO-CROSSING SWITCHING METHOD AND ZERO-CROSSING SWITCHING APPARATUS THEREOF

SUNGROW POWER SUPPLY CO.,...

1. A zero-crossing switching method of an active neutral point clamped inverter, comprising:acquiring an output voltage instruction of a bridge leg of the active neutral point clamped inverter;
determining whether zero-crossing switching occurs in the output voltage instruction; and
controlling switch states of all switches in the bridge leg to change according to a preset logic, in a case that the zero-crossing switching occurs in the output voltage instruction; wherein
the preset logic comprises switching among a sequence of switch state combinations, a first switch state combination of the sequence is defined as a switch state combination of all the switches in the bridge leg of the active neutral point clamped inverter before the zero-crossing switching occurs in the output voltage instruction of the bridge leg and a last switch state combination of the sequence is defined as a switch state combination of all the switches in the bridge leg after the zero-crossing switching occurs in the output voltage instruction of the bridge leg,
while transitioning from the first switch state combination to the last switch state combination, a second switch state combination to a penultimate switch state combination are all safe switch state combinations selected in advance, and in each of the safe switch state combinations, a maximum voltage borne by the switches in the bridge leg is clamped to a safe limit value, and
in a case that the active neutral point clamped inverter is a three-level inverter, the safe limit value is one-half of a direct-current bus voltage, and the safe switch state combinations comprise:
a switch state combination in which at least one clamping transistor in the bridge lea is switched on, and
a switch state combination in which only two inner transistors in the bridge lea are switched on.

US Pat. No. 10,554,164

MODULAR EXTRA LOW VOLTAGE ELECTRIC VEHICLE POWER SYSTEM

SUNGROW POWER SUPPLY CO.,...

1. An electric vehicle power system comprising:a plurality of electrically connected power modules connected to a system communication bus and configured to be activated to deliver electrical power to an electric motor, each power module comprising:
a rechargeable battery module electrically connected to a DC bus;
an inverter circuit electrically connected to the DC bus, wherein the inverter circuit is configured to convert a DC voltage of the DC bus into an AC power signal, and wherein the inverter circuit is configured to be connected to an electric motor;
at least one of:
a single-phase rectifier circuit electrically connected to the DC bus, the single-phase rectifier circuit configured to convert a single-phase AC power signal into the DC voltage of the DC bus; or
a multi-phase rectifier circuit electrically connected to the DC bus, the multi-phase rectifier circuit configured to convert a multi-phase AC power signal into the DC voltage of the DC bus; and
a local controller connected to the rechargeable battery module, the inverter circuit, and the at least one of the single-phase rectifier circuit or the multi-phase rectifier circuit, the local controller configured to generate one or more control signals and determine whether an output power of one of the plurality of electrically connected power modules exceeds a threshold power level;
wherein another power module of the plurality of electrically connected power modules is activated to deliver electrical power to the electric motor in response to determining that the output power of one of the plurality of electrically connected power modules exceeds the threshold power level; and
wherein the plurality of power modules are connected in parallel to at least one electric motor.

US Pat. No. 10,523,011

VOLTAGE COMPENSATION APPARATUS FOR PHOTOVOLTAIC SYSTEM AND PHOTOVOLTAIC SYSTEM

SUNGROW POWER SUPPLY CO.,...

1. A voltage compensation apparatus for a photovoltaic system, applied to the photovoltaic system, whereinthe photovoltaic system comprises: a photovoltaic array, a converter and a transformer;
an output terminal of the converter is connected with a primary side of the transformer, an input terminal of the converter is connected with the photovoltaic array;
the voltage compensation apparatus comprises at least one current direction limiting circuit;
the current direction limiting circuit is configured to conduct a current in one direction; and
the voltage compensation apparatus is connected between at least one phase of the output terminal of the converter and a ground,
wherein the voltage compensation apparatus further comprises a compensation power supply connected in series with the current direction limiting circuit,
the voltage compensation apparatus comprises one current direction limiting circuit and one compensation power supply connected in series, in a case that the photovoltaic system is a single-phase system;
at least one phase is connected with the voltage compensation apparatus in a case that the photovoltaic system is a three-phase system;
the voltage compensation apparatus comprises one current direction limiting circuit and one compensation power supply connected in series, in a case that one phase is connected with the voltage compensation apparatus;
the voltage compensation apparatus comprises two current direction limiting circuits and one compensation power supply shared by the two current direction limiting circuits or comprises two current direction limiting circuits and two corresponding compensation power supplies, in a case that two phases are connected with the voltage compensation apparatus; and
the voltage compensation apparatus comprises three current direction limiting circuits and one compensation power supply shared by the three current direction limiting circuits or comprises three current direction limiting circuits and three compensation power supplies, in a case that three phases are connected with the voltage compensation apparatus.

US Pat. No. 10,644,626

METHOD AND SYSTEM FOR ACQUIRING ROTOR POSITION OF ROTARY TRANSFORMER

SUNGROW POWER SUPPLY CO.,...

1. A system for acquiring a rotor position of a rotary transformer, comprising: a rotary transformer decoder, a low pass filter and a microprocessor, whereinthe microprocessor comprises a synchronous demodulation module and a calculation module,
the rotary transformer decoder is electrically connected to the rotary transformer through the low pass filter, and is configured to output an excitation signal to drive the rotary transformer and acquire first position information of the motor rotor, the first position information comprising at least a first rotor position and a first rotor speed,
the synchronous demodulation module is electrically connected to the rotary transformer decoder and the rotary transformer, and is configured to collect at least a rotary transformer cosine signal and a rotary transformer sinusoidal signal outputted from the rotary transformer and output a feedback signal, the feedback signal comprising at least a target rotary transformer sinusoidal signal and a target rotary transformer cosine signal,
the calculation module is connected to the synchronous demodulation module, and is configured to perform calculation to acquire second position information of the motor rotor based on the feedback signal and according to a preset algorithm, the second position information comprising at least a second rotor position and a second rotor speed.

US Pat. No. 10,637,253

COOPERATIVE CONTROL METHOD AND DEVICE FOR PHOTOVOLTAIC OPTIMIZER AND PHOTOVOLTAIC INVERTER

SUNGROW POWER SUPPLY CO.,...

1. A cooperative control method for a photovoltaic optimizer and a photovoltaic inverter, applicable to a grid-connected photovoltaic system comprising N photovoltaic components, N photovoltaic optimizers and one photovoltaic inverter, the N photovoltaic components being respectively connected to input sides of the N photovoltaic optimizers, and output sides of the N photovoltaic optimizers being connected to a DC side of the photovoltaic inverter, N being an integer greater than or equal to 1, the cooperative control method comprising:determining an operation parameter of the grid-connected photovoltaic system, the operation parameter reflecting an overall conversion efficiency of the grid-connected photovoltaic system;
judging whether the operation parameter is lower than a preset value; and
adjusting a voltage of the DC side of the photovoltaic inverter until the operation parameter is not lower than the preset value, in a case that the operation parameter is lower than the preset value,
wherein the operation parameter is a product of ?1 and ?2, ?1 is an average conversion efficiency of the N photovoltaic optimizers, and ?2 is a conversion efficiency of the photovoltaic inverter; and
wherein the determining the operation parameter of the grid-connected photovoltaic system comprises:
acquiring the voltage of the DC side of the photovoltaic inverter, a grid voltage, a grid current, and output voltages of the N photovoltaic components;
determining ?2 based on the voltage of the DC side of the photovoltaic inverter, the grid voltage and the grid current,
calculating an average duty cycle of the N photovoltaic optimizers based on the output voltages of the N photovoltaic components and the voltage of the DC side of the photovoltaic inverter according to an equation:
the average duty cycle=the voltage of the DC side of the photovoltaic inverter/(a sum of the output voltages of the N photovoltaic components/M),
wherein M is the number of strings formed by the N photovoltaic components;
determining ?1 based on the calculated average duty cycle; and
calculating the product of ?1 and ?2.

US Pat. No. 10,581,369

MOTOR CONTROLLER

SUNGROW POWER SUPPLY CO.,...

1. A motor controller, comprising: a main circuit, a rotational speed collector, a microprocessor, a monitoring chip, a first logic operation circuit, a second logic operation circuit, an overvoltage detection circuit and a driving circuit, whereinthe microprocessor is configured to output an initial pulse width modulation (PWM) signal and a first shutoff signal, and generate a rotational speed determination signal based on a motor rotational speed signal outputted by the rotational speed collector;
the first logic operation circuit is configured to generate a first control signal based on the initial PWM signal, the first shutoff signal and the rotational speed determination signal;
the monitoring chip is configured to monitor a working state of the microprocessor, and generate and output a second shutoff signal based on the working state or an output instruction of the microprocessor;
the second logic operation circuit is configured to generate a second control signal based on the second shutoff signal and a direct current (DC) bus overvoltage signal of the main circuit outputted by the overvoltage detection circuit; and
the driving circuit is configured to control the main circuit to work normally or enter one of a first safety state and a second safety state in response to the first control signal, and control the main circuit to stop receiving the first control signal and enter one of the first safety state and the second safety state in response to the second control signal.

US Pat. No. 10,643,923

CASE AND ELECTRONIC DEVICE HAVING THE SAME

SUNGROW POWER SUPPLY CO.,...

1. A case, comprising a fan arranged on a case wall of the case, an air inlet and an air outlet in communication with the air inlet arranged in the case wall of the case; wherein, the fan is arranged inside the case and is located between the air inlet and the air outlet; the fan is mounted in a bottom-to-top manner with an air inlet of the fan facing downwards and an air outlet of the fan facing upwards; the air inlet is located at a lower end of the case, the air outlet is located at an upper end of the case, and an air duct from bottom to top is formed by the air inlet, the fan and the air outlet; andwherein the fan is mounted inside the case via a mounting mechanism;
the mounting mechanism comprises one mounting plate, one guide slot, each of the fan is mounted on the mounting plate, and the mounting plate is inserted into the guide slot from one side of the guide slot or the mounting mechanism comprises two mounting plates and one guide slot, in a case that the number of the fan is plural, the plurality of fans are divided into two groups and the two groups of fans are respectively mounted on the two mounting plates, and the two mounting plates are inserted into the guide slot respectively from two opposite sides of the guide slot; and
the mounting mechanism further comprises a baffle, the baffle is mounted in the guide slot, and an end, inserted into the guide slot, of the mounting plate is provided with a clamp slot, and the clamp slot is engaged with a side of the baffle facing the corresponding clamp slot after the mounting plate is inserted into the guide slot.

US Pat. No. 10,637,252

ELECTRICAL ENERGY CONTROL METHOD AND APPARATUS FOR PHOTOVOLTAIC SYSTEM

SUNGROW POWER SUPPLY CO.,...

1. An electrical energy control method for a photovoltaic system, applied to an electrical energy control apparatus, wherein the electrical energy control apparatus has one end connected to a photovoltaic module and the other end arranged with a direct current capacitor, and the electrical energy control method for the photovoltaic system comprises:determining, by the electrical energy control apparatus, whether a preset electrical energy reverse flow condition is met;
controlling the photovoltaic module to stop outputting electrical energy, if the electrical energy control apparatus determines that the preset electrical energy reverse flow condition is met; and
controlling to transmit electrical energy on the direct current capacitor to the photovoltaic module, wherein the preset electrical energy reverse flow condition is one of the following conditions;
a voltage across the direct current capacitor is greater than a first threshold or less than a second threshold, the first threshold being greater than the second threshold; or
output power of the photovoltaic module is less than a third threshold or an output current of the photovoltaic module is less than a fourth threshold; or
an amplitude of an electrical parameter corresponding to a preset frequency is less than a threshold, or a ratio of an amplitude of an electrical parameter corresponding to the preset frequency to a sum of amplitudes of the electrical parameter corresponding to a preset frequency band is less than a threshold, wherein the preset frequency is a multiple of a power grid voltage frequency, a multiple of a characteristic frequency of an inverter, or a multiple of a resonant frequency of the photovoltaic system, and the electrical parameter is an input voltage of the direct current capacitor, an input current of the direct current capacitor, input power of the direct current capacitor, an output voltage of the photovoltaic module, an output current of the photovoltaic module, or output power of the photovoltaic module; or
a reverse electrical energy transmission control instruction is received.

US Pat. No. 10,581,239

DEVICE AND METHOD FOR PROTECTING DIRECT CURRENT SOURCE

SUNGROW POWER SUPPLY CO.,...

1. A device for protecting a direct current source, comprising a hiccup driver circuit and a switching device, whereinpower supply terminals of the hiccup driver circuit are connected with a positive output terminal and a negative output terminal of the direct current source respectively;
an input terminal of the hiccup driver circuit receives an enable signal;
the hiccup driver circuit is configured to store electric energy outputted from the direct current source, receive the enable signal, and generate a driving signal based on the enable signal and the electric energy stored internally;
a control terminal of the switching device is connected with an output terminal of the hiccup driver circuit;
a first terminal of the switching device is connected with the positive output terminal of the direct current source, with a connection point between the first terminal of the switching device and the positive output terminal of the direct current source being a positive output terminal of the device for protecting the direct current source;
a second terminal of the switching device is connected with the negative output terminal of the direct current source, with a connection point between the second terminal of the switching device and the negative output terminal of the direct current source being a negative output terminal of the device for protecting the direct current source; and
the switching device is configured to be periodically switched on according to the driving signal in a case that the enable signal is an OFF-ENABLE signal, and
wherein the hiccup driver circuit comprises a voltage limiting circuit and a driver circuit,
input terminals of the voltage limiting circuit are the power supply terminals of the hiccup driver circuit,
the voltage limiting circuit is configured to store the electric energy outputted from the direct current source and generate a supply voltage based on the electric energy stored internally,
a first input terminal of the driver circuit is the input terminal of the hiccup driver circuit,
a second input terminal of the driver circuit is connected with an output terminal of the voltage limiting circuit,
a third input terminal of the driver circuit is connected with the negative output terminal of the direct current source,
an output terminal of the driver circuit is the output terminal of the hiccup driver circuit,
the driver circuit is configured to:
receive the enable signal,
generate a driving signal for controlling the switching device to be switched on and consume the electric energy stored internally, in a case that the enable signal is an OFF-ENABLE signal and the supply voltage meets a first preset condition, and
generate a driving signal for controlling the switching device to be switched off in a case that the enable signal is a NON-OFF-ENABLE signal or the supply voltage meets a second preset condition, and
wherein the voltage limiting circuit comprises a first diode, a first capacitor, a first resistor, a Zener diode, a second capacitor, a second resistor and a third capacitor, wherein
an anode of the first diode is connected with the positive output terminal of the direct current source,
a cathode of the first diode is connected with a first terminal of the first capacitor, a first terminal of the first resistor and a first terminal of the second capacitor,
a second terminal of the first capacitor, an anode of the Zener diode and a second terminal of the third capacitor are connected with the negative output terminal of the direct current source,
a second terminal of the first resistor is connected with a second terminal of the second capacitor, a cathode of the Zener diode and a first terminal of the second resistor, and
a second terminal of the second resistor is connected with a first terminal of the third capacitor, with a connection point between the second terminal of the second resistor and the first terminal of the third capacitor being the output terminal of the voltage limiting circuit.

US Pat. No. 10,680,550

CASCADED PHOTOVOLTAIC GRID-CONNECTED INVERTER, CONTROL METHOD AND CONTROL DEVICE FOR THE SAME

SUNGROW POWER SUPPLY CO.,...

1. A control method for a cascaded photovoltaic grid-connected inverter, comprising:determining that at least one of inverter units of the cascaded photovoltaic grid-connected inverter is over-modulated based on a grid-connected current effective value being less than ?2*idcmax, wherein idcmax is a maximum value of output currents of photovoltaic arrays;
injecting a reactive current to a power grid to make the grid-connected current effective value greater than or equal to ?2*idcmax in a case that at least one of the inverter units of the cascaded photovoltaic grid-connected inverter is over-modulated;
determining a voltage U0 required for grid connection for the cascaded photovoltaic grid-connected inverter corresponding to a current grid-connected current effective value; and
adjusting an output active voltage of each of the inverter units according to Ujd=Pj/P0*U0d, and adjusting an output reactive voltage of each of the inverter units in a case that none of the inverter units is over-modulated, wherein a sum of the output reactive voltage of each of the inverter units is equal to U0p, U0d is an active component of U0 and U0p is a reactive component of U0, Pj and Ujd are respectively an output active power and an output active voltage of a same inverter unit, and P0 is a sum of the output active power of each of the inverter units.

US Pat. No. 10,707,782

BI-DIRECTIONAL ENERGY CONVERTER WITH MULTIPLE DC SOURCES

SUNGROW POWER SUPPLY CO.,...

1. An energy conversion system comprising:a plurality of basic inversion units coupled to a plurality of direct current (DC) sources, wherein each of the plurality of basic inversion units is coupled to a respective one of the plurality of DC sources through a positive node and a negative node of the respective one of the plurality of DC sources;
wherein the plurality of basic inversion units are connected in series to form a stacked phase, the stacked phase comprising a first terminus and a second terminus, wherein the first terminus is a first node of a first basic inversion unit of the plurality of basic inversion units in the stacked phase and wherein the second terminus is a first node of a last basic inversion unit of the plurality of basic inversion units in the stacked phase, wherein the first terminus and the second terminus are coupled to an alternating current (AC) power system, and wherein the stacked phase is configured to output an aggregate sinusoidal voltage waveform to the AC power system: and
a plurality of local controllers, wherein each of the plurality of basic inversion units comprises a respective one of the plurality of local controllers, and wherein each of the plurality of local controllers is configured to provide control signals to a respective basic inversion unit of the plurality of basic inversion units such that the respective basic inversion unit outputs a sinusoidal voltage waveform,
the system further comprises:
a system controller coupled between the stacked phase and the AC power system, wherein the system controller is configured to communicate with the plurality of local controllers using system control signals in order to create the aggregate sinusoidal voltage waveform, wherein the system control signals control the plurality of local controllers to ensure that the sinusoidal voltage waveform of each of the plurality of basic inversion units is in phase, and wherein the combination of the sinusoidal voltage waveform of each of the plurality of basic inversion units creates the aggregate sinusoidal voltage waveform.

US Pat. No. 10,693,297

CENTRALIZED MPPT EXITING AND SWITCHING METHOD AND APPLICATION THEREOF

SUNGROW POWER SUPPLY CO.,...

1. A method for exiting a Maximum Power Point Tracking (MPPT) centralized mode of a photovoltaic inverter, wherein the photovoltaic inverter comprises a plurality of direct current (DC) chopper circuits and an inverting circuit, the inverting circuit is connected to an output side of the plurality of DC chopper circuits on which side the plurality of DC chopper circuits are connected in parallel to a DC bus, and a plurality of photovoltaic strings are connected in parallel to the DC bus via the plurality of DC chopper circuits, the method comprising:obtaining a maximum power point for each of the plurality of photovoltaic strings, by performing a MPPT control individually on each of the plurality of photovoltaic strings in response to the photovoltaic inverter operating in the MPPT centralized mode and in response to the plurality of DC chopper circuits which are stopped from operating;
determining output voltages of the plurality of photovoltaic strings, which correspond to the obtained maximum power points;
determining one of the plurality of photovoltaic strings having a standard voltage value, which is a maximum or minimum one among the determined output voltages of the plurality of photovoltaic strings according to a type of the plurality of DC chopper circuits;
determining whether a voltage difference between the output voltage of a further one of the plurality of photovoltaic strings and the standard voltage value of the one of the plurality of photovoltaic strings exceeds a preset voltage difference; and
restarting the DC chopper circuit connected to the further one of the plurality of photovoltaic strings in response to the determined voltage difference exceeding the preset voltage difference.