US Patent No. 9,124,210

MOTOR CONTROL APPARATUS WITH POWER FAILURE DETERMINATION UNIT


Patent No. 9,124,210
Issue Date September 01, 2015
Title Motor Control Apparatus With Power Failure Determination Unit
Inventorship Kenta Yamamoto, Yamanashi (JP)
Assignee FANUC CORPORATION, Yamanashi (JP)

Claim of US Patent No. 9,124,210

1. A motor control apparatus comprising:
a PWM rectifier for performing a bidirectional power conversion between AC power at an AC power supply side and DC power at
a DC link being on a DC side;

an inverter for performing a bidirectional power conversion between DC power at the DC link and AC power being drive power
for a motor or regenerative power, the inverter being connected to the DC link;

an AC voltage detection unit for detecting an AC voltage value at the AC power supply side of the PWM rectifier;
a phase calculation unit for calculating a power supply voltage phase from the AC voltage value;
an AC current detection unit for detecting an AC current value at the AC power supply side of the PWM rectifier;
a current loop control unit for generating an AC voltage command to control a power conversion operation of the PWM rectifier
based on an error between an input current command and the AC current value and the power supply voltage phase;

a current loop saturation state determination unit for determining a current loop saturation state when a magnitude of the
AC voltage command is equal to or larger than a predetermined voltage prescribed value;

an operation determination unit for determining whether the PWM rectifier is in a powering operation state in which AC power
is converted to DC power or in a regenerative operation state in which DC power is converted to AC power;

a power failure determination unit for determining a presence or absence of a power failure at the AC power supply side of
the PWM rectifier by using determination results of the operation determination unit and the current loop saturation state
determination unit;

a DC voltage detection unit for detecting a DC voltage value at the DC link;
a voltage loop control unit for generating the current command to be input to the current loop control unit based on an error
between an input DC voltage command and the DC voltage value; and

a voltage loop saturation state determination unit for determining to be in a voltage loop saturation state when a magnitude
of the current command is equal to or larger than a predetermined current prescribed value,

wherein the power failure determination unit determines that a power failure occurs at the AC power supply side of the PWM
rectifier by using a first requirement that the operation determination unit determines to be in the regenerative operation,
a second requirement that the current loop saturation state determination unit determines to be in the current loop saturation
state and a third requirement that the voltage loop saturation state determination unit determines to be in the voltage loop
saturation state.