US Patent No. 9,118,239

POWER SUPPLY CONTROL METHOD FOR CONSTANT CURRENT CONSTANT POWER CONTROL


Patent No. 9,118,239
Issue Date August 25, 2015
Title Power Supply Control Method For Constant Current Constant Power Control
Inventorship Shanguang Xu, Plano, TX (US)
Zhong Ye, Plano, TX (US)
Assignee TEXAS INSTRUMENTS INCORPORATED, Dallas, TX (US)

Claim of US Patent No. 9,118,239

11. A switching power supply, comprising:
an input configured to receive input power from a connected source;
an output operative to provide output power to a connected load;
at least one switch operative according to a switching control signal to selectively convert the input power from the input
to provide the output power to the output; and

a power supply controller operative to provide the switching control signal to the at least one switch, the power supply controller
comprising:

a voltage control circuit, including:
a voltage error circuit providing a voltage error signal or value representing a difference between a reference voltage signal
or value and an output voltage of the switching power supply, and

a voltage compensator circuit with a digital adder circuit providing an integrator signal or value based at least partially
on a current error value and previous error samples, the voltage compensator circuit providing a voltage control duty cycle
signal or value based at least partially on the voltage error signal or value and on the integrator signal or value, the voltage
compensator circuit comprising a digital proportional integral derivative (PID) circuit operative to compute a proportional
compensation value based on the digital voltage error value and a proportional constant, to compute an integral compensation
value based on a current sample of the digital voltage error value, the integrator value, and an integral constant, to compute
a derivative compensation value based on a difference between a current sample of the digital voltage error value and a preceding
sample of the digital voltage error value, and a derivative constant, and to compute a digital voltage control duty cycle
value as a sum of the proportional compensation value, the integral compensation value, and the derivative compensation value,
and

a presetting circuit operative to provide the voltage control duty cycle signal or value as either the digital voltage control
duty cycle value or as the predetermined duty cycle signal or value based on a preset control signal,

a current control circuit, including:
a current error circuit providing a current error signal or value based at least partially on a reference current signal or
value and an output current of the switching power supply, and

a current compensator circuit providing a current control duty cycle signal or value based at least partially on the current
error signal or value,

a pulse width modulation circuit operative to pulse width modulate at least one switch of the switching power supply at least
partially according to a duty cycle input signal or value, and

a control circuit selectively operative in a first mode to provide the voltage control duty cycle signal or value as the duty
cycle input signal or value, and in a second mode to provide the current control duty cycle signal or value as the duty cycle
input signal or value, the control circuit comprising a logic circuit operative to switch the control circuit from the first
mode to the second mode if a sum of the voltage control duty cycle signal or value plus a predetermined non-zero hysteresis
value is greater than the current control duty cycle signal or value, to selectively preset the voltage control duty cycle
signal or value to a predetermined duty cycle signal or value by providing the preset control signal to the presetting circuit
if the current control duty cycle signal or value is less than the voltage control duty cycle signal or value and then switch
the control circuit from the second mode to the first mode if the voltage control duty cycle signal or value is less than
the current control duty cycle signal or value, and to selectively prevent increase of the integrator signal or value of the
voltage compensator circuit while the control circuit is in the second mode.