Patent ID: 7359224
Filing Date: 2008-04-15
Classification: G05F,H02M,Y02B

Abstract:
1. A circuit for providing power factor correction including: a boost converter circuit having a boost inductance and a power factor correction switch coupled in series with the boost inductance, the boost inductance and power factor correction switch being coupled across the output of a rectifier being supplied with AC power from an AC line, the boost converter circuit further comprising a boost diode coupled to a junction between the inductor and the switch, an output of the boost diode coupled to an output capacitor, a DC bus voltage being provided across the output capacitor, further comprising a control circuit receiving as inputs a rectified AC input voltage from the rectifier, a signal proportional to current through the inductor and the DC bus voltage across the capacitor, and wherein the control circuit provides a pulse width modulated signal to control the on time of the power factor correction switch, the control circuit further comprising: a voltage regulator providing a regulated voltage signal based on a reference voltage and the DC bus voltage; a multiplier operable to multiply the regulated voltage signal by the rectified AC input voltage to provide a current reference signal; a current regulator receiving the current reference signal and the signal proportional to the inductor current, wherein the current regulator further comprises: a difference device operable to subtract the signal proportional to the inductor current from the current reference signal, a PI controller adapted to receive the output of the difference device and provide a first control signal; a feed forward device operable to receive the rectified AC input voltage and to provide a second control signal, wherein the second control signal has a smaller dynamic range than the AC input voltage; an adder operable to add the first control signal to the second control signal to provide a PWM reference signal; and a pulse width modulated signal generator operable to provide the pulse width modulated signal to control the on time of the PFC circuit, wherein the pulse width modulated signal generator utilizes the PWM reference signal to generate the pulse width modulated signal.