Input current modulation for power factor correction

摘要

A nonlinear carrier controlled power factor correction circuit operates in the continuous and discontinuous conduction modes and provides unity power factor at the input of a power supply by only sensing the output voltage and the current flowing through a diode of a rectifier circuit. The power factor correction circuit monitors a level of current flowing through the diode and generates an integrated voltage signal representative of the level of current flowing through the diode. The integrated voltage signal is compared to a periodic, carrier waveform signal generated using a feedback signal corresponding to a level of an output voltage delivered to a load. A difference between the feedback signal and a reference signal determines the waveshape and characteristics of the carrier waveform. Preferably, leading edge modulation is used to control the duty cycle of a switch within the rectifier circuit. The switch is turned on when the integrated voltage signal reaches a level greater than the value of the carrier waveform. The switch is turned off at the leading edge of the clock reference signal. The duty cycle of the switch will vary as the level of the output voltage varies in reference to the reference signal and as the level of current through the diode varies.