RESONANCE MODE CONVERTER CONTROL METHOD, PFC CONVERTER CONTROL STRUCTURE, AND CASCADE-CONNECTED POWER CONVERTER

摘要

PPROBLEM TO BE SOLVED: To provide a control device that controls a cascade-connected PFC and a LLC converter. PSOLUTION: The LLC converter 11 has an input coupled to an output of the PFC converter 10 and providing an output voltage that decreases with increasing switching frequency. The control device produces a sawtooth waveform with a linear ramp for controlling the LLC converter switching frequency, and hence its output voltage, in dependence upon a feedback signal. The control device also produces a PWM signal having a frequency equal to or one integer-th of the LLC converter switching frequency for the PFC converter to switch on/off the PFC converter during the cycles whose saw-tooth waveforms differ respectively by comparing the two different thresholds and linear lamps during these different cycles. The logic circuit prevents the PFC converter switch transition from occurring simultaneously with switching transitions of the LLC converter. PCOPYRIGHT: (C)2009,JPO&INPIT