A parallel feed-forward compensation type three-phase power factor
correction circuit for a three-phase power supply comprises a primary
rectifying circuit I, and a feed-forward compensation circuit II which is
in parallel with the primary rectifying circuit I. The primary bridge
rectifier circuit I comprises a three-phase bridge and a filter
capacitor. The feed-forward compensation circuit II comprises a plurality
of bi-direction switches, a rectifying circuit, a boost converter, an
output current sampler and a control circuit. In the corresponding phase
interval the feed-forward compensation circuit sequentially closes the
phase of that whose absolute value of the voltage is the higher one of
the two phases at same polarity. The other two phases are rectified by
bridge rectifying circuit and forced to export a compulsive current
waveform. In this configuration, it can amend the current waveform of
each phase, reduce harmonic distortion and improve the efficiency of the
power supply with very little power.