Patent ID: 7091704

Claim:
A three-phase three-wire active power filter, comprising: a dc capacitor providing a regulated dc voltage; a power converter including a two-arm power electronic switch set, the power electronic switch set having a pair of ac terminals and a pair of dc terminals; a filter inductor set connected the power converter, and used to suppress a high frequency ripple current due to the switching behavior of the power converter; a reactive power compensating capacitor set connected in series with the filter inductor set for generating a reactive power; a combined capacitor/resistor filtering set parallel connected between the serial-connection of the filter inductor set with the reactive power compensating capacitor set and a power line such that the combined capacitor/resistor filtering set being in cooperation with the filter inductor for filtering harmonics generated from the power converter; and a control circuit generating switching signals for driving the power electronic switch set of the power converter to generate a compensating current; wherein the compensating current being injected into the power line, and thereby three-phase utility currents supplied from a three-phase three-wire power system being approximated as sinusoidal waveforms.