Patent ID: 6130832
Filing Date: 2000-10-10
Classification: H02J,H02M,Y02E

Abstract:
An active filter for reducing switching carrier currents between three-phase AC mains and an AC/DC switched bridge converter, said active filter comprising:a transformer for each phase of said AC mains, each transformer having a primary winding and having a secondary winding connected between the corresponding phase of said AC mains and a related node of said converter;means for synthesizing a voltage waveform for each of said phases, each synthesized waveform being substantially identical to the actual waveform of switching carrier frequency voltage generated by said converter in the related phase; anda plurality of pulse width modulation controllers, each connected to drive one of said primaries in response to a corresponding one of said synthesized voltage waveforms;each of said secondaries being poled so that the voltage across it is substantially 180.degree. out of phase with the corresponding one of said switching carrier frequency voltages.