Abstract: An active damping circuit for an electromagnetic interference (EMI) filter for power factor correction (PFC) circuit is provided which simulates a line damping impedance which actively varies according to sensed line current. The active damping circuit comprises an nth-order, Cauer-Chebyshev, low-pass filter having input series damping impedance (Z.sub.d) simulated with a power operational amplifier and high-frequency isolation transformer. The simulated damping impedance offers greatly reduced size and power dissipation as compared to prior art passive schemes which typically require large impedance components for damping. A passive damping circuit is also shown which involves providing an alternate inductive current path in parallel with a damping resistor whereby lower frequency currents are diverted through the alternate current path and higher frequency currents continue to flow through the damping resistor.

Abstract: A novel switching rectifier circuit that combines the conventional three-phase, 6-stepped PWM rectifier/inverter circuit with a simple, low-power switch commutation circuit to provide zero-voltage turn-on for the switches, and soft turn-off for the diodes. The main features of the new circuit include elimination of switching losses on the power switches and reverse recovery problems on the diodes, elimination of the need for any snubbers in the three-phase bridge, possibility of use of slower diodes in the power bridge, constant frequency operation, and no increase in component current and voltage stresses over the conventional PWM rectifier.

Abstract: A three-phase, pulse-width-modulated, switching rectifier, with zero-voltage-switching.