Active input current waveshaping method for three-phase diode rectifiers with zero switching losses

A zero voltage switched active network which can be used in conjunction with single-phase or three-phase AC to DC diode rectifiers is presented. It is shown that application of the proposed switching network in a three-phase AC to DC boost converter yields zero switching losses while maintaining a unity input power factor. Active network capacitor, C/sub s/, diodes D/sub 7/ and D/sub 8/ maintain a zero voltage during turn-off of Q/sub 1/ and Q/sub 2/. Capacitor discharges through the boost inductors of the circuit, thus limiting the rate of rise of current during turn-on. Moreover, the advantage of the proposed active network is that it can maintain a zero voltage switching over the entire range of the duty cycle of the operation. Consequently, boost stage can be used directly to control the DC bus voltage by varying the duty cycle at constant switching frequency.<>