An Improved Complementary Impulse-Commutated Inverter using Saturable Inductors

A new forced-commutated inverter circuit is described in which saturable inductors are used to support the dc link voltage during the brief period of commutation. It is shown that the circuit has several advantages: It has lower trapped energy as compared to the conventional complementary impulse-commutated inverter. It has good output voltage waveform. It is possible to turn off all the thyristors in the bridge circuit by the gate-control circuit. Besides, any fault resulting from spurious triggering of a blocking thyristor is of self-healing type. The commutation performance of such an inverter circuit is analyzed and is shown to be similar to the McMurray inverter. Design of the commutation elements is presented. The analytical results are experimentally verified and discussed.