Basics of Soft‐switching Three‐phase Converters

This chapter introduces the basic knowledge of soft‐switching three‐phase converters. The three‐phase converter is one of the most important power conversion building blocks in power electronic systems. A converter is composed of three parts: DC bus, a switch bridge, filters, and three‐phase loads. Switching power loss happens due to nonideal characteristics of semiconductor switching power devices. Soft‐switching is realized by either changing converter topology and/or introducing a unique control to reduce the overlapping of voltage and current of the semiconductor power switches during switching commutation. The DC‐side resonance only needs one auxiliary resonant circuit regardless of the number of AC phases of the converter. Distinctive advantage of the AC‐side resonance is that the auxiliary circuits are in shunt with the switch bridge and conduct the current only in a small fraction of a switching period. Triangular current mode is originally introduced to single‐phase totem‐pole power factor correction converters and extended to three‐phase converters.