Review of Three-phase Soft Switching Inverters and Challenges for Motor Drives

For electric vehicles (EVs), it is necessary to improve endurance mileage by improving the efficiency. There exists a trend towards increasing the system voltage and switching frequency, contributing to improve charging speed and power density. However, this trend poses significant challenges for high-voltage and high-frequency motor controllers, which are plagued by increased switching losses and pronounced switching oscillations as consequences of hard switching. The deployment of soft switching technology presents a viable solution to mitigate these issues. This paper reviews the applications of soft switching technologies for three-phase inverters and classifies them based on distinct characteristics. For each type of inverter, the advantages and disadvantages are evaluated. Then, the paper introduces the research progress and control methods of soft switching inverters (SSIs). Moreover, it presents a comparative analysis among the conventional hard switching inverters (HSIs), an active clamping resonant DC link inverter (ACRDCLI) and an auxiliary resonant commuted pole inverter (ARCPI). Finally, the problems and prospects of soft switching technology applied to motor controllers for EVs are put forward.