An Efficient Three-Phase Soft-Switching Inverter With Simplified Asymmetric Single Auxiliary Circuit on Each Bridge Arm for Low-Speed AC Motor Drive

The paper conducts research on an efficient three-phase soft-switching inverter with simplified asymmetric single auxiliary circuit on each bridge arm to achieve miniaturization and light weight of soft-switching inverters. Main switches can realize zero-voltage switching, bringing about efficient operation of the studied inverter. Since auxiliary switches and resonant inductors are necessary for resonant pole zero-voltage switching inverters, only one auxiliary switch and one resonant inductor, along with two auxiliary diodes and three resonant capacitors, constitute simple auxiliary circuits of each phase. In the designed inverter, few auxiliary switches and auxiliary diodes are beneficial to the use of heat sinks with small volume, thereby achieving the miniaturization of the inverter; the weight of auxiliary circuits mainly depends on resonant inductors, so few resonant inductors can also make the inverter lightweight. The paper conducts a detailed analysis on each working status in one switching cycle and puts forward corresponding design requirements. The experimental waveforms verify the advantage that switches can realize soft-switching. The efficiency comparison in the same experimental conditions demonstrates that the efficiency of the studied inverter reaches 99.2% at rated output power, which is 0.5% and 0.7% higher than that of the two comparison objects with symmetric double auxiliary circuits on each bridge arm, respectively. Thus, the novel asymmetric single auxiliary circuit composed of fewer auxiliary devices on each bridge arm is beneficial for optimizing and popularizing resonant pole zero-voltage switching inverters.