Research on a Novel High-Efficiency Three-Phase Resonant Pole Soft-Switching Inverter

A high-efficiency three-phase resonant inverter is presented to optimize the performance of the inverter. When the auxiliary resonant circuit on each phase bridge arm works in the commutation process of the inverter, the voltage across resonant capacitors in parallel with main switches will form zero state periodically. In this case, main switches can achieve zero-voltage soft-switching. Meanwhile, auxiliary switches can achieve zero-current turn on and zero-voltage turn off during the operation of the auxiliary resonant circuit. Soft-switching can reduce switching loss and make the inverter work efficiently. The novelty of the inverter mainly reflects in the simple structure of the auxiliary circuit and the simple control method of auxiliary switches. This article analyzes the working mode of the circuit and the realization condition of soft-switching. Meanwhile, it discusses theoretical calculation of the power loss of the auxiliary circuit. The experimental results on the 3-kW prototype show that switching devices work in the soft-switching state. The efficiency of the prototype under the rated output power reaches 98.7%, which is higher than that of the same type of other soft-switching inverter. Therefore, the topology is valuable for the research and development of the high-performance three-phase inverter.