An efficient resonant DC link inverter

An efficient three-phase resonant DC link inverter is put forward to optimise the efficiency. The assisted circuit is added on the DC link. When the main switches need to be operated, the assisted circuit has been in resonance state in advance. The voltage across DC link changes to zero, so that the main switches can act in the mode of zero-voltage soft-switching. Besides, the auxiliary switch can also act in the mode of soft-switching. Through control of the interval time of the action of the auxiliary switches, the zero-state duration of the DC link voltage can be adjusted, so that various flexible pulse width modulation strategies can be applied in the inverter. The workflow of the assisted circuit and the implementation conditions of soft-switching are illustrated at length. The experimental results indicate the main switches and the auxiliary switches can act in the mode of soft-switching. The efficiency at 4.5 kW is equal to 98.5%, which is superior to that of other similar inverters. Hence, the topology can provide reference for the design of efficient inverters.