Three-phase ZVS-PWM inverter system with transformer-assisted quasi-resonant DC link and its feasible comparative evaluations

The purpose of this paper is to confirm the reduction level of the switching losses and EMI noise in the novel zero voltage switching (ZVS) PWM three-phase inverter system which composed the transformer-assisted quasi-resonant DC link (TQRDCL) topology by means of comparative experimental study on TQRDCL inverter and conventional hard-switching ones. The operating principle and its characteristics of TQRDCL inverter system are illustrated and discussed. The air-conditioning system on the market is selected as the fundamental system of the experimental apparatus, and it is extend to the TQRDCL experimental system for this comparative study. The loss analysis is performed under various load ranges and system operating frequency. The EMI noise reduction level of the TQRDCL system is also illustrated from comparative experimental results.