Three-phase AC filter inductor design for three-phase PWM inverter for conversion efficiency improvement at low load

The inductor losses in a three-phase AC filter inductor used in a three-phase pulse-width modulation (PWM) inverter are evaluated. First a three-phase inductor is designed to obtain the same value of inductance for each phase. Then, based on the design, a three-phase inductor that uses two magnetic materials is proposed. The conversion efficiency of a 1 kVA three-phase PWM inverter that uses the conventional and proposed AC filter inductors is simulated. Simulation results show that conversion efficiency improves. Finally, the conversion efficiency of an actual three-phase 1 kVA PWM inverter that uses the conventional and proposed AC filter inductors is measured. In the experiment, the conversion efficiency obtained for the case of the proposed inductor improves by approximately 1% at low power load as compared to the conventional inductor. Furthermore, the calculated inductor loss es are in good agreement with measured losses. Improvement in efficiency is verified trough simulations and experiments. © 2017 The Institute of Electrical Engineers of Japan.