Efficiency Improvement of Motor Drive System by using a GaN Three Phase Inverter

This paper shows the effectiveness for employing the GaN-FET inverter for operating the traction motor of a compact Electric Vehicle. Utilizing GaN-FET inverter can not only reduce the conduction loss, but also reduce the switching loss. Therefore GaN-FET inverter can operate motors in higher switching frequency compared with Si-IGBT inverters. It is effective to increase the switching frequency of the inverter to improve the motor efficiency because harmonic iron losses can be reduced dramatically by increasing the switching frequency, but the inverter loss becomes relatively large when the switching frequency is set too high. Therefore, optimized switching frequency should be obtained to maximize the total efficiency of the motor drive system. Experiments are carried out to compare efficiencies of motor drive system with Si-IGBT/GaN-FET inverter in several switching frequencies. Optimization of the switching frequency for maximizing the total efficiency is demonstrated to make effective use of the GaN-FET inverter in the motor drive system.