A matrix converter-based topology for high power electric vehicle battery charging and V2G application

In this paper, a new three-phase converter topology based on a 3x1 matrix converter (MC) is proposed for Plug-in Hybrid or Battery (PHEV/BEV) electric transit buses. In the proposed approach, the MC directly converts the low frequency (50/60 Hz, three-phase) input to a high frequency (6 kHz, one-phase) AC output without a dc-link. The output of the matrix converter (MC) is then processed by a PWM rectifier via a high frequency (HF) isolation transformer to interface with the EV battery system. The MC-PWM rectifier system is made to operate like a dual active bridge (DAB), facilitating bi-directional power flow suitable for charging and Vehicle-to-Grid (V2G) application. The digital control of the system ensures that the input currents are of high quality under both charging and discharging operations. Due to the absence of dc-link electrolytic capacitors, power density of the proposed rectifier is expected to be higher. Analysis, design example and extended simulation results are presented for a three-phase 208 V_LL, 50kW charger.