Soft-switched quasi-Z-source inverter-fed permanent magnet synchronous machine for hybrid/electric vehicle applications

Abstract : The switching frequency of power converters is increasingly high to reduce the size of passive elements and improve the dynamic performance of electric power-train in hybrid/electric vehicle applications. Thus, the development of soft-switching technology devices has taken an accelerated pace. This paper introduces a novel soft switching bidirectional quasi-Z-source inverter (QZSI). By using a resonant capacitor and coupled inductors, the proposed QZSI topology provides a solution to hard-switching problems for variable speed electric drives for hybrid/electric vehicle applications. A soft switching topology is presented, which aims at reducing active devices switching stresses as well as mastering the slew rate dv/dt that have an adverse effect over the motor/generator windings. The effectiveness of the proposed topology has been analytically studied and simulated in Matlab/Simulink and the results have been validated by experiment for both propulsion (motoring) and braking (generating) modes on the laboratory test bench.