Permanent-magnet synchronous motor drive system for electric vehicles using bidirectional z-source inverter

Permanent-magnet synchronous motors (PMSM) are capable of providing high torque-to-current ratios, high power-to-weight ratios, high efficiency and robustness. Owing to these advantages, PMSM are widely used in modern variable speed AC drives, especially in electric vehicle (EV) and hybrid EV applications. In this study, a novel PMSM drive system with a bidirectional Z-source inverter (ZSI) is proposed and tested. By introducing ZSI to the drive system, the DC-link voltage is controllable so that PMSM can operate at high speed without field weakening. The operating principle and modulation method of ZSI are described in this study. After presenting the constraints of the motor maximum line current amplitude and maximum available voltage, a modified vector controlled scheme of PMSM drive is developed by considering voltage boosting. Finally, the feasibility and effectiveness of the proposed system are verified by several simulation and experiment results.