H7 Inverter Using Zener Diode With Model Predictive Current Control for Common-Mode Voltage Reduction in PMSM Drive System

In this paper, a three-phase voltage source inverter (VSI) topology is proposed to reduce the commonmode voltage (CMV) in permanent-magnet synchronous machine (PMSM) drive system. The proposed VSI named H7 inverter has an additional switch connected in series between the dc bus and inverter side and the antiparallel Zener diode connected in parallel with the additional switch. When the additional switch is turned off, the dc-link voltage is blocked by the breakdown voltage of the antiparallel Zener diode. Therefore, this topology can be operated with the low CMV at the zero voltage vector by turning off the additional switch. This paper combines these advantage of the H7 inverter with model predictive control (MPC) method, where one zero voltage vector is utilized, to obtain fast transient responses and relatively low total harmonic distortion (THD) of load current. This paper also proposes a reasonable MPC method with a simple control algorithm of the additional switch to prevent the unplanned zero voltage voltages during the dead time of VSI. The operation and CMV reduction capability of the proposed topology with MPC method is verified with simulation results.