A nine-switch three-level inverter for electric vehicle applications

This paper presents a nine-switch three-level inverter used as an application for all-electric vehicle (EV) and hybrid-electric vehicle (HEV) motor drives. The proposed three-level inverter consists of a three-phase two-level inverter and three bidirectional power switches. The proposed inverter overcomes some shortcomings of two-level inverters, such as high switching frequency, high dv/dt and electromagnetic interference (EMI). The proposed inverter also reduces the number of power switches from twelve to nine compared with conventional three-level inverters. Fewer switches reduce system cost and improve system reliability. The proposed three-level inverter is suitable for low voltage applications because the voltage stress across part of power switches in this circuit is full of the DC bus voltage. Losses of the proposed inverter are analyzed and compared with other two inverters. The basic principle and control scheme of the proposed three-level inverter are introduced. Analytical, simulation, and experimental results show the superiority of the proposed three-level inverter for electric vehicle applications.