Development of a 12/10 Hex Connection SRM for Electric Vehicle Traction Motors

Currently, permanent magnet synchronous motors (PMSMs) are commonly used for electric vehicle (EV) traction motors. However, there are some problems such as the cost of permanent magnets, low efficiency at high rotation speeds, and the stable supply of rare earth resources. Therefore, induction motors (IMs) have been adopted for EV traction motors, and the application of switched reluctance motors (SRMs) are also being considered. IMs has robust structure and can rotate at high speed, but it has the problem of low power density and efficiency. On the other hand, the SRMs have simple, robust and inexpensive structure. However, SRMs have problems such as a large torque ripple, noise and vibration. In addition, SRMs are driven by a 3-phase asymmetric inverter, and the inverter cost is higher than a 3-phase inverter. Therefore, in order to solve these problems, we have proposed a 12/10 SRM that uses a hex connection and an improved 9-switch inverter. In this paper, a 12/10 SRM with a hex connection for EV traction motors is designed and compared with an induction motor. Finally, the effectiveness of proposed SRM is investigated.