Feasibility of Sinusoidal Flux Drive Design of Reluctance Motor for Reducing Torque and Input Current Ripples with Three-Leg Inverter

Reluctance motors, represented by the switched reluctance motor (SRM) and the synchronous reluctance motor (SynRM), are attractive for vehicle propulsion owing to their high thermal tolerance and simple mechanical construction. However, the SRM exhibits large torque and large input current ripples, deteriorating driving comfort and battery lifespan. Furthermore, a driving system of the SRM requires the special inverter topology with additional switching or rectifying devices, leading to the cost-up. Meanwhile, the SynRM does not have these drawbacks, although this motor tends to be difficult to cover the wide range of the torque and the rotation speed required for vehicle propulsion because of large phase flux induction. To solve the obstacles of these conventional reluctance motors, this paper proposes a novel reluctance motor. The proposed reluctance motor is based on magnetization by the sinusoidal phase flux waveform, whereby the torque and input current ripples are eliminated using a common three-leg inverter without inducing large phase magnetic flux. This paper presents the operating principles of the proposed reluctance motor as well as analysis and simulation results in comparison with the SRM and the SynRM. As a result, the proposed reluctance motor is elucidated to reduce the torque and input current ripples with the three-leg inverter. Furthermore, the proposed reluctance motor can improve the torque range and rotating speed range compared to the SynRM because of the sinusoidal flux waveform with reduced amplitude. These results imply feasibility of the proposed motor for vehicle propulsion.