A Scalar Decoupled PWM Technique for a Three-Level Symmetrical Dual Inverter Fed OEWIM Drive for Electric Vehicle

Abstract

Dual inverter (DI) fed induction motor drives are employed in electric vehicle to control the speed and obtain better performance. Asymmetrical DI, which uses traditional SVPWM, produce a remarkably high common-mode voltage (CMV). The motor bearings are affected, and EMI problems occurs due to the common-mode current. Hence, to overcome this problem and to control a three-level symmetrical DI fed Open End Winding Induction Motor (OEWIM), a novel PWM generation technique named scalar decoupled PWM topology is proposed in this paper. Two three-level inverters are connected to the open-end winding induction motor in this work and a carrier-based scalar technique with decoupled PWM is proposed where the modulating signal can be varied to obtain both continuous and discontinuous modes of operation. In this proposed topology, switching signals of the inverter 1 and 2 can be generated and controlled separately. To examine the efficiency of the proposed topology, its operation under both continuous and discontinuous modes of operation is carried out in simulation and experimental set up. From the acquired results, it is concluded that this proposed topology exhibits reduced CMV and harmonics when compared to traditional PWM topology.