Multiple Sine-Wave Superposition Drive for the Doubly Salient Motor Based on Fourier Linearization Modeling

Abstract

Doubly salient motor (DSM) is a new type of high-speed motor. For aeronautics applications, DSM has a nonsinusoidal nonlinear structure and is driven by the square-wave current. As a result, the driving of DSM is hard to be quantitatively designed and optimized. This article proposes a multiple sine-wave superposition (MSWS) driving method that generates current waveforms composed of fundamental component and harmonic components with specific amplitudes and initial phases. That is based on a new accurate DSM Fourier linearization modeling, completely different from present square-wave driving methods of DSMs. In this article, a simplified linear relation between the current and the torque harmonic component is established. Then, a tradeoff between torque-to-current ratio and torque ripple is made. As a result, the optimal current waveforms of maximum torque-per-ampere and torque ripple suppression are given, and the new driving method is proposed. The MSWS driving is simple, easy to use, and greatly improves torque characteristics and the dynamic performance of DSM compared with square-wave driving. It is proposed for DSMs, however, it could be extended to other nonsinusoidal motors. This driving method is verified on a 12/8 DSM by simulation and experiment.