Influence of Travelling Current Linkage Harmonics on Inductance Variation, Torque Ripple and Sensorless Capability of Tooth-Coil Permanent-Magnet Synchronous Machines

This paper introduces an important source of torque ripple in permanent-magnet synchronous machines with tooth-coil windings (TC-PMSMs). It is theoretically proven that saturation and cross-saturation phenomena caused by the nonsynchronous harmonics of the stator current linkage cause a synchronous inductance variation with a particular periodicity. This, in turn, determines the magnitude of the torque ripple and can also deteriorate the performance of signal-injection-based rotor position estimation algorithms. An improved dq-inductance model is proposed. It can be used in torque ripple reduction control schemes and can enhance the self-sensing capabilities of TC-PMSMs.

I. Introduction

The -model, or rotor flux oriented model for rotating ac electrical machines, was originally introduced to simplify the analysis and control of multi-phase electric motor drives. It significantly reduces the number of control variables. The -model is the enabling technique for controlled ac machine drives and the most important concept to understanding how field-oriented control works.