Direct Harmonic Current Control Scheme for Dual Three-Phase PMSM Drive System

The performance of model predictive control mainly depends on the accuracy of model and parameters, such as the back electromotive force (EMF) harmonics in dual three-phase permanent magnet synchronous motors (PMSMs). However, the back EMF harmonics would vary with the operation conditions. Thus, the parameter mismatches in the harmonic subspace would be inevitable. In this article, a direct harmonic current control scheme is proposed to provide further harmonic current suppression under parameter mismatches in the xy subspace. First, deadbeat control concept is applied to calculate the reference voltage in the αβ subspace. This reference voltage vector is utilized to generate a group of control sets with different voltage vectors in the xy subspace. Then, a slide mode control scheme is provided to deal with the inaccurate parameters in the xy subspace. The reference voltage vector in the xy subspace is obtained with this slide mode control scheme without the remaining inductance parameters. Third, a two-step modulation method and cost function are discussed to further suppress the harmonic currents. The control sets generated by deadbeat control are optimized with the cost function. Moreover, a switching pattern with fixed switching frequency is proposed in this section. Finally, experimental results verify that proposed control scheme could further suppress the harmonic currents.

I. Introduction

Multiphase permanent magnets (PM) machines are alternative of the traditional three-phase permanent magnet synchronous motors (PMSMs) because of their better fault-tolerant capability, lower current per phase, higher torque density, and lower torque ripples [1], [2]. Among them, dual three-phase (DTP) PMSMs, attract more attention in those high power and safety applications, such as electric vehicle, electric ship, electric aircraft, etc. [3]–[5]. Due to the universality of the electromagnetic principle, the major control approaches applied in multiphase PM machines are commonly an extension of the conventional controllers applied in three-phase machines, such as field-oriented control, direct torque control, hysteresis-based control, etc. [6]–[8].