Current Control System for PMSM in Overmodulation Range of Inverter

Abstract

This paper proposes a novel current control system for a PMSM that can stably operate even in the overmodulation range of an inverter. Because an inverter generates harmonic components in this range, an instability problem in the conventional current control system usually occurs. For solving this instability problem, the idea of harmonic current compensation scheme has already been proposed. However, the effectiveness of this method depends directly on the harmonic current estimation accuracy.
There are two new topics in harmonic component estimation that we use in our proposed current control system as follows: (1) the harmonic voltage estimation method that is based on the conventional sinusoidal PWM modulation technique, and (2) the harmonic current estimation method that estimates correctly both in the steady state and transient condition. The effectiveness of the proposed methods is confirmed by computer simulation and experimental results.