An Adjusted Current Control System for Signal-injection-based Position Sensorless Control and Parameter Identification

Abstract

This paper proposes a current controller for signal-injection-based control schemes such as those for parameter identification and position sensorless control. In a conventional current control system with voltage signal injection, the separation of the injected frequency components from the current is carried out by using band stop filters. However, the separation is not accurate, especially when the system is in the transient state and/or when the current controller bandwidth is close to the injected signal frequency. This leads to the distortion of the transient response and affects the stability of the current control system. The proposed controller estimates the injected frequency components in the current on the basis of a motor model by using the injected signal as the input. Therefore, accurate signal separation is accomplished even in the transient state. Moreover, the current controller's stability and dynamic performance are improved significantly. Experimental results are presented to validate the proposed method. Factors that play an important role in the implementation of the controller, such as time delay and parameter variation, are discussed.