Determination of the inductance of a synchronous reactive machine for sensorless control

Resumo

The problem of eliminating rotor-position sensors in ac drives has been the focus of intense research for over two decades. Among the expected benefits of the solution to this problem are reduction of drive cost and size, as well as increased reliability. The methods developed for this purpose are usually called “methods of sensorless control.” It has been shown that sensorless-control methods for ac machines provide high efficiency at medium and high speeds. However, these methods are less efficient at lower speeds and control of the position at low and near-zero speeds is not possible. To overcome this limitation, methods of sensorless control based on the tracking the position of rotor asymmetries have been proposed. These methods measure the response of a machine to the high-frequency component of the excitation signal. One of the most attractive aspects of this method is the absence of limitations when operating at very low or near-zero speeds, which allows one to control the rotor position. This paper presents the results of theoretical and experimental studies of the method for determining inductances Ld and Lq in a synchronous reluctance machine (SynRM) using the injection of a high-frequency component into the stator voltage. This paper discusses the principles of this method and its application to the mathematical model of the SynRM and the M3AL 90LDA 4 engine produced by ABB Co. Determination of these parameters is necessary for the implementation of sensorless-motor-control systems.