Sliding mode sensorless control of an asynchronous motor based on an MRAS-type observer

Abstract

This work deals with the problem of speed control of a sensorless asynchronous motor. Conventional control laws by PI or PID for example, although still widely used, may prove to be insufficient or unsuitable. We then develop control laws by state feedback, their use nevertheless requires the measurement of the state vector. However, in many cases, sensors for measuring all the physical quantities are not available, essentially for cost reasons. An observer, which is a mathematical object, makes it possible to reconstruct this state vector from the only physical measurements available. In this context, we will propose the use of the sliding mode technique, which is a recursive control method and represents a tool for the study of dynamic stability. We will then approach the observers and in particular those resulting from the theory of the reference model (MRAS). In this proposed work, we are interested in the study of the asynchronous motor by the application of the sliding mode which is a relatively recent technique for nonlinear systems. It is combined with the vector control principle with oriented rotor flux to design robust machine control laws. The motor state quantities are estimated by the MRAS algorithm. A comparison of the performances is established to come out with general conclusions and in particular with regard to the use of the observer to estimate the quantities of state of the engine to control it later by this technique.