Sensorless control of a reluctance synchronous machine in the whole speed range without voltage pulse injections

In this paper a position sensorless control applied to a synchronous reluctance machine for an industrial drive application is discussed. For a given stator of an induction machine a synchronous reluctance rotor with flux barriers is designed by finite element methods and a prototype machine is built up. In this application the synchronous reluctance machine drive has already replaced the induction machine. The synchronous reluctance machine saliency can be used to determine the rotor position during a modified PWM pattern without voltage pulse injections by current slope measurement at standstill and low operational speeds. For the high speed range including flux weakening operation a Back-EMF model is presented and applied to the machine. Finally, a sensorless field oriented control of the synchronous reluctance drive in the whole speed range is reached. The sensorless drive combines a high efficiency with a low cost drive architecture. With the investigations in this work the additional benefit of sensorless control in this application shall be demonstrated. The basic principles of both sensorless methods are discussed and experimental results are presented.