On Sensorless Control of Induction Motor Drives

In high - demanding ac drives - as for example traction applications, usually, an encoder or speedsensor is needed on the rotor shaft. Replacing this sensor with speed estimation may result in lower costs and maintenance demands due to one less critical component in the system. By estimating the speed instead of measuring it is called sensorless control. The topic in this book is sensorless control adopted on the induction machine (IM). Research in the area sensorless control is wide and especially control problems at low speed have been an interesting problem to solve.
In this book the focusing topic is 0 Hz crossover problems, which occurs as the machine alters between motoring and regenerating drive. As sensorless control method a rotor flux estimator is adopted in a vector controlled scheme by the so-called voltage model (VM). The VM design is used for estimating the frequency by measured stator voltages and currents. The analysis here mainly considers parameter variations and instability problems, which are two important reasons for control problems at low speed. The proposed final method shows good performance both by linear and nonlinear analysis methods.
The author Ove Glenberg was born in Malmö, Sweden in 1969. He received the M.Sc. in electrotechnics from Linköping University, Linköping Sweden in 1994 and the Licentiate in electronics from Mälardalen University, Västerås Sweden in 2004. For 15 years he has been active in both military and civilian industry within control technical projects.