Analysis and optimization of induction motor drive systems using vector control methods

Analysis and Optimization of Induction Motor Drive Systems Using Vector Control Methods Ismail KAYA Keywords: Induction Motors, Optimal Control, Field Oriented Control, Induction Motor Simulation, Drive Systems Summary : In many applications, induction machines are used together with speed control drive systems. Throughout the last decades, the attention given to the minimization of the losses in the speed control systems has been increased due to the growing importance of the energy conservation. It is known that induction machines operate with higher efficiency near their rated values. However the losses increase for light loads. Thus, an optimal control strategy can be determined for an induction motor operating under variable speed and load conditions. This, thesis deals with the optimal control problem of induction machines. Before the implementation of an appropriate method, the motor losses are first examined and their relationships with the slip are obtained. It is found that a specific slip value can be found in order to minimize the losses under given operating conditions. Various control methods previously given in the literature are discussed and it is concluded that the vector control method can be conveniently applied for the present purpose. In this work, computer simulation programs are developed for examination of the dynamic behavior of an induction machine driven through a current fed inverter. Thiese programs allow the analysis jaf rotor and stator current and torque variations in the time domain. The simulation results are confirmed by experiments and compared with the results presented in the literature. The last chapter is devoted to the desion considerations for optimal vector control and basic relations are given for determination of the optimal slip value under specific load conditions. Finally, design criteria and suggestions are presented for realization of an optimal speed and position control systems for three phase short circuit induction machines. VII