Design of an induction motor drive fed by a matrix converter and a novel approach in application of control algorithms

Variable speed requirements of induction motors, which are widely used in industrial applications, are provided by frequency converters. Various converter applications can be used for having smooth torque, less harmonics, and high efficiency. In conventional converters, ac power at supply frequency is rectified and then filtered in the dc link before being inverted to ac at an adjustable frequency and amplitude. The matrix converter which directly performs ac-ac transformation using bidirectional switches does not require any dc link and it is able to perform the bidirectional power flow. Therefore, they can be fabricated in small sizes. Matrix converters are becoming very popular in variable speed applications of induction motors as an alternative voltage and frequency converter due to many reasons such as; does not need any storage element, having adjustable power factor independent from the load characteristic, providing inherently four-region operation and no need for extra input filters. However, matrix converters have some disadvantages over the other ac-ac converter topologies such as; requiring more switching elements, limitation on voltage gain, and the difficulties in switching commutation due to absence of any freewheeling paths. In this thesis, experimental setup for three-phase to three-phase matrix converter induction motor drive which can be also used in open loop and closed loop applications has been realized. DS1103 dSPACE GmbH controller card has been used to implement the modulation control strategies in real time. The effective solutions to the problems associated with the power circuit have been presented. Matlab/Simulink modeling and simulation of the Space Vector PWM technique and Venturini control algorithm for the matrix converter have been done for various load conditions. Then, these algorithms have been tested on the prototype converter. Special attention was given to the implementation of the switching strategy in Space Vector PWM technique. Furthermore, simulation and implementation of the matrix converter induction motor drive in open loop V/f and slip controls have been performed. The closed loop controller has been designed by using both PI and fuzzy logic controllers. Finally, simulation and experimental results from the prototype have been presented to confirm the correct operation of the drive system. Keywords: Matrix converter, Space vector PWM (SVPWM) algorithm, Venturini control algorithm, V/f speed control, Slip regulation, PI, Fuzzy logic controller