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Available online at www.sciencedirect.com

Procedia Computer Science 5 (2011) 505–512

The 2nd International Conference on Ambient Systems, Networks and Technologies

Mohammed T. Lazima, Muthanna J. M. Al-khishalib,*, Ahmed Isa. Al-Shawia,b
a Associate Professor, Electrical Eng. Dept., Faculty of Engineering, Philadelphia University, Amman - Jordan b,* Associate Professor, Laser andOptoelectronics Eng. Dept, Faculty of Engineering., Nahrain University Baghdad - Iraq a, b Engineer, Radio Network Planning Supervisor, Korek telecom/ Baghdad office, Baghdad - Iraq

Space Vector Modulation Direct Torque Speed Control Of Induction Motor

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Abstract Various aspectsrelated to controlling induction motors are investigated. Different control strategies are explored. The direct torque control (DTC) strategy is studied in details and its relation to space vector modulation (SVM) is emphasized. An SVM-based DTC strategy is suggested and a controller design based on this strategy is presented. A Simulink model representing the controller is developed and verifiedusing MATLAB-7. The model exhibits high modularity which makes it suitable for use in different induction motor control systems simulation scenarios. Each block in the model is developed from the very basic capabilities of Simulink which makes the model very suitable for testing and debugging. A modular model for the induction motor based on Krause’s model is developed. This model is used in thesimulation instead of the built-in Simulink induction motor block, in order to enable testing of various parts of the induction motor model and to gain a deep insight in machine’s operation. This model is tested separately and showed to be working properly through simulating direct AC startup in Simulink. The performance of control is evaluated through simulating the whole system in Simulink and thesuggested SVM-based DTC controlling system is shown to be superior to other controlling strategies investigated in the literature. It also shows that the induction motor settles down faster when using the suggested strategy compared to other previously studied strategies.
Keywords: Direct Torque Control; Multilevel Drives; Space Vector Modulation; Induction Motor Control____________________________________________________________________________________________________________________

1.

Introduction

With the enormous advances made in semiconductor technology during the last 20 years, the required conditions for developing a proper induction motor drive are present. These conditions can be divided mainly into two groups: The decreasing cost and improved performance in powerelectronic switching devices. The possibility of implementing complex algorithms in the new microprocessors. However, one precondition had to be made, which was the development of suitable methods to control the speed of induction motors, because in contrast to its mechanical simplicity their complexity regarding their mathematical structure (multivariable and non-linear) is not a trivial matter. Itis in this field, that considerable research effort is devoted. The aim is to find even simpler methods of speed control for induction machines. One method, which is popular at the moment, is Direct Torque Control (DTC). It has emerged over the last decade to become one possible alternative to the well-known Vector Control of Induction Machines [1, 2]. Its main characteristic is the goodperformance, obtaining results as good as the classical vector control but with several advantages based on its simpler structure and control diagram. DTC is said to be one of the future methods of controlling the induction machine in four quadrants [3, 4]. In DTC it is possible to control directly the 4 stator flux and the torque by selecting the appropriate inverter state. This method still requires...