Control System Design For Switched Reluctance Motor With Small Step Angle

The Switched Reluctance Drive(SRD) is a new-type speed control system which develops rapidly since 1980 s. It has not only advantages of the asynchronous motor, such as simple structure, reliable operation and low cost, but also possesses simple control and excellent speed controlling performance of DC motor.The reactive stepper motor is one kind of small step angle SRM. In this thesis, a small step angle switched reluctance motor control system based on resolver is designed. A three phase reactive stepper motor has been taken as the control object, and the experiments show that the speed and torque of this motor have been improved significantly. Besides, this system can also work in stepper motor mode at very low speed, therefore applications of stepper motor can be expanded greatly.Firstly, this thesis discusses the components of SRD as well as the structure and working principle of the SRM. Then inductance, flux linkage, phases current and electromagnetic torque of the winding are analyzed based on the SRM’s linear model. Furthermore, various control methods of SRM are discussed.Based on the theoretical analysis, a small step angle SRM control system platform with the dsPIC30f4011 as the core controller is established. At first, the resolver decoding system which is designed to detect the rotor’s position is given. Then the hardware circuits including the main circuit, drive circuit, control circuit, protection circuit and current monitoring circuit are developed. After that, the software design based on variable angle and voltage chopper control method is achieved, and the program flows of the main software part are given. besides, the key issues in this control system such as the commutation, speed calculation, PI controller design are also analyzed in this thesis.Finally, a motor control experiment platform has been built and comparisons have been made between several experiments’ results conducted in different control modes. The experiments’ results show that the reactive stepper motor’s speed and torque can be improved significantly when it is controlled in SRM control strategy, which indicates that the system has reached the expected target.