Operation, system design, and control of a switched reluctance motor with multiphase excitation

This dissertation focuses on the operation, system design, and control of a switched reluctance motor (SRM) with multiphase excitation. In order to maximize the average torque of a five-phase 10/8 SRM with multiphase excitation, the relationships between the output torque of this motor and the multiphase excitation modes are investigated in the case of more practical current waveforms. The relevant dynamic performances of each phase current, phase torque, and output torque of the SRM are analyzed and simulated at different modes. Based on the established SRM numerical model and a proposed novel approach, the starting torque of this motor is maximized while the torque-speed curves is considerably improved. The off-line searching process for optimal parameters is achieved by the numerical calculation. Based on the conception of indirect torque control, a novel approach for speed feedback control of the SRM with multiphase excitation is presented. This method can effectively improve the overall dynamic performance of the SRM drive system with robustness against disturbance especially at low speed range. Relevant fuzzy logic based speed PI controller, firing angles' controller, and other considerations for the control system are addressed in details. To implement the real time operation and control of an 8/6 SRM with multiphase excitation, a feasible hardware system based on a DSP TMS320C240 has been designed and fabricated. A generalized 8/6 SRM model at multiphase excitation modes with mutual coupling effects is developed. Two specific models in the cases of three-phase and two-phase excitation modes are further described. A simplified control scheme is described. Based on the designed speed and current loops, feedback control of this SRM system with strong coupling and non-linearity is implemented. The comparison on the average torque between multiphase excitation and single-phase excitation is made at a given speed. It is shown that the SRM at multiphase excitation modes can produce more torque than that at single-phase excitation mode. Therefore, this type of SRM shows a good promise in electric propulsion application, where a high ratio of torque to the weight/volume of an electric motor is desired.