Improved design of switched reluctance motor drives

This dissertation investigates several drives related issues of the switched reluctance motor (SRM). To begin, the flux linkage of a 1/2 hp SRM is measured in the lab. The coenergy is calculated based on the flux linkage and the output torque is predicted from the coenergy data. The output torque is also measured directly and compared with the prediction.; A new graphical method to simulate the operation of the SRM is presented, which reduces computation and provides additional insight into the operation. Instead of solving the nonlinear differential equations, it predicts the current from a graphical representation of flux linkage. The nonlinear characteristics are fully considered. A modified graphical method is presented to improve the accuracy by taking the voltage drop on the phase resistance into account. The accuracy is verified by a comparison of the results of the modified graphical method with a conventional method based on the nonlinear differential equation and experimental results.; The mutual saturation effect is investigated and the experimental results show that the presence of the second phase current will have an influence on the saturation level of the first phase. This results in a change of both flux linkage and output torque. It is indicated that the proper arrangement of the winding connections can increase the output torque in the multiphase operation mode.; The problem associated with the split link converter at start-up and low speed operation is presented and analyzed in detail. A new control algorithm to solve the problem is presented and verified by experimental results. For normal speed operation the calculation of the capacitance in the converter to meet the voltage ripple requirements is derived.; A new SRM drive employing a novel encoder technology is built and tested. It features simple and effective control capability. There is no microprocessor in the drive, no A/D or D/A circuitry, with a drive system that matches the simplicity of the motor construction. Current waveform optimization for the encoder is carried out off line for high efficiency and programmed directly into the encoder. Experimental results validate the concept.