Abstract
Switched reluctance motor (SRM) possesses many structural and converter advantages, but due to the inherent features of double saliency and the nonlinear winding inductance, its torque generating is quite nonlinear and has high torque ripple. Therefore, sophisticated switching and control technologies are needed to improve its driving performance. The purpose of this thesis is to establish a DSP-based SRM drive and perform its driving performance improvement. First, the structural features of a SRM and its converter circuits are surveyed. Then the dynamic model derivation and estimation of a SRM drive are made. For making the performance test and evaluation of the developed control techniques, a DSP-based SRM drive is established. And some experimental results are provided to show its operating characteristics. Owing to the nonlinear winding inductance and non-ideal winding current waveform, the torque generating characteristic is significantly affected by the commutation timing. In performing the research about this issue, the effects of commutation instant variation on the motor torque generating characteristics under speed open and closed loops are first observed. Then accordingly, the intuitive tuning approach is developed to achieve the desired motor driving performance.Another purpose of this thesis is to perform the quantitative and robust speed control of the SRM drive. First, a two-degrees-of-freedom (2DOF) controller, which consists of a feedback controller and a command feedforward controller, is designed at nominal case to meet the given tracking and regulation control specifications. In the 2DOFC, the feedforward controller is basically an inverse drive dynamic model at nominal case. As the variations of parameters and operating condition occur, the desired tracking response trajectory can not be further obtained. To solve this problem, a fuzzy tuning inverse model is employed as the command feedforward controller. The development of fuzzy control scheme is described in detail. Finally, to further improve the operating characteristic under high speed, a front-end converter placed between the battery and the SRM converter is presented. The proposed converter can boost the battery voltage to a higher value. In addition, through proper connection, the converter can be operated as a switching-mode rectifier to charge the battery with good line drawn current power quality.