On-line estimation of instantaneous torque in switched reluctance machine control

An inextensive and simple method to estimate the instantaneous torque of a switched reluctance machine online is developed and discussed in this paper. The presented technique is characterized by its simplicity and robustness in two ways. Only phase current and voltage are required as input variables. Therefore, shaft position-sensors can be avoided. Furthermore, the estimation algorithm can be realized in hardware, i.e. no processor is needed, the digital unit consists only of a simple memory device such as an EPROM. The estimation technique requires the machine characteristics. The method presented in this paper estimates torque as a function of flux linkage and phase current. With this real-time estimation and feedback of the instantaneous torque it is possible to control the torque with a hysteresis controller to obtain high performance drives. Furthermore, it is shown that the performance of the drive regarding torque-ripple can be significantly enhanced. The system is developed for the control of high performance drives as they are used in traction application. Experimental and simulation results are presented in this paper.