Research On Torque Estimation And Predictive Control Of Switched Reluctance Machines

With the development of the power switch and the special high-performance control chip for motor, Switched Reluctance Motor(SRM) has been gained widespread attention, having advantages of the simple structure, high reliability and wide adjustable speed range. While the disadvantage of torque ripple is zhe main problem limit the motor’s application, especially on the low speed, the impact of torque ripple on the overall performance of the motor is more serious. As SRM is a complex, highly nonlinear and strongly electromagnetic coupled system, instantaneous torque estimation and control become a difficult problem.In this paper, a method based on the calculation formula of linear model, using PWM as the drive signal to estimate the instantaneous torque is proposed. Different from the general linear model, without certain flux-linkage and current fuction in the position rage, it’s get the flux-linkage of partial derivative value of the position through the current feedback real-time calculttion. It improves the accuracy of the estimation of the instantaneous torque under the linear model and uses less priori knowledge and less position or flux-linkage imformation comparing the non-linear model.To simulate the actual control process, this paper builds the PWM, current sampling and calculating module in matlab, analyzes the parameters influencing the calculation, and verifies the feasibility of the piecewise linear estimation method finally.On the basis of prior estimate of the instantaneous torque it complete control of phase current and toque control through buiding the predicition model. Since there are peolems like many controllable parameters with mutual influence、no unique solution to the prolem of toque distribution and high requirement of the sensor on the commutation interval, toeque control becomes difficult problem. To address this problem, a strategy of torque dynamic allocation based on the a prediction result is proposed, which is use the results of duty ratio calculation as the basis of the torque distribution to ensure the torque distribution solution’s solvability and feasibility, implements the commutation torque during the period of smooth transition and relized torque’s smooth transition on the commutation interval.The torque sensor is expensive and difficult to measure the instantaneous torque. In order to observe the effect of torque control fast and easy it can be achieved by building a model of the actual motor. So this paper built a testing platform of switched reluctance motor’s static flux-linkage, the experimental platform help to get the motor flux-linkage characteristics easily and quickly.