Switched Reluctance Motor Direct Torque Control Strategy

The Switched Reluctance Drive system features low cost, wide speed variation range, good performance and high reliability. However, its greater torque ripple and noise problems restrict its application in some field. Direct Torque Control is well used in speed adjustment system of ac motor. It aims to control the torque, and could get a good control result on the speed and torque. If we could use it in the switched reluctance motor speed control system, it might inhibit the motor's torque ripple problems. The paper is based on this idea, and does a research on the use of direct torque control technology in the Switched Reluctance Drive system.The paper takes a four-phase 8/6 pole Switched Reluctance Motor as the research object. Aims to get an approximate circle shape stator flux, we compute the instantaneous amplitude and the angle of the flux through the coordinate transformation. And then we chose a suitable vector from the establish switch table to control the switching state of the power converter according to the values of instantaneous flux deviation, torque deviation and flux angle. To improve the performance of the torque, we design a three-step torque regulator and optimize the switch table, and then we carry out some simulation tests about the improved system. Further more we design several improved torque regulator on the basis of the traditional hysteresis regulator and also present some simulation analysis. The simulation results confirmed that the direct torque control technology in the SRD has the feasibility and good speed performance.To further improve the performance of the Switched Reluctance Drive system, in this paper, we propose the fuzzy direct torque control theory on the basis of the traditional direct torque control. It combines the traditional direct torque control with the fuzzy control, and uses the fuzzy controller to replace the original hysteresis regulator for the control of the switching state of the power converter. We also carried on the simulations to the fuzzy direct torque control system, and the results of the simulations show that it is of a better system performance and control effects than the traditional direct torque control.