Research On Improved Direct Instantaneous Torque Control Strategy For Switched Reluctance Motor

The switched reluctance motor(SRM)is a double salient pole motor with variable reluctance.The stator and rotor salient poles are made of silicon steel sheets with high permeability.There are centralized windings only on the stator.The motor has the advantages of simple structure and reliable performance,so it is suitable for running in various environments.The operating principle of SRM is "Magneto-resistive minimum principle",and the magnetic flux is always closed along the path of minimum magneto resistance.The instantaneous torque ripple of the motor in operation is large.At present,torque ripple is reduced mainly by optimizing motor structure and control strategy.The torque ripple is redu,ced and the system performance is improved by optimizing the control strategy in this paper.The torque ripple has become a hot topic in the research of the SRM because of its double salient structure.The basic principle of SRM is described and the mathematical model is established.The relationship between electromagnetic torque and position,inductance and current is analyzed.A direct instantaneous torque control strategy combining hysteresis control strategy and pulse width modulation is adopted.The reason of the ripple of the torque in the control process is analyzed,different control methods were formulated for single-phase and commutation zones.Taking into account the system response characteristics of the hysteresis controller in the hysteresis limit,the PWM equivalent strategy is introduced into the hysteresis limit.The output characteristics of torque under different conditions are analyzed,so that the phase winding could be applied with the corresponding voltage under different torque errors,and the torque can be controlled efficiently.Study on a three-phase 6/4-pole switched reluctance motor,the simulation of the HYPWM-DITC system is carried out through the MATLAB/SIMULINK platform,the operating conditions such as turn-on and turn-off angle of the motor system are set and the validity of torque control strategy is verified.The hardware experiment platform based on TMS320f28335 control chip is built.The peripheral hardware circuit is designed,the algorithm program is written,and the upper computer program based on Lab VIEW virtual instrument is developed.The relevant experimental waveforms are obtained,and the feasibility and control effect of HYPWM-DITC strategy are verified by analyzing the experimental results.