Research On Direct Torque Control System With Variable Flux For SRM

Switched Reluctance Motors(SRMs)have many advantages of intrinsic simplicity,easy control,high efficiency and reliability etc.Compared with traditional AC speed control system,Switched Reluctance Motor Drive(SRD)has good operating performance and economic indicators,even is better than the DC motor system,and has great application prospects.However,due to the double-salient pole structure and the saturation nonlinearity of electromagnetic relationship,resulting in a series of disadvantages of the high torque ripple and noise,which limits its application in low torque ripple situations.In recent years,due to the advantages of direct control,fast response and good robustness,direct torque control(DTC)technology is widely used into the torque ripple reduction for SRM.However,the traditional DTC method still has some limitations:in the traditional DTC system,the amplitude of given flux remains constant,which makes the torque ripple increase with the increasing of speed,even cause the phenomenon that the torque is out of control.In view of the above problems,the reason why torque ripple gradually increases with the increasing of speed is analyzed theoretically in this paper.Then,the DTC strategy with variable flux is proposed.In MATLAB/Simulink environment,the traditional DTC system is compared with the DTC system optimized by the variable flux strategy from the aspects of operation efficiency,torque ripple reduction and dynamic stability,the feasibility of the optimization algorithm is verified.Finally,the hardware experimental platform of SRM based on TMS320F2812 is set up,including the converter,control circuit and so on.The software design flow is given and make a detailed design for the subroutine of the system,then the entire control system is used to make the speed control and load testing.At last,the experimental results show that the proposed DTC strategy based on variable-flux method can effectively reduce the torque ripple,improve the system operating efficiency and has good dynamic stability.