Current Sharing Method For Switched Reluctance Motor Speed Control

Switched reluctance motor(SRM)is a kind of new developed speed regulating motor,which has received extensive attention of the experts at home and abroad in recent years.Switched reluctance motor drive(SRD),composed of SRM and other units,is the new generation of motor drive system developed after the traditional AC/DC motor drive.The SRD is widely used and shows its advantages in many field at present.However,due to its special doubly salient structure and nonlinear magnetic circuit and electric circuit characteristics,the model of SRM is highly nonlinear,which make it impossible to use the method of analytical to get the model.At present,the high performance control for SRM needs to use the model information to realize,or at lest involves to optimize the turn-on angle and the turn-off angle.These problems increase the difficulty of SRM control.First,the basic theory and principle of SRM is proposed in this paper.And then the control strategies for SRM is introduced including the high performance control and the low performance control by quoting a large number of literature.The high performance control is about reducing the torque ripple and excitation parameter control.Most of these control strategies need to use the model of SRM,and involve the switch angle optimization,which greatly limits the application of the SRM.Second,a novel current-sharing method(CSM)is proposed to solve the speed control problem of the switched reluctance motor.According to the idea of the coordinate transformation of the AC motor,the method of the coordinate transformation can be applied to the current transformation of the SRM.Through a series of math computation,the reference phase current of the SRM can be acquired.The reference phase current of the SRM can be used to realize the close-loop control of the current.The proposed method not only need not the mathematics model of the SRM,but also need not the computation of the turn-on and turn-off angle for the SRM.Matlab/Simulink is applied to the simulation of the CSM.The simulation results prove the feasibility of the proposed method.Finally,refered to the research for SRM,a set of SRD based on CSM is developed.The system implementation process involves the design of hardware circuits and software algorithm.The hardware circuit includes a control circuit with digital processor(DSP)TMS320F2812PGFA as the core and rectifier circuit,power conversion circuit,current sensing circuit and optocoupler and trigger circuit.The software algorithm design is made up by two main sections,which is the DSP motor control algorithm program in slave computer and the LabVIEW display interface in principal computer.The speed control of the SRM based on the CSM is tested on the experimentplatform.The experiment results prove rightness and effectiveness of the proposed method.