Design And Research On Sliding Mode Control System Of Switched Reluctance Motor For Electric Braking

Motor is a key part in electric braking system.Its safety,rapidity and stability are of great importance for performance of the braking system.SRM is gradually applied in the aerospace field because of its excellent reliability.In this thesis,the SRM for electric braking system is taken as the research object.In order to solve the problems of torque ripple and nonlinear caused by the special structure of SRM,based on torque sharing function(TSF)and fractional-order terminal sliding mode control,the SRM control strategy is studied.Firstly,in order to simulate the system efficiently and close to the real operation situation,a co-simulation platform based on Maxwell-Simplorer-Simulink is built.This platform can can adjust the motor structure parameters and control strategy at the same time and provide simulation tool support for subsequent research content.Secondly,in order to reduce the torque ripple of SRM control system and the current spike of TSF,an online compensation improved TSF is proposed.Aiming at the torque ripple caused by inductance change during commutation of SRM,the compensation gain is adaptive to the real-time inductance change rate of SRM.For overcoming the current spike problem of TSF,the current and torque of the motor in the next cycle under different control variables are predicted,and the optimal control variable is selected according to the cost function.Thirdly,in order to overcome the problem of difficulty in establishing mathematical models caused by the mutual coupling of SRM variables.Sliding mode control strategy is adopted to control the SRM system.For solving the problem that the dynamic and steady-state characteristics of sliding mode control can not be satisfied at the same time,fractional-order calculus is introduced into sliding mode control.The stability and finite time convergence characteristics of fractional-order SRM control system are proved theoretically.Finally,in order to verify the effectiveness of the proposed content,simulation and experiment are carried out.The simulation results show that the online compensation improved TSF reduces the torque ripple and current spike of the SRM control system.Another simulation results show that the fractional-order terminal sliding mode controller can meet the requirements of electric braking system for the dynamic and steady-state characteristics of SRM control system at the same time.The experiment results are the same as the simulation results,which shows the practicability and feasibility of the proposed content.