Design And Research On Control Properties Of EPS System Based On PMSM

With the rapid development of modern control technology,electronic control system as the target of improving the vehicle driving safety,handling stability and riding comfort has become the research hot spot in the field of vehicle engineering.Do to the traditional EPS system has the problem of large torque ripple and steering torque response lag,this paper researched the control characteristics of EPS system which based on the method of SVPWM and direct torque control of PMSM and combined with assist torque compensation control strategy of EPS system,the research shows that the new control strategy can be better to reduce the EPS system boost motor torque ripple and improve the response rate of output torque.This paper combined with the research content of Education and Research Foundation of Chongqing(KJ120415) which is called “Control mechanism and key technologies of new electric power steering system with the active steering”.While based on the comprehensive consideration of the domestic and foreign status,it has optimization designed the structure of PMSM.At the same time,it has matching designed the reduction mechanism of new EPS system which based on PMSM.Finally,it simulation compared with the control characteristics of the EPS system which based on the method of SVPWM and direct torque control of PMSM and EPS system torque compensation control strategy.The concrete research contents as follows:1)According to the requirements of assist torque of the EPS system,the structure parameters of selection PMSM has been analysed and optimized.It combined with the finite element module of Ansoft Maxwell2 D and analysed the PMSM’s magnetic leakage and determined the magnetic circuit;According to the EPS system assist demands and the theory of motor design,it analysed the main parameters of stator and rotor of the motor,and established the basic model of the PMSM;Finally,it combined with RMxprt optimization module to optimize the structure of PMSM and improved the performance of the PMSM.2)It designed the structure of the transmission mechanism which based on PMSM of EPS system.For the foundation of optimized PMSM and combined with the power transmission project of the EPS system and analysed the structure parameter of the EPS system which based on the PMSM;It based on the PMSM and designed the reduction mechanism of transmission mechanism of the EPS system;Finally,trough combined withthe related control components and optimized PMSM & the reduction mechanism,it established the assembly structure of the EPS system.3)Established the dynamic model of EPS system and have simulated the EPS system which combined with the new control strategy.It analysed the characteristics of the booster,damping and returnability control strategy of the EPS system,and designed the assist characteristic curve of the EPS system;And it combined with PMSM mathematics model and established the simulation model,which based on SVPWM and direct torque control of PMSM and verified the good performance of the motor control strategy;Finally,it combined with torque compensation control strategy and PMSM simulation model and using Matlab/Simulink simulation software to build the simulation model of the EPS system and compared with the torque control characteristics of the motor,which based on classic EPS system control strategy and new strategy of EPS system.The simulation result shows that the new control strategy of the EPS system made the assist power much precise and it also reduced the power torque ripple,which improved the comprehensive performance of the EPS system.