| Vehicle permanent magnet synchronous motor is a crucial component of the new energy vehicle development.Compared with other types of motor,it has certain advantages,such as simple structure,stable operation and small volume.Moreover,as the price of RE drops,the permanent magnet synchronous motor(PMSM)has more development potential.However,as a multivariable,strongly coupling and nonlinear system,the PMSM also has some problems to be solved,e.g.,the load fluctuation,the disturbance in the external environment,and the dynamic condition.These problems will affect the operation performance of the PMSM.Therefore,in order to achieve the robust control of the PMSM within the dynamic conditions,we need to improve and enhance the control strategy.Sliding mode variable structure control(SMVSC),as a nonlinear control strategy,has a certain immunization for the fluctuation of the load by the system and the external environment.This strategy has been widely studied as well as the response of state can be realized quickly during the dynamic condition.Based on the characteristics and application requirements of the PMSM in the hybrid electric vehicle,this paper analyzes the development of the control methods for the motor,and emphasizes the application and development of sliding mode variable structure control.According to the existing problems in the PMSM,the SMVSC is applied to the motor control system.Based on this control strategy,the current loop control and speed loop control are designed for the PMSM.The sensorless control is realized by the principle of observer.Finally,it meets the requirement of the robust control in the dynamic condition.The overall content of the study is as follows:(1)The structure and operation characteristics of the PMSM are introduced,and the mathematical models of the PMSM in the d-q coordinates and the ?-? coordinates are established according to the principle of coordinate transformation.Based on the basic electromagnetic properties,several schemes of vector control strategy are analyzed.Because the general vector control system of the PMSM cannot fully realize current decoupling control,many uncertainties such as the load fluctuation and the external disturbance affect the performance of the control system.In order to solve the problem of uncertain interference during the control process,the vector control scheme ofI_d(28)0 is determined according to the speed and the torque characteristics of the different schemes.The PMSM control system is designed based on the vector control strategy.The strategy is controlled for the PMSM through the current loop and velocity loop.A fractional order sliding mode control strategy for the velocity loop is proposed.The convergence of the system is proved through the Lyapunov function.The feasibility and effectiveness of the proposed strategy is verified by the Matlab/Simulink simulation.This strategy can not only reduce the impact of dynamic condition,but also enhance the immunization of the system under the influence of the external environment.(2)In view of the position sensorless control strategy of the PMSM,the observability is analyzed.Based on this characteristic,a sliding mode observer with an inverse tangent function is proposed to compensate the state delay effect in the observation process by angle compensation,this method is introduced to the position and speed observing.The performance of the sliding mode observer is verified through the Matlab/Simulink simulation.The estimation of the speed and position is obtained,and the estimation accuracy of the speed and position is improved.(3)Based on fractional order sliding mode control in the PMSM,the sliding mode observer is introduced as a sensorless sensor.The designed PMSM control system is applied to different vehicle operating conditions.The control strategy is verified through the simulation,the method is effectively and the robust control is achieved under the different dynamic conditions.The control performance of the PMSM is guaranteed. |
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