Research On Two Degrees Of Freedom Control Of PMSM Based On Model Design

Electric vehicles have become the mainstream of new energy vehicles due to their huge development potential,broad market background and considerable development prospects,which have become the main research direction in the automotive field in our country.The differences from traditional vehicles are that electric vehicles are required to consider factors such as energy consumption,output performance,reliability and cost on the basis of low carbon and environmental protection,which means that higher requirements are placed on the vehicle motor drive system.Compared with other drive motors,permanent magnet synchronous motor(PMSM)are favored by many vehicle companies due to their high energy efficiency,large torque,wide speed range,and good control effect.The PMSM control system is the core of the motor drive system,and the control strategy and system design dominate the performance of electric vehicles.This subject takes PMSM as the control object,conducting a deep research on motor control strategies based on the design of a low-cost,high-practical motor control platform.Due to the long development cycle,large workload,and low efficiency of traditional motor control systems,this topic applies the development method based on model design to the development process of motor control systems,and uses its unique advantages to improve development efficiency and code portability.The traditional PI control strategy is difficult to ensure that the speed response ability and interference suppression ability of the system can be optimized at the same time.To make up for the shortcomings of traditional PI control strategy,this article combines the two degree-of-freedom(2 DOF)control idea with the PMSM control system,and proposes a new type of 2 DOF PI control strategy for PMSM based on error judgment.Firstly,the article introduces the vector control idea of permanent magnet synchronous motor,analyzes and derives the mathematical model of the current loop,and uses the engineering tuning method to set the control parameters of the current loop in the case of various delays;then use the sampling frequency difference of the inner and outer loops equivalently simplifies the mathematical model of the current loop,adopts the multiple dominant pole method to adjust and optimize the PI parameters of the speed loop,and uses the rise time,overshoot and other time domain performance indicators design in consideration of the system steady-state error The 2 DOF PI control parameters are presented,and the feasibility and superiority of the proposed method are verified by comparison with traditional PI control simulation.Finally,a PMSM control hardware platform with TMS320F28335 as the core is designed and built.A control algorithm model that can automatically generate codes is established on the MATLAB/Simulink platform.The functions of the hardware system are tested and corrected.The experimental results show that the 2 DOF control could effectively improve the system performance,which has a certain research value and guiding significance.