Permanent Magnet Synchronous Motor Control And Brake Energy Regeneration Of Electric Vehicle

In recent years,with the gradual improvement of people's living standards,the sales and ownership of automobiles in China are increasing year by year.However,traditional fuel vehicles,which use fossil fuels as power sources,will inevitably emit vehicle exhaust gas and cause air pollution.However,fossil energy is non-renewable energy,and with the use of people will gradually reduce and eventually exhaust.Due to the energy and environmental problem,electric vehicles using clean energy as energy source have attracted more and more attention.However,the current electric vehicles generally have the shortcoming of short range.In the case that power battery technology is too difficult to make breakthrough in a short time,the feedback braking technology can be used to increase the range of electric vehicles,especially in urban traffic conditions where braking is more frequent.In this paper,firstly,the mathematical model of permanent magnet synchronous motor in three-phase static coordinate system and two-phase synchronous rotating coordinate system are analyzed.Two common control methods of permanent magnet synchronous motor,vector control and direct torque control,are deduced.The commonly used voltage vector synthesis method,SVPWM,is expounded in detail.Then the commonly used Dual Active Bridge DAB and the six working modes of DAB in phase-shifted duty cycle mode are analyzed,and the small-signal model of DAB converter circuit is deduced.On the basis the previous theory,according to the definition of feedback braking,the function and structure of the feedback braking system are decomposed,and the shortcomings of the already existing feedback braking system are analyzed,and the feedback braking system of this paper is designed.According to the functional requirements of the system,the DAB converter is selected as the power recovery circuit of the system,and a hybrid energy storage system of power battery and supercapacitor which combined by the DAB converter is built.The time domain analysis of the feedback braking subsystem of PMSG-three-phase PWM rectifier in the feedback braking system is carried out,and the state space equation is derived.The key factors of feedback braking of electric vehicle are analyzed,and the feedback braking strategy of maximum feedback power and maximum feedback efficiency is designed.Finally,a simulation platform of the whole feedback braking system is built under MATLAB/SIMULINK,and two kinds of braking situations,long-time braking and deceleration braking,are simulated respectively.At the same time,the experimental platform of feedback braking is built in the laboratory.The experiments of charging and discharging of the ultra-capacitor,energy feedback from permanent magnet synchronous motor to the ultra-capacitor,and energy feedback from permanent magnet synchronous motor to the ultra-capacitor and batteries via DAB converter are carried out respectively.The simulation and experimental results verify the feasibility and effectiveness of the feedback braking system designed in this paper.