Research And Design Of BLDCM Controller For Electric Vehicle

Traditional cars are major energy consumers,while automobile exhaust is also one of the major sources of air pollutants.As the global energy crisis aggravates and air pollution becomes more and more serious,people pay more and more attention to electric vehicles because electric vehicles can realize zero pollution emission.Electric vehicles are electrically driven and consume clean energy,so developing pure electric vehicles is of great significance and imperative.The Brushless DC motor has the advantages of high power density,small size,strong overload capacity,low price,wide speed adjustment range,simple control mode,etc.Therefore,brushless DC motor is more used in electric vehicles.This paper makes a related research and design on brushless DC motor controller for electric vehicle.This paper introduces the basic structure of brushless DC motor and the basic principles of the motor and the corresponding conduction mode.Based on this,the mathematic model of the motor and the equivalent equation are deduced.The research hotspot of the current brushless DC motor is also introduced.Based on the analysis of the motor principle,aiming at the problems of the original hysteresis control of BLDCM and the lack of control of the bus current,a current following control strategy is proposed and described in detail.Because of the relatively high comfort requirements of electric vehicles,we have studied and analyzed the commutation torque ripple of the motor.By analyzing and mathematical derivation,a commutation current fractional speed restraint strategy can theoretically eliminate the commutation torque ripple.Then for the mileage problem of electric vehicles,we make a correlation analysis of energy feedback braking.After comparing the advantages and disadvantages of half-bridge modulation and full-bridge modulation,a modulation scheme combining half-bridge modulation and full-bridge modulation for electric vehicles is proposed,which can not only maintain the stability of braking but also maintain Energy as much as possible feedback.Based on the theoretical analysis,we build the simulation model of the control system through the combination of MATLAB and PLECS,and verify the rationality and feasibility of the previous control strategy by simulation analysis.Based on the theoretical analysis and simulation,we design a controller based on DSP(TMS320F2833)&CPLD(EPM570T10015).The hardware circuit of the system and the corresponding software flow chart are analyzed in detail.Finally,the related experiments are done on the controller.Experiments show that the current follow-up control strategy proposed in this paper,torque ripple suppression strategy is correct,can control the motor well,the motor current square wave characteristics are good,the motor is relatively stable.At the same time,the experimental results also reflect that the modulation mode that combines half-bridge modulation with full-bridge modulation maintains the stability of braking and keeps the energy as much as possible.