Research And Design On Regenerative Braking Control System Of BLDCM

At present,the world is faced with environmental pollution and oil shortages.Electric vehicles use electric energy as the main energy source,which are environmentally friendly and reduce the dependence on petroleum energy,which is highly concerned by academia and industry.In the braking process,the traditional cars' most of the mechanical energy comes into heat by the braking friction.Electric vehicles use the motor as a driving component,you can use the motor braking power to recover the braking energy.This is not only an important part of vehicle energy management,but also can effectively improve the energy efficiency of electric vehicles and increase the driving range.The study of braking energy feedback is of great significance to reduce the energy consumption of electric vehicles and relieve energy and environmental pressure.In this paper,based on the literature review of brushless DC motor regenerative braking,the rotor rotor structure of brushless DC motor and its working principle are introduced in detail.Then,according to the commonly used two-way conduction,I simplely compared the driving method of electric drive of brushless DC motor.Brushless DC motor to achieve the basic principles of regenerative braking is the boost chopper circuit.Based on this,the general half-bridge regenerative mode PWM-OFF,full-bridge modulation current path and motor state equation are analyzed in detail.According to the problems and shortcomings of these two modulation schemes,a new half-bridge PWM-OFF-PWM modulation scheme is proposed to solve the previous two modulation'sthe continuing flow of the non-conduction phase and regenerative energy problems.A synchronous rectification and regenerative braking mode is also introduced to reduce the power loss.Before the selection of the regenerative braking control strategy,the conditions of continuous and intermittent winding current are obtained,and the conditions of maximum regenerative current and regenerative power are also analyzed.Based on the comparison of the regenerative braking four control strategies,the final selection of the system control mode is the constant current control of the regenerative braking mode.According to the mathematical model and working principle of the motor,a simulation model based on PLECS is set up.The simulation model includes two parts,one is the motor body part and the other is the motor controller model.The purose of the controller model is to verify the previous principle and control the modulation strategy.To sum up,the regenerative braking control system platform of brushless DC motor with DSP&CPLD control chip as the core is set up,and the hardware part of the system is described in detail,and the software flow of the system is designed.Finally,it is concluded that the PWM-OFF-PWM modulation scheme does not have the phenomenon of the continuing flow of the non-conduction phase,and it does not exchange energy with the battery when the brake is regenerated.The square wave characteristic of the motor is good,which verifies the correctness and feasibility of the system design.