Drive Control System Design Of Brushless DC Direct Drive In-wheel Motor

In-wheel drive is one of the most promising technic among many driving modes of electric vehicles(EV).Compared with the traditional vehicles,in-wheel drive vehicles have simpler structure,more efficient transmission chain,better maneuverability and higher energy utilization.Brushless DC(BLDC)direct drive inwheel motor has many advantages,such as high power density,small weight,simple structure,low noise and large output torque,making it widely used in EV in-wheel drive system.In this paper,the BLDC direct drive in-wheel motor has been selected as the main research object.First,the BLDC in-wheel motor drive control system has been designed based on DSP.Then,the sensored and sensorless control strategies have been discussed through the control system.Lastly,the test bench of in-wheel motor has been built to verify the rationality of the control system.The specific research contents are as follows:1)The research and application status of in-wheel motor at home and abroad have been reviewed,and the advantages and disadvantages of different types of in-wheel motors have been compared.The situation of BLDC drive control has been emphatically analyzed,which shows that it is significant to select BLDC direct drive in-wheel motor as research object.2)The basic structure and drive topologies of BLDC in-wheel motor have been introduced,Furthermore,the mathematical model of BLDC hub motor has been established,and the operation principle has been analyzed.The sensored control is unable to work under the position sensor breakdown,to overcome this disadvantage,the sensorless control based on the "back EMF method" has been discussed,and the double closed loop PI controller has been designed to improve the performance of the control system.3)The hardware and software parts of the control system have been designed,and their principle and the circuit parameter have been given in detail,DSP is the core of hardware system,which includes: the power circuit,the drive isolation circuit,the current and the voltage detection conditioning circuit,the protection circuit and so on.The system analysis has been carried on as the first step of software design.Then in order to facilitate the transplantation and reuse of software,the sensored and sensorless control algorithm have been designed respectively through modular design.4)The test bench of in-wheel motor has been built based on the hardware and software,the performance of BLDC in-wheel motor control system has been verified via the bench,and the performance of an in-wheel motor prototype has been tested.The experiment has been carried out under 4 working conditions including low speed and high speed state under load and no-load,the experimental results show that the control system meets the design requirements,and it can ensure the stable operation of the motor.Furthermore,The efficiency test of a prototype has been carried out,the experiment shows that the control system can run stable,and the design rationality of the control system is further verified.The bench can provide experimental support for the design and optimization of in-wheel motor.