Research On Control System Of Brushless DC Motor For Mini Electric Vehicle

With people’s increased awareness of energy conservation and emissions reduction, minielectric vehicle with zero pollution, small size, cost-effective and powerful usability becomeone of the vehicle models consistent with China’s national conditions.Brushless DC motor (referred to as BLDCM) control system is an ideal electric vehicledrive motor, because it both has AC motor’s simple structure and reliable operation and DCmotor’s high efficiency and excellent speed controlling performance characteristics, Therefore,this paper takes control system of BLDCM for mini electric vehicle as study object.The composition and working principle of automotive BLDCM control system is firstlyanalyzed. According to the requirements of mini electric vehicle on the drive system anddynamic indicators, the drive motor, main gear ratio and battery are matched, the overalldesign of control systems for mini electric vehicle is put forward.According to the overall system scheme and the actual need, this paper puts forward thehardware scheme of system and design method of the hardware, designs the hardware circuitincluding the microprocessor as the core of control circuit, power conversion circuit, strongand weak electric isolation circuit etc.On the basis of hardware system, according to the requirements of BLDCM controlsystem for mini electric cars, the software system design is put forward, software program isdeveloped including initialization, the main loop, interrupt, protection of the main functionsof software programs.In order to make the driver have a good driving feel and better recognition intention ofthe driver, the basic idea of intention recognition for the electric car driver is put forward. Andthen designs a synthesis control method of speed limit control and torque control whichrealizes the accurate torque closed loop control and speed limit control.To verify the performance of BLDCM control system with mini electric cars developedaccording to the above control scheme, a series of experiment is conducted including thecontroller performance tests, external characteristic of motor control system performance testand real vehicle experiment, the experiment proved that the control effect is satisfactory, thedesign has a certain practical value.