Design of brushless DC motor control system for electric vehicles based on microcontroller

The Green transportation is especially important as energy scarcity and air pollution from exhaust fumes from fuel vehicles become more and more serious. Electric vehicles have the advantages of non-pollution, low noise, high efficiency and simple structure, which will surely become the mainstream of transportation. Brushless DC motor as the drive motor of electric vehicles, it is much more efficient than the traditional brushed DC motor, can reach 80-90% high efficiency, in the same volume than the brushed DC motor output more power, with higher power density. Due to its simple structure, the maintenance and repair of a brushless DC motor is easier than that of a brushed DC motor. Therefore, this paper designs a brushless DC motor control system for electric vehicles, which is characterized by simple structure, high stability, good starting characteristics, precise speed control and low cost. In this paper, the design of the AT89C51 microcontroller as the main controller, through the microcontroller to generate pulse width modulation (PWM) signals to control the brushless DC motor, the drive circuit uses the H-bridge, the output of variable duty cycle pulse wave (PWM) to control the drive circuit, so as to make the motor for forward and reverse rotation. Twisting the electric car grip, the Hall element inside changes the magnetic field, resulting in a change in the output voltage of the grip, thus adjusting the output duty cycle and realizing speed regulation.