Research And Design Of BLDC Motor Controller

BLDC (Brushless Direct Current Motor, short named BLDC) motor is a new type of DC motor, With development of power electronic technology, control theory and the emergence of the new permanent materials, BLDC is developing. Mechanical reversing device is replaced by electronic commutation device, so it has not spark, at the same time inherited good DC speed control performance.The beginning of this article analyzes the internal structure of BLDC, describe the principle of the motor running and establish the mathematical model of BLDC, introduce the key technology of BLDC controller, including motor control part, drive part arid the detecting of rotor position. According to the overall scheme of controller, setting the controller hardware platform:including the power supply circuit, the smallest system, power drive circuit, the detecting of rotor position, current detection and the power protection circuit control processor. The MC68HC908MR8as the core of the controller, it has a high speed operation, integrated more powerful event manager. Control strategy of speed control is adopted digital PID.Motor speed regulation principle is based on equilibrium equation of electric potential. The armature voltage PWM chopper change effective voltage of the motor to achieve the purpose of speed control.Software code use C language and assembly language programming. Main program is consist of initial subprogram and motor start subroutine, interrupt service subroutine including capture interrupt subroutine and A/D interrupt subroutine.