At present, the control of the brushless dc motor is mainly composed of dispersion device annular pulse distributor, software annular pulse distributor, special integrated chip annular pulse distributor, etc. This design chooses the third way, using PMM8713 three-phase or four phase brushless dc motor pulse distributor, SI -7300 a two phase or four phase power drive, power of four phase brushless dc motor drive circuit, in order to improve the level of integration and reliability of PMM8713 is Japanese sanyo electric company production of brushless dc motor pulse distributor, is applicable to three-phase or four phase brushless dc motor control. Control three phase or four phase brushless dc machine can choose 3 kinds of excitation ways, each phase minimum suction to pull out to 20 ma current, it not only satisfy the requirement of the power amplifier level after input, and are embedded in all of its input Schmitt trigger circuit, strong anti-jamming capability, power brushless dc motor driver circuit can be divided into two kinds of driving mode, the voltage and current. Current drive mode is the most commonly used PWM constant current chopper driver circuit, which is the most common way of high-performance drive, the drive circuit is used in the numerical control plasma arc cutting machine automatically adjustable high pressure system, the system of the motor is 42 byg009 type hybrid brushless dc motor, the driving voltage for dc 24 v. Through practice proved that the power brushless dc motor drive circuit control system has simple structure, stable performance, high efficiency, good torque frequency characteristics, can be widely used in small electromechanical integration equipment.