Brushless dc motor controller and general dc motor with the same working principle and application characteristics, and its composition is not the same. In addition to the motor controller itself, the former is more than a commutation circuit, motor controller itself and the reversing circuit together. Many small power motor of motor controller itself is integrated with commutation circuit, look from the appearance of brushless dc motor controller and dc motor are exactly the same. Brushless dc motor controller of motor controller itself is electromechanical energy conversion part, it besides the armature, permanent magnet motor controller excitation two points, also with sensors. Motor controller itself is the core of the brushless dc motor controller, it is not only related to the performance index, noise, vibration, reliability and service life, etc. , involving the manufacturing costs and product cost. Developed on the basis of the traditional dc motor controller of permanent magnet brushless dc motor controller, on the structure of the basic are the same, different is the permanent magnet brushless dc motor armature winding on the stator of the controller, which is similar to the winding of the ac motor controller, generally takes the form of multiphase, at the same time, the current situation of the application of three-phase most; The rotor of permanent magnet, and USES the electronic commutation, the interaction between the stator magnetic field with permanent magnet rotor magnetic field produces electromagnetic torque. Permanent magnet brushless dc motor controller according to the shape of the permanent magnets and magnetic circuit structure is different, the air-gap magnetic field waveform three square wave, trapezoidal wave, sine wave, the back emf waveform corresponding to the same. In general, the electric potential is a sine wave motor controller called a permanent magnet synchronous motor controller,