Brushless DC motor is developed on the basis of Brushless DC motor. It is based on Faraday's law of electromagnetic induction, and backed by emerging electronic technology and digital technology. Brushless DC motor is mainly composed of permanent magnet motor body, control circuit and position detection. Its rotor is composed of permanent magnets, and there are polyphase windings on the stator. The biggest feature of Brushless DC motor is that there is no mechanical contact machine composed of inverter and brush. In addition, it usually uses permanent magnets as rotors. There is no excitation loss, and the heated armature winding is usually installed on the outer stator, so the thermal resistance is small and it is easy to dissipate heat. Therefore, brushless DC motor has no commutation spark, no radio interference, long service life, reliable operation and simple maintenance. In addition, its speed is not limited by commutation. If air bearings or magnetic bearings are used, it can run at speeds of up to hundreds of thousands per minute. Brushless DC motor has been widely used because of its good performance of servo control.