Maintained a brushless dc motor (BLDCM) have a good control of brush dc motor features, on the magnetic structure and a brush dc motor, but it's the armature windings on the stator, permanent magnets on the rotor. Of brushless dc motor armature winding like ac motor winding, using multiphase form, through the drive to the dc power supply, the stator position sensor was adopted to realize electronic commutation to replace the motor of the brush and commutator, each phase of successive electrical current, the interaction between the main magnetic field and rotor poles, torque is produced. So at present in the advanced industrial countries, has a brush dc motor in the field of industrial automation has been gradually replaced by a brushless dc motor. Equipment imported from abroad, now it is rare to see in a brushless dc motor as executive motor system. These countries related company (Such as the United States, Britain, Japan, Germany, etc. )Mass production is no longer with the brush dc motor servo drive. In industrial applications, the brushless dc motor in power, control, reliability, small volume, light weight, energy saving, efficiency, tolerance has obvious advantages in environment and economy, etc. In recent years, along with the rare earth permanent magnet materials and power electronic device price performance ratio, as small and medium-sized power high performance brushless dc motor (BLDCM) speed control motor and servo motor in the industrial application is more and more widely.
