In order to improve dynamic response, anti-interference ability, general motor phase-locked control of electrical engineers can adopt the following two options: 1) dual mode control. In the large velocity error within the scope of the conventional speed feedback control, once in a preset error with the phase-locked control, avoid the area of nonlinear phase discriminator, only need to take account of stability of near equilibrium, the problems need lamination motor to be solved are two control mode of smooth switch and switch quickly after how to implement fast in a control cycle phase locking. 2) always controlled by phase-locked loop. As a result of the phase discriminator saturation phase characteristics, make the step response speed slower, and want to consider the special phenomenon of nonlinear systems, such as more balance, limit cycles and bifurcation and chaos, it needs to analyze the nonlinear characteristics of the phase discriminator and the global stability of the phase-locked loop, based on the nonlinear controller design phase lock. (2) high speed torque ripple suppression motor driven torque fluctuation is one of the basic motor part cause of speed fluctuation and noise. Flywheel motor speed, big moment of inertia of mechanical filtering effect to some extent, although you can reduce the torque ripple component influence on speed, but still need to through control measure to the disturbing torque in inhibiting within a certain range. Permanent magnet brushless motor electromagnetic torque is a function of the armature counter electromotive force and the armature current, the non-ideal back emf waveform caused by the torque ripple, often through direct the optimization of the current waveform control or suppression and compensation torque feedback loop. For used HALBACH magnet structure of high speed brushless dc motor, because of the nearly sinusoidal aerosols gap magnetic flux density distribution, the characteristics of sine wave modulation and space vector modulation can be used, it is helpful to reduce the torque pulsation of high-speed motor. (3) the method to control and reduce the iron loss High-speed operation of the brushless dc motor rated speed, the loss caused by current increased significantly, the loss occupies a considerable weight in the total loss, the loss including motor power amplifier of the loss, copper loss and motor winding with current caused by the additional loss. Among them, the loss of the first two are relatively small, and is determined by the third loss caused by the current size. Therefore reduce the additional loss caused by motor winding current become another important way for reducing power consumption. This part of the loss of the stator current is discontinuous jumping change caused by the loss in the rotor and stator www.facebook.com/dongfeng.motor current of PWM component caused by the loss of two parts.