Research On Smooth Control Strategy Of Non-inductive Permanent Magnet Synchronous Motor For Fan

In recent years,with the rapid development of rare earth permanent magnet materials,the magneto synchronous motors with rare earth as the main materials have also been improved.Compared with dc motor,it has the advantages of no mechanical commutation structure,small volume,light weight,low rotor heat,long service life.Compared with asynchronous motor,his method of control is simple and it has good performance.And his operation don’t need excitation current,so it has higher power factor.The motor structure is relatively simple and the motor operation efficiency is higher.Because of these reasons,in industrial control,automotive,electrical and other fields,application range of permanent magnet synchronous motor more and more widely used.Usually,Field-Orient Control is a general method to realize the control of permanent magnet synchronous motor,which can realize motor operation with high control accuracy and dynamic performance.It also has wide range of speed regulation,and its calculation formula is relatively simple,easy to implement.But for this Field-Orient Control,the rotor position information and speed is necessary to be knew.Only in this way,can accurately apply magnetic field force to the motor.In engineering practice,a variety of sensors are used to solve the motor position,like hall,photoelectric encoder,rotary transformer.But,to some extent,it will limit the application scenarios and reduce the reliability of the motor.Therefore,the research and further development of necessary technology plays an important role in expanding its application scope and improving its control performance.Combined with practical problems and research status of sensorless control technology,this paper analyzes and introduces the commonly used control methods in detail.According to the different speed range of the motor,the optimization methods for the problems existing in the control of medium high speed and zero low speed were proposed,and the research objectives and work contents of this paper were determined.Firstly,the basic principle of Field-Orient Control was introduced in this paper.To some of these important links,simulation analysis was carried out,include SVPM modulation technology and the coordinate transformation.A sliding mode observer was established in two phase stationary coordinate system,application of sliding mode control theory.The existing problems of sliding mode observer were analyzed.In this paper,quasi-sliding mode functions were introduced to reduce the jitter of SMO.And the low-pass filter was replaced by the complex coefficient filter without phase delay to improve the estimation accuracy.In terms of Angle solving,rotor information was solved by the enhanced phase-locked loop in the two-phase coordinate system.The simulation results show that this method can reduce the jitter frequency and improve the estimation accuracy.Secondly,in order to solve the problem of low reliability of observer at the initial stage of motor startup,the stability of I/F startup was analyzed,the zero low speed control strategy of motor adopted in this paper was determined.A new transition function based on unit arc was designed to adjust the Angle deviation between the open and closed loop controls and realize the smooth operation of the motor within the full speed range.Finally,the hardware platform of the control system was designed and manufactured,and the corresponding software program was written based on IAR.Experiments show that the improved IF start can achieve smooth transition.the proposed sliding mode observer can used to reduce jitter,and the accuracy of speed estimation is improved.The performance of the fan is tested by dynamometer and air volume tester,and the test results meet the requirements.