| In every field of daily life,permanent magnet synchronous motor(PMSM)is often used as spindle motor.Because PMSM has the advantages of small size,high efficiency,high power density and high torque output ratio,it is widely used in daily life,industrial production,aerospace and national defense and other fields where high performance is required.In the high-speed operation of motors,due to the slot effect,winding distribution and other causes of air gap magnetic field distortion of the motor,as well as the non-linear characteristics of inverters caused by dead-time,switching tube voltage drop and so on,a large number of high-order harmonics exist in the phase current of the motor.And the current waveform distortion is serious.Harmonic will increase the loss of motor and cause serious heat.At the same time,it will produce torque ripple,which will affect the vibration,noise and running stability of motor.Therefore,it is very important to study the dynamic characteristics of permanent magnet synchronous motor.According to the theory of motor design,we can reduce the fluctuation and vibration of the motor from two aspects: one is the optimization design of the motor body,the other is the control strategy.However,when optimizing the motor body,too many parameters will be needed,so that the optimal design can not achieve the desired results;and using the control strategy method,some motor parameters can be ignored.The control strategy uses the idea of harmonic injection to suppress the torque ripple of permanent magnet synchronous motor.It uses analytical method to transform coordinates,and bases on the harmonic torque equation and the analysis of the harmonic permanent magnet flux linkage,establishes harmonic current mathematical model in the rotating coordinate system.Through using double closed-loop control in synchronous rotating coordinate system: the harmonic current loop and voltage loop,and using the speed loop as the outer loop,makes actual current track current instruction and actual voltage track voltage instruction.It accelerates the response speed and control precision,using the generated electromagnetic torque offsets the torque ripple of the motor,and improves the harmonic state equation of each order harmonics.By using the synchronous rotation PI controller to control the harmonic current injection,the fifth,seventh,eleventh and thirteenth harmonic currents are extracted and controlled,and the harmonics torque are suppressed.It also reduces the vibration and noise in its operation state.In order to investigate the performance of the motor in the whole control system,the Multi-software simulation is used to control the whole motor.Maxwell,Simplorer and Simulink are combined to conduct joint simulation.The motor parameter model is designed in Maxwell;the inverters and parameter inductors are built in Simpler,which are connected with Maxwell and Simulink to reflect the performance of the whole control process;the control system block diagram of permanent magnet synchronous motor is built in Simulink,and the three parts are combined to form the joint simulation of permanent magnet synchronous motor.After that,the three connected parts need to be connected to Workbench to analyze the vibration and noise of the whole motor control system,so that it is more convenient to observe the vibration and noise of the whole system.Compared with PMSM without high-order harmonics,the proposed harmonic suppression strategy can effectively suppress the torque ripple and the vibration noise of PMSM by means of feedback and feed-forward 5th,7th,11 th and 13 th harmonics injection. |
PDF Full Text Request