The Control Strategy Research On Noise And Vibration For Permanent Magnet Synchronous Motor

With the rapid development of electric vehicles,the research and development of drive motors have received extensive attention currently.The permanent magnet synchronous motor has many advantages such as simple structure,reliable operation,small volume,light weight,small loss and high efficiency,and thus has been widely used.Due to the widespread use of converters to convert the direct current of the vehicle power supply into the three-phase alternating current required for the permanent magnet synchronous motor,the stator current of the motor contains a large amount of time harmonics,so that the air gap magnetic field also generates a large number of harmonics.Especially in the vicinity of the switching frequency of the inverter,the high-order time harmonic of the current generates a high-speed rotating spatial harmonic in the air-gap magnetic field,which significantly affects the amplitude and frequency of the electromagnetic force wave in the air gap magnetic field of the motor,and will cause electromagnetic excitation.The force frequency is close to the natural frequency of some modes of the motor and resonates to cause motor vibration and noise.With the surface-mount permanent magnet synchronous motor as the research object,this work focuses on the research of vector control strategy and spread spectrum modulation strategy of permanent magnet synchronous motor.The harmonic components of the stator current of the motor under four different modulation strategies: fixed switching frequency,periodic switching frequency,random switching frequency and mixed random switching frequency are analyzed.The simulation FFT analysis of the stator currents run by four different modulation strategies shows that the amplitude of the current harmonics run by three optimized control strategies decreases significantly but the differences among three are not obvious,the periodic switching frequency is better compared with others.The influence law from different modulation rate and spread width to the harmonic amplitude are analyzed.The vibration and noise test results also show that the vibration and noise of the motor runby optimized modulation strategy are reduced significantly.The test results show that the vibration and noise tests run by periodic switching frequency control strategy are not steady as others and the random switching frequency control strategy is better than others.The main research contents of this paper are as follows:1.Modeling of the control strategy for permanent magnet synchronous motorThe principle of the vector control strategy of permanent magnet synchronous motor is analyzed.For the motor type selected in this paper,the id=0 control strategy is selected.The vector control strategy is modeled based on the software MATLAB/SIMULINK.The accuracy of the model is determined by analyzing the stator current and the following conditions of the speed.2.Research on Harmonic Magnetic Field and Radial Electromagnetic Force of Permanent Magnet Synchronous MotorThe analytic method is used to analyze the influence of the motor on the magnetic field of the stator and rotor when the sine wave power supply and the inverter are powered.The air gap magnetic field and the radial electromagnetic force are changed due to the reference of the inverter.Radial electromagnetic force is the main source of motor vibration and noise.Therefore,the introduction of the inverter leads to the introduction of harmonics,which is one of the main causes of vibration and noise of the motor.3.Theoretical and Simulation Analysis of Spread Spectrum Modulation StrategyThe FFT transformation of the motor stator current simulation result under the fixed switching frequency modulation strategy is carried out,and the current harmonic amplitude and frequency under the control strategy are analyzed.Analyze the modulation principle of periodic switching frequency,random switching frequency and mixed random switching frequency and carry out modeling and simulation to compare the harmonic amplitude and frequency of the stator current of the motor under the above four different modulation strategies after FFT transformation.4.Experimental verification of spread spectrum modulation strategyBased on the MicroAutoBox II device for rapid control prototype experiment,the software aspect combined with SIMULINK and Controldesk to verify the reliability of theprevious control model after modeling and generating the code in the device.The motor speed in the experiment is reliable,therefore the control strategy is proved.Based on the noise and vibration test platform LMS Test.Lab,the noise and vibration tests of the steady-state motors under four different modulation strategies are tested in the semi-anechoic laboratory.The results of the analysis are compared and the consistency between the simulation and the experiment is verified.This research carried out the influence of the spread spectrum control strategy on the current harmonic amplitude,model and simulate different spread spectrum strategies,and test on noise and vibration of the motor in the semi-anechoic laboratory.The validity of the spread spectrum strategy and the consistency between simulation and experiment have been verified.