| Under the new national pattern of development,electric motors as the core of the manufacturing industry as well as national equipment have ushered in a new development mission.Due to its small size,high efficiency,low loss and wide range of speed regulation,PMSMs are widely used in industrial manufacturing,transportation and other national heavy industries as well as electric vehicles,medical equipment and other daily life areas.The complex air-gap magnetic field of a PMSM can trigger complex electromagnetic force waves,generating vibration noise that can lead to physiological and even pathological changes in the human body.The use of positionless control strategies can reduce system costs and improve robustness and reliability,but the current harmonics introduced by the injected signal can lead to more complex electromagnetic force waves,resulting in increased motor vibration and higher sound pressure level noise,which greatly limits the application of the motor.This paper investigates electromagnetic force waves and vibration noise under position sensorless control using a pulsating high-frequency signal injection method based on an inclined-slot built-in permanent magnet synchronous motor.The main work of this paper is as follows:(1)A mathematical model of a PMSM is established,the basic principles of vector control technology and SVPWM modulation algorithm are explained,the topologies of the rotating high-frequency signal injection method based on the convex pole effect and the pulsating high-frequency signal injection method are studied,and the two control strategies are simulated and verified in Matlab/Simulink.(2)Based on the Maxwell tensor method,the magnetic density of the air gap is calculated analytically using the "magnetic potential times magnetic permeability",and the electromagnetic force wave of the PMSM without the injection signal is analysed from the root cause of electromagnetic vibration,i.e.radial electromagnetic force wave analysis.The electromagnetic force waves are analysed for a)no load,b)considering sinusoidal current supply,c)considering the effect of harmonic currents supplied by the frequency converter,and the electromagnetic force waves of a straight slot and a stator slope motor are compared.The newly introduced current harmonic frequencies and their resulting electromagnetic force wave components are analysed using the pulsating high-frequency signal injection method for the straight axis in the estimated two-phase rotating coordinate system,and a universal expression for the electromagnetic force wave components is obtained.(3)The radial air gap magnetic density and electromagnetic force wave of the PMSM are obtained by joint simulation for the position sensorless control strategy.Firstly,finite element calculations are carried out for the PMSM synchronous motor in the static and transient fields respectively.Then,joint simulations are carried out for the PMSM synchronous motor with vector control strategy.Finally,a joint simulation of the PMSM synchronous motor with a position sensorless control strategy based on the pulsating high-frequency signal injection method is carried out.The simulation results under different operating conditions can verify the theoretical analysis results on the radial air gap magnetic density and electromagnetic force wave of the PMSM with the position sensorless control strategy.(4)Modal analysis,finite element simulation and experimental tests are carried out on the PMSM synchronous motor.An inclined-slot built-in PMSM was fabricated,and its basic electrical and geometrical parameters were consistent with the simulation model built.A three-dimensional model of the PMSM synchronous motor was first built,and finite element analyses were carried out using modal analysis software for the unwound stator,wound stator and nested housing stator respectively.The results obtained will be used as a basis for further analysis of the vibration acceleration and noise experiments of the PMSM synchronous motor based on the pulsating high-frequency signal injection method.(5)A 10kW,8-pole,48-slot inclined-slot built-in PMSM motor drive and vibration noise test platform is built to analyse the motor performance and vibration noise under vector control and position sensorless control.The vibration noise experiments were first carried out on a vector-controlled PMSM with different switching frequencies,and then on a position sensorless PMSM with different operating conditions,to verify the influence of the newly introduced current harmonics on the vibration noise and the correctness of the theoretical derivation and joint simulation of the electromagnetic force wave under position sensorless control.The comparison of the electromagnetic vibration noise is analysed for a)different speeds,b)different injection signal amplitudes,c)different injection signal frequencies and d)different switching frequencies.The theoretical analysis and simulation results of the electromagnetic force wave are verified experimentally and provide a basis for suppressing electromagnetic vibrations in PMSMs at the level of position sensorless control parameters. |
