Research On Vibration Characteristics For Asynchronous Motor Of Sinusoidal Pulse Width Modulation

The pure electric vehicle powertrain system mainly consists of motor and reducer.The vibration and noise of the pure electric vehicles is much smaller than the traditional internal combustion engine vehicle's,but there is still much middle and high frequency noise from the power system in pure electric vehicles.For the pure electric vehicle power system which integrates the motor and gearbox,vibration characteristic are analyzed and summarized to find the source of vibration incentives,which is of great significance for research and improvement of vibration and noise of pure electric vehicle power system.The main research work and conclusions are as follows:(1)3D Geometric Wall Model and Double Fourier Transform are used to derive the Stator Phase Voltage Spectrum for two-level inverter.By converting the phase voltage to the rotating coordinate d/q axis,the relationship between voltage,current and torque signals from the motor equation is derived.Combining the mechanical excitation transmitted by the reducer,the main frequency components in the shell for vibration signal of the electromechanical integrated simulation powertrain system are analyzed by the analytical method.According to the magnetic circuit method,the main frequency components contained in the radial magnetic flux density of an induction motor under sinusoidal pulse width modulation are derived.Based on the Maxwell stress equation,the main frequency components of the radial electromagnetic force acting on a unit area at any point on the stator core are deduced,and the frequency distribution is summarized.(2)A rigid-flexible 3D model of an asynchronous motor-reducer powertrain system was established in LMS Virtual.Lab software.A 1D Model of an asynchronous motor.A OneDimensional is established in Simulink software,including DC power and inverter Model of a Three-Phase Electric Drive Motor.The vibration response under coupled excitation is calculated by Combining 1D and 3D model.The 2D Electromagnetic Coupling Model of Motor is established by Maxwell software.The simulation software is used to calculate the electromagnetic force on the stator using Maxwell and Simulink Co-simulation.(3)The vibration characteristic frequency components are analyzed by running electromechanical Co-simulation.When the rotor of the motor is excited at fixed speed,the vibration response only includes the gear mesh frequency and its harmonics.The vibration response includes the gear mesh frequency and its harmonics,6 times the fundamental frequency and its harmonics,and the 3,9 times fundamental frequency near the one-time switching frequency as the modulation sideband under SPWM control.When a standard sinusoidal voltage is input,the electromagnetic force includes 2 times the fundamental frequency and its harmonics and the rotor tooth harmonics.The electromagnetic force consists of 2 times the fundamental frequency and its harmonics,rotor tooth harmonics,1,3 times the fundamental frequency near the switching frequency and the rotor tooth harmonic as the modulation sideband under SPWM control.The correctness of the simulation analysis was verified by experimental testing and analytical derivation.(4)The induction motor harmonic suppression is analyzed.A method of suppressing the combination of the low-frequency oscillation and the nonlinear compensation of the inverter is proposed by combining the oscillation of the asynchronous motor during light load.By using the proposed suppression method for simulation,the stator current of the motor is stable,and the torque and speed fluctuations are greatly reduced.In addition,certain order harmonics in current and torque are eliminated.