Research And Development Of Speed Fluctuation Suppression Function Of Vehicle Motor Controller

Permanent magnet synchronous motor(PMSM)has been widely used in the field of electric vehicles due to its high efficiency,low cost,wide speed range and other advantages.During the operation of the motor system,the fluctuation of motor speed is mainly due to the change of internal parameters of the system and the change of external working conditions.These fluctuations will greatly reduce the user’s driving experience.This paper studies the suppression of motor speed fluctuation in the case of the change of external working conditions in combination with engineering practice.In terms of suppressing the speed fluctuation technology of electric vehicles,torque compensation and voltage compensation control strategies have been widely used in engineering practice,and the traditional compensation control strategy has poor automatic adjustment function,motor speed jitter delay,and poor control effect due to changes in real-time working conditions.Therefore,a torque compensation and voltage compensation control strategy based on fast Fourier analysis is designed with reference to the existing literature.The control strategy performs fast Fourier analysis on the AC and DC shaft current and motor speed,extracts the largest value in the signal spectrum and its corresponding frequency,as the characteristic value of suppressing motor speed jitter,which will change with the change of working conditions and has strong applicability.For the extracted characteristic values,as the control variables of the parameters in the control strategy,combined with the ACDC shaft current and motor speed signal,the AC-DC voltage compensation signal and motor torque compensation signal are output to generate additional compensation signals and cancel each other out of the original signal of the motor to achieve the purpose of suppressing speed fluctuations.Matlab/Simulink software is used to build a simulation model of permanent magnet synchronous motor system for comparative research and analysis,and the random load signal is input to simulate the change of actual operating conditions,and before and after adding the AC and straight shaft voltage compensation signal and motor torque compensation signal through simulation analysis,The average transcendent voltage fluctuation is reduced by 0.5-1,the average trans-axis voltage fluctuation is reduced by 2.2-3,the motor torque fluctuation is reduced by 0.4-0.5(N*m),and the motor speed is reduced by2000(r/s),and the simulation results show that the control method has obvious effect on suppressing motor speed fluctuation.On the basis of simulation analysis,combined with the actual engineering situation,the actual test is carried out on the whole vehicle,and the parameters of the host computer are controlled to realize the opening and closing of the strategy of suppressing motor speed fluctuation.Through actual tests,it is verified that the motor speed does not fluctuate under different working conditions after the control strategy is turned on,and the driving feeling is good,which shows the application value of the method in engineering.