Interior Noise Analysis And Control Of Pure Electric Vehicle Based On Power-train Excitation

The paper is mainly about the optimization plan of the prominent noise problem from power-train of electric vehicles.It analyzes and optimizes the problem from two aspects,excitation source and transmission path.The way to lower the electromagnetic noise and the high-order noise of the vehicle is mainly about reducing the excitation source.In order to solve the problem of low-order noise,measures are taken to avoid resonance in the optimization path.And then the optimization plan is verified by real vehicle,and the noise of each order inside the vehicle is reduced and meets the request of the standard,which can be put in to the market.The main research contents and conclusions of this paper are as follows:(1)According to the analysis and summary of the characteristics of the noise in electric vehicles,it is concluded that the power-train noise which appears while working is the main noise source.By taking electric vehicle of a certain brand as the research object,three problems were confirmed through evaluation and vehicle test:there is 60-order noise in the vehicle under the working condition of full acceleration;8.58-order noise appears in the car sometime when we do speed up and down while driving;22-order noise shows up while vehicle is sliding with power.(2)After analyzing the mechanism of vibration noise which generates by the motor,motor controller and reducer of the power-train of electric vehicles and making relevant analysis on test vehicles,discoveries about the causes of the 3 noise problems are made: the 60 th order noise in the car is caused by Harmonic Excitation of motor teeth and modal resonance amplification of motor shell;There is no subjective evaluation on the noise made by motor controller which is too quiet;the 8.58 th order noise and 22 th order noise in the car are mainly generated by gear engagement excitation of the reducer.(3)Theory analysis: firstly,according to the theory of model,I made tests and simulation process which are described in the paper.Taking the sub-frame as an example,modal simulation analysis and actual sample modal test are carried out respectively,the relative error control between the simulation results and the test results is within 5.0% which reaches the requirements of finite element analysis.Secondly,according to the principle of transfer path,I analyzed the path generated by the noise in the electric vehicle.Through the test of acoustic transfer function and the test of acoustic transfer function,the key point to solve noise problem is the path aspect,and this provides the basis for the next rectification of real vehicle.(4)Solving the 3 noise problem is from incentive source and path and taking the factors such as cost and cycle into consideration in the meantime,different rectification plans were adopted for each problem and manual samples are made to realize the verification.The real vehicle test shows: the 60-order noise in the car is reduced by 12.0dB(A)on average through the motor shell strengthening plan;the8.58-order noise’ peak is reduced by 5.1dB(A)by the plan of increasing the quality of the front sub-frame and adding reinforcing beam to it;the 22-order noise in the car is reduced by 7.2dB(A)on average through the scheme of reducing the normal pressure angle of the gear.