纯电动汽车高速工况下底盘后部空腔引起低频噪声问题的分析改进

Analysis and Improvement of Low Frequency Noise Caused by Rear Cavity of Chassis in High Speed Condition of Electric Vehicle

随着电机驱动技术以及空气动力学技术的不断提升,纯电动汽车高速化趋势愈发明显。纯电动汽车高速行驶时,底盘后部空腔引起的低频气动噪声峰值可超过60 dB(A),严重影响驾乘舒适性。以某纯电动汽车高速工况下的低频噪声问题为案例,系统地阐述了低频噪声问题的排查分析及产生机理分析验证过程。首先,分析了高速行驶激励源类型,并通过声学风洞进行激励源分离试验,锁定低频噪声为气动噪声类型;其次,对低频气动噪声形成的潜在机理进行推断,并设计试验进行潜在机理排查分析,确定底盘后部空腔涡声耦合自激振荡是引起低频气动噪声的原因;最后,通过仿真分析、半经验公式计算和实车试验验证了潜在机理,并设计工程化方案解决了该低频噪声问题。这对纯电动汽车高速工况气动噪声问题的分析识别与解决具有重要的工程意义。

With the continuous improvement of motor drive technology and aerodynamic technology,the trend of high-speed pure electric vehicles is becoming more and more obvious.At high speed,the peak value of lowfrequency aerodynamic noise caused by chassis cavity may exceed 60 dB(A),which seriously affects driving comfort.Taking the low-frequency noise problem of a pure electric vehicle under high-speed working conditions as a case,the investigation and analysis of low-frequency noise problems and the verification process of generation mechanism analysis are systematically expounded.Firstly,the type of high-speed driving excitation source is analyzed,and the excitation source separation test is carried out through the wind tunnel to lock the low-frequency noise as the type of aerodynamic noise.Secondly,the potential mechanism of low-frequency aerodynamic noise formation is inferred,and the test is designed to check and analyze the potential mechanism.It is determined that the vortex-acoustic coupling self-excited oscillation of the chassis cavity is the cause of low-frequency aerodynamic noise.Finally,the potential mechanism is verified by simulation analysis,semi-empirical formula calculation and real vehicle test,and the engineering scheme is designed to solve the problem.It has important engineering significance for the analysis,identification and solution of aerodynamic noise problems of pure electric vehicles at high-speed conditions.