A Theoretical and Experimental Investigation of NVH of In-Wheel Reducer and Motor Drive System

To enhance the power density of the system and reduce production costs, the high-speed electric drive system featuring integrated design and control is poised to be the future development trend. However, the high speeds of motors and gear reducers can lead to challenges such as system reliability and issues related to NVH. This paper specifically addresses the NVH concerns associated with the in-wheel reducer and motor drive system (IWRMDS). First, a bench test scheme is established, and vibration and noise tests are conducted under a range of conventional operating conditions. The results indicate that at a torque of 200 Nm and a speed of 5500 rpm, the noise sound pressure level reaches 86.2 dB, highlighting significant vibration and noise issues within the system. Subsequently, Operational Deflection Shape (ODS) testing and analysis are performed on the system. It was discovered that the IWRMDS exhibits a relatively rich modal frequency spectrum, with the breathing mode being the most prominent at the 48th order. Finally, to address the 48th order vibration of the motor, this paper introduces an optimization approach for segmented skewed rotors that considers current phase dynamics, resulting in a reduction of nearly 30% in radial electromagnetic force for critical harmonics. This strategy reduces the radial force at its source and offers valuable insights for optimizing the NVH performance of the hub electric wheel system.