Design Optimization of Powertrain Mounting System for Electric Vehicles

Abstract

The development of Noise, Vibration, and Harshness (NVH) optimization methods for newlinePowertrain Mounting Systems (PMS) in traditional Internal Combustion Engine (ICE) vehicles newlinehas been well-established and refined over several decades. However, with the rapid newlineadoption of electric powertrains to meet low-emission standards, a new approach has become newlinenecessary to analyze and address NVH phenomena specific to Electric Vehicles (EVs). newlineThis thesis introduces the development of a multi-objective design optimization approach newlinefor the PMS of EV. Existing theories and design methods for mounting system design optimization newlineused in ICE faced a limitation in addressing the impact on the progression curve, newlinehigh-frequency resonance, durability, and integration robustness. These limitations are addressed newlineby the proposed method, which offered a comprehensive system design framework newlinefor the PMS. newlineThe work was carried out in four stages. The study followed the stage 1 process of a 6 newlineDegrees of Freedom (DOF) mounting system analysis in EV to predict optimal mount dynamic newlinestiffness and location. The primary goal was to optimize kinetic energy decoupling newlinerates and modal separations. The EV mounting system demands the operational torque to be newlinewithin the linear progression zone to ensure mode separation across various driving torques. newlineTherefore, the progressivity analysis has been included in the 6DOF study. The progressivity newlinerefers to the mount s ability to gradually increase stiffness as load or displacement increases, newlineallowing it to adapt to varying driving conditions. This characteristic enhances both ride comfort newlineand vehicle durability by balancing vibration isolation with the necessary support under newlinehigher loads. ICE vehicles tend to produce low-frequency noise from the engine s combustion newlineprocess and exhaust system, whereas EVs generate high-frequency noises from the electric newlinemotor. Therefore, it was essential to analyze the high-frequency motor resonance with the newlinerubber mount eigenmodes, included in stage 1, which was not necessar