ABSTRACT The development and validation of an electric vehicle presents numerous issues that are not normally encountered during the development of a traditional internal combustion powered vehicle. Many of the issues that are encountered involve components that are common to both electric and internal combustion vehicles but are utilized in new or unique ways that may present challenges during the development process. The integration of the electric motors, power supply, batteries, and associated content into a traditional vehicle can bring new and challenging issues to light. This paper discusses the solution for an issue that arose during the testing and development of the chassis and powertrain hardware of an electric vehicle. In particular, the large rotational inertia of the electric drive motor presented significant challenges when it was accelerated by forces that were external to the drive unit. In this instance the acceleration combined with the large inertia of the motor caused excessive loads to be transferred to the powertrain mount system and caused a failure of the mount system. As in any vehicle under development, it was highly desirable to use low mass hardware whenever possible. As such, an innovative control system was developed to monitor the vehicle systems for instances in which excessive rotational acceleration of the electric motor was possible. When the acceleration and corresponding mount loads were predicted to cause damage to the mounting hardware, the control system took preemptive action to dissipate the excessive energy. The newly developed control system was able to reduce the loading in the powertrain mount system significantly and allowed for the use of low mass hardware in the vehicle.INTRODUCTION The development of a hybrid or fully electric vehicle, while relatively well understood, can present significant challenges along the path toward production. The development process may uncover unexpected issues with the low mass components that are common with conventional vehicles. During the recent development of an electric vehicle, the early vehicle testing did not uncover any major issues with the chassis hardware. However, as vehicle development progressed, it was discovered that the powertrain mount system was not strong enough and would fail during severe durability testing. In the particular electric vehicle, the transmission contained two electric motors which were capable of propelling the vehicle. The motors, which were housed inside a transmission or drive unit, could be connected in parallel such that each motor contributed to the propulsion torque. Additionally, the drive unit could be configured through friction clutches such that one motor propelled the vehicle while the other motor was disconnected. In either case, the motors were connected to the final drive system through a planetary gear set which provided a reduction in the final drive speed (i.e. the motors spin faster than the final drive). The powertrain mount system utilized in the particular vehicle consisted of a 3-point pendulum-style mount system. In this system the powertrain was suspended from two upper mounts connected to the frame rails while a third lower link, the torque strut, connected the bottom of the powertrain to the cradle. This system design was efficient at isolating the powertrain vibrations from the rest of the vehicle yet allowed for a limited range of powertrain movement as the engine bay was very tightly packaged with various components. The limited range of motion of the mount system combined with the desired NVH characteristics meant that the system did not Powertrain Mount Load Mitigation on Hybrid and Electric Vehicles2011-01-0949 Published 04/12/2011 Eric Krueger and Patrick Monsere General Motors Company Copyright © 2011 SAE International doi:10.4271/2011-01-0949Downloaded from SAE International by University of Minnesota, Thursday, August 02, 2018have much range of motion before the rubbe