Experimental and Theoretical Analysis of High Power Connectors for Hybrid Vehicles

Abstract

Hybrid electric vehicles (HEV) are the next evolutionary step of the automobile which substantially increases fuel economy and reduces emissions. They are comprised of many new technologies so there is limited information on their overall life and reliability. The electrical connectors used in HEVs conduct much more power and are more susceptible to failure and reliability problems under the vibration, thermal cycling and humidity environment in a vehicle. This work presents a detailed study on the performance of a round pin, silver-plated high power connector used for hybrid vehicles, including experimental testing using a custom-designed test stand and theoretical analysis by finite element methods (FEM). In order to emulate operational and environmental effects, a test stand is designed for the connector that is capable of measuring connector resistance, temperature and motions. When a connector is exposed to vibrations, experimental results show that the connector resistance increases and oscillates significantly. When the vibrations are stopped, connector resistance returns to a value that is close to the original state. In order to analyze this phenomenon, a two-dimensional finite element model is developed to calculate relative displacement between the male part and female part of the connector. After being validated by experiments, the model shows that the simulated relative displacement is closely related to the changes of connector resistance under vibration, as measured in experiments. The relative displacement is then used as input for a three-dimensional finite element model that studies the time response of the contact spring. The simulation has shown periodical contact gaps between the spring and other parts of the connector, which cause the changes in connector resistance during vibration.