Browse Publications Technical Papers 2020-01-1345

Thermal Analysis of Electrical Contactor in Electric Vehicle Li-Ion Battery Packs 2020-01-1345

Modern high-power density automotive Li-Ion battery packs need robust and dedicated components to ensure efficient and safe operation of various constituent battery modules, and sub-systems. One such component is an Electrical Contactor (EC), which is an electronically controlled relay used for switching the high voltage power circuit of the DC battery pack. Specifically, the EC is operated by a control voltage that causes its internal current path to close during normal vehicle operations and open during certain pre-determined overload conditions. Therefore, ECs play an important role in providing a safe and reliable operation of an electric vehicle battery pack. An EC is typically connected to the power circuit of a battery pack through its load terminals via current carrying conductors like busbars and cables. To ensure a continuous operation of an EC under normal load conditions, the Joule heat generated by both the busbars and the internal EC circuity needs to be dissipated. Based on the power demand and voltage of the system, internal heat generation could result in overheating of the EC leading to its permanent breakdown, thus severely impacting vehicle operation and/or possibly causing safety hazards. Therefore, to understand the operation of an EC under various operating conditions within a Li-ion battery pack, analyzing its thermal performance under different loading conditions is of major interest. With that motivation, the current parametric study investigates the effect of the magnitude of electric current on the thermal behavior of a commercially available automotive EC using a time-accurate, conjugate heat transfer CFD analysis. For the numerical study, a general-purpose finite volume code STAR-CCM+ is employed with high spatial resolution grids to discretize different internal components of the EC. Within the numerical simulations, an electrodynamic potential model to calculate current density and the corresponding heat generation. In this paper, results from the experimental thermal measurements are also presented and are used to validate the numerical simulations with temperature dependent material properties. In the end, the spatial distribution of temperature, current and voltage in the EC and its connected components are presented and compared for various input current values


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