Passive solution for Battery Disconnect Unit thermal management for electric vehicle fast charging: numerical study and experimental validation

Charging time is a major problem with electric vehicles development and use. The difficulty of finding a charging station and especially the duration needed for a full charge are becoming more and more important topics in electric vehicles selling points. Fast-charging is more and more used on new developed vehicles but also on existing vehicles. One of the limits of fast-charging electric vehicles is the overheating of the different components in the car, the station, and the charging system. One of the key components in this system is the battery disconnect unit. This element is responsible for monitoring, activating and deactivating the high voltage battery system. It is essential to maintain it at convenient temperatures and prevent it from overheating. These components are designed today for normal charging power, but with increasing charging powers and reducing charging time, thermal management of these components become essential. This paper presents a passive way to allow the battery disconnect unit to transfer more power without having to change the entire cooling system or vehicle high voltage power distribution system. A study is carried with simulations and experiments to validate the solution presented. A first test campaign is conducted to identify the hottest points of the system. The component that heats up the most is studied and the cooling solution is applied at this location. The thermal performance of this element is modeled on the GT-power software.