Multi-Attribute Thermal Balancing on an Electric Vehicle, Focusing on Comfort and Fuel Economy

Hari Vijay

doi:10.4271/2012-01-2174

One of the key challenges faced by every engineer in the electrical vehicle development is to get the maximum range out of a single battery charge. There are several factors that impact the vehicle's range like the ambient temperature, electrical load, cooling system's efficiency, etc. Increasing only the vehicle range poses problems with another important vehicle attribute which is the passenger comfort. So, it is imperative for the engineer to understand the trade-off between comfort and range so that he chooses the right control strategy.

One of the important factors in affecting the vehicle range is the ambient temperature. At low temperatures, electrical power from the battery is used to warm up the cabin to improve the passenger comfort, thus discharging the battery very quickly. On the contrary, when the ambient temperature is high, it is important to cool batteries, electronics and electric motors to keep their efficiency high. To cool these units, cabin air-conditioning air is bypassed over different heat exchangers, thus bypassing the cabin. This increases the electrical load from the a/c compressor thus reducing the SOC quickly.

In this paper, author uses a system simulation approach using LMS Imagine Lab AMESIM to represent the various subsystems in an electric vehicle: electrical loads, batteries, air conditioning system, electronics and cabin models. All these subsystems are integrated into a complete vehicle and simulated over various FTP cycles to understand the trade-offs between range and passenger comfort.

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Multi-Attribute Thermal Balancing on an Electric Vehicle, Focusing on Comfort and Fuel Economy 2012-01-2174

SAE MOBILUS