Thermal Management in Electric Vehicles

All EV manufacturers are focusing on developing efficient, low cost battery-powered vehicles with a long driving ranges. In this respect, thermal management systems play a vital role in helping improve the overall range of the EV.

Here we broadly talk about 3 such systems.

1.       Battery Thermal Management System

2.       Electric Motor & Power Electronic Thermal Management

3.       Vehicle Interior Climate Control

  

Battery Thermal Management System

As everyone knows lithium ion batteries are widely used in electric vehicles as they have a high energy density and a good cycle life. However, performance of these batteries is highly dependent on working temperatures. The more the current that flows through the battery more are the losses experienced by the battery. These losses are in the form of heat generated in the cell. High temperature in the cell degrades its quality and reduces its life. This brings Battery Thermal Management System into the picture. Battery Thermal Management can be achieved through an active system or a passive one.

Another scenario in which a Battery Thermal Management system plays a role is in extreme external air temperatures. For example, when the air outside is well below freezing, the range of the battery drops considerably due to slower chemical reactions, whereas very high temperatures – say more than 400C – could damage the battery permanently.

 

Electric Motor & Power Electronic Thermal Management

As mentioned above current flow results in heat generation. So, along with the battery, all power electronic components as well as the electric motor also need to be cooled or heated. All these components operate at different temperature ranges and so the goal of the Thermal Management System is to always maintain them in their respective optimal zones.

Having different cooling or heating systems for each component wouldn’t actually help because all it would do is add complexity and additional load on the battery. So, the challenge is to develop a system with a minimum number of circuits while maintaining all components in their respective optimal temperature ranges.

 

Vehicle Interior Climate Control

Another thermal management system while not directly related to the battery but which can definitely hamper the battery’s performance has to do with controlling the climate in the vehicle’s interior. Maintaining comfortable air temperature inside the vehicle requires different cooling or heating circuits. Apart from maintaining temperature, designs also need to take extreme environmental situations – like the defrosting of the windshield – into consideration. Such conditions add even more load on the battery.

 

To conclude, electrically powered vehicles pose their own special challenges in the development of thermal management systems and to improve performance of the EV, optimum design of all these systems is essential.