Thermal management in electric vehicle battery systems

In the wake of growing concerns over petroleum supplies and air pollution, electric vehicles (EVs) including hybrid electric vehicles (HEVs) are being developed and refined as cost effective, reliable and safe alternatives to conventional gasoline and diesel engines. The race is on to design electric batteries as the power source for this new class of vehicles. Competition is intense and the stakes are high. Organizations that succeed in bringing cost-effective, long-lasting batteries to market first are in a strong position to dominate the future automotive industry, not to mention reap a sizeable share of profits. One of the major concerns in the development of lithium-ion battery packs for EVs is thermal management. The temperature of all cells must be strictly maintained within limited degrees C across the entire pack. Cells are vulnerable to overheating from rapid discharging, overcharging or excessive ambient heating. Such overheating and uneven temperature distribution can lead to rapid cell degradation and shorten battery life. In extreme cases, thermal runaway may occur in a cell as heat builds up uncontrollably, possibly causing catastrophic destruction, such as fire and explosion. For these reasons, EV battery packs/systems/cells incorporate extensive cooling systems to dissipate heat and provide for uniform temperatures throughout the battery pack In this thesis, the design and thermal management of the electric vehicle battery systems are investigated. Thermal management works are made with finite element analyses in ANSYS Icepak programme. At the result of analyses, the design is validated and thermal performance is upgraded. The effect of the battery boundary conditions on the battery system is clearly demonstrated.