Two dimensional thermal model based observer design for lithium ion batteries

The safety, life, and performance of lithium ion batteries are all related to its thermal performance. The battery thermal process is a typical distributed parameter system which is spatiotemporal distributed. The online estimation of temperature distribution in vehicle battery systems is not easy as only few surface temperatures can be measured for the distributed parameter process. In this paper, a state observer is designed for lithium ion battery thermal process described by two dimensional partial differential equations. Based on the physical model of battery thermal process, a reduced order operational model suitable for online application is first obtained through Karhunen-Loeve decomposition. An adaptive observer is then designed based on the reduced order model. The whole temperature filed can then be reconstructed with the designed observer and measured voltage, current, and few surface temperature dates. Numerical simulation demonstrates the effectiveness of the designed observer.