An observer looks at the cell temperature in automotive battery packs

• A generic observer for LPV systems limiting the influence of measurement noise.
• Battery diagnosis offered by internal resistance reconstruction for electric vehicle.
• Polytopic observer, simple to implement, with experimental results.
• Good quality of Li-ion battery cell temperature and internal resistance estimations.

The internal temperature of Li-ion batteries for electric or hybrid vehicles is an important factor influencing their ageing. Generally not measured, it can be reconstructed from an external measurement and a model. This paper presents the simplified modelling of heat transfers in a battery module, leading to a Linear Parameter-Varying (LPV) model. Then, a polytopic observer is proposed to estimate the cell temperature and internal resistance, ensuring a tradeoff between the convergence speed and the noise of the estimated states. Experimental results show the good quality of the estimation and the diagnosis potential offered by internal resistance reconstruction.