Online temperature distribution estimation of lithium-ion battery considering non-uniform heat generation characteristics under boundary cooling

•A fan cooling system is designed to cool the battery boundary.•A thermal model of tab area is constructed by using lumped parameter method.•A difference equation of temperature distribution of the core area is constructed by using the heat balance method.•A disturbance observer is designed to estimate the state and disturbance simultaneously. Lithium-ion batteries (LIBs) generate a lot of heat in the course of use, which will lead to a highly uneven distribution of the temperature, thus affecting the accuracy of battery modeling, parameter estimation and thermal management. In order to solve this potential threat, an on-line temperature distribution estimation method of LIB considering non-uniform heat generation under boundary cooling is proposed in this paper. Firstly, a thermal model of tab area is constructed by using lumped parameter method based on the analysis of the heat generation and heat transfer mechanism, and this tab thermal model is regarded as the first kind of boundary condition of the cell core. Secondly, a difference equation of the temperature distribution of the core area is constructed by using the heat balance method, and the boundary conditions and convection coefficient model are also deduced. Finally, a disturbance observer is designed to estimate the state and disturbance simultaneously to further improve the accuracy of temperature estimation. Additional stability analysis shows the convergence of the proposed disturbance observer. Experiments and verification demonstrate that the proposed method is effective and has better estimation performance compared with the other traditional methods under four different cycles, and the estimation error is less than 1.5 °C.