State and parameter estimation of lithium-ion battery by Kreisselmeier-type adaptive observer for fractional calculus system

Lithium-ion battery´s complicated dynamics can be described as simple equivalent circuit (Randles circuit) containing Warburg impedance, which can be expressed as the fractional calculus. In order to control or identify lithium-ion battery system described as fractional order system containing unknown variable parameters, online parameter estimate mechanism for the coefficients of transfer function containing fractional order (like s^0.5) must be needed. In this paper, we designed the Kreisselmeier-type adaptive observer for the linear time-variable fractional order system. Then, we applied the proposed observer to the lithium-ion battery modeled by Randles circuit under semi-infinite linear diffusion, and confirm the effectiveness of our observer by numerical simulation.