A State Observer Design for Simultaneous Estimation of Charge State and Crossover in Self-Discharging Disproportionation Redox Flow Batteries
For redox flow battery management, this work addresses the challenge of estimating unknown crossover flux alongside charge state, but the approach is incremental as it combines existing observer techniques with a parametric model.
This paper designs an augmented state observer for simultaneous estimation of charge state and crossover flux in disproportionation redox flow batteries, achieving exponential error convergence to a bounded residual set. Experimental validation on a laboratory prototype shows effective performance during self-discharge.
This paper presents an augmented state observer design for the simultaneous estimation of charge state and crossover flux in disproportionation redox flow batteries, which exhibits exponential estimation error convergence to a bounded residual set. The crossover flux of vanadium through the porous separator is considered as an unknown function of the battery states, model-approximated as the output of a persistently excited linear system. This parametric model and the simple isothermal lumped parameter model of the battery are combined to form an augmented space state representation suitable for the observer design, which is carried out via Lyapunov stability theory including the error-uncertainty involved in the approximation of the crossover flux. The observer gain is calculated by solving a polytopic linear matrix inequality problem via convex optimization. The performance of this design is evaluated with a laboratory flow battery prototype undergoing self-discharge.