Robust Polynomial Approach for State of Charge Estimation in Ni-MH Batteries

R.H. MILOCCO, J.E. THOMAS, B.E. CASTRO

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2011

0360-3199

In this work we estimate the state of charge (SOC) of Ni-MH rechargeable batteries using a robust optimal filter based on a simplified electrochemical model. The robust filter guarantees that the supremum of the error variance -difference between real and estimated SoC- with respect to all admissible uncertainties be minimum. First, we briefly describe the complete electrochemical model of the $NiMH$ battery. The full model is further reduced in a cascade of two parts, a simple integrator followed by a static nonlinearity. The inverse of the static nonlinearity works as a sensor software in such a way that its output is filtered, with the proposed robust design, to obtain SoC estimations. The results are compared with those obtained using the linear Kalman filter. We conclude that both estimations have similar performance, although the robust filter is easier to tune. Experimental results with commercial batteries are provided to illustrate the estimation procedure and it performance.