An interlaced co-estimation technique for batteries

The problem of simultaneous online co-estimation of the battery state of charge (SOC) and the parameters of the open circuit voltage (OCV) vs. SOC characteristic is investigated. It is shown that any co-estimation technique requires at least one known point in the function that approximates the OCV vs. SOC map. A third-order bilinear co-estimator based on the equivalent circuit model of the battery is then proposed and its well-posedness is analyzed. The technique is validated on real data coming from an automotive application.