Noriyasu Iwane
Abstract
After we succeeded in launching the lead-acid battery state sensor as the only one supplier in Japan, we have been making our best effort in improving the accuracy to gain more market share. From the viewpoint of controlling the automotive fuel efficiency and securing the reliability of the automotive power source, we think that it is definitely most important to detect the battery charge rate (SOC = State of Charge). It is necessary to combine several different elemental techniques to improve the estimated accuracy of the SOC. One of the typical ones among these techniques is the full charge detection. Its purpose is to detect that the battery reaches almost full charging state and set the SOC at the point as Full-Charge 100% to be the starting point from there on. Therefore, this accuracy will influence the whole estimated accuracy from there on. We have developed our original full charge detection technique applied from our original detection index “resistance ratio” which is based on the combination of the internal resistance increasing at charging and our battery equivalent circuit model learning technique from the pulse discharge. And we have succeeded in improving the SOC detection accuracy. Here, we are going to report the outline of our success mentioned above.
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