| 摘要 |
PURPOSE: To prevent the estimated error of remaining capacity by finding out the correlation coefficient based on the collected data per specified collecting time and stopping calculating the remaining capacity during the period when it does not show a significant correlation continuously for the specified times. CONSTITUTION: The voltage and load current of a battery 3 which are detected by a voltage sensor 9 and current sensor 7 are outputted from a input circuit 12, and a computer 19 samples them every 1ms up to 100ms, for example, in order to calculate their average values, then it makes the average data of 100 samples for the respective voltage and current. A correlation coefficient r is obtained from the data, and when the coefficient r is -0.9 or above, and it is 0.9 or below and furthermore the correlation does not continue for three times at the same time, the computer goes back to the data sampling step. When the correlation continues for three times, a data on the approximate straight line corresponding to the second correlation coefficient out of three times is used to obtain the voltage value corresponding to the specified discharge current, and the result is converted to obtain the remaining capacity of the battery, then its indication is updated. Thus, even when a regeneration braking is given or the current shows a slight change, an errorneous remaining capacity is hardly indicated.
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