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19,867,000 Yen (FY1996 6,792,000 Yen)
Wide spreading of electric vehicles(EVs) is anticipated to reduce the emission of carbon di-oxide in traffic use. In practical EVs operation, un-conditional battery management leads the battery pack to severe functional disease, and this reduces the EV efficiency and the life of battery system significantly.
In this study, the prototype battery management system, that can monitor the dynamic information of each battery cell under the operating condition, has been made to improve the efficiency and life of the battery system of EVs. Utilizing this system, causes and mechanisms of this functional disease were clarified. The result shows that one of the main causes is un-uniformity of cell condition, (but un-uniformity of module battery condition) and once the un-uniformity occurred particular cell capacity falls in a high rate due to its frequent over charge/discharge conditions. This result was confirmed by checking the un-uniformity in practical EVs battery pack used nearly two years.
This system was also applied to manage the charging/discharging operation in practical EV settled on chassis dynamometer to find the proper managing algorithm during simulated driving test. The result shows that it is essential to manage the cell voltage (but module voltage) to prevent un-uniformity of battery pack. The result also shows that the charging procedure for equalizing is another key technology to improve the efficiency and life of battery system.
Electric Vehicle, Battery Management, Range