| 摘要 |
A battery charger (3, Fig. 1) applies a charging current Ich to a plurality of series connected battery blocks 22, each having a plurality of battery units. To ensure that the battery blocks can be quickly charged to equal charge levels, each battery block 22 has a respective by-pass device 24 which is controlled to by-pass a part Ip of the charging current Ich when its battery block has reached a charge finishing stage. A by-pass device 24 may be initially activated when the voltage of its battery exceeds a reference voltage, when the rate of change of voltage exceeds a predetermined value or becomes negative, when the rate of change of battery temperature exceeds a preset value, or when the charge current becomes lower than a certain value. The by-pass device 24 may be controlled so that the current Ib through the battery decreases step-wise, Fig.5, or continuously (Fig. 6), towards a minimum value which may be applied for a specified time. The charger (3) may be turned off when all the battery blocks are receiving the minimum current, or when any by-pass device 24 fails. The charger (3) may be commanded to reduce the charging current Ich if the terminal voltage of a battery block reaches a specified value and the charge current Ich from the charger is still larger than a specified value. A 336 volt lead-acid traction battery in an electric vehicle may have seven battery blocks (22(1) to 22(7), Fig.1), each block being formed by four 6-cell unit batteries. Each battery block may incorporate a current sensor (14,15, Fig. 10), a temperature sensor (16,18), a voltage sensor (20), and a by-pass device 24. |
