Battery monitoring systems
First Claim
1. A charging system for a traction battery pack divided into a plurality of sub-packs comprising:
- means for charging the battery pack according to a predetermined charging cycle, the charging cycle having a plurality of phases,means for measuring the voltages of the individual sub-packs,means for selecting the sub-pack having the lowest voltage,means for determining the rate of rise of the voltage of said selected sub-pack, andmeans for determining when said rate of rise falls below a predetermined level,one of said phases of the charging cycle being terminated when said rate of rise falls below said predetermined level.
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Accused Products
Abstract
A microprocessor based electric vehicle traction battery monitoring system evaluates the state of charge, interfaces with a traction motor control system, and controls recharging. The state of charge is evaluated during the first part of discharge by integrating the current after compensating it for rate of discharge and during the last part of discharge by dividing the battery into sub-packs and evaluating the state of charge from the lowest sub-pack voltage compensated for polarization voltage. The charge storage capacity is also calculated from the lowest sub-pack voltage. The maximum traction motor current is progressively limited during the last part of discharge. During charging, the charge withdrawn is replaced while progressively reducing the charging current and the battery is then charged at a constant current until the rate of rise of the lowest sub-pack voltage falls below a fixed level.
50 Citations
22 Claims
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1. A charging system for a traction battery pack divided into a plurality of sub-packs comprising:
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means for charging the battery pack according to a predetermined charging cycle, the charging cycle having a plurality of phases, means for measuring the voltages of the individual sub-packs, means for selecting the sub-pack having the lowest voltage, means for determining the rate of rise of the voltage of said selected sub-pack, and means for determining when said rate of rise falls below a predetermined level, one of said phases of the charging cycle being terminated when said rate of rise falls below said predetermined level. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of charging a traction battery pack comprising:
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performing a predetermined charging cycle on the pack, the cycle having a plurality of phases, dividing the battery pack into a plurality of sub-packs, measuring the voltage of each individual sub-pack, selecting the sub-pack having the lowest voltage, dtermining the rate of rise of voltage of said selected sub-pack, and determining when said rate of rise falls below a predetermined level, one of said phases of the charging cycle being terminated when said rate of rise falls below said predetermined level. - View Dependent Claims (8, 9, 10, 11, 12, 19, 20, 21, 22)
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13. A charging system for a battery comprising:
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means responsive to the battery current during charging and discharging for obtaining a current value, means for integrating the current value with respect to time to obtain a charge withdrawn value, and means for charging the battery according to a predetermined cycle, said cycle including a phase in which the battery is supplied with a charge equivalent to the charge withdrawn, the current being varied during said phase in accordance with the charge withdrawn value. - View Dependent Claims (14, 15, 16, 17)
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18. A method of charging a battery comprising:
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measuring the battery current during charging and discharging to obtain a current value, integrating the current value with respect to time to obtain a charge withdrawn value, and charging the battery in accordance with a predetermined cycle including a phase in which the battery is supplied with a charge equivalent to the charge withdrawn value, the charge being varied during said phase in accordance with the charge withdrawn value.
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Specification