Traction battery management system
First Claim
1. A traction battery management system, comprising:
- detecting means for detecting battery conditions of a traction battery composed of a plurality of batteries and mounted on an electric vehicle;
calculating means for calculating battery charge and discharge conditions of the traction battery on the basis of the detected battery conditions; and
means for equalizing charging the traction battery on the basis of the calculated battery charge and discharge conditions, in such charging characteristics that charge current is relatively smaller and charge time is relatively longer, as compared with those in an ordinary battery charge, continuously after the ordinary battery charge.
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Abstract
To equally charge a plurality of batteries constituting a traction battery, when the number of times of the ordinary charges increases beyond a reference value or when the sum total watt-hour (charged energy or charged and discharged energy) of the traction battery increases beyond a reference value or when a difference in terminal voltage between the maximum and minimum values among the battery blocks increases beyond a reference value, the traction battery is automatically equalizing charged at a small charge current for a long charge time, continuously after the ordinary battery charge, periodically, thus facilitating the maintenance of an electric vehicle. Further, whenever the traction battery is equalizing charged, the remaining battery capacity meter can be reset to a full scale automatically to eliminate an accumulated error. In addition, the battery life is estimated for battery replacement.
195 Citations
15 Claims
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1. A traction battery management system, comprising:
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detecting means for detecting battery conditions of a traction battery composed of a plurality of batteries and mounted on an electric vehicle; calculating means for calculating battery charge and discharge conditions of the traction battery on the basis of the detected battery conditions; and means for equalizing charging the traction battery on the basis of the calculated battery charge and discharge conditions, in such charging characteristics that charge current is relatively smaller and charge time is relatively longer, as compared with those in an ordinary battery charge, continuously after the ordinary battery charge. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of equalizing charging a traction battery composed of a plurality of batteries, comprising the steps of:
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detecting traction battery current (A); detecting traction battery voltage (V); calculating power (P1 =A×
V) of the traction battery;calculating watt-hour (P2 =P1 ×
Δ
t) of the traction battery;calculating a sum total watt-hour (P2S(n) =Σ
P2) both during charge and discharge;calculating a difference (Δ
P2S(n) =P2S(n) -P2S(n-1)) in watt-hour between the sum total value (P2S(n)) to current sampling time and the sum total value (P2S(n-1)) to preceding sampling time;checking whether the calculated difference (Δ
P2S(n-1)) is zero or positive;if yes, checking whether the calculated difference (Σ
P2S(n)) is negative;if yes, counting the number of times that the calculated difference changes from positive to negative as the number of peaks (Nc); comparing the counted number of peaks (Nc) with a reference value (Nref); and if the counted number of peaks (Nc) is equal to or larger than the reference value (Nc), generating an equalizing charge command and clearing the counted peaks (Nc). - View Dependent Claims (14, 15)
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12. A method of equalizing charging a traction battery composed of a plurality of batteries, comprising the steps of:
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detecting traction battery current (A); detecting traction battery voltage (V); calculating power (P1 =A×
V) of the traction battery;calculating watt-hour (P2 =P1 ×
Δ
t) of the traction battery;obtaining an absolute value of the calculated watt-hour (P2AB =|P2 |); calculating a sum total absolute watt-hour (P2ABS =Σ
P2AB) both during charge and discharge;comparing the calculated sum total absolute watt-hour (P2ABS) With a reference value (P2ABSC); and if the calculated sum total absolute watt-hour (P2ABS) is equal to or larger than the reference value P2ABSC), generating an equalizing charge command and clearing the calculated sum total absolute watt-hour (P2ABS).
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13. A method of equalizing charging a traction battery composed of a plurality of batteries, comprising the steps of:
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detecting traction battery current (A); detecting traction battery voltage (V); detecting a maximum terminal voltage (Vmax) among the respective batteries constituting the traction battery; detecting a minimum terminal voltage (Vmin) among the respective batteries; comparing a difference (Vmax -Vmin) in terminal voltage between the maximum and minimum values among the respective batteries with a reference value (Vref); and if the difference (Vmax -Vmin) is equal to or larger than the reference value (Vref), generating an equalizing charge command.
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Specification