Abnormality detecting system for battery assembly
First Claim
1. An abnormality detecting system for a battery assembly having a plurality of battery cells connected in series, comprising:
- a plurality of detection units provided for the plurality of battery cells, respectively, each of the detection units being arranged to compare an output voltage of a corresponding one of the battery cells with a predetermined criteria voltage, the plurality of detection units operating sequentially in response to a start trigger, and sequentially transmitting a detection signal that reflects a result of the voltage comparison, so as to output an abnormality signal indicative of whether the output voltage of any of the plurality of battery cells becomes lower than the criteria voltage;
a current detector that detects a current that passes through the plurality of battery cells; and
an abnormality monitoring circuit that checks if an internal resistance abnormality as an increase of the internal resistance to a level larger than an upper limit thereof occurs in any of the plurality of battery cells, based on the detection signal received from the plurality of detection units and a current detection value obtained by the current detector,wherein the abnormality monitoring circuit comprises;
a current sampling unit that samples the current detection value of the current detector a predetermined number of times according to a predetermined sampling cycle;
a correction amount setting unit that sets a current correction amount that reflects a ripple component of the current, with respect to a criteria current corresponding to a current value obtained by dividing the criteria voltage by the upper limit of the internal resistance; and
a current comparing unit that detects the internal resistance abnormality when the abnormality signal indicates that the output voltage of any of the plurality of battery cells becomes smaller than the criteria voltage, and when the maximum value of a plurality of current sampling values obtained by the current sampling unit is smaller than a current value obtained by subtracting the current correction amount from the criteria current, andwherein the current sampling unit sets the sampling cycle such that a first current sampling time is set at a point in time at which a given length of time that is equal to or less than a half of the sampling cycle period elapses from the beginning of voltage comparisons for the plurality of battery cells in the plurality of detection units, and such that a final current sampling time is set at a point in time that precedes the end of voltage comparisons in the plurality of detection units, by a given length of time that is equal to or less than the half of the sampling cycle period.
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Accused Products
Abstract
An abnormality detecting system sequentially compares the output voltages of n-piece battery cells that are connected in series, with a criteria voltage, at respective points in time Tv1-Tvn, and produces a determination signal indicative of the presence or absence of any battery cell whose voltage becomes lower than the criteria voltage at time Tvc. The battery current Ib is sampled a predetermined number of times at intervals of a predetermined sampling cycle period ΔTi. The current sampling times Ti1-Ti3 are provided within a period that lies inside a voltage sampling period Ta-Tb including the above-indicated times Tv1-Tvn, with a given period of time (ΔTi−2) or less provided at each side of the period. When detecting an increase in the internal resistance based on a comparison between the maximum value of the current sampling values and a criteria current, the abnormality detecting system corrects the criteria current in view of a current variation in a half of the sampling cycle period due to current ripple.
22 Citations
6 Claims
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1. An abnormality detecting system for a battery assembly having a plurality of battery cells connected in series, comprising:
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a plurality of detection units provided for the plurality of battery cells, respectively, each of the detection units being arranged to compare an output voltage of a corresponding one of the battery cells with a predetermined criteria voltage, the plurality of detection units operating sequentially in response to a start trigger, and sequentially transmitting a detection signal that reflects a result of the voltage comparison, so as to output an abnormality signal indicative of whether the output voltage of any of the plurality of battery cells becomes lower than the criteria voltage; a current detector that detects a current that passes through the plurality of battery cells; and an abnormality monitoring circuit that checks if an internal resistance abnormality as an increase of the internal resistance to a level larger than an upper limit thereof occurs in any of the plurality of battery cells, based on the detection signal received from the plurality of detection units and a current detection value obtained by the current detector, wherein the abnormality monitoring circuit comprises; a current sampling unit that samples the current detection value of the current detector a predetermined number of times according to a predetermined sampling cycle; a correction amount setting unit that sets a current correction amount that reflects a ripple component of the current, with respect to a criteria current corresponding to a current value obtained by dividing the criteria voltage by the upper limit of the internal resistance; and a current comparing unit that detects the internal resistance abnormality when the abnormality signal indicates that the output voltage of any of the plurality of battery cells becomes smaller than the criteria voltage, and when the maximum value of a plurality of current sampling values obtained by the current sampling unit is smaller than a current value obtained by subtracting the current correction amount from the criteria current, and wherein the current sampling unit sets the sampling cycle such that a first current sampling time is set at a point in time at which a given length of time that is equal to or less than a half of the sampling cycle period elapses from the beginning of voltage comparisons for the plurality of battery cells in the plurality of detection units, and such that a final current sampling time is set at a point in time that precedes the end of voltage comparisons in the plurality of detection units, by a given length of time that is equal to or less than the half of the sampling cycle period. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification