Battery diagnosis method, battery diagnosis apparatus and battery system for providing the method
Discussed is a battery diagnosis apparatus that includes a measuring unit to measure a battery voltage at opposite ends of a battery, and a battery current flowing through the battery; a storage unit to store an internal resistance value of the battery calculated based on the battery voltage and the battery current at each diagnosis time point; and a control unit to calculate, for the each diagnosis time point, a moving average that is an average of a plurality of internal resistance values corresponding to a number of previously stored samples based on the diagnosis time point, and comparing the internal resistance value calculated for the each diagnosis time point with an upper band threshold that is larger than the moving average by a predetermined value and a lower band threshold that is smaller than the moving average by a predetermined value to diagnose a defect in the battery.
1 . A battery diagnosis apparatus, comprising:
a measuring unit configured to measure a battery voltage at opposite ends of a battery including a plurality of battery cells, and a battery current flowing through the battery;
a storage unit configured to store an internal resistance value of the battery that is calculated based on at least one of the battery voltage and the battery current at each diagnosis time point; and
a control unit configured to extract a plurality of previous diagnosis time points corresponding to a predetermined number of samples based on a diagnosis time point for the each diagnosis time point, calculate a moving average that is an average of a plurality of internal resistance values corresponding to the plurality of diagnosis time points, respectively, the plurality of internal resistance value including the internal resistance value, and compare the internal resistance value with an upper band threshold that is larger than the moving average by a predetermined value and a lower band threshold that is smaller than the moving average by a predetermined value to diagnose a defect in the battery,
wherein the control unit is further configure to:
calculate an error value by multiplying a standard deviation average value, which is an average of a plurality of standard deviations corresponding to the plurality of diagnosis time points, respectively, by a predetermined multiple,
calculate the upper band threshold by adding the error value to the moving average, and
calculate the lower band threshold by subtracting the error value from the moving average.
2 . The battery diagnosis apparatus of claim 1 , wherein:
when the internal resistance value exceeds the upper band threshold,
the control unit diagnoses that a disconnection defect has occurred in at least one of the plurality of battery cells.
3 . The battery diagnosis apparatus of claim 1 , wherein:
when the internal resistance value is less than the lower band threshold,
the control unit diagnoses that a short defect has occurred in at least one of the plurality of battery cells.
4 . The battery diagnosis apparatus of claim 1 , wherein:
when the internal resistance value is within a range that is equal to or greater than the lower band threshold and is equal to or less than the upper band threshold,
the control unit diagnoses that the plurality of battery cells is in a normal state.
5 . A battery system, comprising:
a battery including a plurality of battery cells;
a measuring unit configured to measure a battery voltage at opposite ends of the battery, and a battery current flowing through the battery;
a storage unit configured to store an internal resistance value of the battery calculated based on the battery voltage and the battery current at each diagnosis time point; and
a control unit configured to extract a plurality of previous diagnosis time points corresponding to a predetermined number of samples based on a diagnosis time point for the each diagnosis time point, calculate a moving average that is an average of a plurality of internal resistance values corresponding to the plurality of diagnosis time points, respectively, the plurality of internal resistance values including the internal resistance value, and compare the internal resistance value with an upper band threshold that is larger than the moving average by a predetermined value and a lower band threshold that is smaller than the moving average by a predetermined value to diagnose a defect in the battery,
wherein the control unit is further configured to:
calculate an error value by multiplying a standard deviation average value, which is an average of a plurality of standard deviations corresponding to the plurality of diagnosis time points, respectively, by a predetermined multiple,
calculate the upper band threshold by adding the error value to the moving average, and
calculate the lower band threshold by subtracting the error value from the moving average.
6 . The battery system of claim 5 , wherein:
when the internal resistance value exceeds the upper band threshold,
the control unit diagnoses that a disconnection defect has occurred in at least one of the plurality of battery cells.
7 . The battery system of claim 5 , wherein:
when the internal resistance value is less than the lower band threshold,
the control unit diagnoses that a short defect has occurred in at least one of the plurality of battery cells.
8 . A battery diagnosing method, comprising:
a battery data collecting operation of collecting a measurement value of each of a battery voltage at opposite ends of a battery including a plurality of battery cells, and a battery current flowing through the battery;
a sample group determining operation of extracting, at a predetermined diagnosis time point, a plurality of diagnosis time points previously obtained and corresponding to a number of samples based on the predetermined diagnosis time point;
a reference value determining operation of calculating a moving average, which is an average of a plurality of internal resistance values corresponding to the plurality of diagnosis time points, respectively, an upper band threshold larger than the moving average by a predetermined value, and a lower band threshold smaller than the moving average by a predetermined value; and
a defect diagnosis operation of diagnosing a defect in the battery by comparing an internal resistance value corresponding to the predetermined diagnosis time point with the upper band threshold and the lower band threshold, from among the plurality of internal resistance values,
wherein the reference value determining operation includes:
calculating an error value by multiplying a standard deviation average value, which is an average of a plurality of standard deviations corresponding to the plurality of diagnosis time points, respectively, by a predetermined multiple,
calculating the upper band threshold by adding the error value to the moving average, and
calculating the lower band threshold by subtracting the error value from the moving average.
9 . The battery diagnosis method of claim 8 , wherein the defect diagnosing operation includes:
when the internal resistance value exceeds the upper band threshold,
diagnosing that a disconnection defect has occurred in at least one of the plurality of battery cells.
10 . The battery diagnosis method of claim 8 , wherein the defect diagnosing operation includes:
when the internal resistance value is less than the lower band threshold,
diagnosing that a short defect has occurred in at least one of the plurality of battery cells.