Device, method, and non-transitory recording medium storing program for specifying abnormality-occurrence area of secondary battery system
An apparatus for identifying a position of an abnormality occurred in a secondary battery system includes an information acquisition unit for acquiring information about a module (module information) from among a plurality of modules included in a module series that accommodates a block for which the difference between a block voltage value and a block voltage value after a primary delay has changed so as to exceed a voltage threshold within a preset time before and after the point in time at which the block voltage value and series current value stopped being correlated, a notification reception unit for receiving a notification about the occurrence of an abnormality in a secondary battery, and a module specification unit for specifying at least the module corresponding to the latest module information as the module in which an abnormality occurred when the notification reception unit receives a notification.
1. A method of identifying a position of an abnormality occurred in a secondary battery system, the secondary battery system comprising a plurality of modules each accommodating one or more blocks, the blocks each being formed by connecting battery cells of two or more secondary batteries, the method comprising the steps of:
performing voltage measurement by detecting voltage of the secondary batteries on a block by block basis, and outputting the detected voltage as a block voltage value;
performing string current measurement by measuring electric current of a module string formed by connecting the plurality of modules in series to output the measured electric current as a string current value;
performing information acquisition by acquiring module information of, among the plurality of modules included in the module string, a module accommodating a block where a difference between the block voltage value and the block voltage value with a first-order lag has been changed to exceed a voltage threshold value in a predetermined time period around a time point at which correlation between the block voltage value and the string current value is lost;
performing report reception by receiving a report of an abnormality occurred in the secondary batteries; and
performing module identification by identifying, as a module having the abnormality, the module corresponding to the module information at time of receiving the report in the report reception step.
2. The method according to claim 1 , further comprising the step of performing correlation determination by determining correlation between the block voltage value and the string current value,
wherein the correlation determination step comprises the steps of:
performing differential voltage accumulation by accumulating differences between the block voltage values sampled in a predetermined fixed period and the block voltage values with the first-order lag;
performing differential current accumulation by accumulating differences between the string current values sampled in the fixed period and the string current values with the first-order lag; and
performing correlation coefficient computation by dividing an accumulated differential voltage value obtained in the differential voltage accumulation step by an accumulated differential current value obtained in the differential current accumulation step to obtain a correlation coefficient in the fixed period;
wherein in a case that the correlation coefficient obtained in the correlation coefficient computation step is deviated from a predetermined range, correlation between the block voltage and the string current value is determined as lost.
3. The method according to claim 2 , wherein the predetermined range is determined based on an I-V characteristic of the block.
4. The method according to claim 1 , wherein a time constant of the first-order lag is selected in accordance with behavior where the block voltage drops temporarily due to short circuiting of at least one of the battery cells.
5. The method according to claim 1 , wherein, as the voltage threshold value, a voltage value of a temporary drop in the block voltage due to short circuiting of at least one of the battery cells is selected.
6. The method according to claim 1 , further comprising the step of performing error output by receiving the module information from the information acquisition step, and outputting the module information together with an error message.