Patent ID: 9246337
Filing Date: 2016-01-26
CPC Classification: G01R,H01M,H02J,Y02E,Y02T

Claim Text:
1. A battery pack that is electrically connected to a load, and that performs charging and discharging between the load, comprising: a plurality of battery units mutually connected in parallel, each including a cell group in which one or two or more secondary cells are connected in series, and a first current control element that is connected in series with the cell group; a first control unit that controls the charging/discharging current for each battery unit by controlling the operation of the first current control element included in each of the battery unit; a voltage measurement unit that measures the voltage of the cell group or cells included in each of the battery unit; and a diagnosis unit that diagnoses a deterioration level or a fault of each battery unit on the basis of the voltage of the cell group or cells measured by the voltage measurement unit, wherein the diagnosis unit calculates the DC internal resistance value of each battery unit on the basis of the voltage under load of the cell group or cells measured by the voltage measurement unit when the first control unit turns the first current control element on and the charging/discharging current is flowing to the load, on the basis of the charging/discharging current, and on the basis of the open circuit voltage of the cell group or cells measured by the voltage measurement unit when the first control unit turns the first current control element off and intercepts the charging/discharging current, and thereby diagnoses the deterioration level of each battery unit on the basis of the results of this calculation; and wherein: each of the battery units further includes a second current control element and a discharge resistor for forced discharge, connected in parallel with the cell group; the battery pack further comprises a second control unit that controls the operation of the second current control element possessed by each of the battery units; and the diagnosis unit calculates the DC internal resistance value of each battery unit on the basis of the open circuit voltage of the cell group or cells measured by the voltage measurement unit when, in the state in which the first control unit turns the first current control element off and intercepts the charging/discharging current, the second control unit turns the second current control element off, on the basis of the voltage under load of the cell group measured by the voltage measurement unit when the second control unit turns the second current control element on, and on the basis of the resistance value of the discharge resistor, and thereby diagnoses the deterioration level of each battery unit on the basis of the results of this calculation.