Apparatus and method for estimating battery state of health

An apparatus for estimating a state of health of a battery, the apparatus comprising:

• a memory configured to load a program for calculating a state-of-balance value by voltage of a plurality of cells constituting a battery and estimating a state-of-health balance value that is a state-of-health value of the battery to which the state-of-balance value by voltage is applied;
• and
• a processor configured to execute instructions included in the program loaded by the memory,
• wherein the processor is configured to, according to execution of the program:
• set a voltage difference allowable limit value within a voltage difference between a fully charged state voltage of the battery and a discharged state voltage thereof and set an allowable limit quantile that subdivides an allowable limit range to which the voltage difference allowable limit value is applied into one or more analysis sections based on an average voltage value derived from measured voltage values of the cells;
• calculate a quantile drop rate that is a voltage drop rate in the allowable limit range based on the average voltage value, wherein a quantile order that is an order of an analysis section in which all measured voltage values for each cell are initially included within the allowable limit quantile is derived;
• determine a power storage amount of the battery based on a current applied to the battery and convert a Q-V graph showing a relationship between a voltage of the battery and the power storage amount of the battery into a V-dQ/dV graph showing a relationship between the voltage of the battery and the ratio of an amount of change in the power storage amount to an amount of change in the voltage of the battery;
• detect feature points including a reference point and a measurement point from the V-dQ/dV graph;
• and
• calculate the state-of-balance value by voltage based on the quantile drop rate, the quantile order, and dQ/dV values of the feature points and estimate the state-of-health balance value by applying the state-of-balance value by voltage to the state-of-health value calculated based on a remaining capacity of the battery, and
• the quantile drop rate is calculated using the following equation;
• Y
• :
• Y
• =
• 100
• /
• X
• where Y is the quantile drop rate of the battery meaning the voltage drop rate in the allowable limit range based on the average voltage and X is the allowable limit quantile.