Cell voltage estimation method and battery system providing the same

A battery system comprising:

• a battery including a plurality of battery modules connected in series, each of the plurality of battery modules comprising a plurality of battery cells connected in parallel;
• a temperature sensor to measure a cell temperature of each of the plurality of battery cells during a N-th estimation period;
• and
• a battery management system (BMS),
• wherein the BMS is configured to determine an estimated cell resistance value corresponding to a measured cell temperature value by using a first look-up table for each of the plurality of battery cells,
• wherein the BMS is configured to calculate an estimated cell current value using the estimated cell resistance value and an estimated cell voltage value determined during a (N−1)-th estimation period, N being a natural number greater than or equal to 1,
• wherein the BMS is configured to determine an estimated cell capacity corresponding to the estimated cell current value by using a capacity estimation model, and
• wherein the BMS is configured to determine the estimated cell voltage value corresponding to the estimated cell capacity as the estimated cell voltage value during the N-th estimation period using a second look-up table,
• wherein the BMS is configured to determine whether to perform a module balancing between each of the plurality of battery modules connected in series based on the estimated cell voltage value for each of the plurality of battery cells, and
• wherein the BMS is configured to perform the module balancing between the plurality of battery modules based on a determination that the module balancing is required.

A method for determining an estimated cell voltage value for each of a plurality of battery cells in a battery system, the battery system including a plurality of battery modules connected in series and the plurality of battery cells connected in parallel in each of the plurality of battery modules,

• wherein the method comprises:
• receiving a measured cell temperature value of each of the plurality of battery cells during a N-th estimation period;
• determining an estimated cell resistance value corresponding to the measured cell temperature value by using a first look-up table;
• calculating an estimated cell current value using the estimated cell resistance value and an estimated cell voltage value during a (N−1)-th estimation period, N being a natural number greater than or equal to 1;
• determining an estimated cell capacity corresponding to the estimated cell current value by using a capacity estimation model;
• determining the estimated cell voltage value corresponding to the estimated cell capacity as the estimated cell voltage value using a second look-up table during the N-th estimation period,
• determining whether to perform a module balancing between the plurality of battery modules based on the estimated cell voltage value for each of the plurality of battery cells, and
• performing the module balancing between the plurality of battery modules based on a determination that the module balancing is required.