Secondary Battery Charge State Estimation via Combined Current

The patent combines the current integrating method with the open circuit voltage (OCV) method to create a hybrid estimation approach. The current integrating unit continuously integrates current to provide baseline SOC estimation, while the OCV estimating unit periodically estimates OCV during stable states to correct accumulated errors. This merging of two methods resolves the contradiction by maintaining the simplicity of current integration while adding the accuracy of OCV measurement only when conditions permit.

The patent performs preliminary identification of stable states using the combined current value before proceeding with OCV estimation. By预先 (in advance) determining whether the battery is in a stable state through the combined current threshold check, the system ensures that OCV estimation is only performed when conditions are favorable, thereby maintaining accuracy without continuously complicating the measurement process.

The patent dynamically adjusts the estimation approach based on the battery's operational state. The combined current calculating unit continuously adapts the current value by integrating past current history, and the stable state determination dynamically switches between current integration mode and OCV estimation mode. This dynamic adaptation allows the system to achieve high accuracy when stable states are reached without permanently increasing system complexity.

The combined current value serves as an intermediary indicator to determine whether the battery is in a stable state. Rather than directly monitoring multiple parameters to assess stability, the system uses this intermediate combined current metric to trigger OCV estimation only when appropriate, thereby simplifying the control logic while maintaining estimation accuracy.