Battery Module Capacity Estimation via Dynamic Isolation
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Solution Overview
Problem
Existing methods for estimating the full charge capacity of power supply devices with battery packs or modules connected in series do not accurately account for state-of-charge (SOC) changes, leading to degradation in input and output performance.
Innovation Solution
A full-charge-capacity estimating device that forcibly isolates or connects battery modules based on the power supply device's state, measuring integrated current values and SOC changes to estimate each module's capacity accurately without degrading performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all battery modules are charged or discharged to estimate full charge capacity, then the full charge capacity can be obtained, but the input and output performance of the battery pack degrades due to SOC changes
Solution Approach 1:
The battery pack is divided into multiple battery modules, and the estimation process is segmented into two parts: (1) a reference battery module that undergoes full charge/discharge cycles for accurate capacity measurement, and (2) other battery modules that maintain normal operation to preserve input/output performance. This segmentation allows simultaneous achievement of measurement accuracy and system reliability.
Solution Approach 2:
One battery module is extracted from the normal series connection for dedicated capacity estimation purposes. This extracted module serves as a reference for determining the full charge capacity of the entire battery pack, while the remaining modules continue to operate normally, thus separating the measurement function from the power delivery function.
2Reliability
If battery modules are forcibly isolated or connected based on power supply state, then capacity estimation can be performed without degrading performance, but the control complexity increases
Solution Approach 1:
The connection state of battery modules is made dynamic rather than fixed. The control system dynamically adjusts which modules are connected in series and which are isolated based on the real-time power supply state (powering or regenerating), enabling flexible capacity estimation without permanent structural changes or complex hardware additions.
Solution Approach 2:
The system changes the operational parameters of battery modules based on power supply state. During powering state, certain modules are isolated to maintain their charge level for reference measurements, while during regenerating state, modules are reconnected to allow capacity estimation. This parameter-based control achieves performance preservation through software logic rather than hardware complexity.
Data Source
AI summary
Provided is a full-charge-capacity estimating device that has one or more of a plurality of battery modules, as battery-modules-to-be-measured, charged or discharged by means of a first switch element and a second switch element according to whether a power supply device is in a powering state or a regenerating state, measures an integrated current value and a change in the state-of-charge of the battery-module-to-be-measured, and then estimates the full charge capacity of the battery-module-to-be-measured from the integrated current value and the change in the state-of-charge.