Battery Voltage Alignment via Dynamic Threshold Discharge
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Solution Overview
Problem
In battery packs with multiple cells connected in series, uneven degradation can lead to voltage value disparities, causing full charging capacity imbalances and repeated discharging to align voltages, which is inefficient and may result in premature cell degradation.
Innovation Solution
An electric storage system comprising multiple electric storage elements connected in series, a voltage detecting circuit, a discharging circuit, and a controller that identifies and discharges cells with significant voltage differences, adjusting the threshold values based on reference voltage levels to align voltages efficiently and prevent further disparities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If voltage alignment is performed by discharging cells with higher voltage, then voltage uniformity is improved, but the frequency of discharging operations increases and cell degradation accelerates
Solution Approach 1:
The patent applies preliminary action by performing voltage alignment during the charging process rather than waiting until discharge is needed. The voltage alignment operation is executed in advance during charging, which prevents the need for frequent corrective discharging operations later, thereby reducing overall operation frequency and cell degradation.
Solution Approach 2:
The patent implements feedback by continuously monitoring cell voltages during charging and using this information to dynamically adjust the charging current. When voltage differences between cells exceed a threshold, the system automatically reduces charging current to allow slower-charging cells to catch up, creating a closed-loop control that maintains voltage uniformity without requiring discrete discharging operations.
2Stability of the object's composition
If charging current is reduced to align voltages, then voltage uniformity is improved, but charging speed decreases
Solution Approach 1:
The patent applies periodic action by implementing a charging process that alternates between normal charging current and reduced charging current in predetermined steps. The charging current is reduced only when voltage differences between cells exceed a threshold, and restored when uniformity is achieved, creating a periodic pattern that balances charging speed with voltage alignment requirements.
Solution Approach 2:
The patent implements dynamics by making the charging current adjustable and variable rather than fixed. The charging current dynamically changes based on real-time voltage measurements and the charging state of individual cells, allowing the system to optimize between charging speed and voltage uniformity at different stages of the charging process.
Data Source
AI summary
An electric storage system includes plural electric storage elements, a voltage detection circuit, a discharging circuit, and a controller. The controller is configured to: (a) control an operation of the discharging circuit on the basis of the voltage values detected by the voltage detecting circuit, (b) determine a first reference voltage value indicating a lowest voltage value from the voltage values of the plurality of electric storage elements, (c) discharge the electric storage element indicating the voltage value of which a voltage difference from the first reference voltage value is greater than a first threshold value, and (d) set the first threshold value to a smaller value as the first reference voltage value becomes lower.