SOC-Based Balance Correction for Series Battery Cells
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Solution Overview
Problem
Existing balance correction circuits for electric storage cells fail to effectively manage variability in State of Charge (SOC) due to differences in cell characteristics such as deterioration, temperature, and capacity, leading to inefficiencies in voltage balancing between cells connected in series.
Innovation Solution
A balance correction control apparatus that determines target SOC settings for each electric storage cell based on obtained cell characteristics, adjusting discharge or charge currents accordingly to maintain balance, using a cell characteristic obtaining unit and a target setting determining unit that considers deterioration, temperature, and capacity, and applies pulse-like currents to achieve balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a balance correction circuit is used to correct voltages between electric storage cells, then voltage balance is improved, but SOC variability between cells cannot be effectively managed
Solution Approach 1:
The patent applies local quality by determining individual target SOC values for each electric storage cell based on their specific characteristics (capacity, temperature, deterioration degree). Instead of uniform voltage correction, the system tailors the correction target to each cell's unique state, thereby managing SOC variability effectively while maintaining voltage balance.
Solution Approach 2:
The patent changes the control parameter from fixed voltage targets to dynamic SOC targets that vary according to cell characteristics. The target SOC is adjusted based on capacity, temperature, and deterioration degree, allowing the system to adapt to each cell's state and resolve the contradiction between voltage balance and SOC variability management.
2Device complexity
If uniform voltage correction is applied to all cells, then voltage balance is simplified, but cell variability due to different characteristics is not addressed
Solution Approach 1:
The system implements local quality by obtaining individual characteristics (capacity, temperature, deterioration degree) for each cell and using these to determine cell-specific target SOC values. This approach maintains relatively simple control logic while effectively addressing cell variability through localized parameter adjustment.
3Reliability
If target SOC is adjusted based on cell characteristics, then SOC variability is managed, but control complexity increases
Solution Approach 1:
The patent changes the control parameter to target SOC values that are dynamically determined based on cell characteristics. The control system obtains capacity, temperature, and deterioration degree data, then calculates appropriate target SOC values for each cell. This parameter change approach manages SOC variability while keeping the control structure relatively simple through systematic parameter adjustment.
Solution Approach 2:
The system employs feedback by continuously monitoring cell characteristics (capacity, temperature, deterioration degree) and using this information to determine appropriate target SOC values. The balance correction control apparatus adjusts correction targets based on feedback from cell state measurements, enabling effective SOC variability management through adaptive control.
Data Source
AI summary
Provided is a balance correction control apparatus to control a balance correction apparatus designed to correct a balance between voltages of a first electric storage cell and a second electric storage cell connected in series based on a target setting for an SOC of each of the first electric storage cell and the second electric storage cell. The balance correction control apparatus includes a cell characteristic obtaining unit operable to obtain at least one cell characteristic selected from the group consisting of a degree of deterioration, a cell capacity and a temperature of each of the first electric storage cell and the second electric storage cell, and a target setting determining unit operable to determine the target setting for the SOC of each of the first electric storage cell and the second electric storage cell based on the at least one cell characteristic obtained by the cell characteristic obtaining unit.