Battery Cell Equalization via Closed Circuit Voltage Measurement
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Solution Overview
Problem
Existing charging rate equalization devices struggle to perform equalization processing in auxiliary batteries of vehicles that require continuous power supply, as they cannot separate the auxiliary battery from the load to measure open circuit voltage (OCV).
Innovation Solution
A charging control device that measures closed circuit voltage (CCV) of battery cells during charging, executes discharging processing to eliminate potential differences, and maintains high state of charge (SOC) to enable equalization even in assembled batteries that cannot be separated from the load, using a control unit, measuring unit, and executing unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the auxiliary battery is separated from the load to measure open circuit voltage (OCV), then measurement precision is improved, but ease of operation deteriorates because the auxiliary battery requires continuous power supply
Solution Approach 1:
The patent introduces a relay as an intermediary component that enables the auxiliary battery to be electrically separated from the load during OCV measurement. The relay acts as a switch that can disconnect the load while maintaining the battery's operational connection, thus enabling accurate voltage measurement without compromising the continuous power supply requirement
Solution Approach 2:
The patent performs preliminary actions by controlling the relay to disconnect the load before measuring the open circuit voltage. This preliminary disconnection ensures that no current flows through the battery during measurement, allowing accurate OCV reading to be obtained before the battery needs to resume power supply to the load
2Manufacturing precision
If equalization processing is performed using OCV measurement, then equalization accuracy is improved, but device complexity increases due to the need for relay and separation mechanism
Solution Approach 1:
The patent makes the relay serve multiple functions: it acts as both a load isolation switch for accurate OCV measurement and as a control element for managing battery equalization. By making the relay multi-functional, the patent avoids adding separate components for measurement and control, thus reducing overall system complexity while maintaining equalization accuracy
Solution Approach 2:
The patent combines the measurement function and the control function into a unified process managed by the same control unit. The control unit both operates the relay for measurement purposes and manages the equalization charging process, merging multiple functions into a single integrated system that reduces complexity
3Productivity
If charging is performed in flat region of SOC-OCV curve, then productivity is improved, but measurement precision deteriorates due to small OCV change
Solution Approach 1:
The patent changes the measurement parameter from relying on OCV variations to using absolute OCV values in combination with current integration. Instead of detecting SOC through OCV changes (which are minimal in flat regions), the system uses the actual OCV value together with ampere-hour integration to calculate SOC, making the measurement precision independent of OCV curve slope
Solution Approach 2:
The patent implements feedback by continuously monitoring the OCV and comparing it with expected values based on the charging current and capacity. The control unit uses this feedback to adjust the equalization charging rate, ensuring accurate SOC determination even in flat regions where OCV changes are minimal
Data Source
AI summary
A charging control device includes a processor. The processor is configured to control charging of a plurality of battery cells that configure an assembled battery, during charging, in a case in which a voltage value of a battery cell having a highest voltage among the plurality of battery cells is equal to or greater than a threshold value and a current value is equal to or less than a set value, measure a closed circuit voltage (CCV) of the plurality of battery cells, and for a battery cell for which a potential difference with respect to a voltage of a battery cell with a lowest measured CCV is equal to or greater than a predetermined value, execute discharging processing so as to eliminate the potential difference.