Battery Management Apparatus for Cell Voltage Imbalance Control
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Solution Overview
Problem
As the number of component unit cells in a battery pack increases, it becomes difficult to control charge and discharge within permissible current ranges due to state variations, and existing techniques fail to consider battery impedance and temperature variations.
Innovation Solution
A storage battery managing apparatus that includes cell voltage detection, storage battery voltage detection, and current detection means, along with processing means to calculate SOC imbalances and determine permissible charge and discharge currents based on cell voltages, average SOC, and impedance, ensuring optimal charge-discharge control across multiple unit cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of component unit cells in the battery pack is increased, then the total energy storage capacity is improved, but the difficulty of controlling charge and discharge within permissible current ranges increases due to state variations
Solution Approach 1:
The patent segments the battery pack into multiple unit cells with individual voltage detection, and further segments the control strategy by identifying extreme cells (highest and lowest voltage cells) to represent the state variations across all cells. This segmentation allows manageable control of a large-scale battery system.
Solution Approach 2:
The patent changes the control parameter from individual cell-level control to a simplified representation using extreme cell voltages and their deviations. By monitoring voltage deviations of extreme cells from the average voltage, the system manages complexity while maintaining effective control over charge-discharge currents.
2Measurement precision
If periodic calculation of SOCs of all unit cells is performed, then the accuracy of charge-discharge control is improved, but the throughput requirement of the controlling apparatus increases
Solution Approach 1:
The patent extracts only the essential information needed for control by focusing on the extreme cells (highest and lowest voltage cells) rather than processing all unit cells. This extraction reduces the computational burden while maintaining sufficient accuracy for charge-discharge control.
Solution Approach 2:
Instead of performing complete SOC calculation for all cells, the patent applies partial action by calculating voltage deviations only for extreme cells. This partial approach provides sufficient control information without the excessive computational resources required for full cell analysis.
3Device complexity
If charge-discharge control is performed without considering battery impedance and temperature, then the device complexity is reduced, but the reliability of charge-discharge control deteriorates
Solution Approach 1:
The patent performs preliminary detection of extreme cells and their voltage deviations before charge-discharge operations. By pre-identifying the cells with highest and lowest voltages and calculating their deviations from average voltage, the system prepares control parameters in advance, improving reliability without adding complex real-time computation during charge-discharge cycles.
Data Source
AI summary
A storage battery managing apparatus which ensures charge-discharge control of a storage battery in consideration of state variation of each unit cell even if the battery pack includes a number of component unit cells, and a vehicle controlling apparatus providing the same. A storage battery includes a plurality of chargeable-dischargeable unit cells connected in which battery management ICs detect the cell voltage of each unit cell, a voltage sensor detects a storage battery voltage and a current sensor detects currents to be charged and discharged in the storage battery. A degree of SOC imbalance is obtained by use of detected cell voltage of each unit cell when the storage battery is being neither charged nor discharged.