Battery Cell Balancing via Relay Inactivation
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Solution Overview
Problem
Electric vehicles and hybrid vehicles face challenges in managing inter-cell voltage deviations within battery packs, leading to non-uniform cell voltages and reduced State Of Charge (SOC), which affects the overall performance and efficiency of the battery system.
Innovation Solution
A system and method for cell balancing using a cell balancing device that detects inter-cell voltage deviations, determines when to perform balancing based on threshold values and control signal magnitudes, and inactivates relays to restrict charge/discharge and balance cell voltages, ensuring uniformity and optimal SOC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a relay is connected to a battery pack to supply power, then large power can be supplied, but inter-cell voltage deviation in the battery pack increases
Solution Approach 1:
The system performs cell balancing before the relay is activated and before the battery pack is connected to the vehicle. The controller detects inter-cell voltage deviations and balances the cells in advance, ensuring uniform voltage distribution before high-power operation begins. This preliminary action prevents voltage deviation from accumulating during power supply operations.
Solution Approach 2:
The battery pack is divided into individual cells with separate voltage detection and balancing circuits for each cell. The controller independently monitors and balances each cell's voltage, allowing precise control over inter-cell voltage uniformity while maintaining the overall pack's high power capability through the relay connection.
2Manufacturing precision
If cell balancing is performed continuously, then inter-cell voltage deviation is reduced, but system complexity and operation time increase
Solution Approach 1:
The system performs cell balancing periodically rather than continuously. The controller checks inter-cell voltage deviations at predetermined intervals and activates balancing only when deviations exceed a threshold. This periodic approach maintains voltage uniformity while minimizing the activation time of balancing circuits and reducing overall system complexity.
Solution Approach 2:
The cell balancing system uses the existing battery pack structure and relay infrastructure to perform balancing operations. The controller leverages the natural electrical connections within the battery pack, using minimal additional components to detect and correct voltage deviations, thereby reducing system complexity while maintaining effective balancing.
3Manufacturing precision
If cell balancing is performed during vehicle operation, then voltage uniformity is maintained, but vehicle performance may be restricted
Solution Approach 1:
The system performs cell balancing during predetermined periods when the vehicle is not in high-demand operation, such as during idle periods or low-load conditions. By scheduling balancing operations during these windows, the system maintains voltage uniformity without restricting vehicle performance during critical driving periods.
Solution Approach 2:
The cell balancing operation is dynamically adjusted based on vehicle operating conditions. The controller monitors vehicle state and adapts the timing and intensity of balancing operations to match demand requirements, ensuring voltage uniformity is maintained while minimizing impact on vehicle performance and productivity.
Data Source
AI summary
A system and method of cell balancing of a battery pack using a cell balancing device of a battery pack is provided and includes a controller that detects an inter-cell voltage deviation in the battery pack. In addition, the controller is configured to determine whether to perform cell balancing on the battery pack and inactivate a relay connected with the battery pack. The controller is further configured to perform cell balancing in the battery pack.