Battery Module Switching Circuit for Series-Parallel Voltage Equalization
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Solution Overview
Problem
Voltage deviations among battery modules in battery packs lead to overcharging or overdischarging, causing degradation and reducing the lifespan of the battery pack, and replacing modules to achieve balance is cumbersome and inefficient.
Innovation Solution
A battery system with a switching circuit controlled by a battery management system (BMS) connects battery modules in series or parallel to balance voltages, using an external power conversion system to adjust power amounts, allowing modules to be connected in parallel for balancing and then in series for discharge or charge, maintaining stability and extending pack life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If battery modules are connected in series to supply power, then power output is improved, but voltage deviation among modules causes overcharging or overdischarging leading to degradation
Solution Approach 1:
The patent implements dynamic switching between series and parallel connections of battery modules based on real-time voltage balance status. The system transitions from a fixed series connection to a dynamic configuration where modules can be reconnected in parallel when voltage deviation exceeds a threshold, and switched back to series when balanced, thereby adapting the system structure to maintain both power output and reliability
Solution Approach 2:
The system changes the connection configuration parameter (series/parallel) based on voltage balance parameters. When voltage deviation among modules exceeds a predetermined threshold, the system switches to parallel connection for balancing; when balanced, it returns to series connection for power supply, thus using parameter changes to resolve the contradiction between power output and lifespan
2Stability of the object's composition
If battery modules are replaced to maintain voltage balance, then voltage balance is improved, but the replacement process is cumbersome and time-consuming
Solution Approach 1:
The system performs self-balancing by automatically switching connections between series and parallel configurations based on voltage deviation detection. This eliminates the need for manual module replacement or external balancing operations, as the system self-corrects voltage imbalances through controlled reconfiguration, saving time and reducing operational complexity
Solution Approach 2:
The system performs preliminary voltage balancing by switching to parallel connection before the voltage deviation becomes critical. By proactively detecting voltage imbalances and switching to parallel configuration for balancing, the system prevents severe deviations that would require module replacement, thus saving time and maintaining optimal performance
3Stability of the object's composition
If battery modules are connected in parallel for balancing, then voltage balance is improved, but power supply capability is reduced
Solution Approach 1:
The system dynamically switches between parallel connection (for balancing) and series connection (for power supply) based on real-time voltage balance status. This temporal separation ensures that the system maintains power supply capability by operating in series mode during normal operation, while temporarily switching to parallel mode only when balancing is required, thus resolving the contradiction between voltage balance and power capability
Data Source
AI summary
A method of voltage balancing among a plurality of battery modules connected in series and supplying power to an external device, and a battery system providing the same, and the battery system of the present invention includes: a battery pack including a plurality of battery modules; a switching circuit connecting the plurality of battery modules in series or in parallel; and a battery management system (BMS) controlling the switching circuit so as to connect the plurality of battery modules in series in a discharge mode to supply power from the battery pack to an external device, a charge mode to charge the battery pack by receiving the power from the external device, and a module balancing mode to charge the plurality of battery modules with the power applied from the external device until a voltage difference is a predetermined reference value or less.