Battery Module Bypass and Balancing for Full Capacity Use
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Solution Overview
Problem
In power storage systems with multiple battery modules connected in series, the increase in the number of bypass mechanisms leads to inefficient battery capacity utilization due to differences in deterioration states among modules, causing some modules to reach full charge or discharge earlier than others, thereby limiting the overall usable battery capacity.
Innovation Solution
The system incorporates inter-cell and inter-module balancing units to equalize voltages across storage battery cells and modules, respectively, and employs bypass circuits to manage the connection and bypass states of storage battery modules, allowing for cooperative control by a controller to prevent overcharge and over-discharge, thus optimizing battery capacity utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of bypass mechanisms is increased to accommodate more storage battery modules, then the voltage of the storage battery string can be increased, but the system complexity and cost increase proportionally
Solution Approach 1:
Multiple storage battery modules are grouped under a single bypass mechanism. The bypass mechanism includes a first switch connecting modules in series and a second switch on a bypass line, allowing one bypass mechanism to manage multiple modules rather than requiring separate bypass mechanisms for each module.
Solution Approach 2:
A single bypass mechanism is designed to serve multiple storage battery modules simultaneously. The bypass mechanism can switch between connecting modules in series and bypassing them, providing multi-functional control over voltage regulation and battery management for multiple modules.
2Device complexity
If multiple storage battery modules are shared by one bypass mechanism, then the number of bypass mechanisms can be reduced, but modules with different deterioration states reach full charge or discharge at different times, causing premature bypassing and reducing usable battery capacity
Solution Approach 1:
The system performs state estimation of storage battery modules in advance to determine their charge and discharge states. Based on this preliminary assessment, the controller selectively activates or deactivates specific storage battery modules before they reach full charge or discharge, preventing premature bypassing and maximizing usable capacity.
Solution Approach 2:
The system dynamically adjusts the configuration of storage battery modules connected in series based on real-time state estimation results. The controller can flexibly select which modules to include in the active circuit, adapting to the varying deterioration states and charge levels of different modules to optimize overall system performance.
3Reliability
If selective module activation based on state estimation is implemented, then usable battery capacity can be maximized, but the control system complexity increases
Solution Approach 1:
The system implements state estimation of storage battery modules to continuously monitor their charge and discharge states. This feedback information is used by the controller to make informed decisions about which modules to activate or bypass, enabling optimized capacity utilization through data-driven control.
Solution Approach 2:
The bypass mechanism includes built-in switching capabilities that automatically connect or bypass modules based on control signals. The system uses its own state estimation and control logic to manage its operation, reducing the need for external complex control infrastructure.
Data Source
AI summary
A power storage system includes a plurality of storage battery units connected in series, and a plurality of bypass circuits respectively provided for the storage battery units and each configured to switch the corresponding storage battery unit between a bypass state and a connection state. Each of the storage battery units includes a plurality of storage battery modules connected in series, and each of the storage battery modules includes a plurality of storage battery cells connected in series. The storage battery modules are respectively provided with inter-cell balancing units each configured to execute cell balancing for equalizing voltages of the storage battery cells in the corresponding storage battery module, and the storage battery units are respectively provided with inter-module balancing units each configured to execute module balancing for equalizing voltages of the storage battery modules in the corresponding storage battery unit.