Parallel Battery String Bypass Control for Fault Voltage Equalization
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Solution Overview
Problem
In electric vehicles, existing battery systems face challenges in maintaining high capacity and reliability while minimizing installation space and costs, particularly due to the need for redundancy in battery modules, which leads to inefficiencies when a fault occurs, resulting in energy loss and reduced range.
Innovation Solution
A method for operating a battery system with multiple strings connected in parallel, where individual battery cells or modules can be independently switched off and bypassed using coupling units, allowing for voltage equalization across strings, thereby minimizing energy loss and maintaining maximum capacity during faults without requiring additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple battery modules are interconnected in parallel to achieve redundancy, then reliability is improved, but installation space and costs increase
Solution Approach 1:
The battery system is divided into multiple independent strings, each comprising battery modules that can be individually switched on or off. This segmentation allows the system to maintain functionality by isolating faulty segments while keeping healthy segments operational, thereby achieving reliability without requiring complete redundancy of the entire battery system.
Solution Approach 2:
The system employs dynamic switching capabilities through coupling units that can independently connect or disconnect individual battery modules or cells from the circuit based on their operational status. This dynamic reconfiguration allows the battery system to adapt to faults in real-time, maintaining reliability while optimizing the use of available installation space.
2Reliability
If a faulty battery cell is bypassed to maintain system operation, then reliability is improved, but intact battery cells must also be bypassed to equalize voltage, resulting in capacity loss
Solution Approach 1:
The coupling units enable localized switching at the level of individual battery cells or modules, allowing the system to isolate only the faulty component while maintaining connectivity for healthy components. This localized approach prevents the need to bypass intact battery cells for voltage equalization, thereby preserving overall battery capacity while ensuring reliability.
3Reliability
If complete string switching off is implemented when multiple modules in one string have faults, then reliability is improved, but energy loss and range reduction occur
Solution Approach 1:
The battery system is divided into multiple independent strings, each comprising battery modules that can be individually switched on or off. This segmentation allows the system to maintain functionality by isolating faulty segments while keeping healthy segments operational, thereby achieving reliability without requiring complete redundancy of the entire battery system.
Solution Approach 2:
The system employs dynamic switching capabilities through coupling units that can independently connect or disconnect individual battery modules or cells from the circuit based on their operational status. This dynamic reconfiguration allows the battery system to adapt to faults in real-time, maintaining reliability while optimizing the use of available installation space.
Data Source
AI summary
A method for operating a battery system. The battery system includes parallel-connected strings. Each string includes at least one battery module. In the battery module, multiple battery cells are interconnected in a series connection and/or in a parallel connection. The strings are switchable on and off from one another. The battery cells and/or battery cell packets are switchable on and off from one another and are bypass-able. The method includes: recognizing a fault of a battery cell; switching off and bypassing the faulty battery cell and/or the faulty battery cell packet which includes the faulty battery cell; switching off the faulty string, which includes the faulty battery cell and/or the faulty battery cell packet; comparing the string voltage of the faulty string to the string voltage of intact strings, in which no fault was recognized; discharging the intact strings if voltage differences between the strings exceed a voltage threshold value.