Battery String Reconfiguration for Faulty Cell Bypass
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Solution Overview
Problem
In high-voltage batteries for electric vehicles, if a cell fails or there is an interruption within a battery string, the entire string is disconnected, leading to a loss of capacity and useful life, without providing a means to utilize the still-intact cells.
Innovation Solution
A method for operating an electrochemical energy storage system that involves ascertaining the actual state variables of the energy storage cells, comparing them to target variables, disconnecting faulty energy storage strings, bypassing faulty cells within those strings, and reconnecting the disconnected strings to a DC voltage converter to supply low-voltage consumers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a battery string is completely disconnected when a cell fails, then system safety is maintained, but the still-intact cells are lost and total capacity decreases
Solution Approach 1:
The battery system is segmented into multiple independently controllable strings, each with individual switching devices. When a fault occurs in one string, only that specific string is disconnected while other strings remain operational, preventing complete system shutdown and preserving capacity from healthy cells.
Solution Approach 2:
The system dynamically reconfigures its topology based on fault conditions. Switching devices actively change the electrical connections to bypass faulty cells or strings while maintaining connections to healthy ones, allowing the system to adapt its structure to preserve operational capacity.
2Reliability
If a defective battery string is completely lost, then system reliability is simplified, but the useful life of the battery system decreases
Solution Approach 1:
Instead of discarding the entire defective string, the system recovers functionality by isolating only the faulty cells or segments while maintaining operation of the remaining healthy cells in the same string, thereby extending the overall useful life of the battery system.
3Reliability
If the entire battery string is switched off due to a cell failure, then fault isolation is achieved, but the available charging power for the low-voltage battery decreases
Solution Approach 1:
The battery system is divided into independently controllable strings with individual switching devices. When a fault occurs, only the affected string is disconnected while other strings remain operational, preserving charging power capacity from healthy strings.
4Quantity of substance
If more battery strings are connected in parallel to increase capacity, then total capacity increases, but the probability of having at least one faulty string increases
Solution Approach 1:
The battery system is segmented into multiple independently controllable strings. When a fault occurs in one string, the independent switching devices allow that specific string to be isolated while other strings continue operating, maintaining system reliability even as capacity is scaled through parallel connections.
Data Source
AI summary
A method for operating an electrochemical energy storage system with a plurality of energy storage strings which comprise a plurality of electrochemical energy stores. The energy storage strings can be electrically connected in parallel by means of first switches.