Battery String Reconfiguration With DC-DC Voltage Hold Under Cell Faults
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Solution Overview
Problem
Current electrochemical energy storage systems in electric vehicles and mobile work machines fail completely when a single energy storage module or cell defects, leading to loss of power and reduced mobility, as redundancy increases costs and design complexity without ensuring continuous operation.
Innovation Solution
A method that involves ascertaining actual and target state variables of electrochemical energy stores, bypassing faulty units, and using a DC-DC converter to maintain output voltage by connecting non-bypassed stores to the converter, allowing for continuous operation without power reduction, even with multiple faults, and optimizing design without redundant components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coupling devices for bypassing cells or modules are implemented, then reliability is improved by allowing defective units to be bypassed, but device complexity increases due to additional switching components
Solution Approach 1:
A DC-DC converter is introduced as an intermediary device between the battery modules and the electrical machine. This converter actively regulates the output voltage by controlling the switching of battery strings, thereby maintaining stable voltage without requiring complex bypass switches at each cell or module level. The converter acts as a mediator that compensates for voltage variations caused by defective units.
Solution Approach 2:
The system changes the operational parameters by dynamically adjusting which battery strings are connected to the DC-DC converter based on the state of charge and health of individual modules. By selectively activating or deactivating specific battery strings through the converter's switching mechanism, the system maintains optimal voltage output while simplifying the overall architecture compared to individual bypass switches for each module.
2Reliability
If redundant electrochemical energy stores are added, then reliability is improved by providing backup capacity, but costs and design space increase
Solution Approach 1:
The system implements dynamic reconfiguration of battery strings based on real-time monitoring of state of charge and module health. The DC-DC converter dynamically switches between different battery string configurations to maintain operational capability. This dynamic adaptation allows the system to continue operating with existing components rather than requiring static redundant backup batteries, thereby improving reliability without increasing design space.
3Power
If multiple battery cells are connected in series to achieve high voltage, then power output is improved, but reliability deteriorates because a single cell defect causes complete battery failure
Solution Approach 1:
The battery system is segmented into multiple independent battery modules, each containing series-connected cells that form a battery string. The DC-DC converter is configured to selectively connect and disconnect these modular strings. When a cell or module fails, only the affected string is disconnected while other strings remain operational, maintaining system voltage and power output. This segmentation isolates failures and prevents single-point defects from causing complete system failure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the electrochemical energy storage system to maintain unaltered output voltage and prevent vehicle incapacitation, ensuring mobility and availability by adjusting voltage levels and compensating for faults without redundant components, thus reducing costs and design complexity.
Implementation Method 1
connecting a main switch arranged between the electrochemical energy stores and a DC-DC converter, thereby electrically connecting the electrochemical energy stores to an input of the DC-DC converter
Data Source
AI summary
A method for operating an electrochemical energy storage system with a plurality of electrochemical energy stores.