Battery Cell Bus Bar Isolation Without Pack Power Cutoff
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Solution Overview
Problem
Conventional methods for disconnecting a failing battery cell in a battery pack result in stopping power supply to the entire system, such as in electric vehicles, due to the cutoff of the power line, which is inefficient and disruptive.
Innovation Solution
A battery pack design with a sensor unit and controller that identifies failing battery cells and disconnects the corresponding bus bars using switches, allowing for the disconnection of the failing cell without affecting other cells, and includes a breaking mechanism that irreversibly disconnects the bus bar upon short-circuit current application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main switching device or main protection device is opened to cut off the power line of a battery module including a failing battery cell, then the failing battery cell is isolated, but power supply to the motor is stopped causing the vehicle to stop
Solution Approach 1:
The battery module is segmented into individual battery cell units, each with its own switching device. This allows isolation of only the failing battery cell unit while keeping other units operational, rather than isolating the entire battery module. The segmentation enables selective disconnection at the cell level, resolving the contradiction between isolating failing cells and maintaining vehicle operation.
Solution Approach 2:
Each battery cell unit is equipped with its own switching device and protection mechanism, creating local control capability. When a failure is detected in one cell unit, only that local unit is disconnected while other units continue to function. This local quality approach allows the system to maintain overall productivity while ensuring reliability by isolating only the problematic local component.
2Reliability
If the power line of a battery module is cut off when a battery cell fails, then safety is improved by isolating the failing cell, but the entire battery module becomes unusable
Solution Approach 1:
The battery module is divided into multiple independently controllable battery cell units. Each unit can be individually disconnected without affecting others. This segmentation allows the system to maintain safety by isolating failing cells while preserving the usable capacity of healthy cells, thus resolving the contradiction between safety and available battery capacity.
Solution Approach 2:
The system discards (disconnects) only the failing battery cell units while recovering and continuing to use the healthy battery cell units. This selective discarding and recovery approach maximizes the usable battery capacity while maintaining safety, rather than discarding the entire battery module when a single cell fails.
3Reliability
If a main protection device is used to disconnect a failing battery cell, then the failing cell is isolated, but the device complexity increases and other battery cells are affected
Solution Approach 1:
The protection system is segmented into distributed switching devices, with each battery cell unit having its own switching device. This segmentation distributes the complexity across multiple simple local units rather than requiring one complex central protection device, thereby achieving reliable cell isolation while managing device complexity through modular architecture.
Solution Approach 2:
Each switching device is designed to be universal and multi-functional, serving both as a normal operating switch and as a protection device for its associated battery cell unit. This universality eliminates the need for separate specialized protection devices for each cell unit, reducing overall device complexity while maintaining reliable disconnection capability.
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 safe management of the battery pack by isolating failing cells without interrupting power to other cells, maintaining system functionality and safety.
Implementation Method 1
a sensor unit configured to sense states of a plurality of battery cells included in the battery module
Implementation Method 2
a first switch connected to the first battery cell in parallel... close the first switch to disconnect the first cell bus bar
Implementation Method 3
the first cell bus bar may be irreversibly disconnected by heat applied from short-circuit current flowing through the first battery cell, the first cell bus bar, and the first switch for the designated time
Data Source
AI summary
A battery pack according to an embodiment disclosed herein can includes a battery module including a plurality of battery cell units connected in parallel, a main power line electrically connected to the plurality of battery cell units. A first battery cell unit of the battery cell units can include a first battery cell, a first cell bus bar configured to electrically connect a positive electrode of the first battery cell and a negative electrode of the first battery cell to the main power line, and a first switch connected to the first battery cell in parallel. A sensor unit of the battery pack can be configured to sense a condition of the battery cells A controller can be configured to close the first switch to disconnect the first cell bus bar upon identifying a failure of the first battery cell based on the condition of the first battery cell.