Battery Pack Coupling Circuit for Balanced Cell Group Discharge
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Solution Overview
Problem
As the number of cells in a battery pack increases, the electrical voltage between the terminals also increases, requiring electrical units to withstand higher voltages, which leads to increased financial costs and complexity, and uneven discharge of cells can reduce the battery pack's lifespan and efficiency.
Innovation Solution
A device is coupled to a battery pack, dividing its cells into groups and using current mirror circuits to ensure equal current flow through each cell, reducing the voltage applied to the device and preventing uneven discharge by controlling load units based on measured currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of cells in a battery pack increases to achieve higher energy storage capacity, then the energy storage capacity is improved, but the electrical voltage increases requiring more expensive and complex components
Solution Approach 1:
The battery pack is divided into multiple groups of cells (first group, second group, etc.), with each group connected to separate terminals. This segmentation allows the device to interface with smaller voltage subsets rather than the total pack voltage, reducing component voltage requirements while maintaining overall energy storage capacity through the combined groups.
2Quantity of substance
If the number of cells in a battery pack increases to achieve higher energy storage capacity, then the energy storage capacity is improved, but the financial costs increase
Solution Approach 1:
By segmenting the battery pack into multiple groups that can be independently accessed through separate terminals, the device uses lower-voltage-rated (and thus lower-cost) electrical components. This reduces the overall system cost while achieving the same total energy storage capacity through the combined cell groups.
3Power
If cells are connected in series to increase voltage, then the voltage is improved, but uneven discharge occurs reducing battery pack lifespan
Solution Approach 1:
The device incorporates a sensor unit that measures current in one circuit string and uses this measurement to control load units in other circuit strings. This feedback mechanism ensures that current flow is balanced across all cell groups, preventing uneven discharge and extending battery pack lifespan while maintaining the voltage benefits of series connection.
Solution Approach 2:
The device uses universal current control through load units that can be applied to multiple circuit strings. The same control mechanism (load units) serves both to regulate current distribution across different cell groups and to maintain balanced discharge, thereby improving reliability without sacrificing voltage.
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
This approach allows for equal discharge of all cells, reduces the need for expensive and complex components, and enables a more cost-effective and compact battery pack design with improved energy storage capacity and longevity.
Implementation Method 1
the first sensor unit comprises a first current mirror circuit including at least two transistors referred to as first sensor transistor and first mirror transistor
Implementation Method 2
the second load unit comprises a second current mirror circuit including at least two transistors referred to as second sensor transistor and second mirror transistor
Data Source
AI summary
The present disclosure relates to a device comprising: a first terminal, a second terminal, a third terminal, a first load unit, a first sensor unit, and a second load unit, wherein the device is configured to be coupled to a first group of cells of a battery via the first and second terminals, wherein the device is configured to be coupled to a second group of cells of a battery via the second and third terminals, wherein a first circuit string of the device extends between the first and second terminals, wherein the first load unit is integrated into the first circuit string, wherein the first sensor unit is configured to measure a first current in the first circuit string, wherein a second circuit string of the device extends between the second and third terminals, wherein the second load unit is integrated into the second circuit string, and wherein the device is configured to control the second load unit based on the first current such that the second load unit causes a second current in the second circuit string corresponding to the first current. The present disclosure also relates to a system comprising the device and the battery pack. Further, the present disclosure also relates to a method for the device.