Battery Balancing Circuit Using Switched Capacitor Cell Charging
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Solution Overview
Problem
Conventional energy storage devices take a long time to balance the voltages of battery cells due to low charging currents, especially when a battery cell with a significantly low voltage is present, leading to prolonged voltage balancing times.
Innovation Solution
A battery management circuit that includes a first switching circuit connecting a capacitor and a battery cell in parallel, a second switching circuit connecting the capacitor to multiple series-connected battery cells, and a control circuit to repeatedly switch between these connections, applying a higher voltage to the capacitor to increase the charging current for the battery cell with lower voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional voltage balancing is used with simple capacitor switching, then device complexity is kept low, but the voltage balancing time becomes excessively long
Solution Approach 1:
The battery cell group is divided into multiple subsets, with dedicated switching circuits for each subset. This segmentation allows parallel voltage balancing operations across multiple cell groups simultaneously, dramatically reducing total balancing time while keeping each individual switching circuit relatively simple
Solution Approach 2:
The switching circuits dynamically select which battery cell subsets to balance based on real-time voltage differences. The system adaptively activates only the necessary switching circuits for cells that need balancing, optimizing the balance between complexity and performance
2Loss of time
If higher charging current is applied to balance low voltage cells faster, then voltage balancing time is reduced, but risk of overcharging and cell damage increases
Solution Approach 1:
The control unit continuously monitors the voltage of each battery cell and uses this feedback to regulate the charging current. When a cell reaches the target voltage, the control unit automatically reduces or stops the charging current to that cell, preventing overcharging while maintaining fast balancing speed
Solution Approach 2:
Each switching circuit is dedicated to specific battery cell subsets and can independently control charging parameters for those cells. This localized control allows high current to be applied only where needed without affecting other cells, maintaining safety while achieving fast balancing
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 solution significantly shortens the time required for voltage balancing by increasing the charging current for the battery cell with lower voltage, thereby reducing the overall balancing time for all battery cells.
Implementation Method 1
a first switching circuit that connects a first capacitor and a first battery cell in parallel
Data Source
AI summary
A battery management circuit is a battery management circuit that manages an energy storage device including battery cells and capacitors, and includes: a first switching circuit that connects a first capacitor among the capacitors and a first battery cell among the battery cells in parallel; a second switching circuit that connects the first capacitor and two or more series-connected battery cells other than the first battery cell among the battery cells in parallel; and a control circuit that performs a first control of repeatedly switching between the connection by the first switching circuit and the connection by the second switching circuit.