Battery Charging Circuit with Cell Current Modulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In battery packs with cells connected in parallel, differences in electrical characteristics lead to imbalanced charging currents, uneven aging, and potential stress on cells, as the charging current preferentially flows through the cell with the lowest impedance, causing unpredictable current distribution and risk of fast aging.
Innovation Solution
A method and circuit that set and modulate individual cell charging currents based on sensed currents, using comparators and modulators to ensure each cell receives a desired charging current, allowing for continuous feedback to maintain optimal charging conditions, regardless of cell differences, and includes a partitioner to divide the total current among cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cells with different electrical characteristics are connected in parallel for charging, then the charging process can proceed, but the charging current becomes imbalanced and flows preferentially through the cell with the lowest impedance
Solution Approach 1:
The patent divides the total charging current into separate controllable paths for each cell using individual switching elements (MOSFETs) and control circuits. Each cell's current is independently regulated through its own sensing and control loop, transforming the unified parallel charging into segmented, independently controlled charging paths.
Solution Approach 2:
The patent implements feedback control by sensing the actual current flowing through each cell and comparing it with the desired current distribution. The control circuit adjusts the switching elements based on this feedback to maintain balanced current distribution, ensuring that cells with different characteristics receive appropriate charging currents.
2Productivity
If cells with different characteristics are charged with imbalanced currents, then charging can proceed quickly, but uneven aging and fast aging of cells occur
Solution Approach 1:
The control circuit continuously monitors the charging current of each cell and adjusts the switching elements to prevent any cell from receiving excessive current. This feedback mechanism ensures that cells are charged within safe current limits, preventing fast aging and extending cell lifespan while maintaining efficient charging.
Solution Approach 2:
The patent dynamically adjusts the charging current parameters for each cell based on their individual characteristics. By changing the current magnitude for each cell according to its impedance and state of charge, the system optimizes charging efficiency while preventing conditions that would lead to premature aging.
3Reliability
If fuses are interposed between cells to prevent current imbalance, then cell protection is improved, but device complexity increases
Solution Approach 1:
The patent introduces active switching elements (MOSFETs) and control circuits as intermediaries between the charger and the cells. These intermediaries provide intelligent current regulation and protection, replacing passive fuse-based protection with active control that offers superior protection while enabling precise current management.
Solution Approach 2:
The control circuit automatically detects current imbalances and adjusts the switching elements to correct them without external intervention. The system self-regulates the charging current distribution, providing continuous protection and optimization without requiring manual fuse replacement or complex external protection circuits.
4Reliability
If cells are selected to be as similar as possible to build a battery pack, then current balance is improved, but adaptability to different cell types is reduced
Solution Approach 1:
The patent applies local quality control by tailoring the charging current to each cell's specific characteristics rather than using a uniform approach. Each cell receives a customized current based on its impedance, capacity, and state of charge, allowing the system to handle diverse cell types while maintaining current balance and optimization.
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 ensures balanced charging currents across all cells, preventing undue stress and ensuring consistent aging, even with varying cell characteristics, allowing for the use of cells with different capacities and chemistries without the need for extensive redesign of the charger.
Implementation Method 1
a sensing element apt or configured to sense a total current provided by the current source
Implementation Method 2
a plurality of cell sensing elements apt to sense a cell current flowing through each cell of the plurality
Implementation Method 3
comparing a value proportional to each set cell charging current with a value proportional to the cell current for the same cell
Data Source
AI summary
A method to charge a battery pack including a plurality of cells connected in parallel, the method including setting a plurality of set cell charging current, a set cell charging current for each cell of the battery pack; charging the battery back with a total current from a single current source; sensing a plurality of cell currents which flows through each cell of the battery pack; comparing a value proportional to each set cell charging current with a value proportional to the cell current for the same cell; and modulating each cell current on the basis of the comparison for the same cell. A battery charging circuit for a battery pack is also provided.