Capacitor-Based Charge Balancing for Battery Packs
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Solution Overview
Problem
Existing battery pack charge balancing systems are inefficient, costly, and slow, leading to potential catastrophic failures due to charge imbalances, especially during high energy transfer rates, as they rely on complex circuits with sensors and capacitors that are not fast enough to prevent charge imbalance amplification.
Innovation Solution
A charge balancing system using a capacitor and processor to selectively couple donor and receiver cells in various configurations, allowing for rapid charge transfer between cells through optimized voltage potential differences, with the ability to switch between modes for different usage scenarios to balance charge efficiently and effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex charge balancing circuits with sensors and capacitors are used to balance charge between cells, then charge balancing capability is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent extracts the charge balancing function from complex per-cell circuits and implements it through a centralized controller that manages a smaller number of external components (capacitors and switches). This removes the need for sensors and capacitors at each cell, significantly reducing device complexity while maintaining charge balancing capability.
Solution Approach 2:
The controller serves multiple functions: it monitors cell voltages, determines charge imbalance conditions, selects appropriate balancing modes, and controls the switching of capacitors and switches. This multi-functionality eliminates the need for separate dedicated balancing circuits at each cell, reducing overall system complexity.
2Reliability
If charge balancing circuits transfer charge between imbalanced cells using voltage potential difference, then charge transfer is achieved, but the process becomes very slow when voltage difference is relatively small
Solution Approach 1:
The patent introduces external capacitors as intermediary energy storage devices that can be charged from high-voltage cells and discharged to low-voltage cells. This intermediary mechanism enables faster charge transfer compared to direct cell-to-cell transfer, especially when voltage differences are small, because the capacitors can store and release energy more rapidly.
Solution Approach 2:
The charge balancing process operates in periodic cycles where the controller alternates between charging capacitors from donor cells and discharging them to receiver cells. This periodic action allows the system to accumulate charge transfer capacity over multiple cycles, achieving effective balancing even when individual transfer rates are limited by small voltage differences.
3Power
If high rate of energy transfer occurs to and from the battery pack during high power charge or discharge, then power delivery is improved, but charge imbalance is amplified in a substantially short period of time
Solution Approach 1:
The controller continuously monitors cell voltages and proactively initiates charge balancing operations before significant imbalance develops. By detecting voltage differences and activating the balancing circuit in advance, the system prevents imbalance amplification that would otherwise occur during high power charge or discharge events, maintaining reliability without reducing power 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
The system significantly increases the speed and efficiency of charge balancing within battery packs, preventing failures by optimizing charge transfer rates and efficiencies, allowing for healthier battery pack operation across various usage scenarios.
Implementation Method 1
A charge balancing system may include a capacitor, a processor that is configured to select a combination of donor cells and receiver cells from the plurality of cells
Data Source
AI summary
A system for balancing charge within a battery pack with a plurality of cells connected in series, including a capacitor; a processor configured to select a combination of donor cells and receiver cells from the plurality of cells in one of the following two modes: (1) a first mode where the number of donor cells is equal to the number of receiver cells, and (2) a second mode where the number of donor cells is greater than the number of receiver cells; and a plurality of switches that electrically connect the capacitor to the donor cells to charge the capacitor, and that electrically connected the capacitor to the receiver cells to discharge the capacitor. The transfer of charge between cells in the plurality of cells through the capacitor balances the charge within the battery pack.