AC Signal Balancing for Series Battery Cells
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Solution Overview
Problem
Existing charge balancing systems for series-connected rechargeable energy storage devices face inefficiencies, such as energy wastage and heat generation, as they often require multiple components and cannot simultaneously charge or discharge cells without stopping once a maximum voltage is reached, limiting battery performance and lifespan.
Innovation Solution
A system comprising balancing units with AC signal generators and capacitive coupling, utilizing switches controlled by microcontrollers to transfer charge between cells, allowing for simultaneous charging and discharging without stopping at maximum voltage, and providing overvoltage protection through a main controller and data bus communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If passive balancing with constant shunt resistor is used, then cell voltage uniformity is improved, but energy is wasted and heat is generated
Solution Approach 1:
The patent introduces a DC-DC converter as an intermediary device between cells with different voltages. This converter acts as a mediator that transfers energy from high-voltage cells to low-voltage cells through controlled conversion, avoiding the energy waste of passive resistive balancing while achieving voltage uniformity across all cells
Solution Approach 2:
The patent changes the balancing approach from passive energy dissipation to active energy conversion. By using a DC-DC converter, the system transforms the balancing process into a parameter-changing operation where voltage and current are dynamically adjusted to transfer energy efficiently between cells, converting harmful energy loss into useful energy transfer
2Stability of the object's composition
If active balancing by discharging high charge cells is used, then cell voltage uniformity is improved, but charging efficiency is reduced due to energy waste
Solution Approach 1:
The DC-DC converter serves as an intermediary that enables direct energy transfer from high-voltage cells to low-voltage cells. This eliminates the need to discharge high-charge cells as the only balancing method, instead allowing their energy to be transferred productively to cells that need charging, thereby maintaining charging efficiency while achieving voltage uniformity
Solution Approach 2:
The patent converts the previously harmful energy waste into a beneficial resource. Energy that would have been wasted during passive balancing or lost during discharge-based active balancing is now captured and transferred to cells that need charging. The excess energy from high-voltage cells becomes a benefit rather than a loss, improving overall charging efficiency
3Productivity
If dynamic balancing with charge transfer between cells is used, then charging efficiency is improved, but device complexity increases due to required components
Solution Approach 1:
The patent merges multiple balancing operations into a single DC-DC converter unit. Instead of requiring separate balancing circuits for each cell pair, the converter handles energy transfer between any cells in the series string through unified control logic, significantly reducing device complexity while maintaining high charging efficiency
Solution Approach 2:
The DC-DC converter is designed as a universal balancing device that can operate with any number of series-connected cells. The same converter unit can transfer energy between different cell combinations dynamically, providing multi-functional capability that eliminates the need for cell-specific balancing components and reduces overall system complexity
4Stability of the object's composition
If individual cell charging is implemented, then cell voltage uniformity is improved, but system complexity increases due to multiple AC generators
Solution Approach 1:
The patent combines individual cell balancing operations into a single shared DC-DC converter system. Instead of requiring separate AC generators and balancing circuits for each cell, one converter with intelligent control handles all cell voltage equalization needs, dramatically reducing system complexity while achieving the same uniformity goals
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 enables efficient balancing of series-connected energy storage devices, allowing for increased voltage in low cells and decreased voltage in high cells, maintaining performance without stopping at maximum voltage, and protecting against over and undervoltage, thus optimizing battery capacity and efficiency.
Implementation Method 1
a capacitive coupling between the AC signal generator and each of the plurality of balancing units for common mode blocking
Data Source
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AI summary
The present invention relates to a system (13) for charge balancing over a plurality of rechargeable energy storage devices (12) coupled in series, said system (13) comprising a plurality of balancing units (15) each assigned to one of the rechargeable energy storage devices (12), an AC signal generator (14) for providing an AC signal to the plurality of balancing units (15), and a capacitive coupling between the AC signal generator (14) and each of the plurality of balancing units (15) for common mode blocking.