Multi-Cell Battery Balancing via Power Line Communication
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Solution Overview
Problem
Rechargeable battery packs with multiple lithium cells face instability due to varying voltage outputs as cells age, requiring effective voltage balancing to ensure safe operation and extend battery life, while existing systems are complex and costly due to extensive wiring for monitoring.
Innovation Solution
A battery management system processor that communicates with each cell to obtain and adjust voltage, current, and temperature data, using programmable cell balance shunts to equalize cell voltages and reduce wiring complexity by enabling data communication over power lines, with microcontrollers in each cell responding to control signals to adjust internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional wiring-based monitoring systems are used for each battery cell, then measurement precision and reliability are improved, but device complexity and wiring costs increase significantly
Solution Approach 1:
The power lines serving battery cells are made to serve dual functions: both power delivery and data communication. The same wires that supply power to each cell are used to transmit voltage, current, and temperature data back to the management system, eliminating the need for separate monitoring wiring and reducing overall system complexity while maintaining measurement precision
Solution Approach 2:
The patent merges the power transmission function and data communication function into a single wiring infrastructure. By combining these two functions that were previously performed by separate systems, the overall device complexity and wiring costs are reduced while preserving the ability to accurately monitor each cell's electrical status
2Device complexity
If passive balancing methods are used for voltage equalization, then device complexity is reduced, but energy loss increases due to resistive heating
Solution Approach 1:
The balancing system dynamically adjusts the resistance of programmable shunts based on real-time cell voltage measurements and management system commands. This dynamic control allows the system to optimize the balancing process, reducing unnecessary energy dissipation while maintaining effective voltage equalization, unlike fixed passive balancing circuits
Solution Approach 2:
The patent changes the resistance parameter of balance shunts programmatically based on cell conditions. By dynamically modifying the resistance value rather than using fixed passive components, the system can minimize energy loss during balancing while still achieving effective voltage equalization across cells
3Manufacturing precision
If extensive wiring is used for cell monitoring and control, then measurement and control precision are improved, but manufacturing cost and installation complexity increase
Solution Approach 1:
Power lines are designed to perform multiple functions simultaneously: delivering power to cells and communicating cell status data (voltage, current, temperature) back to the management system. This multi-functionality eliminates the need for separate monitoring wiring, significantly reducing installation complexity and manufacturing costs while maintaining precise cell status monitoring 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
This method effectively balances cell voltages, reduces wiring costs, and enhances the safety and longevity of battery packs by automatically adjusting cell conditions without significant power loss, ensuring stable operation and reduced risk of damage.
Implementation Method 1
obtain cell voltage, cell current, cell temperature and cell fuse status data for each of a plurality of battery cells by transmitting and receiving via the data communications circuit
Implementation Method 2
programmable cell balance shunts to equalize cell voltages and reduce wiring complexity
Implementation Method 3
Such battery packs can become unstable as the individual cells age and the voltage output from each cell begins to vary with respect to other cells during operation thereof
Data Source
AI summary
Multi-cell battery management devices, systems, and methods are disclosed herein. A multi-cell battery management device comprises a battery pack including a power output terminal and a plurality of battery cells each having a positive and a negative terminal and connected in series fashion. Each of the plurality of battery cells includes: i) a cell control processor to monitor cell voltage, cell current, cell temperature, and cell fuse status; ii) a programmable shunt controlled by the cell control processor that varies the internal resistance of each of the cells; and iii) a data communications circuit connected to the cell control processor and to the positive and negative terminals of each cell, the communications circuit enabling data communication over the battery cell positive and negative output terminals, and wherein the cell control processor responds to commands received via the data communications circuit to vary the operating state of the programmable shunt.