Wireless Cell Modules for Battery SOC Balancing
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Solution Overview
Problem
Existing battery management systems for motor vehicle traction batteries face challenges in effectively balancing the state of charge (SOC) across cells, leading to inefficiencies and potential damage due to uneven charging and discharging.
Innovation Solution
A wireless control module system is implemented, where each cell is associated with a wireless control module that includes a controller, temperature sensor, and balancing resistor, allowing for dynamic and real-time balancing of SOC by matching cells to a target SOC through passive or active balancing methods, and utilizing a mesh network for communication with a battery management system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a wireless sensor network is used to monitor cells, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The battery management system is segmented into multiple independent wireless control modules, each associated with a specific cell or cell group. Each module contains its own controller, temperature sensor, and balancing resistor, allowing distributed monitoring and control without requiring a complex centralized system.
Solution Approach 2:
The patent replaces traditional wired mechanical connections with wireless communication technology. Controllers communicate with the battery management system via wireless transceivers, eliminating the need for extensive physical wiring while maintaining measurement precision and reducing system complexity.
2Reliability
If individual cell balancing is implemented, then reliability is improved, but device complexity increases
Solution Approach 1:
Each wireless control module is equipped with local temperature sensors and balancing resistors that operate independently for their associated cells. This local quality approach allows individual cell balancing without requiring complex centralized control, as each module autonomously monitors and balances its own cell based on local measurements.
Solution Approach 2:
The controllers in each wireless control module are configured to autonomously determine when balancing is required and execute balancing operations without continuous external control. The modules self-manage the balancing process by comparing cell voltages and activating balancing resistors only when needed, reducing overall system complexity while improving reliability.
3Measurement precision
If temperature sensors are bonded to electrodes, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The temperature sensor, controller, and balancing resistor are merged into a single integrated wireless control module. This consolidation allows the temperature sensor to be positioned optimally for accurate measurement while the entire assembly is managed as one unit during manufacturing, reducing the precision requirements for individual component placement.
Solution Approach 2:
The controller acts as an intermediary that processes temperature data from the sensor and makes balancing decisions. This allows the temperature sensor to be positioned for optimal measurement accuracy without requiring extremely precise bonding, as the controller can compensate for minor positioning variations through software algorithms.
4Ease of manufacture
If passive balancing with resistors is used, then ease of manufacture is improved, but energy loss increases
Solution Approach 1:
The balancing resistors are activated only partially or intermittently, only when and where needed to equalize specific cells. The controllers monitor cell voltages continuously and activate balancing resistors only for cells that exceed the target voltage threshold, avoiding unnecessary energy dissipation while maintaining manufacturing simplicity.
Solution Approach 2:
The balancing system is dynamic rather than static. The controllers continuously adjust the activation state of balancing resistors based on real-time cell voltage measurements, activating them only when balancing is required and deactivating them when cells are balanced. This dynamic operation reduces energy loss while maintaining the simplicity of passive resistor-based 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 ensures uniform SOC across cells, enhancing battery performance, increasing usable capacity, and protecting cells during charging and discharging by dynamically adjusting charging cycles based on measured characteristics like voltage and temperature.
Implementation Method 1
the wireless control modules each comprises a temperature sensor; and wherein the temperature sensor is bonded or mechanically crimped to a negative electrode of the corresponding one of said plurality of cells
Implementation Method 2
A dissipative balancing circuit can be provided to selectively shunt selected cells with selected value resistors to remove charge from the highest charged cells
Data Source
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AI summary
The present invention relates to a battery (1) for a motor vehicle. The battery (1) is made up of a plurality of electrically interconnected cells (3(x,y)). A wireless control module (1(x,y)) is associated with a corresponding cell (3(x,y)). The wireless control module (1(x,y)) is configured to substantially match the state of charge (SOC) of the corresponding cell with a target SOC. The target SOC can be based on the SOC of one or more of the other cells (3(x,y)) in the battery (1). The invention also relates to a wireless control module (1(x,y)); a cell (3(x,y)); and a power system for a motor vehicle.