Battery Management System Cell Balancing via Thermal Discharge
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Solution Overview
Problem
Efficient management of batteries in energy storage systems is crucial for extending battery life and ensuring stable power supply, but existing systems lack effective cell balancing methods, particularly for handling temperature variations across battery cells.
Innovation Solution
A battery management system (BMS) that includes a measurement circuit for monitoring voltage and temperature, a balancing circuit with discharge resistors, and a control unit to selectively apply voltage to low-temperature battery cells for cell balancing, stabilizing DC link voltage, and managing power flow between renewable energy sources, the grid, and loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cell balancing is performed using a fixed discharge resistor, then the circuit is simple, but temperature variations across battery cells cannot be effectively managed
Solution Approach 1:
The patent applies dynamics by making the discharge resistor values variable rather than fixed. The balancing circuit dynamically adjusts the resistance value for each battery cell based on its temperature and voltage state. This allows the system to adapt to temperature variations across different cells, effectively managing thermal uniformity while maintaining a relatively simple overall circuit architecture.
Solution Approach 2:
The patent changes the resistance parameter of the discharge resistors based on battery cell temperature and voltage conditions. By varying the resistance value according to measured parameters, the system optimizes the balancing process for each cell, ensuring effective temperature management without requiring complex additional hardware.
2Stability of the object's composition
If cell balancing is performed on all battery cells simultaneously, then voltage balance is improved, but energy waste increases due to unnecessary discharge of already balanced cells
Solution Approach 1:
The patent applies local quality by performing cell balancing selectively on individual battery cells that require it, rather than uniformly treating all cells. The control unit identifies specific cells with voltage deviations beyond a predetermined threshold and applies balancing only to those cells. This localized approach maintains voltage balance across the battery pack while minimizing energy waste by avoiding unnecessary discharge of already balanced cells.
Solution Approach 2:
The patent uses partial action by applying cell balancing only to the extent necessary - specifically to cells that exceed the voltage threshold. Rather than continuously balancing all cells (excessive action), the system intervenes partially and selectively, achieving sufficient voltage balance while conserving energy by leaving properly balanced cells undisturbed.
3Productivity
If discharge resistor value is increased to improve balancing speed, then cell balancing efficiency is improved, but heat generation increases causing temperature rise
Solution Approach 1:
The patent changes the resistance parameter dynamically based on temperature conditions. When a battery cell or discharge resistor becomes too hot, the system adjusts the resistance value to reduce current and heat generation. This parameter adjustment allows the system to maintain efficient balancing speed when conditions permit while preventing excessive temperature rise when thermal limits are approached.
Solution Approach 2:
The patent implements feedback by continuously monitoring the temperature of battery cells and discharge resistors, then using this information to adjust the balancing process. The control unit receives temperature data and modifies the discharge resistor values or balancing timing accordingly, creating a closed-loop system that maintains balancing efficiency while preventing dangerous temperature increases.
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 BMS effectively extends battery life by maintaining optimal temperature and voltage balance across cells, ensuring stable power supply and efficient energy storage and distribution, even during grid abnormalities.
Implementation Method 1
a balancing circuit (22) connected to the plurality of battery cells (10-1 to 10-4), and configured to perform balancing by applying voltage to a low temperature battery cell among the plurality of battery cells using a discharge resistor
Data Source
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AI summary
A battery management system (20) for a battery (10) comprising a plurality of cells (10-1, 10-2, 10-3, 10-4) comprises a balancing circuit (22) including a resistance corresponding to and positioned adjacent each cell; a measurement circuit (21) configured to measure a voltage and a temperature of each cell; and a selection unit (25) configured to select a high voltage cell for balancing, the high voltage cell having a voltage higher than the other cells, and to select a low temperature cell having a temperature below a threshold. The battery management system is configured to discharge the selected high voltage cell through the resistance corresponding to the selected low temperature cell to increase the temperature of the low temperature cell.