Forced-Discharge Resistor Selection Under Battery Heating Limits
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Solution Overview
Problem
Current methods for selecting the resistance of a resistor for forced discharge of battery cells are inadequate, as they either lead to excessive heat generation or slow energy consumption, increasing the risk of thermal runaway.
Innovation Solution
A forced discharge test apparatus and method that includes a heating circuit, discharge circuit, temperature sensor, and control unit to determine the optimal resistance for preventing thermal runaway by testing various resistance and temperature settings, using a heating film and power supply to simulate heat generation and a switch to control discharge, determining the maximum valid temperature and resistance for safe discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the resistance of the resistor is too low, then the forced discharge rate increases and internal energy consumption improves, but the temperature of the resistor sharply rises and heat generation from the battery increases
Solution Approach 1:
The patent applies parameter changes by systematically varying the resistance value of the discharge resistor across multiple test groups. Each group tests a different resistance value (e.g., 0.1Ω, 0.5Ω, 1Ω, 2Ω, 5Ω, 10Ω, 20Ω, 50Ω, 100Ω) to identify the optimal resistance that balances discharge rate and temperature control. This approach directly addresses the contradiction by finding the specific parameter value that satisfies both requirements.
2Temperature
If the resistance of the resistor is too high, then the resistor temperature remains low, but the internal energy of the battery decreases too slowly
Solution Approach 1:
The patent systematically changes the resistance parameter to resolve this contradiction. By testing a wide range of resistance values from low (0.1Ω) to high (100Ω), the patent identifies the optimal resistance value that achieves sufficient energy consumption rate while maintaining acceptable temperature levels. The parameter change approach allows quantitative optimization of the trade-off between these two opposing requirements.
3Reliability
If inappropriate resistance is selected for forced discharge, then thermal runaway prevention capability improves, but the risk of thermal runaway increases
Solution Approach 1:
The patent employs feedback mechanisms by continuously monitoring temperature during forced discharge tests and using this information to determine the optimal resistance value. The temperature data from each test group feeds back into the selection process, allowing the patent to identify resistance values that prevent thermal runaway while maintaining safe operating temperatures. This feedback loop ensures reliable thermal runaway prevention.
4Measurement precision
If multiple test groups with different resistance values are conducted, then determination accuracy of optimal resistance improves, but test time and complexity increase
Solution Approach 1:
The patent applies segmentation by dividing the overall test into multiple independent test groups, each testing a specific resistance value. This segmentation allows systematic evaluation of different resistance options while organizing the test process efficiently. Each test group can be conducted independently, and results from all groups are combined to determine the optimal resistance, balancing accuracy with manageable test complexity.
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
Enables accurate determination of the optimal resistance for preventing thermal runaway in battery cells and cell groups, ensuring safe and efficient energy consumption during forced discharge.
Implementation Method 1
a heating circuit configured to heat at a predetermined heating rate in response to a first control signal
Implementation Method 2
it is important to appropriately select the resistance of a resistor that consumes the energy of the battery as Joule heat during forced discharge
Data Source
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AI summary
A forced discharge test apparatus includes a heating circuit; a discharge circuit; a temperature sensor; and a control unit. When the control unit receives a test command indicating a test resistance and a test temperature, the control unit outputs a first control signal to the heating circuit to increase the temperature of a battery cell. The control unit outputs a second control signal to the discharge circuit to discharge the battery cell when the temperature of the battery cell reaches the set test temperature. The control unit determines that the test temperature is valid with respect to the test resistance when the temperature of the battery cell is equal to or lower than the upper temperature limit at a time point at which a predetermined heating time has passed from a time point when the first control signal is outputted.