Battery Pack Current Monitoring Without Shunt Resistor Failure
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Solution Overview
Problem
Rechargeable battery packs face challenges in detecting short circuits due to faulty current sensing resistors, which can lead to overheating, damage, or explosion, as the protection mechanism fails to monitor voltage across the resistor when it becomes faulty.
Innovation Solution
A current monitoring system comprising a signal detection unit, logic unit, and current path control unit is introduced, which detects voltage signals and generates logic signals to control a current path switch, allowing for alternative monitoring of charging and discharging currents on the current path, even when the current sensing resistor is abnormal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current sensing resistor with large resistance is implemented to obtain a larger voltage difference for current detection, then the current monitoring capability is improved, but the resistor becomes prone to overheating and potential failure
Solution Approach 1:
The patent introduces a virtual voltage signal generated through calculation (using Kirchhoff's voltage law with voltages from other cells/terminals) as an intermediary to represent the voltage across the current sensing resistor. This virtual signal allows current monitoring without directly measuring across the physical resistor, thereby avoiding the overheating problem while maintaining detection capability.
2Temperature
If the current sensing resistor resistance is minimized to prevent overheating, then the safety is improved, but the voltage difference for current detection becomes too small
Solution Approach 1:
The patent uses a mathematical calculation intermediary (applying Kirchhoff's voltage law) to amplify the detectable signal. By calculating the voltage across the low-resistance current sensing resistor as the difference between voltages measured across other cells/terminals, the system achieves high measurement precision without requiring high resistor resistance.
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 effectively prevents battery pack damage by detecting short circuits and controlling current flow, ensuring safety by maintaining or cutting off current paths as necessary, even when the current sensing resistor is faulty.
Implementation Method 1
detecting at least one voltage signal of the group of cells and/or of the positive terminal of the battery pack
Implementation Method 2
controlling the current path switch according to the logic signal
Data Source
AI summary
A battery pack includes a group of cells, a current path switch coupled to the group of cells, and a current monitoring system. The current monitoring system includes a signal detection unit, a logic unit and a current path control unit. The signal detection unit is coupled to the group of cells and/or a positive terminal of the battery pack, and used to detect at least one voltage signal of the group of cells and/or of the positive terminal of the battery pack. The logic unit is coupled to the signal detection unit, and used to generate a calculated value of a voltage signal of the at least one voltage signal and generate a logic signal according to the calculated value. The current path control unit is coupled to the logic unit and the current path switch, and used to control the current path switch according to the logic signal.