Dual-Resistor DC Fuse Sensing for False Trip Suppression
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Solution Overview
Problem
Existing direct current (DC) circuit breakers suffer from erroneous disconnections due to the influence of inductance components, particularly when there are large changes in current caused by noise or sudden accelerations, leading to inaccurate current detection.
Innovation Solution
A DC short circuit protection device incorporating a fuse with a bus bar and dual current detectors, each with different resistance values, integrated with the bus bar, and a disconnection control circuit that processes signals from these detectors to suppress the influence of inductance components, ensuring accurate current detection and preventing erroneous disconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single current detector with inductance component is used, then the device structure is simple, but erroneous disconnection occurs due to counter-electromotive voltage during large current changes
Solution Approach 1:
The single current detector is divided into two separate current detectors (first and second current detectors), each with its own resistor. This segmentation allows the system to process multiple detection signals and cancel out counter-electromotive voltage effects through differential calculation, thereby improving reliability while maintaining reasonable structural complexity
Solution Approach 2:
The disconnection control circuit acts as an intermediary that processes the detection signals from both current detectors. It calculates the difference between the two detection signals to eliminate the counter-electromotive voltage component, serving as a mediator that transforms the problematic inductance effect into an cancelable artifact
2Measurement precision
If dual current detectors with different resistance values are integrated with the bus bar, then current detection accuracy is improved by canceling counter-electromotive voltage, but device complexity increases
Solution Approach 1:
The two current detectors are integrated directly with the bus bar structure, merging the detection function into the existing current-carrying component. This integration approach reduces the need for separate external detectors and simplifies the overall device configuration while maintaining the dual-detector functionality for accurate current measurement
Solution Approach 2:
The first and second resistors are positioned at different locations along the bus bar, creating local variations in resistance values. This local quality differentiation allows the system to detect current at multiple points and use the differences to cancel out inductance effects, improving measurement precision through spatial distribution
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 device effectively suppresses erroneous disconnections by canceling out the counter-electromotive voltage components, allowing precise current detection and reliable operation under varying conditions.
Implementation Method 1
a first current detector that includes a first resistor and detects a current flowing through the bus bar, a second current detector that includes a second resistor and detects the current flowing through the bus bar
Implementation Method 2
when there is a large change in the flowing current because of noise or the like, a counter-electromotive voltage (V=−L×di/dt) is generated because of the influence of an inductance component in a sensor
Data Source
AI summary
A direct current short circuit protection device includes a fuse that includes a bus bar and cuts off the bus bar in response to an ignition signal, a first current detector that includes a first resistor and detects a current flowing through the bus bar, a second current detector that includes a second resistor and detects the current flowing through the bus bar, and a disconnection control circuit that outputs the ignition signal to the fuse based on a first detection signal output from the first current detector and a second detection signal output from the second current detector, wherein the first resistor and the second resistor are integrated with the bus bar, and a current having a same magnitude as the current flowing through the bus bar flows in the first resistor and the second resistor, and the first resistor and second resistor have resistance values different from each other.