Short-Circuit Detection Circuit Using Resistive and Inductive Sensing
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Solution Overview
Problem
Conventional overcurrent protection devices are slow and require high current levels to trigger, leading to potential damage from excessive heat generation in electrical systems, and existing short circuit detection methods are inflexible and inefficient across various voltage sources and loads.
Innovation Solution
A short circuit detection apparatus with a programmable arithmetic unit that combines voltages from resistive and inductive elements in a current path, using amplifiers, a comparator, and a microcontroller to detect short circuits, and can be adapted to different application requirements through user-programmable arithmetic operations and threshold settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional overcurrent protection devices (fuses, electromechanical circuit breakers) are used, then they provide basic protection against overcurrent, but they respond slowly and require high current levels to trigger, allowing excessive heat generation and potential damage
Solution Approach 1:
The patent replaces mechanical protection devices (fuses, electromechanical circuit breakers) with an electronic protection circuit that uses electronic components (operational amplifiers, comparators, transistors) to detect and respond to short circuits. This substitution enables much faster response times because electronic circuits can detect current changes and trigger protection switches in microseconds, compared to the slow thermal-mechanical response of conventional devices.
Solution Approach 2:
The protection circuit continuously monitors the current through the load using sensing resistors and operational amplifiers, automatically detecting short circuit conditions and triggering the protection switch without external intervention. The circuit performs self-diagnosis and self-protection, eliminating the need for manual intervention or slow thermal accumulation to trigger protection.
2Reliability
If conventional protection circuits with fixed characteristics are used, then they provide stable protection for specific applications, but they are inflexible and cannot be adapted to different voltage sources and load types
Solution Approach 1:
The patent implements a programmable arithmetic unit that can be configured through software or hardware to perform different arithmetic operations (addition, subtraction, multiplication, division) on the sensed current signals. This dynamic reconfigurability allows the same physical circuit to be adapted to different application requirements, voltage sources, and load types by simply changing the arithmetic operation mode, providing both stability and versatility.
Solution Approach 2:
The protection circuit is designed with universal components and a programmable arithmetic unit that can handle multiple types of calculations and detection algorithms. The same circuit hardware can serve different applications (DC-DC converters, AC-DC power supplies, motor drives, etc.) by reprogramming the arithmetic operations and threshold values, making it a multi-functional protection solution.
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
Provides rapid and reliable short circuit detection, adaptable to diverse voltage sources and loads, minimizing damage by quickly triggering protective switches, and offering real-time monitoring and self-diagnostic capabilities.
Implementation Method 1
a first voltage provided by a resistive element of the monitored current path and being proportional to the electrical current flowing via the monitored current path
Implementation Method 2
a second voltage provided by an inductive element of the monitored current path and depending on a derivative of the electrical current flowing via the monitored current path
Data Source
AI summary
A short circuit detection apparatus (1) for detection of an electrical short circuit current flowing in at least one monitored current path comprises an evaluation circuit (8) including at least one programmable or preprogrammed arithmetic unit (8A) adapted to perform at least one arithmetic combination operation, ACOP, on a first voltage, UR, provided by a resistive element (6) of the monitored current path and being proportional to the electrical current, I, flowing via the monitored current path and on a second voltage, UL, provided by an inductive element (7) of the monitored current path and depending on a derivative of the electrical current, dI/dt, flowing via the monitored current path to provide a combined sensor voltage, and including a comparator (8D) adapted to compare the combined sensor voltage provided by the programmable or preprogrammed arithmetic unit (8A) with a preset or an adjustable threshold voltage to generate a short circuit detection signal (SCDS) if the combined sensor voltage exceeds the threshold voltage.