Hybrid Load Protection Apparatus for Fast Overcurrent Interruption
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Solution Overview
Problem
Conventional overcurrent protection devices are inefficient and unreliable, often requiring high current levels to trigger switch-off and resulting in significant power loss and potential damage to electrical loads, as they operate slowly and rely on fuses or semiconductor switches that can be damaged by excessive voltage drops.
Innovation Solution
A hybrid load protection apparatus with a primary power supply path using a controllable mechanical switch and a secondary power supply path with a semiconductor switch, where both paths are designed to interrupt the current quickly and independently, using driver circuits to trigger switch-off based on current rise speed and voltage drops, respectively, to suppress arc generation and ensure safe and efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional semiconductor switches are used for overcurrent protection, then the protection can be triggered automatically, but the switch-off period is long and the semiconductor switch may be damaged by excessive voltage drops
Solution Approach 1:
The patent divides the protection system into two independent paths: a primary power supply path with a mechanical switch and a secondary power supply path with a semiconductor switch. This segmentation allows each path to operate independently with its own trigger mechanism, enabling the mechanical switch to provide fast physical interruption while the semiconductor switch provides electronic control, thereby resolving the contradiction between fast switch-off and protection reliability
Solution Approach 2:
The patent introduces a current transformer as an intermediary element that couples the primary and secondary power supply paths. The current transformer detects the current in the primary path and triggers the semiconductor switch in the secondary path, enabling fast response without directly exposing the semiconductor switch to high voltage drops, thus resolving the contradiction between automatic protection and switch-off speed
2Reliability
If fuses are used for overcurrent protection, then the load can be protected against high current amplitudes, but much electrical energy is transferred to the load before the fuse melts
Solution Approach 1:
The patent implements preliminary protection action by using the current transformer to detect overcurrent conditions and trigger the semiconductor switch before the fuse would melt. The semiconductor switch interrupts the current flow in the secondary path preemptively, preventing excessive energy transfer to the load while maintaining protection reliability
Solution Approach 2:
The patent replaces the purely mechanical fuse melting process with an electronic control system using semiconductor switches and current transformers. This substitution enables faster response time and more precise control, preventing excessive energy transfer to the load while maintaining reliable protection
3Reliability
If conventional protection circuits are used, then the switch-off mechanism can be triggered by voltage drop evaluation, but the switch-off occurs only after current reaches high amplitude
Solution Approach 1:
The patent implements feedback control by using the current transformer to continuously monitor the current in the primary path and provide trigger signals to the semiconductor switch in the secondary path. This feedback mechanism enables the system to respond to current changes in real-time, allowing switch-off at lower current amplitudes and reducing power loss while maintaining reliable protection
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 hybrid approach significantly enhances operational safety by rapidly interrupting the power supply, reducing power loss and preventing damage to electrical loads, while allowing for quick reactivation and extended service life of the protection apparatus.
Implementation Method 1
a primary coil (4A-1) coupled inductively to a secondary coil (4A-2) providing a voltage, UA, corresponding to a current rise speed
Implementation Method 2
a primary coil (4A-1) coupled inductively to a secondary coil (4A-2) providing a voltage, UA
Implementation Method 3
detect an increasing electrical current flowing through the secondary power supply path caused by the interruption of the primary current path on the basis of a voltage drop generated by the further coil
Data Source
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AI summary
A hybrid load protection apparatus (1) comprising a primary power supply path (1A) provided between an input terminal (2) and an output terminal (3) of said hybrid load protection apparatus (1) and having a controllable mechanical switch (5A) connected in series with a primary coil (4A-1) coupled inductively to a secondary coil (4A-2) providing a voltage, UA, corresponding to a current rise speed of the electrical current flowing through the primary power supply path (1A), wherein the provided voltage, UA, is applied directly to a driver input (IN) at a low voltage side of a first driver circuit (6A) associated with the primary power supply path (1A) to trigger automatically a switch-off of the mechanical switch (5A) within a first switch-off period (Δt1) to interrupt the primary power supply path (1A); and comprising a secondary power supply path (1B) provided in parallel to the primary power supply path (1A) between the input terminal (2) and the output terminal (3) of said hybrid load protection apparatus (1) and having a further coil (4B) connected in series with a semiconductor power switch (5B). wherein a second driver circuit (6B) associated with the secondary power supply path (1B) is provided to detect an increasing electrical current, I, flowing through the secondary power supply path (1B) caused by the interruption of the primary current path (1A) on the basis of a voltage drop (ΔU4) generated by the further coil (4B) and a non-linear voltage drop (ΔU5) along the semiconductor power switch (5B) applied as a sum voltage (UB) directly to a driver input (DESAT) at a high voltage side of the second analog driver circuit (6B) to trigger automatically a switch-off of the semiconductor power switch (5B) provided in the secondary power supply path (1B) within a second switch-off period (Δt2) to interrupt the secondary power supply path (1B)