Over-Current Protection Circuit With EMI-Stable Auto Reset
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Solution Overview
Problem
Conventional over-current protection devices are inefficient due to unstable switching devices caused by electromagnetic interference, and they lack a reset function to reconnect electrical devices to the circuit once normal current flow is restored, requiring external intervention.
Innovation Solution
An over-current protection system that includes a sensing device, comparators, and transistors to detect and manage current flow, disconnecting electrical devices from the circuit during over-current conditions and reconnecting them when current flow returns to a safe level, without external intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional switching devices are used to disconnect electrical devices during over-current conditions, then the protection function is provided, but the switching devices become unstable due to electromagnetic interference from ground
Solution Approach 1:
The patent introduces an intermediary circuit stage between the comparator output and the control device. This intermediary circuit processes the comparator output signal through additional transistors and resistors, isolating the control device from direct electromagnetic interference while maintaining signal integrity for reliable switching operation.
2Extent of automation
If conventional over-current protection devices disconnect electrical devices during over-current flow, then device protection is achieved, but the devices cannot be automatically reconnected when current returns to normal levels
Solution Approach 1:
The patent implements a feedback mechanism where the comparator continuously monitors the current through the sensing device and automatically adjusts the switching state. When current drops below the threshold after an over-current event, the comparator output changes state, automatically resetting the switching devices and reconnecting the electrical devices without external intervention.
Solution Approach 2:
The protection system performs self-service by automatically detecting over-current conditions, disconnecting the load, and then automatically reconnecting the load when conditions normalize. The system serves itself through the automatic reset function without requiring external manual intervention, improving operational convenience.
3Productivity
If switching devices are used to protect against over-current, then disconnection function is provided, but the devices may not efficiently disconnect due to instability
Solution Approach 1:
The patent prepares the switching circuit in advance by designing a stable biasing network and signal conditioning stage before the actual switching action is needed. The intermediary circuit and proper component selection ensure that when disconnection is required, the switching devices are already in the optimal state for rapid and efficient operation.
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 system effectively protects electrical devices from damage during over-current conditions and automatically resets the circuit when conditions return to normal, enhancing safety and operational efficiency.
Implementation Method 1
The sensing device is adapted to sense current flowing to an electrical device
Implementation Method 2
The at least one comparator adapted to compare a signal received from the sensing device and a reference signal to generate any one of high signal and low signal
Implementation Method 3
The at least one first transistor connected to the output signal of the at least one comparator to control the at least one first transistor, wherein the at least one first transistor is in a conductive state when the output signal of the at least one comparator is high signal
Data Source
AI summary
The invention herein provides an over-current protection system. The over-current protection system includes a sensing device, a comparator, a first transistor, and a second transistor. The sensing device is adapted to sense current flowing to an electrical device. The comparator is adapted to compare a signal received from the sensing device and a reference signal to generate any one of high signal and low signal, the output of the comparator being connected to a control device. The first transistor connected to the output signal of the comparator to control the first transistor, while the first transistor is in a conductive state when the output signal of the comparator is high signal. The second transistor connected to and controlled by the first transistor, while the second transistor is in a conductive state when the first transistor is in the conductive state.