Series Power Switch Circuit for MOSFET Damage Shutdown
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Solution Overview
Problem
Semiconductors used in power switching applications, such as MOSFETs, can deteriorate and lead to uncontrollable overheating and potential fires due to issues like rapid oxidation, causing short-circuits and making them difficult to switch off, and existing solutions like PCB fuses are cumbersome and risky.
Innovation Solution
An electrical power switching circuit with two semiconductor switches connected in series, where a comparator monitors and compares voltage drops across each switch, generating signals to shut down the undamaged switch if a predetermined threshold is exceeded, thereby interrupting current through the damaged switch and preventing overheating and fires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single semiconductor switch is used for power switching, then the device is simple and easy to operate, but it becomes uncontrollable and hazardous when damaged due to short-circuit between gate and drain
Solution Approach 1:
The patent divides the single semiconductor switch into two separate semiconductor switches connected in series. This segmentation allows independent monitoring and control of each switch, so that when one switch becomes damaged or uncontrollable, the other switch can still be controlled to interrupt current flow, preventing the hazardous situation of complete loss of control
Solution Approach 2:
The patent introduces voltage monitoring circuits and control circuits as intermediary elements between the power source and the semiconductor switches. These intermediaries continuously monitor the voltage across each switch and can independently control each switch's operation, providing an additional layer of control that prevents total system failure when one switch becomes damaged
2Reliability
If PCB fuses are used to protect against overcurrent, then overcurrent protection is provided, but high temperatures are produced during melting and fire risk increases
Solution Approach 1:
The patent implements preliminary monitoring of voltage across semiconductor switches before overcurrent conditions develop. The control circuits continuously detect voltage changes and can preemptively adjust or shut down switch operation, preventing the development of dangerous overcurrent conditions that would require fuse melting and associated fire hazards
Solution Approach 2:
The patent replaces the mechanical/thermal protection mechanism of PCB fuses (which rely on melting to interrupt current) with electronic control mechanisms that use voltage monitoring and electronic switching to interrupt current flow. This substitution eliminates the high-temperature melting process and associated fire risks while maintaining overcurrent protection capability
3Measurement precision
If voltage monitoring is implemented to detect damaged switches, then switch damage can be detected, but the damaged switch cannot be switched off due to short-circuit between gate and drain
Solution Approach 1:
The patent segments the switching function into two independent switches, each with its own control circuit. When voltage monitoring detects damage to one switch, the control circuit can still independently control the other undamaged switch to interrupt current flow, maintaining shutdown capability even when one switch becomes uncontrollable
Solution Approach 2:
The patent introduces control circuits as intermediaries between the voltage monitoring system and the semiconductor switches. These control circuits receive voltage information from monitoring circuits and execute switching decisions, providing a bridge that allows the system to respond to detected damage even when direct control of the damaged switch is lost
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 reduces the risk of overheating and fire by detecting damaged switches through voltage drop comparison and automatically shutting off the undamaged switch, ensuring operational safety and preventing further damage.
Implementation Method 1
a comparator configured to compare a first voltage to a second voltage and to output a first electrical signal if the first voltage exceeds the second voltage by a first predetermined threshold and to output a second electrical signal if the second voltage exceeds the first voltage by a second predetermined threshold, wherein the first voltage corresponds to a voltage drop across the first semiconductor switch (Q1) and the second voltage corresponds to a voltage drop across the second semiconductor switch (Q2)
Implementation Method 2
A prominent example is a metal-oxide-semiconductor field-effect transistor (MOSFET) also called power MOSFET. It comprises an insulated gate and an input and an output called drain and source, respectively. The voltage or potential at the gate controls the conductivity between drain and source.
Data Source
AI summary
Disclosed is an electrical power switching circuit. The electrical power switch circuit includes a first semiconductor switch having a first control input and a second semiconductor switch having a second control input. The first semiconductor switch and the second semiconductor switch are connected in series. The electrical power switch circuit includes a comparator configured to compare a first voltage to a second voltage and to output a first electrical signal if the first voltage exceeds the second voltage by a first predetermined threshold and to output a second electrical signal if the second voltage exceeds the first voltage by a second predetermined threshold. The electrical power switch circuit includes a combiner configured to combine the first signal and the second signal and to feed a combined signal to the first and second control inputs of the first and second semiconductor switches.