Semiconductor Circuit Breaker Bypass Circuit for Inrush Current Control
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Solution Overview
Problem
Existing solid-state circuit breakers face issues with high sensitivity to inrush currents during initial startup, leading to malfunctions and increased size due to the need for large capacitors and resistors in snubber and freewheeling circuits to manage residual currents.
Innovation Solution
A solid-state circuit breaker design utilizing a transient voltage suppressor (TVS) device to consume residual current energy, along with a bypass electric circuit and inrush current suppression resistor to manage inrush currents, reducing the circuit's size and preventing malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a solid-state circuit breaker uses high-speed power semiconductor switches for fast circuit interruption, then the circuit interruption speed is improved, but the sensitivity to inrush current increases causing malfunction
Solution Approach 1:
The patent introduces a bypass circuit as an intermediary component that provides an alternative current path during inrush current events. This bypass circuit allows the main semiconductor switches to operate at high speed for fault interruption while the bypass circuit handles the inrush current, preventing malfunction. The bypass circuit acts as a mediator between the high-speed switching requirement and the inrush current sensitivity problem.
2Reliability
If snubber circuits and freewheeling circuits are added to suppress voltage rise and consume residual current energy, then the reliability is improved, but the device size increases
Solution Approach 1:
The patent merges the functions of snubber circuits and freewheeling circuits into a single integrated bypass circuit. Instead of having separate components for voltage suppression and residual energy consumption, the bypass circuit performs both functions simultaneously. This consolidation reduces the overall device size while maintaining the reliability benefits of both original circuits.
Solution Approach 2:
The bypass circuit is designed as a multi-functional component that serves multiple purposes: it suppresses voltage rise across semiconductor switches, consumes residual current energy, and provides an alternative path for inrush current. This universal design eliminates the need for multiple dedicated circuits, thereby reducing device size while improving reliability.
3Reliability
If large capacitors and resistors are used in snubber and freewheeling circuits to handle larger residual currents, then the reliability is improved, but the device size and weight increase
Solution Approach 1:
The patent changes the operational parameters of the bypass circuit, specifically controlling the turn-off timing of semiconductor switches and the operation of bypass switches. By optimizing these parameters, the circuit can handle residual currents effectively without requiring large capacitors and resistors. The parameter optimization allows smaller components to achieve the same reliability performance.
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 design effectively consumes residual current energy, suppresses inrush currents, and prevents malfunctions by using a TVS device and bypass circuit, resulting in a smaller and more reliable circuit breaker.
Implementation Method 1
a voltage across both ends of the semiconductor switch may increase due to an abnormal current that has already flowed thereinto. Accordingly, a typical solid-state circuit breaker further includes at least one additional circuit, such as a snubber circuit 15 and freewheeling circuits 16a, 16b as shown in FIG. 1, for suppressing a voltage rise due to a residual current.
Implementation Method 2
a bypass electric circuit connecting a drain terminal of a first semiconductor switch and a source terminal of a second semiconductor switch... and an inrush current suppression resistor to manage inrush currents
Data Source
AI summary
The present invention comprises: a semiconductor switch unit including a first semiconductor switch having a drain terminal connected to a power grid, a second semiconductor switch having a drain terminal connected to a load, and first and second diodes each having a positive electrode and a negative electrode respectively connected to a source terminal and the drain terminal of each semiconductor switch; a bypass circuit which connects the drain terminal of the first semiconductor switch to the source terminal of the second semiconductor switch; and a control unit which supplies a current to the load through the bypass circuit and the second diode by closing the bypass circuit while the first and second semiconductor switches are turned off, and which turns on the first and second semiconductor switches so as to open the bypass circuit so that a current is supplied to the load through the semiconductor switch unit.