Semiconductor Circuit Breaker Zero-Current Cutoff for Surge Suppression
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Solution Overview
Problem
Semiconductor circuit breakers using self-arc-extinguishing switches face challenges in cutting off currents at non-zero points, leading to surge voltages and increased size and cost, especially when loads like motors are connected.
Innovation Solution
A semiconductor circuit breaker with a control system that detects accidents or current zero points to quickly cut off currents before reaching the switch's withstand current, using insulated gate bipolar transistors (IGBTs) and controlling them to be non-conductive, and optionally incorporating a current limiter to manage inductive loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a semiconductor switch controlled by a control signal is used to cut off current before the current zero point, then the current can be interrupted quickly without generating an arc, but a high surge voltage may be generated when the load is an induction load such as a motor
Solution Approach 1:
The circuit detects the current zero point in advance and schedules the current cutoff to occur at this predetermined timing. By performing the cutoff action at the optimal moment (current zero point) rather than immediately upon accident detection, the system prevents surge voltage generation while maintaining relatively fast interruption capability
Solution Approach 2:
The control system dynamically adjusts the current cutoff timing based on real-time detection of current waveform characteristics. Instead of using a fixed immediate cutoff response, the system adapts the interruption timing to match the dynamic state of the AC current, specifically waiting for the current zero point before executing the cutoff
2Loss of time
If the current is cut off at other than the current zero point, then the current can be interrupted quickly, but a high surge voltage is generated that may damage the semiconductor switch
Solution Approach 1:
The system performs preliminary detection of the current zero point and prepares the cutoff action to be executed at this predetermined safe timing. This preliminary identification of the optimal cutoff moment allows the system to balance speed and safety by planning the interruption in advance rather than reacting immediately
Solution Approach 2:
The control system continuously monitors the current waveform and uses this feedback information to determine the precise timing of the current zero point. This feedback mechanism enables the system to adaptively adjust the cutoff timing based on actual electrical conditions, ensuring reliable operation while maintaining efficient current interruption
Data Source
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AI summary
Provided are a semiconductor circuit breaker and a circuit breaking device that suppress generation of a surge voltage when a current is cut off using a semiconductor switch controlled to be conductive or non-conductive by a control signal. The semiconductor circuit breaker includes a semiconductor switch unit (10) connected to an AC circuit, and a phase control unit (20) that controls conduction and non-conduction of the semiconductor switch unit (10) by the control signal. The phase control unit (20) includes an accident detection unit (21) to detect an accident based on a current detected from the AC circuit, a zero point detection unit (22) to detect a current zero point based on the current detected from the AC circuit, and a control signal output unit (23) to output the control signal for setting the semiconductor switch unit (10) to be non-conductive when the accident detection unit (21) detects the accident or when the zero point detection unit (22) detects the current zero point in response to a command to cut off the current.