Y-Type DC Solid-State Circuit Breaker With MOV-Off Clamping
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Solution Overview
Problem
Existing DC solid-state circuit breakers face challenges such as high conduction losses, complex system design, high design cost, and reliability issues during reclosing and rebreaking processes, particularly in thyristor-based systems, which affect their efficiency and safety.
Innovation Solution
A new Y-type SSCB design utilizing a capacitor-capacitor pair for ultrafast countercurrent pulse injection, minimizing mechanical disconnector use, and disconnecting MOVs from the power line during OFF-state to enhance compactness and reliability, with a design procedure optimizing component selection for fast operation and reliable reclosing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If IGBTs are used in SSCBs to achieve fast operation, then switching speed is improved, but conduction losses increase
Solution Approach 1:
The patent transitions from IGBT technology to wide bandgap devices (such as GaN HEMTs), which represent a fundamental parameter change in semiconductor material properties. This change enables both fast switching speeds and low conduction losses simultaneously, resolving the technical contradiction by achieving high electron mobility and wide breakdown voltage characteristics inherent to wide bandgap materials.
2Loss of energy
If wide bandgap devices are used in SSCBs to reduce conduction losses, then energy efficiency is improved, but design cost increases
Solution Approach 1:
The patent adopts a modular architecture where wide bandgap devices are used strategically in specific critical components (such as the main switch and auxiliary circuitry) rather than throughout the entire system. This segmentation approach allows the design to benefit from wide bandgap performance where most needed while controlling overall cost through selective implementation.
3Speed
If passive commutation is used in thyristor-based SSCBs to achieve fast protection, then fault isolation speed is improved, but overload protection capability is lost
Solution Approach 1:
The patent merges passive commutation mechanisms with active control elements to create a hybrid system. The passive commutation components (such as RC circuits and auxiliary thyristors) provide fast fault isolation, while integrated sensing and control circuitry enable overload detection and protection. This combination allows the system to achieve both fast protection and versatile protection capabilities simultaneously.
4Reliability
If a large number of thyristors and capacitors are added to AR-based SSCBs to achieve complete protection, then protection capability is improved, but system complexity increases
Solution Approach 1:
The patent extracts and eliminates redundant components from traditional active resonance breaker designs. By using wide bandgap devices with inherent fast switching capabilities and lower loss characteristics, the design removes the need for large numbers of auxiliary thyristors and capacitors, achieving complete protection capability with a simplified component set.
5Reliability
If IGBTs are connected in series with main thyristors in LCS-based SSCBs to achieve complete protection, then protection reliability is improved, but efficiency and current capability decrease
Solution Approach 1:
The patent replaces IGBTs with wide bandgap devices (such as GaN HEMTs), which represent a fundamental parameter change in semiconductor characteristics. These devices offer higher electron mobility, lower on-resistance, and faster switching speeds, thereby improving both efficiency and current capability while maintaining the series connection architecture for complete 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 Y-SSCB achieves fast fault current isolation, minimizes reclosing preparation time, enhances reliability, and addresses MOV degradation issues, ensuring efficient and safe operation with improved voltage utilization rate.
Implementation Method 1
an ultrafast countercurrent pulse injection by a capacitor-capacitor pair to implement a complete commutation
Implementation Method 2
a metal-oxide varistor (MOV) holds the voltage across the IGBT
Data Source
AI summary
A thyristor-based dc solid state circuit breaker (SSCB) named Y-type includes a new complementary commutation circuit including a capacitor-capacitor pair, which features three advantages. First, a fast commutation is achieved using a countercurrent pulse injection by the capacitor-capacitor pair structure. Second, metal-oxide varistors (MOVs) are disconnected from the power line when SSCB is OFF, which solves the reliability issue due to the MOV degradation and enhances the voltage utilization rate of the main switch. Third, benefiting from the capacitor-capacitor pair structure, reliable reclosing and rebreaking are obtained for practical applications.