Wireless-Coupled MVDC Solid-State Breaker for Zero-Current Switching
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Solution Overview
Problem
Medium voltage DC (MVDC) systems face challenges in fault detection and current interruption due to high fault currents, leading to voltage oscillations and potential damage, with existing circuit breakers having limitations in response speed, efficiency, and cost.
Innovation Solution
A solid-state DC breaker system utilizing stacked MV SiC devices, wireless capacitive couplers, and a modular pulse power supply to achieve zero-current switching, reducing voltage oscillations and improving reliability, efficiency, and scalability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If mechanical circuit breaker is used, then cost is low and structure is simple, but response speed is slow and arcing problems occur
Solution Approach 1:
The patent replaces the mechanical switch in traditional circuit breakers with solid-state semiconductor devices (IGBTs or MOSFETs) to eliminate mechanical moving parts. This substitution achieves fast response speed (microsecond level) and completely eliminates arcing problems that plague mechanical circuit breakers, while maintaining circuit breaker functionality through electronic switching.
Solution Approach 2:
The patent changes the operating parameters of semiconductor devices by using parallel connection configurations to achieve both fast switching speed and current handling capability. By carefully selecting switching timing and controlling the number of parallel devices engaged, the system achieves rapid fault response without the arcing issues of mechanical contacts.
2Reliability
If solid-state circuit breaker is used, then response speed is fast and arcing is eliminated, but cost is high and efficiency is low
Solution Approach 1:
The patent divides the circuit breaker into multiple parallel branches, each containing semiconductor devices. During normal operation, multiple branches share the current, reducing the current burden on each device and minimizing conduction losses. This segmented architecture maintains high reliability while improving efficiency by distributing electrical stress across multiple paths.
Solution Approach 2:
The patent employs selective activation of parallel semiconductor branches based on operating conditions. During fault conditions, only the necessary number of branches are activated to handle the fault current, avoiding unnecessary conduction losses in idle branches. This partial action approach optimizes the balance between reliability and energy efficiency.
3Adaptability or versatility
If hybrid circuit breaker is used, then merits of mechanical and solid-state devices are combined, but response time needs improvement
Solution Approach 1:
The patent merges multiple solid-state switching paths in parallel to create a unified circuit breaker system that combines the advantages of different semiconductor device configurations. This merged architecture provides both mechanical-like robustness and solid-state speed, achieving universal adaptability while maintaining microsecond-level response times through coordinated switching of parallel branches.
4Reliability
If DC breaker interrupts high fault current, then fault protection is achieved, but voltage oscillations occur and electrical stress is imposed on devices
Solution Approach 1:
The patent implements preliminary current redistribution by activating parallel branches before the main switching event. When a fault is detected, the system pre-charges or pre-positions parallel current paths to be ready for immediate engagement. This preliminary action ensures smooth current transition during fault interruption, minimizing voltage oscillations and electrical stress on switching devices while maintaining effective fault 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 proposed solution enables fast and reliable fault protection in MVDC systems by achieving zero-current switching, reducing voltage oscillations, and enhancing the efficiency and scalability of the circuit breaker, thus improving system reliability and safety.
Implementation Method 1
wireless capacitive coupler
Implementation Method 2
resonant circuit
Data Source
AI summary
With the fasting growth of renewable energy resources and DC supplied loads, DC electrical systems have been increasingly received attentions all over the world. DC breaker systems play a key role in protection systems for disconnecting sources and loads, and they are also used mainly for removing faulted sections from the system accurately and reliably. Solid state DC breakers benefit from fast response time and compactness features; however, due to the lack of zero current realization and high-power losses, the reliability and efficiency of these devices is low. The system proposes a solid-state DC breaker for medium voltage DC (MVDC) systems. The presented structure have two main parts: 1) a main conduction branch including stacked MV Silicon-Carbide (SiC) devices to improve the efficiency and provide a fast response time, 2) a breaker branch including a wireless capacitive coupling to avoid metal-to-metal contact and increase the overall reliability, and also a modular current pulse power supply to realize zero-current switching.