Wireless-Coupled Solid-State Circuit Breaker for Medium-Voltage DC (MVDC) Systems

Background

Direct current (DC) power systems are becoming increasingly vital for efficient power transmission, driven by the rapid integration of renewable energy sources and modern DC loads. Within this landscape, medium voltage DC (MVDC) systems serve a critical role in bridging high-voltage and low-voltage networks. However, the widespread adoption of MVDC grids necessitates advanced protection mechanisms capable of swiftly and reliably interrupting fault currents to prevent catastrophic equipment damage and ensure overall grid stability.

Current approaches to DC fault interruption face significant limitations, primarily because DC waveforms lack a natural current zero-crossing. Traditional mechanical circuit breakers suffer from slow response times and severe arcing, while hybrid breakers still struggle with response speed. Although solid-state circuit breakers (SSCBs) offer faster interruption, existing designs are expensive, incur high conduction losses, and exhibit poor reliability. When interrupting high currents without a zero-crossing, standard SSCBs interact with circuit parasitic inductances and capacitances. This interaction induces severe voltage overshoots and oscillations, which places extreme stress on the semiconductor devices and risks false turn-on events or permanent component failure.

Technology

This solid-state circuit breaker (SSCB) is designed to provide fast, reliable fault interruption for medium-voltage DC (MVDC) systems ranging from 1 to 100 kV. The architecture features a main conduction branch composed of stacked silicon carbide (SiC) MOSFETs arranged for scalable voltage ratings and bidirectional current flow. Paired with this is a breaker branch containing a modular pulse power supply (PPS) and active injection circuits. These two branches are linked via wireless capacitive coupling, which provides galvanic isolation without direct metal-to-metal contact. The system also integrates a metal-oxide varistor (MOV) branch for energy absorption and a wireless, current-transformer-based gate-drive power supply. During a fault, the modular PPS uses precomputed look-up tables to inject a programmable resonant current pulse that cancels the fault current, enabling safe interruption within microseconds.

This technology is differentiated by its ability to artificially induce zero-current switching (ZCS) in DC networks, overcoming the critical challenge of interrupting DC faults that lack natural current zero-crossings. Unlike slower, arcing mechanical breakers or traditional solid-state solutions that suffer from high losses, this design eliminates parasitic voltage overshoots and gate oscillations, preventing device damage and false turn-ons. Furthermore, the use of wireless capacitive coupling and a domino-type wireless gate-drive system ensures superior high-voltage isolation and mechanical reliability. Its modular PPS architecture offers unprecedented scalability while time-sequence logic eliminates the need for complex real-time current sensing. Finally, an integrated resistor and series switch alongside the MOV accelerate voltage decay and eliminate leakage current, drastically reducing system reset times.

Benefits

• Enables zero-current switching during fault interruption, eliminating voltage overshoots and oscillations to prevent device damage and extend lifespan
• Delivers ultrafast fault interruption and high power efficiency by utilizing stacked medium-voltage silicon carbide devices
• Enhances system reliability and galvanic isolation through wireless capacitive coupling and wireless gate-drive power transfer, avoiding direct metal-to-metal contact
• Provides scalable voltage and current ratings via a compact, modular architecture that adapts to various medium-voltage DC system requirements
• Simplifies control implementation by using precomputed look-up tables and time-sequence logic rather than complex real-time current sensing
• Reduces system reset time and eliminates post-interruption leakage current for faster reclosing readiness

Applications

• Medium-voltage DC grid protection
• Renewable energy grid integration
• Electric shipboard power distribution
• Data center DC microgrids
• EV fast-charging station protection

Additional info

Fei Lu is an Associate Professor in the Department of Electrical and Computer Engineering at Lehigh University. His areas of research include: Electrical Engineering, Power Electronics, High Voltage DC Power Systems, Semiconductor Device Packaging, Renewable Energy

Assignee: Lehigh University; the patent record also identifies Drexel University as an assignee