Solid-State Circuit Breaker With Capacitor Discharge for DC Fault Isolation
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Solution Overview
Problem
Traditional solid-state circuit breakers face challenges in responding quickly to direct-current short-circuit faults, leading to large upstream currents and overstress in switching devices due to lack of free-wheeling circuits, which complicates selectivity and safety in power systems.
Innovation Solution
A solid-state circuit breaker design incorporating a first switch, a second switch, a capacitor, and diodes, along with transient voltage suppressors and inductors, provides fast response and bidirectional protection by discharging short-circuit energy through internal capacitors and forming free-wheeling circuits to manage inductive energy, reducing stress on switching devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional solid-state circuit breakers are used, then the circuit breaker structure is simple, but the response time is slow and selectivity cannot be achieved due to large upstream current at short-circuit moment
Solution Approach 1:
The circuit breaker is divided into multiple functional modules: first switching device for main circuit control, second switching device for capacitor control, capacitor for energy storage, and diode for current direction control. This segmentation allows each module to perform its specific function efficiently, achieving fast response while maintaining manageable complexity through modular design.
Solution Approach 2:
The capacitor is pre-charged to stored energy before short-circuit occurs. When short-circuit happens, the capacitor immediately discharges through the second switching device to provide counter-current, achieving microsecond-level response. This preliminary energy storage eliminates the delay of traditional thermal-magnetic mechanisms.
2Reliability
If traditional solid-state circuit breakers disconnect main circuit switching devices, then the short-circuit is interrupted, but the inductor energy has no free-wheeling circuit causing overstress in switching devices
Solution Approach 1:
The diode serves as an intermediary component that provides a dedicated free-wheeling path for inductor current. When the main switching device disconnects, the diode immediately conducts the inductor current, preventing voltage spikes and overstress on the switching devices. This intermediary component solves the energy dissipation problem without compromising switching device reliability.
Solution Approach 2:
The circuit design anticipates the inductor energy release issue and provides a pre-configured free-wheeling path through the diode. This beforehand cushioning prevents the harmful voltage spikes before they can damage the switching devices, ensuring reliable operation during and after circuit interruption.
3Measurement precision
If traditional solid-state circuit breakers are used, then the device structure is simple, but selectivity cannot be achieved due to large upstream current change at short-circuit moment
Solution Approach 1:
The circuit incorporates current detection that monitors upstream current changes and provides feedback control. When short-circuit is detected, the control system activates the capacitor discharge and diode free-wheeling path, creating a feedback mechanism that maintains precise current control and enables selective protection while managing system complexity through intelligent control.
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
Ensures fast and reliable protection against short-circuits with minimal upstream current change, extends device life, and reduces losses by managing inductive energy through internal capacitors and free-wheeling circuits, while supporting bidirectional protection for direct-current systems.
Implementation Method 1
an internal capacitor of the circuit breaker discharges to the short-circuit load to provide short-circuit energy
Implementation Method 2
the energy of the inductor of the line can be absorbed through the load or through the internal capacitor of the circuit breaker
Data Source
AI summary
A solid-state circuit breaker, including a first switch, a second switch, a first capacitor, and a first diode, wherein, a first terminal of the first switch is connected to a positive electrode of an input terminal, a second terminal of the first switch is connected to a first terminal of the second switch, a second terminal of the second switch is connected to a positive electrode of an output terminal, a first terminal of the first capacitor is connected to the first terminal of the second switch, a second terminal of the first capacitor is connected to a negative electrode of the input terminal, a cathode of the first diode is connected to the second terminal of the second switch, and an anode of the first diode is connected to a negative electrode of the output terminal.