Self-Powered DC Solid-State Circuit Breaker for Fault Interruption
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Solution Overview
Problem
Existing DC power systems face challenges in providing reliable circuit protection during short circuit faults, as conventional solid-state circuit breakers require external power supplies and complex sensing circuits, which may not be available during fault events, and existing solutions have limitations in response time and lifetime.
Innovation Solution
A family of unidirectional and bidirectional solid-state circuit breakers that utilize voltage sensing across the switch to detect short circuits, employing DC-DC converters to generate power for current interruption without an external power supply, using semiconductor switches like JFETs and HEMTs with voltage sensing and power supply circuits, including blocking diodes, resistors, capacitors, and metal-oxide varistors to rapidly turn off the switch during faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid-state circuit breakers use external power supplies and complex sensing circuits, then they can provide current interruption protection, but they become unreliable during short circuit fault events when power may not be available
Solution Approach 1:
The circuit breaker uses its own internal energy storage capacitor to power the control electronics during fault conditions, eliminating the need for external power supplies. The capacitor is charged during normal operation and automatically discharges to trigger the tripping mechanism when a short circuit is detected, making the device self-sufficient and reliable during power failures.
Solution Approach 2:
The invention extracts and eliminates the external power supply requirement from the system. By using an internal capacitor that stores energy during normal operation, the patent removes the vulnerability to external power failure while maintaining all necessary control functions during fault conditions.
2Device complexity
If electromechanical DC circuit breakers are used, then they provide simple two-terminal design, but they suffer from slow response time of 30-100 milliseconds and limited lifetime due to arcing
Solution Approach 1:
The patent replaces the mechanical moving contacts and arcing mechanisms of traditional circuit breakers with solid-state semiconductor switches (IGBTs or MOSFETs). This eliminates mechanical wear and arcing while enabling microsecond-level response times through electronic control, achieving both simplicity and high speed performance.
3Speed
If DC solid-state circuit breakers use power semiconductor switching devices like IGBTs or SiC JEFTs, then they achieve fast response time of tens to hundreds of microseconds and longer lifetime, but they require complex and expensive over-current sensing circuitry and external power supplies
Solution Approach 1:
The circuit breaker uses its own internal energy storage capacitor to power the control electronics during fault conditions, eliminating the need for external power supplies. The capacitor is charged during normal operation and automatically discharges to trigger the tripping mechanism when a short circuit is detected, making the device self-sufficient and reliable during power failures.
Solution Approach 2:
The patent employs a single voltage sensing mechanism that simultaneously detects both over-voltage conditions and short circuit faults. This multi-functional approach eliminates the need for separate over-current sensing circuitry and external power supplies, reducing complexity while maintaining fast response capability.
4Use of energy by moving object
If stand-alone SSCB uses leakage power to cut off fault current, then it minimizes power consumption during normal operation, but it requires very fast dynamic response DC-DC converters
Solution Approach 1:
The control capacitor is pre-charged during normal operation to store the energy needed for fault interruption. This preliminary energy storage eliminates the need for high-power real-time conversion during faults, allowing the use of simpler, lower-cost DC-DC converters that only need to maintain the capacitor charge at a trickle level during normal operation.
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 solution provides fast and reliable current interruption during short circuit faults without an external power supply, reducing the need for complex sensing circuits and extending the lifetime of the circuit breakers, while also minimizing die size and costs.
Implementation Method 1
The power is drawn from the high voltage built across the switch using a DC-DC converter
Implementation Method 2
The sudden increase in the voltage across the switch, 'desaturation,' provides the power to turn and hold off the switch
Data Source
AI summary
A solid-state circuit breaker for a DC power system which may operate unidirectional and bidirectional and does not require an external power supply to provide current interruption protection during an event of a short circuit fault.