Solid-State Circuit Breaker Clamping for MVDC Fault Currents
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Solution Overview
Problem
Hybrid electric propulsion systems face challenges in fault current management due to the high power ratings and rapid fault current rise in medium voltage direct current (MVDC) systems, which traditional circuit breakers struggle to address effectively, leading to potential damage and inefficiencies.
Innovation Solution
A solid state circuit breaker design incorporating a metal oxide varistor (MOV) connected in series with thyristors, breakover diodes, and Zener diodes, along with additional passive components like RC snubbers and reverse blocking Zener diodes, allows for independent selection of clamping and withstand voltages, reducing peak clamping voltage and enhancing fault current handling capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional circuit breaker is used in MVDC systems, then the system can handle fault currents, but the response time is too slow and the clamping voltage is too high causing damage
Solution Approach 1:
The patent replaces traditional mechanical circuit breakers with a solid-state circuit breaker using semiconductor switches (IGBTs or MOSFETs) that can respond in microseconds to fault conditions, eliminating the slow mechanical operation and achieving ultra-fast response times required for MVDC fault protection
Solution Approach 2:
The patent changes the response time parameter from milliseconds (mechanical) to microseconds (solid-state), and modifies the clamping voltage parameter by using voltage-clamping devices like TVS diodes or Zener diodes to maintain lower clamping voltages during fault conditions, thereby protecting the system effectively
2Loss of time
If a solid state circuit breaker is used to achieve rapid response, then response time is reduced, but the clamping voltage remains too high causing potential damage
Solution Approach 1:
The patent merges the semiconductor switch (for rapid response) with voltage-clamping devices (TVS diodes, Zener diodes, or MOVs) in a hybrid configuration, combining the speed advantage of solid-state devices with the voltage protection capability of nonlinear resistors to achieve both fast response and low clamping voltage
Solution Approach 2:
The patent introduces voltage-clamping devices as intermediary components between the semiconductor switch and the load, where these devices (TVS diodes, Zener diodes, or MOVs) act as mediators that limit the peak voltage during fault conditions while allowing the semiconductor switch to maintain ultra-fast response capability
3Reliability
If high voltage-rated semiconductors are used to handle fault currents, then fault protection is improved, but power loss and efficiency increase
Solution Approach 1:
The patent changes the voltage rating parameter of the semiconductor devices from high voltage (causing high conduction losses) to low voltage ratings, and compensates for this by adding voltage-clamping devices that activate only during fault conditions, thereby reducing normal operating power loss while maintaining fault protection capability
Solution Approach 2:
The patent uses low voltage-rated semiconductors for normal operation (reducing power loss) and adds voltage-clamping devices that provide excessive voltage protection only when needed during fault conditions, avoiding the continuous power loss associated with high voltage-rated devices operating in their linear region
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
This design reduces power loss, minimizes weight and size, and improves efficiency by allowing the use of lower voltage-rated semiconductors and thyristors, effectively managing high fault currents while maintaining system reliability and simplicity.
Implementation Method 1
a metal oxide varistor (MOV) that is connected in series to a thyristor, the MOV to clamp voltage of current flowing through the solid state circuit breaker
Implementation Method 2
a breakover diode to activate at a target voltage level to allow the current to flow to the MOV along a second path
Implementation Method 3
a Zener diode to close the gate and allow current to flow along the first path in response to the current on the second path
Data Source
AI summary
A solid state circuit breaker that may include a metal oxide varistor (MOV) that is connected in series to a thyristor, the MOV to clamp voltage of current flowing through the solid state circuit breaker; the thyristor including a gate to control flow of the current to the MOV along a first path to the MOV; a breakover diode to activate at a target voltage level to allow the current to flow to the MOV along a second path; and a Zener diode to close the gate and allow current to flow along the first path in response to the current on the second path.