Power Converter Fault Current Mitigation Without Shaft Cutting
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Solution Overview
Problem
Conventional electric and hybrid-electric propulsion systems in aircraft face challenges in mitigating high fault currents during electrical faults, which can lead to conductor heating, system failure, and potential fires, and existing solutions like shaft cutting compromise system reliability and fault tolerance.
Innovation Solution
A control method that drives negative sequence converter current to zero, bypassing fault currents through the converter instead of the faulted path, maintaining converter voltage at both AC and DC links to reduce or eliminate fault currents and torque oscillations without requiring shaft cutting or terminal disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional fault mitigation methods (shaft cutting or terminal disconnection) are used, then fault currents are interrupted, but system reliability and fault tolerance are compromised
Solution Approach 1:
The patent introduces a control system as an intermediary that actively manages fault currents by detecting faults and adjusting converter output voltages to redirect currents away from faulted paths. This mediator approach allows continuous operation without mechanical disconnection, maintaining system reliability while mitigating harmful fault effects
Solution Approach 2:
The patent replaces mechanical fault mitigation methods (shaft cutting devices or terminal disconnection mechanisms) with an electronic control system that uses voltage regulation and current redirection. This substitution eliminates the need for physical system disruption while achieving fault current mitigation, thereby preserving system integrity and reliability
2Object-affected harmful factors
If shaft cutting is used to mitigate fault currents, then fault tolerance is improved, but device complexity and system reliability deteriorate
Solution Approach 1:
The patent replaces complex mechanical shaft cutting devices with a simpler electronic control system that regulates converter output voltages to redirect fault currents. This electronic approach reduces mechanical complexity while achieving the same fault mitigation effect
Solution Approach 2:
The patent extracts the fault current mitigation function from the mechanical domain and implements it purely through electronic control of the converter. By separating the control function from mechanical components, the system achieves fault tolerance without adding mechanical complexity
3Object-affected harmful factors
If terminal disconnection is used to stop fault currents, then harmful effects are reduced, but productivity and system availability deteriorate
Solution Approach 1:
The patent maintains continuous operation of the propulsion system by using control-based fault current redirection instead of disconnection. The converter continues to operate and supply power to healthy phases, ensuring uninterrupted useful action while mitigating conductor heating through active current management
Solution Approach 2:
The control system acts as an intermediary that allows the system to continue operating during faults by actively managing current paths. This mediator enables continuous productivity by preventing complete system shutdown while still protecting against harmful thermal effects
4Reliability
If additional sensors and shutdown mechanisms are added for fault protection, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent makes the existing converter control system multi-functional by enabling it to perform both normal power conversion and fault current mitigation. The same control hardware and software that manage converter operation during normal conditions are extended to detect faults and redirect currents, eliminating the need for separate dedicated fault protection components
Solution Approach 2:
The converter control system serves itself by incorporating fault detection and mitigation capabilities directly into its existing control architecture. The system monitors its own operation and automatically adjusts its behavior during faults without requiring external protection systems, reducing overall device complexity while maintaining reliability
Data Source
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AI summary
An electric power conversion system (300) comprising: an alternating current (AC) source (302) comprising a plurality of AC terminals (306) for conducting AC power; a voltage source (334) electrically coupled to the AC terminals (306); and a controller (80) operably coupled to the voltage source (334), the controller (80) being configured to: operate the voltage source (334) to apply a fault reducing voltage at the AC terminals (306) that reduces an AC line-to-line fault current (If).