Power Contactor Protection With Pyrofuse for DC Short Circuits
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Solution Overview
Problem
Existing electrical protection systems for high-voltage DC power supplies, such as those used in eVTOL and eCTOL aircraft, fail to adequately protect against soft short-circuits and very high short-circuit currents, leaving a gray area where the wiring is unprotected, and can damage contactors or delay fuse tripping.
Innovation Solution
An electrical protection device comprising a power contactor, Hall effect sensors, a pyrotechnic breaking device (pyrofuse), a relay, and a controller, which together detect and respond to different current levels to open the circuit, using a pyrofuse for high currents and the contactor for lower currents, with optional additional components like a fuse and magnetic probe for enhanced protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power contactor is used for protection, then soft short-circuits are protected, but very high short-circuit currents can make the contactor levitate and damage it
Solution Approach 1:
The pyrofuse acts as an intermediary protection device for very high current scenarios. When extreme currents are detected, the pyrofuse activates first to interrupt the circuit, preventing the contactor from being exposed to damaging current levels that would cause levitation and damage.
Solution Approach 2:
The system prepares multiple protection layers in advance. The pyrofuse is pre-positioned as a backup protection mechanism specifically for extreme current events, cushioning the contactor from damage before such high currents can affect it.
2Reliability
If very high short-circuit currents occur, then the contactor may levitate and be damaged, but the fuse tripping is delayed due to limited current flow
Solution Approach 1:
Hall effect sensors provide real-time feedback on the actual fault current magnitude. The controller continuously monitors this feedback and dynamically selects the appropriate protection response, ensuring the fastest possible intervention by matching the protection mechanism to the actual current level rather than using a fixed response.
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 device effectively protects the electrical installation by promptly opening the circuit in response to overloads or short-circuits, ensuring comprehensive protection against a range of current levels, including high currents, thereby preventing damage to the electrical system.
Implementation Method 1
at least two Hall effect sensors configured to measure the electrical currents flowing between the electrical power supply and the power contactor
Implementation Method 2
The pyrotechnic electrical breaking device, more commonly known as a pyrofuse, is capable of opening the power circuit by fuse effect when currents are high
Data Source
AI summary
An electrical device for protecting an electrical installation intended to be placed between a power supply and an electrical load, the device including: a power contactor comprising two contacts that are intended to be connected to the power supply; at least two Hall sensors configured to measure the electric currents at the input of the power contactor; an electrical precharging circuit intended to be placed between the power supply and the power contactor and connected to the electrical load; a relay configured to connect or disconnect the electrical precharging circuit; a pyrotechnic electrical cutoff device intended to be connected to the power supply and to the power contactor, and a controller configured to receive the measurements from the Hall sensors and to open or close the power contactor and the relay.