MEMS Magneto-Optical Current Sensing for EMI-Resistant Surge Detection
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Solution Overview
Problem
Current magnetic field sensing apparatuses for surge and impulse current registration, such as loop antennas and Rogowski coils, are susceptible to electromagnetic interference (EMI) and have limitations in bandwidth, making them unsuitable for applications like lightning detection in aircraft and wind turbines.
Innovation Solution
A micro-electromechanical (MEMS) current sensing apparatus using an optical path with a magneto-sensitive element, a light source, and a photo-detector, which measures the magnetic field induced by current through the Faraday effect in optical crystals or ferrimagnetic materials, providing robustness against EMI and enabling wide frequency spectrum and range measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If loop antennas or Rogowski coils are used for current sensing, then the device can detect magnetic field changes, but the device becomes susceptible to electromagnetic interference (EMI)
Solution Approach 1:
The patent replaces traditional electromagnetic sensing mechanisms (loop antennas, Rogowski coils) with a magneto-optical sensing mechanism. A magneto-sensitive element modulates light properties in response to magnetic field changes, and this optical signal is detected by a photodetector, converting the sensing mechanism from electromagnetic to optoelectronic to eliminate EMI susceptibility.
Solution Approach 2:
The patent introduces light as an intermediary medium between the magnetic field and the detection system. The magneto-sensitive element acts as a mediator that couples the magnetic field information to optical signals, which are then detected without direct electromagnetic coupling, thereby isolating the system from EMI.
2Measurement precision
If traditional magnetic field sensing apparatuses are used, then current measurements can be made, but the bandwidth for current and magnetic field measurements is limited
Solution Approach 1:
The patent changes the fundamental operating parameters of the sensing system by using optical frequencies instead of electromagnetic induction at power frequencies. The magneto-optical effect operates at optical frequencies, enabling the system to respond to much faster magnetic field changes, thereby increasing the measurement bandwidth and frequency response.
3Adaptability or versatility
If loop antennas and Rogowski coils are used, then magnetic field detection is possible, but integration into complex structures like wind turbines and aircraft is difficult
Solution Approach 1:
The patent segments the sensing system into discrete, modular components: a magneto-sensitive element, light source, and photodetector. This segmentation allows the sensor to be configured in different geometries and integrated into complex structures like wind turbine blades and aircraft airfoils, where space and mounting constraints vary.
Solution Approach 2:
The patent transitions from planar, two-dimensional antenna structures to a three-dimensional magneto-optical sensing arrangement. The optical path can be routed through the structure in multiple dimensions, allowing integration into complex geometries where traditional planar antennas cannot be mounted.
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 MEMS current sensing apparatus effectively registers lightning and surge currents with high signal-to-noise ratio, resistance to EMI, and reduced weight, making it suitable for applications in environments prone to electromagnetic interference, such as wind turbines and aircraft.
Implementation Method 1
measures the magnetic field induced by current through the Faraday effect in optical crystals or ferrimagnetic materials
Data Source
AI summary
An apparatus includes an optical portion disposed on a carrier portion. The optical portion includes an optical path of and a magneto-sensitive element within the optical path. A light source is disposed on the carrier portion in operative communication with a first end of the optical path, and a photo-detector is disposed on the carrier portion in operative communication with a second end of the optical path.