Characterisation of FBG based Magnetic Field Sensor Response Sensitivity to Excitation Orientation for Rotating Electric Machine Applications

Abstract

This paper reports an experimental study aimed at characterising the response of an in-situ fibre optic fibre Bragg grating / magnetostrictive flux sensor when exposed to excitation in orientations aligned with and perpendicular to its optimal performance axes. The study is aimed at improving the understanding of the potential for non-invasive in-situ application of this sensing technology in devices with confined geometries which impose restrictions on possible magnetic excitation axis alignment with that of the sensor, such as those encountered in rotating electric machinery.

Fibre optic sensors for the monitoring of rotating electric machines: a review

“…Other EM practical issues and parameters are monitored by employing FOS systems as well, including the EM's electric (Marignetti et al 2016;Fusiek et al 2008) or magnetic fields (Barczak et al 2009;Melecio et al 2019) (i.e. current, flux, and power), partial discharge detection (Rosolem et al 2010;Wang et al 2018) and dynamic eccentricity monitoring (Sousa et al 2016).…”

Electrical Machine Permanent Magnets Health Monitoring and Diagnosis Using an Air-Gap Magnetic Sensor

“…The core functionality of the magnetic sensor proposed in this study is based on combining the FBG inherent strain sensing feature with high magnetostriction properties of Terfenol-D material [16], [17]. The following sub-sections present the details of the sensor design, prototyping and calibration procedures.…”

“…To ensure optimal sensor performance while delivering a minimally invasive and fully retrofittable monitoring capability the sensor is designed to be integrated within a modified stator slot wedge structure: this allows for effective exposure of the Terfenol-D plate to the rotating PM radial field, while minimally interfering with the main flux paths into the stator teeth and requiring no physical disturbance to the machine magnetic circuit or structure. Furthermore, to simplify the sensor application and allow for a more practical design while retaining sensing functionality, a Terfenol-D plate directed axially, lengthwise along the slot wedge structure and with its anisotropy axis perpendicular to the observed PM field, is used [16]. This ensures the magnetic sensor is located as close as possible to the rotor magnets.…”

“…The FBG sensing technology, with its advanced features such as small size, Electromagnetic Interference Immune (EMI), multiplexing and multi-physical sensing presents a promising proposition for enabling targeted in-situ monitoring of machine multi physical operating conditions. FBG magnetic sensing applications for electrical machine monitoring are only starting to be examined, with very recent reports suggesting encouraging potential for this application in non-permanent magnet machines (induction machine and hydro generator) but not exploring PM machine applications [14]- [16]. Furthermore, the application of reported magnetic sensing methods to a wider range of electrical machines would be practically limited, due to their design imposing either requirements for invasive installation methods, or limitations on the sensor integration within an arbitrary test machine geometry.…”