A study of distributed embedded thermal monitoring in electric coils based on FBG sensor multiplexing

This paper reports the design of an embedded FBG sensing system aimed at facilitating real-time distributed internal thermal conditions monitoring in wound coils of electric machines. The proposed system utilizes the multiplexing property of FBG sensors to achieve multipoint distributed thermal monitoring in arbitrary points within the coil structure. The sensing system architecture and operating features are discussed and its performance evaluated in laboratory tests on prototype coils operated in representative static and dynamic thermal conditions. The findings demonstrate that the presented system is capable of reliable real-time monitoring of coil internal thermal conditions and provides a versatile platform that can be expanded and modified to cater for arbitrary coil geometries and designs, and enables a much improved understanding of key thermal operating conditions. The presented results set a base for further research on the integration of the reported embedded sensing architecture with dedicated real-time computing and power control resources to develop novel closed loop thermal management systems for electric coils and machines and improve their utilization.