A remote FBG-OFDR thermometry sensor for EV energy systems

A Distributed thermometry technique based on fiber optical frequency domain reflectometry using Bragg grating (FBG) is proposed and developed as a versatile temperature distribution sensor. The sensor can accommodate a discontinuity in the measuring optical fiber, enabling temperature distribution measurements of systems that are physically separated as well as those that rotate or oscillate relative to the sensor. However, the presence of a discontinuity in the sensor presents a challenge, to a point where measurements are no longer possible. In response, FBGs were embedded along the measuring optical fiber and a high reflectivity mirror was implemented on the measuring fiber to increase the SNR. Experimental validation of a single and multiple FBGs were conducted. The sensor was then demonstrated on a rotating Lithium-ion battery cell at various discharge rates. Results showed accurate temperature measurements that would otherwise be difficult to probe due to space constraints and physical incompatibilities.