Influence of Position on Optoelectronic Strain Measurement Systems for Flywheels

The main component of flywheel energy storage systems (FESS) is the flywheel rotor itself: a rotating mass which stores kinetic energy. Ongoing research in the field of FESS requires constant condition monitoring of the flywheel rotor, especially when new composite materials and flywheel rotor manufacturing methods are investigated. Optoelectronic strain measurement (OESM) is a method to contactlessly measure the flywheel rotor's radial deformation as well as its position in the radial plane via a special reflective pattern on the flywheel which is read via optical sensors. This letter presents a simulation model to estimate the influence of pattern offset and in-plane movement of the flywheel on an array of multiple sensors. The measurement values from multiple sensors can be fused to mitigate the influence of cross sensitivity between flywheel deformation and position measurements. The influence of out-of-plane movement on the measured values is evaluated via measurements on a test bench setup, where the sensor distance can be controlled by a stepper motor.