Experimental Validation of a Compensation Method for Ultra-High-Speed Absolute Rotary Encoders

Emerging applications, such as turbo-electric aircrafts, require electrical machines with increasingly high rotation speeds (> 100 krpm) to achieve targeted power densities and direct drive with gas turbines. These electrical machines would benefit from accurate angular measurement for control, analysis and redundancy, but are currently limited to employ sensorless control as, to the authors’ knowledge, no accurate position encoder solution is available for such high rotation speeds. This paper presents a method to compensate the position of an absolute rotary encoder and make it usable at high rotation speeds. The compensation method considers known system delays and computes a position increment from Kalman filter observed speed. An existing magnetic absolute rotary encoder specified to 10 krpm operation was used to successfully validate the compensation method at 130 krpm. These results suggest that adjustments to existing absolute rotary encoders could provide a cheap position measurement solution for the field of ultra-high-speed electrical machine, as well as other domains requiring precise position measurement from standstill to full operational speeds.