Synchronous Reluctance Machines as Drives for Rotary Anode X-Ray Tubes-A Feasibility Study

This paper investigates the possibility of replacing the rotor of an existing X-ray tube induction machine (IM) with that of a synchronous reluctance machine (SynRM), while keeping the existing IM stator. When compared with other applications, such machines operate with a very large air gap. Furthermore, their non-laminated rotors are placed in a vacuum and may heat up as high as 450°C. The primary design criteria for this special application is to reach a minimum speed of 10800 rpm in less than 3 sec, requiring an output torque of 1Nm. Three different types of SynRM rotors are considered. The capability of these alternative machines to provide the same output torque as the original 1M was assessed. In the next step, the losses of the different machines were identified and compared. While all machine designs were identified to be able to provide the desired output torque, the axially-layered rotor proved to be the best option, with more than 25 % reduction of the total losses when compared with the original 1M.