Structural Analysis and Determination of Critical Speed of a 10,000 rpm Switched Reluctance Machine Rotor

High-speed machines are gaining popularity in the modern age due to their high power density. While they offer advantages, they also pose several electrical and mechanical challenges. In a particular high-speed application like turbo-machines, the rotor is subjected to the high temperature of order 500°C or above. In such operating conditions, switched reluctance machines with solid rotor are viable solutions as it does not contain any winding and permanent magnets on its rotor. The mechanical characteristics of the rotor, such as stress, deformations, natural frequencies, and critical speeds, need to be found for a given rotor design to ensure the safe and reliable operation. This paper presents an analysis of solid rotors used in 10,000 rpm Switched reluctance machines (SRM) using the finite element analysis (FEA) tool, ANSYS. The FEA analysis determines the maximum stress and deformation of rotor at various loads and speeds. The natural frequencies and mode shapes of the rotor are determined under free-free condition. Further, the critical speed of the rotor are estimated considering the effect of the bearing stiffness and rotor speed on the natural frequencies. This study confirms the rigid rotor operation at 10,000 rpm with a separation margin of 33% from the critical speed (i.e., 15,000 rpm).