Investigation of rotor strength and rotor dynamics for high‐speed high‐power switched reluctance machines

This study proposes an investigation scheme of the rotor strength and rotor dynamic characteristics for high‐speed high‐power switched reluctance machines (SRMs). The analytical model and finite element analysis model are established to predict the maximum stress and deformation in the rotor. The Mises yield criterion is employed to verify the strength of the rotor at 1.2 times the rated speed. For the rotor dynamics, critical speed, unbalance response, and stability of the shaft system are analysed in detail. In the developed critical speed calculation scheme, the gyroscopic effect and the impact of the rotation speed on the stiffness and damping are considered. Then, the critical speeds acquired by the developed scheme are compared with those derived by using the conventional method. The unbalance response curves at different nodes are adopted for the unbalance response calculation, while the stability of the shaft system is verified by calculating the logarithmic decrement rates. The critical speed measurement experiment is performed on a 160 kW and 18,000 r/min SRM prototype, and the proposed critical speed calculation scheme is proved to be effective and accurate. The effectiveness of the unbalance response calculation method and the stability judgement technique are also verified by experiment.