Numerical and analytical calculation of the rotor mechanical stresses of a synchronous electricfl machine with incorporated permanent magnets

This paper proposed methods for determining mechanical stresses in the inductor of a synchronous electric machine with magnetoelectric excitation and incorporated V-shaped permanent magnets, intended for use as an auxiliary generator of a gas compressor station driven by a gas turbine engine. Along with the advantages: high energy efficiency, large electromagnetic torque and specific power, the ability to create a small airgap between the stator and the rotor, machines with such an inductor design have a significant drawback - large magnetic flux dissipation in the area of ​​external and internal saturation bridges, which is all the more significant as the bridges are wider. To decrease leakage fluxes and ensure acceptable energy performance, it is desirable to reduce the width of the bridges, but this weakens the mechanical strength of the rotor. Analytical models of two levels are proposed for assessing mechanical stresses in the inductor design, on the basis of which the configuration option for permanent magnets and rotor pole pieces is selected. The first level model assumes knowledge of the inductor geometric dimensions, which can be obtained at the stage of the electric machine electromagnetic calculation. Therefore, it is more suitable for the estimated calculation of mechanical stresses on external bridges. The second-level model was obtained using analytical dependencies based on the analogy of a magnet-pole tip system with a beam with rigid clamping on supports and a distributed load along it. It is suitable for determining mechanical strength during optimization design, when it is necessary to operate with large volumes of data. The results of calculating mechanical stresses using analytical models are checked and refined by solving the strength problem using the finite element method in the Ansys Structural software package.