Motor Modal Analysis Calculation Based on Standard Installation‐Type Foot Model

Accurately predicting the natural frequency of a motor is an important foundation for achieving quantitative analysis of electromagnetic vibration. However, ignoring the stiffness and mass distribution of the foundation structure may lead to inaccurate modal prediction. This article proposes an analytical modal calculation method for standard mounted foot motors based on composite shell theory and energy method. Firstly, by comparing the modal frequencies of cylindrical shell motors and motors with standard mounting feet, the necessity of considering the foot structure in the calculation of motor natural frequencies is demonstrated. Then, the stator core, casing, stator teeth, and standard mounting feet are uniformly modeled as a coupled ribbed composite cylindrical shell structure. Decompose the irregular geometric features of the foot section, derive the centroid and moment of inertia of the foot, and introduce them into the expressions for kinetic and potential energy. The accuracy of the proposed method was verified through finite element analysis and hammer impact modal experiments. Finally, the sensitivity of key structural parameters of the foundation to the natural frequency of the motor was analyzed. The results indicate that the proposed method can improve computational efficiency while ensuring high computational accuracy. © 2026 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.