An improved FE inductance calculation for electrical machines

The analysis and design of electrical machines often require analytical-models for performance assessment and system simulation. Inductances are important parameters of these models. The principles and drawbacks of the existing inductance calculation methods for electrical machines based on generalized electrical machine theory and the finite-element (FE) method are reviewed in this paper. To help alleviate some of the problems associated with these existing methods, the author has developed an improved FE inductance calculation method, and used it to evaluate inductances of equivalent circuit models. The new technique utilizes the same finite-element field solutions of electrical machines under actual multiphase excitations as are used for torque calculations. This eliminates the need for specially designed FE solutions, or for multiple solutions under current perturbations such as are required by existing FE methods. The new method has been verified by test results using a 30 hp permanent magnet synchronous machine under different load conditions.