Automated technique for building high-frequency equivalent circuits of motors based on electromagnetic field analysis

Abstract

To estimate in advance the high-frequency impedance of a motor, and its internal voltage distribution when an inverter surge is applied, a technique to derive the circuit constants of various parts of a motor based on electromagnetic field analysis and build its high-frequency equivalent circuit, where each turn of the coils is separately modeled, has been developed. By switching between 2D and 3D analyses and between 1-slot and 1-pole models to accelerate the calculation method and by automating them in parallel, the developed technique even enables non-experts to build an accurate high-frequency equivalent circuit of a motor. Based on the accuracy verification, the shared voltage of coils can be estimated with an error of 20% or less by considering the frequency characteristics of the resistance and inductance of each turn of the coils and modeling a lead wire in the measurement setup.