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

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.