Estimation of high-frequency parameters of AC machine from transmission line model

This paper proposes a modeling method to estimate the high frequency (HF) characteristics of stator winding in an ac machine. From the frequency response of windings, the proposed method extracts frequency-dependent per-unit-length (PUL) transmission line parameters, which are simplified to a PUL equivalent circuit, including low-frequency and HF components. The newly developed PUL circuit provides a simple distributed-element winding model that captures HF behaviors accurately, and the modeling procedure can be easily adopted for an initial design with simulation data. To verify the proposed method, input impedance from a constructed equivalent circuit of an induction machine was compared with the measurement results. In addition, the concept of effective length, which is involved with antiresonance phenomena, is presented based on the proposed method.