Analysis of the steady state characteristics of doubly fed synchronous machines

A theoretical and experimental analysis of the steady-state characteristics of a doubly fed synchronous machine (DFSM) is presented. The basic equations and the equivalent circuit that represent the steady state of the DFSM are derived. In the experiments, a three-phase symmetrical wound-rotor terminals were connected to the three-phase bus, and the rotor terminals were connected to the slip-frequency source. A DC generator was directly connected to the DFSM as a load. An AC generator driven directly by a DC motor was used as the slip-frequency source. The theoretical results were confirmed. The rotor iron loss remains an important factor, but its effect is shown to be small when slip is small.<>