High speed AC generator (7200 RPM, 60 Hz) for autonomous power systems

The authors analyze the features of an electric generator whose angular speed is twice that of the rotating field. Two versions are studied: series- and parallel-connected windings. A technical analysis is presented in order to determine which type of machine to choose for specific applications. The relevant mathematical models are deduced. Self-excitation of the machine feeding an autonomous power system is ensured by two sets of capacitors. The on-load characteristic curves of the machine when operating as a generator are presented, and the strategies to be used to maintain constant voltage are described. The experimental results, obtained on a small power machine at Rome University´s Department of Electric Energy, are given