Ricerc@Sapienza

A wound-rotor three-phase induction generator with eccentric rotor and parallel connections in both stator and rotor can be represented by five equivalent sequence-circuits of virtually centered-rotor machines, as mathematically proved in previous papers. The five circuits allow the calculation of stator and rotor fault-related currents, in form of 2(p±1)-pole space vectors for 2p-pole machines.

The doubly-fed induction machine has long been reputed as a curiosity with few practical applications. Consequently, very often there was not enough space to treat this machine in undergraduate electrical machines curricula in the past. But times changed and today this machine is often an integral part of wind turbines as electric generator. This way, getting familiar with the relevant operating principles becomes a desirable task for undergraduate students. This paper proposes a circuit-based theoretical approach which may serve as a template for an undergraduate lecture.