Investigation on the Dynamic Performance of an Induction Machine Using a Novel Concept of a Rotating Converter with a Floating Capacitor

This paper explores a topology of induction machine drive with a novel concept of a wound rotor fed by a converter with a floating DC-link capacitor. The Y-connected stator windings are connected to the grid, while Y-connected rotor windings are connected to a three phase converter with a floating DC-link capacitor. By integrating the converter into the wound rotor, the slip-rings and the brushes becomes unneeded. Constant speed operation can be achieved at various loads by controlling the fundamental frequency of the converter. The stator power factor can be effectively improved over a wide range of load at constant speed. Particularly, unity power factor can be obtained within +/- 25% of the rated load. Moreover, harmonic spectra of the stator and rotor currents are presented.