Generalized Root-Loci Theory for the Static Scherbius Drive

Generalized root-loci techniques, developed in the mid 70´s for squirrel cage motors, have been extended in the static Scherbius configuration to wound rotor, slip energy, recovery systems. This arrangement is now applied to large power drives in the 0.5 to 50 MW range. In this paper, general results applicable to all machines are presented for the open-loop control scheme, but only the subsynchronous rmode of operation in which a voltage source type inverter is used is addressed.