A magnetically self-compensated induction machine for natural thyristor commutation

A new type of reactive-kilovoltampere-generating cagerotor induction machine has recently been developed which is capable of providing enough leading current when interfaced with a current-source inverter (CSI) to load commutate thyristor devices at medium and high frequencies. Two brushless rotary machines of this type have been built at the 35- and 150-hp level [1] ; they combine the torque characteristics of a conventional cage machine with the leading power-factor capability of an overexcited dc-field synchronous condenser in one unit using a common cage rotor and a common stator core. They operate continuously in the transient mode with respect to both space and time transients, for which the peculiar stator arrangement induces an abnormally large de-component of rotor current. The first theoretical analysis of the electromagnetics at 112 kW is presented.