A Novel Type of Smoothly Variable Speed, A-C Motor Having Widely Adjustable Power-Factor Characteristics

In this paper a new type of a-c motor, using d-c excitation to the stator and 2-phase a-c variable voltage to the armature through synchronously revolving brushes, is described. The new machine has smoothly adjustable speed characteristics of a d-c motor and power-factor (pf) control characteristics of a synchronous motor. The motor can also be used in single-phase systems. Again, it is possible to operate the machine with series-and compound-connected excitation in addition to using it as an autosynchronized converter, if additional stationary brushes are provided.