Induction-excited alternator

The paper describes a new form of alternator excitation. No sliding contacts are used and no rectifiers rotating on the shaft are required. The rotor consists of N equally spaced rotor windings in which approximations to a square wave of current are induced. Over sections of the machine, when the rotor coils are carrying substantially constant current, the output windings behave like sections of a d.c.-excited alternator with 2N poles. Two experimental machines are described and a comparison is made between the induction-excited alternator and (a) a d.c.-excited alternator and (b) an inductor alternator.