A New Self-Excited Synchronous Induction Motor

Two early forms of the synchronous induction motor are described and their performance analyzed with special reference to synchronizing torque. A new self-excited form of this type of motor devised by the author is then described, its mode of operation and characteristics are elucidated and the principles governing its design explained with the help of vector diagrams. An analysis of the synchronizing torque shows that whereas prior machines all exhibit an alternating synchronizing torque of either slip, or double the slip frequency, the synchronizing torque in the new motor is substantially unidirectional and pulsating. The machine is particularly well suited for smaller units and operates with unity or leading power factor throughout its normal load range without taking an excessive current at any load or requiring any adjustment other than that automatically provided by its inherent regulating capacity.