Abstract: A brushless excitation system for a synchronous motor with a holding current resistor connected across the motor field winding to insure turning on of a semiconductor excitation control switch due to a gating pulse of limited duration.

Abstract: A winding technique for multiphase machines is presented that utilizes a core of Q slots and P poles for M phases where Q/M is an integer but the number of slots per phase per pole Q/M/P is a non-integer expressible as a fraction N/D reduced of common factors and M and D have a common factor of at least two. Fractional-slot, nearly but not quite balanced, windings are provided by providing a distant coil grouping for D poles in which the number of coils in the coil groups for the D poles equals N for an individual phase and the pattern is repeated for the additional poles to provide the total of P pole windings. The near balancing of the windings succeeds in achieving sufficient voltage balancing and low torque harmonics for successful operation and is advantageous for avoiding a need to provide additional core designs.

Abstract: A pole amplitude modulated dynamoelectric machine having a specific harmonic suppressed by expanding the electrical angle of the phase belts as well as the method for doing the same is disclosed.

Abstract: A static control system for applying excitation to synchronous motors, especially of the brushless type, by firing a semiconductor switch to apply direct current excitation to the field of the motor. A post-synchronization firing circuit is provided for firing the switch in response to the voltage across the switch if the motor pulls into synchronism before the switch is fired. A control circuit is provided for inhibiting the operation of the post-synchronizing firing circuit during subsynchronous operation.

Abstract: Two cascaded induction machines provide asynchronous power transmission between two independent generating networks. The shafts of the two induction machines are mechanically connected for concurrent rotation and the rotor windings of the two machines are electrically connected in a reverse phase sequence. The cascaded induction machines are geared to a relatively low power variable speed drive which accurately controls the position and rotation of the shafts. A control system supplies low frequency excitation current for the variable speed drive and is capable of continuous operation through zero frequency to reverse the direction of rotation. The control system determines the level of power flow within the induction machines and is unresponsive to the difference in frequency of generation of the two generating networks so that the power flow is controlled even under transient load conditions.

Abstract: A starting control system for synchronous motors is provided in which the usual separately mounted discharge resistor is eliminated. A relatively high resistance coil of small size is wound on each field pole, in addition to the normal field winding, and these coils are connected together and utilized as a discharge resistor during starting of the motor.