GB630455A - Improvements in dynamo-electric machines - Google Patents

Abstract

630,455. High - frequency machines. PLEBANSKI, J. May 20, 1947, No. 13571. Convention date, Nov. 20, 1946. [Class 35] The stator or rotor of a dynamo-electric machine has a pair of electrically-coupled quadrature windings connected to sources of high-frequency currents of slightly different frequencies, the machine running at a speed dependent on the beat frequency. The device is described as a motor, but it is stated that it may also act as a generator. In a freely rotatable form shown, the stator carries windings 1-1 and 2-2 fed with frequencies Vo - f and Vo + f respectively, the circuits being joined by a mutual inductance or capacitance M or by mutual inductance between the windings. The resultant flux is stated to rotate at a speed equal to half the beat frequency. The rotor may be of squirrelcage form so as to rotate asynchronously or it may carry a winding 3 externally energized, as shown, by a supply of frequency Vo so that it rotates synchronously at half the beat frequency. Alternatively, the rotor winding may be connected to a condenser producing resonance at the frequency Vo. The machines may be air or iron cored and it is stated that the speed and rotation can be changed by altering the beat frequency. A speed control circuit for a motor comprising a pair of oscillators with differentially ganged tuning is described. Alternatively, the side-bands of a modulated carrier can be used. An arrangement is also described in which a large beat-frequency motor is fed from a pair of alternators whose speed is differentially controlled. In an oscillating form, the machine is only permitted limited rotation under the control of springs and may be used to energize loud-speakers or microphones from an amplitude, phase or frequency modulated signal.