From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
The magnetising flux density and stator currents of a variable frequency induction motor transformer.
Identifier | ExFiles\Box 32\4\ Scan063 | |
Date | 28th October 1929 | |
X1581 28.10.29. VARIABLE FREQUENCY INDUCTION MOTOR TRANSFORMER. THREE PHASE STATOR TO SINGLE PHASE ROTOR. Magnetising flux density b = B sin(pt - qx) a travelling wave, in which p is the electrical angular velocity of the wave and p/q the linear velocity. This travelling wave produces a single phase E.M.F. in the rotor winding. Rotor flux due to rotor current when rotor (loaded) is turning with electrical angular velocity r or linear velocity r/q a = -2A sin(rt - qx+α) cos(p - r)t = -A sin(pt - qx+α)-A sin{(2r - p)t - qx+α} which consists of a forward travelling wave differing in phase by π - α with the stator flux wave plus a travelling wave of electrical angular velocity 2r - p. Stator currents additional to those required to produce b, must flow to produce stator fluxes of a1 = A sin(pt - qx+α) and a2 = A sin{(2r - p)t - qx+α} in order to annihilate the fluxes due to the rotor current. a1 is supplied by a normal system of three phase currents, and a2 must be supplied by a three phase system of currents of frequency (2r - p) / 2π | ||