IMPROVED ROTARY INDUCTOR ELECTRICAL DEVICE

1298616 Dynamo-electric machines ALLISCHALMERS MFG CO 6 May 1970 [13 May 1969] 21848/70 Heading H2A A rotary machine giving an output signal representing the vector sum of electrical input signals comprises a ferromagnetic stator having sets of angularly displaced first and second teeth, a first energizing winding having turns on one first tooth and a second energizing winding having turns on one second tooth, an output winding having turns on both the one first and the one second teeth, and a ferromagnetic rotor arranged so that the permeance of the flux paths between the teeth and rotor varies cyclically. The rotor may have a lobe 28, as shown, or may be circular and have regions of differing permeability, or may comprise skewed, segmented laminations. The embodiment shown comprises two sets of teeth 1, 3, 5 ... 11, and 2, 4, 6 ... 12, energizing windings on all of the teeth of each set being connected in series to a respective signal source 101 or 102. Each of the three output phase windings includes turns on teeth of both sets, e.g. phase A output winding includes part windings 81, 84, 87 and 90 respectively on teeth 1, 4, 7 and 10, the part windings on teeth of each set being connected subtractively. The rotor is driven by a motor 34 so that the output is modulated at a frequency dependent on motor speed, has an amplitude dependent on the amplitudes of energizing signals V c and V s , and a phase dependent on the relative magnitudes of V c and V s . The output may be used, as shown, to control a motor control circuit 35, e.g. a cycloconverter, energizing the windings of motor 34. The machine may form part of a circuit for controlling the speed and torque of a synchronous motor (Fig. 7) as in Specification 1,198,980. The first and second teeth may be formed on separate stators 150, 153, Fig. 15 (not shown), and co-operate with different rotors (125, 1251). Alternatively, the teeth of one set are bunched together at one part of the stator circumference and the teeth of the other set are bunched together substantially diametrically opposite the first set to reduce interference between the fluxes of the two energizing windings. The energizing windings may be A.C. excited as shown, or D.C. excited, Fig. 14 (not shown). The rotor may be inside or outside the stator.