Abstract: An actuator in which, when the reduction ratio of a reduction gear unit is 1/N, the number of pulses of a second encoder is set to be equal to N times (the number of pulses of a first encoder), whereby a pulse processing circuit for detecting a torsion angle is made remarkably simple.

Abstract: A rotary encoder comprises a rotator having ring-shaped multipole magnet and stator having magnetic field detecting sensors concentrically provided with the ring-shaped multipole magnet. The stator is provided with a plurality of zero-magnetostrictive amorphous ferromagnetic cores arrayed in correspondence to the magnetic pole pitch of the multipole magnet. Rotation angles of the rotor are detected by coils extended across the plurality of amorphous magnetic cores to be magnetically coupled with the same.

Abstract: In a rotary electric machine including a stator core and a stator winding received in slots of the stator core, a cooling medium baffling device is provided which comprises a cooling medium baffle plate fixed to the inner peripheral edge of one end of the stator core by mounting bolts protruding axially from the end of the stator core, wherein the circumferential position of each of the mounting bolts is displaced from the circumferential position defining the boundary between the different modes of phase currents flowing through the coils constituting the stator winding, thereby effectively eliminating generation of excessive heat due to excessive eddy current losses occurring locally at the end of the stator core.

Abstract: An electric rotary machine is provided with a stator having a stator core of laminated iron plates with a given lamination thickness in an axial direction of the machine and a stator winding wound around the core and a rotor rotatably disposed inside the stator, having a rotor core and a rotor winding. The axial length of the stator core is selected with respect to that of the rotor core in such a way that, when the rotor is thermally extended, the end of the rotor core never extends beyond the end of the stator core. With such a constructional arrangement, there is eliminated an excessive temperature rise at the ends of the stator core, and prevented an insulation deterioration of the stator winding and the burning of the stator core.

Abstract: A cooling system for a rotary electric machine having a stator including a stator core and a stator frame for supporting the stator core and a rotor including a yoke, a plurality of salient magnetic poles mounted on the periphery of the yoke and shield plates bridging the tips of the adjacent magnetic poles wherein the cooling system comprises groups of air-discharging and air-charging ducts radially penetrating the stator core, each group of the ducts being axially aligned with a predetermined distance from each other and air-discharging windows formed in the shield plates at predetermined axial positions thereof, and the axial area of each group of the air-discharging ducts is larger than the axial area of the air-discharging window of the corresponding shield plate thereby increasing the flow rate of the cooling air through the rotary machine.

Abstract: A rotary electric machine comprises a rotor axially shorter than the lamination thickness of the stator core and having a coil retaining ring at each end of the coil thereof. The rotary electric machine further comprises a magnetic transmission device between each of the adjacent teeth of the stator core opposed to the coil retaining ring.

Abstract: A rotor of a permanent magnet type synchronous motor comprises a rotary shaft, a rotary supported by the rotary shaft and including an alternate disposition of a core section in the form of a lamination of a magnetic material which is stacked in the axial direction and a reinforcement section of a non-magnetic material and cavities axially formed in the core and reinforcement sections by passing therethrough, permanent magnets received in the cavities, and a strap interposed at least between the radial outer surface of respective permanent magnets and the opposing inner wall of the cavity, whereby distribution of pressures resulting from a centrifugal force due to the rotation of the rotor, which pressures are imparted on the inner wall of the cavity by the outer surface of the permanent magnet, is uniformed or shared by the strap, thereby preventing the permanent magnet from being fractured.

Abstract: A method and an apparatus for controlling the operation of the synchronous motor are disclosed in which the synchronous motor is started with a starting power supply and operated with a steadying power supply. The starting power supply is adapted to alternately repeat acceleration and deceleration of the synchronous motor in the neighborhood of the frequency thereby to bring the synchronous motor into the point where the synchronous motor is in synchronism with the steadying power supply. The starting power supply comprises a current control circuit and a phase angle control circuit, which circuits control the motor current in such a manner as to prevent the voltage drop due to the synchronous reactance of the motor from exceeding the induced voltage of the motor, while at the same time controlling the power factor angle to be in the range from a lead 90.degree. to the angle corresponding to a maximum output point produced by said motor current.

Abstract: In the control of a synchronous motor driven by a power converter of voltage source type, the phase of the current flowing into the motor is detected and gate signals are produced on the basis of the phase of the current, so that the output frequency of the power converter is controlled by the gate signals so as to control the motor.

Abstract: A synchronous motor is provided with a rotor including magnetic poles composed of a permanent magnet fixed around a rotor shaft, a stator facing the outer periphery of the rotor with an air gap formed therebetween, and a guard ring made of a non-magnetic material of low resistivity and fitly disposed around the outer periphery of the permanent magnet to restrain the surface loss caused by the magnetic flux linking with the guard ring, thereby preventing the reduction of the efficiency of the synchronous motor.