79results about How to "Reduce magnetic noise" patented technology

An object of the present invention is to provide a motor control apparatus having excellent harmonic current control performance, that can simplify circuit configuration and circuit processing while, at the same time, achieving improved control accuracy. To achieve this object, detected motor currents are converted by coordinate converters 19 and 20 into an nth-order dq-axis signal and an mth-order dq-axis signal, and their DC components are extracted by low-pass filters 22 and 23; then, the differences of the DC components relative to respective command values are converted back into three-phase AC signals to control the motor currents.

The invention provides techniques for reducing or altering the magnetic noise of an AC rotary electric machine. A magnetic noise reducing harmonic current of order n, whose frequency is n times the frequency of the fundamental frequency component of a polyphase AC current fed to an armature of a polyphase AC rotary electric machine, is superimposed on the polyphase AC current, thereby reducing or altering a harmonic component having a frequency (n−1) times the frequency of the fundamental frequency component and occurring due to a radial magnetic excitation force acting radially on an iron core of the AC rotary electric machine. Magnetic noise is caused by a vibration whose energy is the sum of the circumferential and radial vibrations of the iron core occurring due to the magnetomotive force of the rotor, and altering the radial vibration is particularly effective in altering the magnetic noise; as the harmonic component of the radially acting magnetic excitation force, occurring due to harmonic components having frequencies 3, 5, 7, and 13 times the fundamental frequency, has a frequency 6 or 12 times the fundamental frequency, the magnetomotive force of the rotor can be effectively reduced or altered when a current having a frequency 7 or 13 times the fundamental frequency is superimposed on the stator current.

In a vehicular alternator, a stator is arranged to oppose a rotor in a housing. The stator includes a stator core, which forms a plurality of slots extending in an axial direction of the stator core, and a stator winding wound around the stator core. The stator winding includes electric conductors held in the slots. Each of the electric conductors has a circumferential width that is smaller than a circumferential distance between a first wall and a second wall defining the slot. The first wall and the second wall oppose each other in a circumferential direction. The electric conductors are alternately in contact with one of the first wall and the second wall.

A rotary machine comprising a stator 2 composed of a stator iron core 3 having a plurality of slots formed in the direction of the rotation axis and stator windings inserted into the plurality of slots, wherein the stator windings are composed of a plurality of conductors 4 respectively inserted into the plurality of slots in the direction of the rotation axis and the stator 2 has a connection ring 1 having slots 13 into which the plurality of conductors 4 are inserted in the direction of the rotation axis.

A polyphase electrical machine, in particular, a polyphase generator, includes a stator which features a core body having a circumferential slot pitch, and a winding configuration having a plurality of windings. It is provided that each winding and each slot of the group of slots that extends over one pole pitch is assigned to one of the phases, and the windings have winding sections that lie in assigned slots and between which, in each case, a winding-head connection is formed, the winding-head connections of different windings being disposed radially in layers relative to each other, and the number of phases being five. A method for producing a polyphase electrical machine is also provided.

A high density magnetic recording medium which has coercivity suitable to a magnetic record, fine grains, and a uniform grain size distribution, and which includes a FePtC alloy thin film containing an optimum carbon content, and a method of manufacturing the high density magnetic recording medium. The magnetic recording medium includes the FePtC alloy thin film containing 25 volume % carbon, thus having microscopic magnetic and structural properties suitable to the high density magnetic recording medium.

A yoke includes a plurality of recessed portions. A teeth block includes a plurality of protruding portions being coupled or fitted into the recessed portions of the yoke. The recessed portions and the protruding portions are disposed as a plurality of pairs in the lamination direction. The protruding portions and the yoke are fixed with a teeth fixing pin.

A nanogranular thin film consisting of nonmagnetic matrix and ferromagnetic fine particles in nano scale is improved to enhance the thermal stability and the S / N ratio. The ferromagnetic fine particles consist of (FeaCo1-a)1-xPtx, (0.3<=x<=0.7, 0.1<=a<=1), (FeaCo1-a)1-xPdx, (0.3<=x<=0.7, 0.1<=a<=1) or (FeaCo1-a) 1-x(PtbPd1-b)x, (0.3<=x<=0.7, 0.1<=a<=1, and 0<b<1).