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

Provided is a highly accurate optical pumping magnetometer, in which a static magnetic field and an oscillating field to be applied to a vapor cell are stabilized. To this end, the optical pumping magnetometer includes: Helmholtz coils for applying a constant static magnetic field to a vapor cell serving as a magnetic field detector; fluxgate magnetometers for detecting environmental magnetic noise in two directions of X-axis direction and Y-axis direction other than Z-axis direction which is a direction for detecting a magnetic field coming out of a measurement object while locating the vapor cell in the center thereof; magnetometer drive circuits for driving the fluxgate magneotometers; current converters for converting outputs of the magnetometer drive circuits into amount of currents; and magnetic field generating coils for generating a magnetic field in a phase opposite to the environmental magnetic noise in the two directions.

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 field-winding type of synchronous machine comprises a stator with an armature winding wound phase by phase, a rotor having a rotor core with a field winding wound, and a circuit enabling an armature current to pass the armature winding, the armature current corresponding to a synchronous current producing a rotation field rotating at an electrical-angle rotation speed agreeing to a rotation speed of the rotor. The synchronous machine further comprises a current suppressor and a current supplier. The current suppressor is connected to the field winging and suppresses, into a unidirectional current, an induced alternating current induced through the field winding in response to the armature current passing the armature winding. The current supplier supplies, phase by phase, to the armature winding a rotor exciting current whose waveform is different from the synchronous current only during a predetermined period of time shorter than one cycle of the synchronous current.

A current perpendicular to plane (CPP) magnetoresistive sensor having a front edge that is recessed from the air bearing surface (ABS). The sensor includes a pinned layer structure a free layer structure and a spacer layer sandwiched between the free layer and the pinned layer. The free layer is an AP coupled structure that includes a first magnetic layer F1 a second magnetic layer F2 and a coupling layer sandwiched between F1 and F2. The first magnetic layer F1 extends to the ABS while the other sensor layers terminate at the recessed front edge. In this way, the F1 layer acts as a flux guide that reacts to a magnetic field from a magnetic medium. The AP coupled structure of the free layer allows each magnetic layer F1 and F2 to be thicker than would be possible in a conventional single layer free layer, which increases the GMR effect of the sensor and increases the effectiveness of the flux guide (F2).

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.

The invention describes a family of sensors for assaying macro-molecules and / or biological cells in solution. Each sensor has the form of a well (a hollow cylinder having a floor but no lid) or a trench whose walls comprise a plurality of GMR or TMR devices. Suitably shaped magnets located below each well's floor pull labeled particles into the well / trench and up against the inner wall where a field gradient orients them for optimum detection. Any unattached labels that happen to also be in the well / trench are removed through suitably sized holes in the floor.

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).