78results about How to "Reduce magnetic noise" patented technology

A magnetoresistive sensor having a novel free layer and a method of producing the same are disclosed. The magnetoresistive sensor comprises a pinned layer, a barrier layer disposed over the pinned layer, and a free layer disposed over the barrier layer. The free layer comprises a first magnetic layer disposed over the barrier layer. The first magnetic layer has a positive spin polarization, a positive magnetostriction, and a polycrystalline structure. The free layer further comprises a second magnetic layer disposed over the first magnetic layer. The second magnetic layer has a negative magnetostriction and comprises at least cobalt (Co) and boron (B).

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.

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.

In a ferromagnetic material containing at least one kind of rare-earth element, a layer containing at least one kind of alkaline earth element or rare-earth element and fluorine is formed at the grain boundary or near the powder surface of the ferromagnetic material. A further layer containing at least one kind of rare-earth element, having a fluorine concentration lower than that of the layer described first and having a rare-earth element concentration higher than that of the host phase of the ferromagnetic material, or an oxide layer containing a rare-earth element is formed in adjacent with a portion of the layer described first.

In a magnetic measurement system for a battery, a magnetic signal generated by electric currents in the battery for charging and discharging can be accurately measured without saturating the output of a magnetic sensor even in an environment having strong magnetic noise, and electric current distribution in the lithium-ion battery is visualized. Generating a antiphase magnetic field having an antiphase magnetic field to a magnetic field measured by each magnetic sensor into the cancel coil disposed around each the magnetic sensor before charging and discharging; thereafter, reducing magnetic noise by subtracting the magnetic data recorded before charging and discharging (the correction-magnetic field data) from the magnetic data for charging and discharging; and accurately measuring the magnetic signal generated from the lithium-ion battery for charging and discharging are included.

The present invention discloses a triaxial magnetoresistive sensor. It comprises a substrate integrated with a biaxial magnetic field sensor, a Z-axis sensor that has a sensing direction along Z-axis perpendicular to the two axes of the biaxial magnetic field sensor, and an ASIC. The biaxial magnetic field sensor comprises an X-axis bridge sensor and a Y-axis bridge sensor. The Z-axis sensor and the two-axis sensor are electrically interconnected with the ASIC. A single-chip implementation of the triaxial magnetic field sensor comprises a substrate, onto which a triaxial magnetic field sensor and an ASIC are stacked. The triaxial magnetic field sensor comprises an X-axis bridge sensor, a Y-axis bridge sensor, and a Z-axis bridge sensor. The above design provides a highly integrated sensor with high sensitivity, low power consumption, good linearity, wide dynamic range, excellent thermal stability, and low magnetic noise.

A Lundell type rotor core with a pair of side cores and a magnetic-pole cylindrical portion has a structure in which the magnetic-pole cylindrical portion is mated between both the side cores (also referred to as “pole cores”) in a radial direction at an outside of a field coil wound on a boss portion in the side cores. The magnetic-pole cylindrical portion is made of plural magnetic steel sheets laminated in the axis direction, and is easily deformed rather than both the side cores. The easy deformation characteristic of the magnetic-pole cylindrical portion prevents generation of a gap during the assembling process of the magnetic-pole cylindrical portion and the side cores. Without paying strict dimension control of the components for the rotor core, it is easily possible to prevent any generation of a gap between the side cores and the magnetic-pole cylindrical portion while assembling. It is thereby possible to prevent a deterioration of a magnetic flux flowing in the rotor core.

An automotive alternator including a rotor having a plurality of poles; a plurality of phases in operable communication with the plurality of poles; and a stator core in operable communication with the rotor, the stator having a number of slots defined by:

S=(P×PH)+((M×PH)+N)

where S=number of slots P=number of poles PH=number of phases M=a whole integer greater than or equal to 0 N=a whole integer selected from a group of integers ranging from, and including, 1 through the number of phases minus 1. A method for reducing magnetic noise in an automotive alternator includes selecting a number of poles, selecting a number of phases, selecting a number of stator core slots, the foregoing selections interacting in the automotive alternator to produce an order of frequency of a tangential force different than any multiple of the number of phases and different than an order of frequency of a radial force of the alternator.

To provide a magnetic reading head that features high resolution and low noise, and that can support a hard disk with terabit-level surface recording density. A current is caused to flow from a pinned layer with its magnetization direction fixed by an antiferro magnetic material, to a non-magnetic thin wire having a portion affected by an external magnetic field and a portion not affected by the external magnetic field, so that spin polarized electrons are accumulated in the non-magnetic thin wire. A distance between voltage terminals of a voltmeter is set to less than the spin diffusion length of the non-magnetic thin wire. A change in the external magnetic field modulates some of the accumulated spin polarized electron, but does not others. Accordingly, an electrical potential difference depending on the external magnetic field is generated between the both end surfaces of the non-magnetic thin wire, and measured with the voltmeter.

The electric rotating machine includes a rotor around which a field coil is wound, and a stator including a stator core around which an armature winding is wound. The armature winding includes a first three-phase winding whose phase coils are delta-connected to form a delta winding, and a second three-phase winding whose phase coils are connected to corresponding nodes of the delta winding to form a star winding. The delta winding and the star winding are wound around the stator core such that the phase coils of the delta winding and the phase coils of the star winding share the same slots of the stator core.

An automotive alternator is disclosed which includes an annular core disposed to surround the radially outer peripheries of all magnetic pole claws of magnetic pole cores. The annular core has, on an outer surface thereof, a plurality of protrusions, a plurality of recesses, and a plurality of slopes. Each of the protrusions is so provided as to be coincident with a corresponding one of the magnetic pole claws of the magnetic pole cores in the circumferential direction of a rotary shaft. Each of the recesses is alternately formed with the protrusions so as to be coincident with a corresponding one of air gaps formed between the magnetic pole claws of the magnetic pole cores in the circumferential direction. Each of the slopes is inclined to the radial direction of the rotary shaft and connects a circumferentially adjacent pair of one of the protrusions and one of the recesses.

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<=x<=1), (FeaCo1-a)1-xPdx, (0.3<=x<=0.7, 0.1<=x<=1) or (FeaCo1-a)1-x(PtbPd1-b)x, (0.3<=x<=0.7, 0.1<=x<=1, and 0<b<1).

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.

Systems and methods for suppressing magnetically active surface defects in superconducting quantum circuits are provided. A method includes providing one or more superconducting quantum circuits, and arranging the one or more superconducting quantum circuits in a hermetic enclosure capable of isolating the one or more superconducting circuits from ambient surroundings. The method also includes controlling an environment in the hermetic enclosure to suppress magnetically active surface defects associated with the one or more superconducting quantum circuits. In some aspects, the method further includes introducing an inert gas into the hermetic enclosure to passivate a surface of the one or more superconducting quantum circuits. In other aspects, the method further includes coating a surface of the one or more superconducting circuits with a non-magnetic encapsulation layer. In yet other aspects, the method further includes irradiating the one or more superconducting circuits using ultraviolet light.

An image pickup apparatus includes an image pickup element converting an object image to an electric signal, a magnetic shield member arranged in front of the image pickup element, a fixing member to which the image pickup element and the magnetic shield member are attached, and an elastic member arranged between the magnetic shield member and the image pickup element, and configured to press the image pickup element so as to surround a circumference of a light receiving plane of the image pickup element and to press the magnetic shield member toward the fixing member.