194 results about "Magnetic noise" patented technology

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 electric rotating machine is disclosed which includes a stator and a rotor. The stator includes a hollow cylindrical stator core and first and second three-phase stator coils. The stator core has a plurality of stator core teeth formed at a predetermined pitch in a circumferential direction of the stator core. Each of the first and second three-phase stator coils is comprised of three phase windings. Each of the phase windings of the first and second three-phase stator coils is wound around each of a predetermined number of the stator core teeth by a predetermined number of turns. The rotor has a plurality of magnetic poles the polarities of which alternate between north and south in the circumferential direction of the stator core. Further, the first and second three-phase stator coils are offset in the circumferential direction of the stator core to have a phase difference of π/6 therebetween.

A torque sensing device for measuring the torque applied to a rotatable shaft, and also measuring the magnetic field noise affecting the device. The device incorporates a switching function thereby enabling the device to operate in a common signal detection mode and a differential noise detection mode. The device is capable of determining the torque applied to the rotatable shaft based upon output signals obtained from magnetic field sensors operating in both the common signal detection mode and the differential noise detection mode. The device is capable of accurately measuring a torque induced magnetic field and is capable of canceling measurement error resulting from noise induced magnetic fields.

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.

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.

An electrical generator having a stator, a rotor, two windings, and a rectifying circuit. The stator has a first winding arranged in a wye configuration and a second winding arranged in a delta configuration. The wye winding is wound in a full pitch pattern around three stator teeth while the delta winding is wound in a short pitch pattern around two stator teeth, or vice versa. The wye and delta windings are connected to a single bridge rectifying circuit.

Each of program cell and memory cells includes a magnetic storage portion of the same configuration. The program cell further includes a state change portion. That is, the program cell has the same structure as the memory cell, except that the state change portion is additionally provided thereto. As such, the program cell can be provided efficiently, as it can be designed the same as the memory cell in terms of the magnetic storage portion and others. The state change portion makes a transition to a fixed state based on an electrical change. Thus, the state change portion prevents program information from being rewritten by a magnetic noise or the like, and ensures stable storage of the program information.

In an electric rotating machine, a stator coil is comprised of first and second winding groups. The stator coil is wound around a stator core in a concentrated winding manner so that the phase difference in electrical angle between each corresponding pair of windings of the first and second winding groups is equal to π/6. Further, the windings of the first and second winding groups are connected to form Δ-Y connections. Consequently, the sixth harmonic components of the electromagnetic forces created by the windings of the first winding group can be offset by those of the electromagnetic forces created the windings of the second winding group. As a result, the total magnetic noise and torque ripple generated in the machine can be reduced. Moreover, the machine can be driven with only a single three-phase inverter to achieve the effects of reducing the total magnetic noise and torque ripple.

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.

Noise compensation in controlled source electromagnetics (CSEM) comprises measuring time-varying magnetic gradients of the marine environment subjected to CSEM. From the measured magnetic gradients, oceanographic electric and magnetic field noise is determined and used for noise compensation of CSEM measurements of electric and magnetic fields. Selection of magnetic gradient measurement provides improved measurement of oceanographic magnetic noise as other electromagnetic noise sources produce negligible magnetic gradients in the marine environment. Electric field noise is then predicted from the magnetic measurements.

The invention discloses an on-line detecting method for three-dimensional force in closed iron magnetic shell, which adopts Barkhausen magnetic noise detection device, applies variable-frequency electromagnetic excitation and rotating electromagnetic excitation to the iron magnetic shell to be measured, to obtain electromagnetic MBN, MAE signals at different depths in the iron magnetic shell body, performs three-dimensional rebuilding to the MBN, MAE signals, and ultimately detects the three-dimensional stress and flaw distribution in the iron magnetic shell to be measured. The invention has beneficial technology effects of simple operation, wide application range, non harm to human body during operations, and capability of performing three-dimensional scanning and detection to the internal stress and defect in the iron magnetic shell.

An electrical machine (20) includes a stator core (54) having slots (80) and a set of windings (58) disposed within the slots (80). The windings (58) are configured in 2N+1 phases, where N in greater than 1. Such a machine is particularly useful for automotive alternators.

A differential circuit includes first and second side circuits which are coupled to receive control signals in such a way as to introduce an intentional imbalance in the differential circuit for certain benefits discussed herein. An exemplary pseudo-differential LC tank circuit is described which includes first and second side nodes, and an inductance circuit and a variable capacitance circuit coupled between the nodes. The inductance and variable capacitance circuits may be broken out into separate tanks to achieve certain magnetic noise reduction benefits. Each exemplary variable capacitance circuit includes a first variable capacitance coupled between the first side node and a common ground node, and a second variable capacitance coupled between the second side node and the common ground. Each of the first and second variable capacitances is coupled to receive control lines for controlling the capacitance of the first and second variable capacitance circuits in a pseudo-differential manner. Each variable capacitance includes at least one of many types of switch-capacitor cells, some of which are described herein.

An object tracking system includes a sensor grid having a plurality of sensor clusters configured to sense the presence of a magnetic field of an object. Each sensor cluster includes three or more single-axis magnetic sensors. The sensors in a cluster may be arranged with their axes parallel to one another. The sensor grid may account for ambient magnetic noise by measuring the magnetic field in a zone a distance away from the object to update the ambient magnetic field noise measurement. The sensor grid or a portion thereof may include a plurality of sensors printed on a common sheet. The sensor grid may comprise one or more sheets overlapped or interconnected. The system may track an object and determine up to three degrees of positioning and three degrees of orientation by using a geometric solution of the intercepts of magnetic field strengths obtained from information collected by the magnetic sensors.

The invention relates belongs to the technical field of communication and relates to a monitoring system, in particular to a transformer partial discharge online monitoring system. The transformer partial discharge online monitoring system comprises a diagnostic analysis unit, and a communication unit is connected to the diagnostic analysis unit. A plurality of collecting units are connected to the communication unit, and a plurality of sensing units connected with an electric transducer are connected to each collecting unit. A plurality of different types of sensors bound together are connected to each sensing unit, and a power supply module is arranged on each sensor. Compared with the prior art, the transformer partial discharge online monitoring system has the advantages that a piezoelectric sensor keeps away from the magnetic noises of an iron core and the mechanical vibration and noises of a transformer; a super-high-frequency sensor does not play a role of capacity coupling but plays a role of an antenna for receiving super-high-frequency signals, the diagnostic analysis unit can simultaneously start the operation of a plurality of modules to realize data reference among the different modules; the communication unit has diversified ways and also can be suitable for all kinds of environment in the data transmission process.

A magnetic ink character reading apparatus has a magnetic detection unit for detecting magnetic ink characters on the check and generating magnetic detection signals, a noise data generator for generating magnetic noise data by accumulating magnetic detection signals before the check passes the magnetic detection unit, and a magnetic noise cancellation unit for removing magnetic noise by subtracting the magnetic noise data from the magnetic detection signals.

Embodiments of the present invention help to reduce mag-noise in a magnetoresistive head without deterioration in reproduced output and improve the signal/noise ratio (SNR) of the magnetoresistive head. According to one embodiment, the magnetoresistive head uses a synthetic ferri free layer and it is arranged such that the magnetic field which is applied to an end of a free layer with smaller film thickness and saturation magnetization in the track width direction by a coupling field is larger than the magnetic field which is applied to it by a bias layer.

The invention belongs to the technical field of environmental protection and particularly relates to a preparation method of intelligent magnetic noise-reducing polyurethane foam. The preparation method comprises the following specific steps: treating the surface of carbonyl iron powder with a silane coupling agent; mechanically dispersing and prepolymerizing treated carbonyl iron powder, polyhydric alcohol and a chain extender; adding a crosslinking agent, a surfactant, a catalyst and isocyanate, rapidly stirring and pouring; and under the action of an external magnetic field, enabling carbonyl iron particles to form chain structures and be arranged in a foam skeleton and foaming at room temperature to produce anisotropic magnetic polyurethane foam. The entire preparation process has specific flow and is relatively simple and convenient to operate. The magnetic polyurethane foam is prepared by a one-step foaming process, the product combines the advantages of magnetic particles and polyurethane foam, has a flexible damping characteristic and is conductive to weakening the sound so that controllable acoustic and mechanical properties are achieved and the magnetic polyurethane foam can be used as a sound-absorption noise-reducing material. The magnetic polyurethane foam can be applied in fields such as civil use, automobiles and aerospace and has higher application values.

the present invention aims to achieve that geomagnetism can be sensed in high precision while eliminating an adverse influence by magnetic noise with respect to a geomagnetic sensor provided in a housing, and correct azimuth information can be acquired.

A portable terminal apparatus according to the present invention is arranged by that both a first housing (11) and a second housing (12) are coupled to each other by way of a hinge portion (13) under pivotable condition, a geomagnetic sensor (33) is provided on a circuit board (32) in the second housing (12), and also, a speaker (19) is provided on the side of a rear surface thereof. Both this geomagnetic sensor (33) and a speaker (19) corresponding to a component for generating magnetic noise which gives an adverse influence with respect to the geomagnetic sensor (33) are provided in the vicinity of each other within the same second housing (12), and both the members are arranged on the same plane. In this structure, since a magnetic force line (35) which is caused by magnetic noise generated from a magnet (19a) of the speaker (19) is intersected with respect to the geomagnetic sensor (33) at a right angle, and thus, a horizontal direction component thereof is not produced, the geomagnetic sensor (33) can correctly sense the geomagnetism without being adversely influenced by the magnetic noise.

Methods and apparatus for precisely tracking a borehole using electronically controlled DC current switching in a source loop in the vicinity of the borehole together with measurements of the apparent Earth's magnetic field are disclosed. A field averaging method optimally gives the location of points in the borehole in the presence of intense magnetic noise. The expected uncertainty of these locations can be found from a method of generating an ensemble of simulated surveys using a noise characterization parameter found from apparent Earth field measurements. Time synchronization between apparent Earth field measurements and the instants of switching to positive current flow into the loop is found using a correlation method in conjunction with different time durations for positive and negative current flow in the source loop.