The present application relates to a technical field of determining an irreversible demagnetization of a grain boundary diffusion NdFeB magnet, and more particularly, to a method for identifying an irreversible demagnetization of a grain boundary diffusion NdFeB magnet by magnetic field distribution. After applying a reverse magnetic field to a saturatedly magnetized grain boundary diffusion NdFeB magnet, if a number of magnetic poles on a non-diffusion face of the grain boundary diffusion NdFeB magnet is increased, it is determined that there is an irreversible demagnetization in the grain boundary diffusion NdFeB magnet.

The invention relates to a method for controlling the production of a magnet (12) using a sensor able to emit a presence signal for a magnetic induction and defining a measuring axis, the magnet (12) being a permanent magnet with symmetry of revolution relative to its axis, called mechanical axis, the magnet (12) having a center and a maximum dimension, the method comprising at least the following step: a) performing a first measurement of a component of the magnetic induction produced by the magnet u(12) sing the sensor, b) performing a second measurement of a component of the magnetic induction produced by the magnet (12) using the sensor, and c) calculating the angular deviation of the equivalent magnetic moment of the magnet (12) from the first measurement and the second measurement.

A Hall sensor may include a Hall sensing element configured to produce a Hall voltage indicative of a magnetic field when traversed by an electric current, and a first pair of bias electrodes mutually opposed in a first direction across the Hall sensing element. The Hall sensor may include a second pair of bias electrodes mutually opposed in a second direction across the Hall sensing element. The Hall sensor may include a first pair of sensing electrodes mutually opposed in a third direction across the Hall sensing element, and a second pair of sensing electrodes mutually opposed in a fourth direction across the Hall sensing element. The fourth direction may be orthogonal to the third direction, each sensing electrode being between a bias electrode of the first pair and a bias electrode of the second pair.

The magneto-optical Kerr effect (MOKE) is used to capture variations in magnetic permeability and magnetization to determine the presence of sensitization. MOKE-magnetometry-based systems and apparatus may be used to provide in-field magnetic measurements, and may be particularly useful in methods for assessing changes in composition, crystal structure, and grain size in magnetic materials.

An apparatus for monitoring a magnetic core, wherein the apparatus provides a measurement winding which is magnetically coupled to the magnetic core to be monitored, a comparison inductance which is electrically connected in series with the winding and an electronic processing unit which is designed to determine the saturation behavior of the magnetic core to be monitored. The electronic processing unit is also configured to record a first electrical signal occurring at the measurement winding and a second electrical signal occurring at the comparison inductance in response to an electrical measurement signal applied to the measurement winding, and to determine the saturation behavior of the magnetic core to be monitored on the basis of the first and second electrical signals. This makes it possible to easily monitor the saturation behavior of a magnetic core and to reliably detect the occurrence of saturation of the magnetic core.

In a magnetic field analysis calculation, there is a need to consider a characteristic that a magnetic field and a flux density face in different directions from each other by a stress in a magnetic material. Therefore, a measured value of a magnetic characteristic on a condition that the magnetic field, the magnetic flux density, and a mechanical stress are parallel is used. In a method and a device for magnetic field analysis calculation, a stress magnetic anisotropy is calculated using a relation between a magnetostriction of the magnetic material, the magnetic flux density, and the stress and a relation between a magnetization curve of the magnetic material, the magnetic flux density, and the stress which are measured on a condition that the magnetic field and the stress in the magnetic material are parallel.

A magnetic property determination apparatus that determines the magnetic materials on a paper sheet transported through a transport path includes a magnetization unit and a magnetic detection unit. The magnetization unit generates a magnetization magnetic field including a first magnetic field region and a second magnetic field region on the transport path. A magnetic field intensity and a magnetic field direction are set different between the first magnetic field region and the second magnetic field region so that the magnetic materials are magnetized in different magnetization directions depending on coercive forces of the magnetic materials. The magnetic detection unit that generates a bias magnetic field on the transport path downstream in a transport direction of the magnetization unit, and that detects a magnetic charge of the magnetic materials by detecting variations of the bias magnetic field.

Volume susceptibilities (s) of dispersoid particles (s) dispersed in a dispersion medium (m) are first obtained by magnetophoresis. Affinity of the dispersoid particles (s) for the dispersion medium (m) is then analyzed using the volume susceptibilities (s) of the respective dispersoid particles (s) and a volume susceptibility (m) of the dispersion medium (m).

A Hall sensor may include a Hall sensing element configured to produce a Hall voltage indicative of a magnetic field when traversed by an electric current, and a first pair of bias electrodes mutually opposed in a first direction across the Hall sensing element. The Hall sensor may include a second pair of bias electrodes mutually opposed in a second direction across the Hall sensing element. The Hall sensor may include a first pair of sensing electrodes mutually opposed in a third direction across the Hall sensing element, and a second pair of sensing electrodes mutually opposed in a fourth direction across the Hall sensing element. The fourth direction may be orthogonal to the third direction, each sensing electrode being between a bias electrode of the first pair and a bias electrode of the second pair.

A method of diagnosing a magnetization fault of a permanent magnet motor is provided. The method includes calculating a resolver offset value for offset correction of a resolver mounted at the motor, calculating a correction deviation, namely, a difference value between the calculated resolver offset value and a predetermined reference value to compare the calculated correction deviation to an allowable error, comparing a difference value between the calculated correction deviation and a predetermined phase difference value of reverse magnetization of the permanent magnet to the allowable error when the calculated correction deviation is more than the allowable error, and determining that the motor is in a reversely magnetized state when the difference value between the calculated correction deviation and the predetermined phase difference value of reverse magnetization of the permanent magnet is equal to or less than the allowable error.