A flux gate current sensor includes a magnetic core, a measurement winding, an excitation circuit arranged to generate a digital excitation signal, an acquisition circuit arranged to acquire an analog measurement voltage from the terminals of the measurement winding and to produce a digital measurement signal, a demagnetization servocontrol circuit arranged to use the digital measurement signal to produce a digital demagnetization signal for compensating magnetic flux produced by the current that is to be measured, a summing circuit arranged to sum the digital excitation signal and the digital demagnetization signal so as to obtain a digital injection signal, and an injection circuit arranged to produce an analog excitation current from the digital injection signal and to inject the analog excitation current into the measurement winding.

A measurement transformer includes a printed circuit and a magnetic core. The printed circuit includes an insulating layer, a primary through assembly and a secondary through assembly. The primary through assembly includes first primary plated through holes and second primary plated through holes extending through the insulating layer. The primary through assembly forms a portion of a primary winding of the transformer. The primary winding has a single turn. The secondary through assembly includes first secondary plated through holes and second secondary plated through holes extending through the insulating layer. The secondary through assembly forms a portion of a secondary winding of the transformer. The secondary winding includes a plurality of turns connected in series. The magnetic core extends in the thickness of the printed circuit.

A current sensor for detecting a magnitude of a current flowing through a measuring object has a magnetic core having a first magnetic core and a second magnetic core that is arranged magnetically in parallel to the first magnetic core, wherein the first magnetic core has a magnetic permeability that is higher than that of the second magnetic core in a first frequency band, and the first magnetic core has a magnetic permeability that is lower than that of the second magnetic core in a second frequency band, the second frequency band being higher than the first frequency band, and the current sensor detects the magnitude of the current in a frequency band that is constituted by combining the first frequency band and the second frequency band.

Technology includes a current sensor that detects electric current flowing through an object. The current sensor includes a magnetic core through which the object is inserted, a coil wound around the magnetic core, a transmission line that transmits electric current supplied from the coil, a terminating resistor that converts electric current from a terminating end of the transmission line into voltage and outputs the voltage, and an impedance matching unit that implements impedance matching between the coil and the terminating resistor. The impedance matching unit raises, to a characteristic impedance of the transmission line, at least one of an impedance viewed from the terminating end of the transmission line toward the terminating resistor and an impedance viewed from a starting end of the transmission line toward the coil, in a band of frequency components involving amplitude attenuation among frequency components of the voltage output from the terminating resistor.

A current sensor includes a current sense coil disposed about a conductive lead, the current sense coil configured to sense a current passing through the conductive lead. The current sense coil includes: a first outer coil configured to detect a first magnetic field generated by the current; a second outer coil configured to detect the first magnetic field, the second outer coil further configured to cancel an electrical field induced in the first outer coil; and an inner conductor disposed between the first outer coil and the second outer coil, the inner conductor configured to detect a second magnetic field generated by the current.

Fluxgate based current transducer for measuring a primary current flowing in a primary conductor, comprising a fluxgate magnetic field detector and a measuring circuit. The fluxgate magnetic field detector includes an excitation coil driven by an oscillating excitation current (I.sub.fluxgate) supplied by the measuring circuit. The measuring circuit is configured to provide a first and a second measurement output of the oscillating excitation current. The transducer further comprises a signal output processing unit for comparing in real-time the first and second measurements outputs, wherein the signal output processing unit is configured to send an error signal output if the difference between said first and second measurements outputs exceeds a tolerance value.

A printed circuit includes a first track, a second track, and at least one insulating layer extending between the first track and the second track. The printed circuit further includes a first through assembly of at least one first plated through hole and a second through assembly of at least one second plated through hole. Each first plated through hole and each second plated through hole connect together the first track and the second track by extending through the insulating layer. The first through assembly and the second through assembly respectively form a first branch and a second branch of a current divider bridge.

An excitation unit applies, to an excitation coil, an excitation voltage with a voltage level alternately changing between a first high voltage value higher than a reference voltage value and a first low voltage value lower than the reference voltage value. The excitation unit includes a comparison circuit and a voltage switching circuit. The comparison circuit outputs a comparison signal having a voltage level switching between a high level and a low level depending on whether a detection voltage is greater than, or equal to or less than, a threshold voltage. The voltage switching circuit switches the voltage level of the excitation voltage between the first high voltage value and the first low voltage value according to the voltage level of the comparison signal.

A transformer arrangement comprises a primary winding and a secondary winding, which are magnetically coupled. The transformer arrangement also comprises a compensating arrangement, which is circuited to provide a link between a terminal of the primary winding and a terminal of the secondary winding. The compensating arrangement is configured such that a change of a magnetic flux through the primary winding and the secondary winding induces a voltage in the compensating arrangement. The compensating arrangement comprises at least one coupling capacitor configured to block a DC current and to pass a current caused by the induced voltage. The compensating arrangement is configured to at least partially compensate a current that is caused by an inter-winding capacitance between the primary winding and the secondary winding using the current caused by the induced voltage.

An object of the present invention is to provide a magnetic sensor capable of detecting a magnetic field to be measured through closed loop control even when the magnetic field is weak. A magnetic sensor includes magnetic layers 41 and 42 opposed to each other through a magnetic gap G1, a magneto-sensitive element R1 disposed on a magnetic path formed by the magnetic gap G1, and a compensation coil 60 generating canceling magnetic flux ϕ4 to cancel magnetic flux ϕ2 applied to the magneto-sensitive element R1. According to the present invention, magnetic flux ϕ2 flowing in the magnetic layers 41 and 42 each functioning as a yoke is applied to the magneto-sensitive element R1, so that even when a magnetic field to be measured is weak, it can be detected.

In addition, closed loop control can be performed due to the presence of the compensation coil 60 that cancels magnetic flux ϕ2.