RU218324U1 - Magnetoelectric current sensor - Google Patents

Abstract

The utility model relates to the field of measuring technology and can be used in various fields of science and industry when creating a current sensor. A magnetoelectric current sensor containing a magnetoelectric element, an amplifier, an excitation winding fed from an alternating current generator, the signal from which is also fed to a synchronous detector, characterized in that the magnetoelectric element is made in the form of a ring, in the central hole of which a wire with the measured current passes.

Description

The utility model relates to the field of measuring technology and can be used in various fields of science and industry when creating a current sensor.

Known current sensor (IN Solovyov, MI Bichurin). Low-frequency magnetoelectric current sensor. Bulletin of the Novgorod State University, 2013, No. 75, V.1, pp. 35-36) containing a magnetoelectric element, inductors designed to create an alternating exciting magnetic field and a constant bias magnetic field, a high-frequency signal generator and a recording electronic circuit.

The device works as follows: an electric current passing through the current bus creates a magnetic field that acts on a nearby magnetoelectric element, and it generates an alternating electrical voltage, the amplitude of which is proportional to the magnitude of the measured current.

The disadvantage of this device is the coincidence of the frequency of the measured signal with the frequency of the alternating magnetic field, which limits the sensitivity of the sensor. Detuning from the excitation frequency is a complex technical problem. The second disadvantage of the device is the non-linear dependence of the output signal on the measured current, due to the non-linearity of the dependence of the voltage generated by the magnetoelectric element on a constant magnetic field.

A current sensor is also known (W. He, J. Zhang, C. Qu, J. Wu, J. Peng. A Passive Electric Current Sensor Based on Ferromagnetic Invariant Elastic Alloy, Piezoelectric Ceramic, and Permalloy Yoke, IEEE Transactions on Magnetics 52( 7):1-1 · July 2016), containing a magnetostrictive iron-nickel alloy beam fixed at one end, with a piezoelectric plate fixed on it, a magnetic circuit, permanent magnets and an electronic circuit. The device allows you to register an alternating current with a frequency of 50-60 Hz, coinciding with the resonant frequency of the bending vibrations of the beam. The device works as follows: an alternating electric current passing through the current bus creates an alternating magnetic field that excites bending vibrations of the magnetostrictive beam, a piezoelectric element mounted on the beam generates an alternating electric voltage, the amplitude of which is proportional to the magnitude of the measured current. disadvantage device is the inability to measure direct currents.

The closest to the proposed utility model is a non-contact current sensor described in (RU 171066 U1 dated 10/04/2016.), containing a magnetic circuit, a magnetically sensitive element, an amplifier, a compensation winding and a measuring resistance, the magnetically sensitive element is made of a magnetoelectric, an additional excitation winding is placed on the magnetic circuit , powered by an alternator, the signal from which is also fed to the synchronous detector, and after it is fed to a power amplifier loaded on the compensation winding and measuring resistance.

The disadvantage of the described device is the presence of a double gap between the magnetoelectric and the magnetic circuit, the value of which greatly affects the sensitivity of the sensor and is reflected in the reliability of the information.

The proposed utility model is aimed at solving a technical problem to eliminate this drawback.

The technical result is achieved by the fact that in a current sensor containing a magnetoelectric element, an amplifier, an excitation winding fed from an alternator, the signal from which is also fed to a synchronous detector, characterized in that the magnetoelectric element is made in the form of a ring, the central hole of which serves for placement of a wire with a measured current in it.

These features of the utility model are essential and the totality of these features is sufficient to obtain the required technical result.

In FIG. 1 shows a block diagram of the claimed utility model. It contains a magnetoelectric 1, an excitation winding 2, a wire with a measured current 3, a generator 4, an amplifier 5, and a synchronous detector 6.

In FIG. 2 shows the device of the magnetoelectric element. It consists of a magnetostrictive ferromagnet 7, a piezoelectric 8 containing electrodes 9.

The device works as follows. The direct current I passing through the wire 3 creates a constant magnetic field around itself. This field is concentrated by a ferromagnet 7 (Fig. 2), the alternating voltage supplied from the generator 4 to the exciting winding 2 creates an alternating magnetic field of pumping. The alternating voltage with frequency F coming from the generator 4 to the excitation winding 2 creates an alternating magnetic field of pumping. The frequency F of the alternating voltage corresponds to the frequency of natural radial mechanical oscillations of the magnetoelectric 1. This leads to an increase in the alternating voltage generated by the piezoelectric 8 (Fig. 2) on its electrodes 9 by the value of its mechanical quality factor. The voltage taken from the electrodes 9 (figure 2) is supplied to the amplifier 5, and then to the synchronous detector 6, where it is rectified. The output voltage in this device is proportional to the measured current.

To test the performance of the proposed device, a mock-up was made, which is not the only possible one, but clearly demonstrates the achievement of the required technical result.

The ring magnetic circuit of the device was made of Metglas with dimensions of 25 mm x 10 mm x 0.02 mm. The piezoelectric element of an annular shape with dimensions of 25 mm x 10 mm x 0.5 mm is made of TsTS-19 material.

The ferromagnet and the piezoelectric were glued together with epoxy glue. A toroidal excitation winding containing 50 turns of wire 0.2 mm in diameter was wound on the resulting structure. Leads were soldered to the electrodes of the piezoelectric element. The resulting structure was placed in a plastic frame. The measuring circuit used a standard synchronous detector, a standard low-frequency oscillator, standard amplifiers, and voltage meters. The measurements showed that the frequency of radial mechanical oscillations of the magnetoelectric element was 60 kHz. The quality factor of the acoustic resonance was 90. FIG. Figures 3 and 4 show the measured dependences of the output voltage on the value of the measured current I in the absence and presence of mechanical resonance, respectively. It can be seen that this dependence is almost linear.

Claims (1)

A magnetoelectric current sensor containing a magnetoelectric element, an amplifier, an excitation winding fed from an alternating current generator, the signal from which is also fed to a synchronous detector, characterized in that the magnetoelectric element is made in the form of a ring, the central hole of which serves to accommodate a wire with a measured current.

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