RU165999U1 - MAGNETOELECTRIC MAGNETIC FIELD SENSOR - Google Patents

Abstract

A magnetoelectric magnetic field sensor containing a magnetoelectric element, an excitation winding, an amplifier, a synchronous detector, a frequency generator, a phase shifter, a recording device, a variable frequency signal coming from the generator to the excitation winding is three times less than the frequency of the mechanical resonance of the magnetoelectric element, the alternating magnetic field being the excitation coil of a magnitude at which the deformation of the magnetostriction of the ferromagnet, which is an element of the magnetoelectric, reaches 0, 7 ÷ 0.8 from saturation strain.

Description

The utility model relates to the field of measurement technology and can be used in various fields of science and industry to create magnetic field sensors.

Sensors of constant and alternating magnetic fields based on the magnetoelectric effect are known, for example (Petrov R.V., Leontyev B.C. Magnetoelectric magnetometer. Bulletin of Novgorod State University No. 75 T1 2013).

The device described in the article contains a sensitive magnetoelectric element, an inductor, a generator and signal processing elements, including: an amplifier, detector, ADC, microprocessor, indicator and control panel.

The disadvantage of this device is the coincidence of the excitation frequency and the frequency of the measured sensor signal. Detuning from the excitation frequency is a complex technical task and this limits its sensitivity. Another disadvantage of this sensor is the presence of magnetostrictive hysteresis, i.e. the initial upward dependence of the sensor output signal does not coincide with the inverse.

The present invention is aimed at solving a technical problem to eliminate these disadvantages.

The technical result achieved in this case is to increase the sensitivity and accuracy of the magnetoelectric magnetic field sensor in a large dynamic range.

The specified technical result is achieved in that in a magnetoelectric magnetic field sensor containing a magnetoelectric element, an excitation winding, an amplifier, a synchronous detector, a frequency generator, a phase shifter, a recording device, a variable frequency signal coming from the generator to the excitation winding is three times less than the frequency of mechanical resonance magnetoelectric element, moreover, an alternating magnetic field in the field winding of such a magnitude at which the magnetostriction deformation of the ferromagnet ka, which is an element of a magnetoelectric, reaches 0.7–0.8 of the saturation strain.

These signs are significant and interrelated with the formation of a stable set of essential features sufficient to obtain the desired technical result.

In FIG. 1 shows the frequency spectrum of the signal at the output of the magnetoelectric element with the specified excitation conditions and in the presence of a constant magnetic field - H ₌ . When using a magnetoelectric structure with a high quality factor of mechanical resonance, it can act as an amplifier and a filter. It should be noted that a signal with a frequency f / 2 is spurious and cannot be used in this case due to its large nonlinearity from the measured field.

In FIG. Figure 2 shows the dependence of the output signal of the experimental magnetometer on the measured constant magnetic field. We used a two-layer structure containing a piezoelectric layer of langatate with dimensions of 25 mm × 4 mm × 0.7 mm and a ferromagnetic layer of amorphous alloy with dimensions of 25 mm × 4 mm × 30 μm, connected using epoxy adhesive. The choice of materials is due to the following reasons. The La ₃ Ga _5.5 Ta _0.5 O ₁₄ (LGT) langatate single crystal (FOMOS-Materials, Moscow, Russia) had a piezoelectric module d ₁₁ = 5.2 pm / V, permittivity ε≈20, acoustic Q factor Q≈10 ⁴ and provided a large generated voltage. An amorphous alloy of FeBS composition (Metglas 2605S3A Magnetic Alloy) had saturation magnetostriction λ _S ≈20 · 10 ^-6 in the saturation field H _S ≈20 G and had the highest piezomagnetic coefficients. It can be seen from the graph that the dependence is almost linear, and hysteresis is not detected within the error range.

In FIG. 3 shows a block diagram of the inventive utility model.

The present invention is illustrated by a specific example of execution, which, however, is not the only possible, but clearly demonstrates the receipt of the required technical result.

The magnetoelectric sensor operates as follows. The generator - G produces two frequencies f _p and f _p / 3, the first enters through the faurator - PV to the synchronous detector - SD, and the second to the field winding - OB. In the absence of a constant magnetic field - H _{= the} signal is absent and appears only if it is present, passing through the amplifier - Y, the synchronous detector and enters the recording device. Where is displayed in a convenient form.

It should be noted that since the excitation frequency and the frequency of the useful signal are very spaced, the penetration of the first into the useful signal is not noticeable.

Claims (1)

A magnetoelectric magnetic field sensor containing a magnetoelectric element, an excitation winding, an amplifier, a synchronous detector, a frequency generator, a phase shifter, a recording device, a variable frequency signal coming from the generator to the excitation winding is three times less than the frequency of the mechanical resonance of the magnetoelectric element, the alternating magnetic field being the excitation coil of a magnitude at which the deformation of the magnetostriction of the ferromagnet, which is an element of the magnetoelectric, reaches 0, 7 ÷ 0.8 from saturation strain.

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