RU30835U1 - Magnetometer device - Google Patents

Description

MAGNETOMETRIC DEVICE

The utility model relates to the field of geophysical research of wells and can be used to build magnetic azimuth converters in inclinometers, as well as to build magnetometers for various purposes.

A known azimuth converter for an inclinometer, comprising a generator connected by a first output through a frequency divider to the excitation circuits of the flux gates, seven keys, an amplifier, first and second integrators and a switch, while the inputs of the first three keys are connected respectively to the signal windings of the flux gates and through a resistor to a common wire circuits, and the outputs are combined and through a circuit consisting of a series-connected amplifier, a fourth key, a first integrator and a fifth key, are connected to the input of the second integrator, u The ninth and seventh keys are connected in parallel to the capacitors of the integrators, the control inputs of the fourth and fifth keys are connected to the second and third outputs of the generator, and the control inputs of the remaining keys are connected to the outputs of the switch RF Patent No. 2018645, Е 21 В 47/02, publ. in BI No. 16, 1994.

The disadvantage of the azimuth transducer is the complexity of its circuit, due to the use of seven keys and two integrators, the complexity of the switch due to the need to control the five keys, as well as low stability and, therefore, low accuracy due to the absence of negative feedback in the signal conversion channel of the flux gates.

An azimuth converter for an inclinometer is also known, which contains a generator connected by the first and second outputs to the excitation windings of differential flux probes, a series-connected bandpass filter, a synchronous detector, a DC amplifier and an analog-to-digital converter, analog switches, the input of one of which is 21 in 47/02

rykh is connected to the common wire of the circuit, and the inputs of the remaining keys are connected through resistors to the signal windings of the flux gates, the control unit, the input of which is connected to the third output of the generator, and the outputs to the control inputs of the keys, a synchronous detector, and an analog-to-digital converter, as well as a resistor, connected between the output of the DC amplifier with a common connection point of the input of the bandpass filter and the combined outputs of the analog keys Certificate for utility model No. 21818, E 21 V 47/02, publ. in BI No. 2, 2002.

Compared with the previous analogue, this converter has greater stability and accuracy, because feedback is organized in it, compensating for the nonlinearity of flux gates. However, its disadvantage, like that of the transducer considered above, is the use of differential flux-gates, which are relatively complex in design and tuning. Due to their principle of operation, these flux-gates can increase the relative level of information harmonics in the composition of their signals, but require the use of such complex functional elements as band-pass filters and synchronous detectors to convert signals. This also leads to a complication of generators, which in this case must have high frequency stability and generate special signals to ensure the operation of synchronous detectors.

Thus, the use of differential fluxgates complicates the design of known transducers not only in itself, but also in connection with the use of complex functional elements necessary for processing the signals of these fluxgates.

The closest in technical essence to the proposed magnetometric device is a device for measuring magnetic fields, which is adopted as a prototype and contains a magnetomodulating transducer made in the form of a permalloy rod with an excitation winding and a signal winding on top of it, a generator connected to the transformer excitation winding, a line delays, the input of which is connected to the output of the signal winding of the converter, as well as the adder, the inputs of which are connected to the input and the output of the delay line and the output of the resonance amplifier and via a detector connected to the measuring instrument Copyright certificate №1078368, G 01 R 33/02, publ. in BI No. 9, 1984.

The advantage of this device is the use of a magnetomodulating transducer that is simpler than differential flux gates and contains only two windings and does not require adjustment. However, it also has significant drawbacks. These include low stability and accuracy due to the absence of negative feedback in the signal conversion channel of the magnetomodulating converter, complexity and low stability due to the use of a delay line and a resonant amplifier, the parameters of which are highly sensitive to changes in ambient temperature environment, as well as the need to use a highly stable generator to ensure the natural functions of the delay line and cy- amplifier. Significant disadvantages of the device also include the fact that it does not allow to determine the direction (sign) of the measured magnetic field, because there are no phase-sensitive elements in his circuit.

The proposed utility model solves the problem of simplifying structures, increasing its accuracy and stability. In comparison with the prototype, it also solves the problem of determining the sign of the projection of the vector of the measured magnetic field on the sensitivity axis of the magnetomodulating transducer.

Derived results that can be obtained using the model include the lack of settings and the possibility of microminiature designs of magnetometric devices.

The solution of these problems is achieved by the fact that in a magnetometric device containing a magnetomodulating transducer, which includes a ferromagnetic rod with an excitation winding and a signal winding over it, a generator connected to the excitation winding of the magnetomodulating transducer, as well as an adder and a first detector, in contrast to the prototype a second detector and a resistor are introduced, while the outputs of the detectors are connected to the inputs of the adder, the output of which is connected through a resistor to a common point neniya output signal winding magnitomodulyatsionnogo converter inputs and detectors, the detectors are made by schemes providing rectification positive half cycles signal by a first detector and negative half-periods of the signal by the second detector, and the adder has a low-pass filter characteristics.

In the proposed device, the formation of a useful signal and suppression of unnecessary odd harmonics in the signal of the magnetomodulating transducer is carried out by separately detecting the positive and negative components of the signal of the magnetomodulating transducer using linear half-wave detectors and adding the resulting signals through the adder. Thus, the device does not have elements with pronounced frequency-selective properties. This is a significant difference between the proposed device and known devices, because in them the indicated operations are carried out using frequency-selective elements - bandpass filters, selective amplifiers, synchronous detectors and circuits formed by a combination of delay lines and adders.

We also note that the sign of the signal at the output of the proposed magnetometric device, corresponding to the sign of the projection of the vector of the measured magnetic field on the sensitivity axis of the magnetomodulating transducer, is formed by comparing the amplitudes of the positive and negative components of the signal of the primary magnetomodulating transducer. This also leads to a significant difference between the proposed device and the known devices in which the sign of the information signal is formed by synchronously detecting signals generated by differential sensors (flux probes).

Figure 1 presents the functional diagram of the magnetometric device, and figure 2 is a timing diagram of the signal at the output of the signal winding of the magnetomodulating transducer.

The magnetometric device comprises a magnetomodulating transducer (MMP) 1, which includes a ferromagnetic rod with an excitation winding and a signal winding, a generator 2 connected to the excitation winding of the MMP 1, half-wave amplitude detectors 3.4, the combined inputs of which are connected to the output of the signal winding MMP 1, adder 5 connected by inputs to the outputs of the detectors 3,4, as well as a resistor 6 connected between the output of the adder 5 and the common connection point of the signal winding of MMP 1 and inputs d 3,4 detectors.

The device operates as follows. The generator 2 feeds the excitation winding of the MMP 1 with alternating current, the strength of which is sufficient to saturate the ferromagnetic rod of the converter. As a result of this, the signal acting at the output of the signal winding of the MMP 1 is a sequence of short pulses (Fig. 2), the leading edges of which are formed at the moments of transition through zero current in the excitation winding of the MMP 1.

In the absence of magnetization of the rod by an external measured magnetic field, the positive and negative pulses have the same amplitudes and shapes. However, under the influence of an external magnetic field, the pulse amplitudes change. In this case, the magnitude and sign of the difference in amplitudes of positive and negative pulses change in accordance with changes in the magnitude and sign of the projection of the vector of the measured magnetic field onto the sensitivity axis of the IMF 1.

The amplitudes of the positive and negative pulses of the signal MMP 1 can be expressed in the form (figure 2)

Ui U (0) + 5Ub

U2 - U (0) + 5U2. (1)

where U (0) are the values of the amplitudes of the pulses in the absence of an external measured field, and 5Ui, 5U2 are the increments of the amplitudes of the pulses caused by the external magnetic field, they are magnetized; they have the IMF rod 1. The maximum values of the relative increments; the amplitudes of the amplitudes of the pulses are 5Ui / U (0) and 5U2 / U (0) depend on the magnitude of the measured fields and the magnetic permeability of the material of which the rod MMP 1 is made, and are 0.05 0.25.

By means of detectors 3.4, available; their identical transmission coefficients K, the pulse amplitudes are converted into proportional DC voltages

which are summed with the aid of adder 5. As a result, the output of the adder, which is the output of the magnetometric device, has a signal proportional to the sum of increments; the amplitudes of the positive and negative pulses of the MMP 1 signal, i.e.

Us ICKi (U, + U2) KKi (6U, + 5U2), (3)

where K is the transfer coefficient of the adder 5.

Due to the fact that the adder 5 has the characteristic of a low-pass filter, it drains; smooths out possible voltage ripples at the outputs of the detectors 3.4 and thereby ensures the necessary signal quality at the output of the magnetometric device.

U3 KUi,

U4 KU2, (2)

Due to the nonlinearity of the magnetization reversal characteristic of the MMP rod 1, the dependence of the signal Us at the adder output on the magnitude of the measured magnetic zero is nonlinear and is described by an odd function. Therefore, in order to reduce the nonlinearity of this dependence and increase the accuracy of measuring the magnetic field in the magnetometric device, negative feedback is organized by means of the resistor 6. In this case, the static characteristic of the device has the form

where R is the resistance of resistor 6, A is the direct conversion coefficient of MMP 1, B is the inverse conversion coefficient of MMP 1, which characterizes the magnitude of the magnetic field created in the ferromagnetic rod by the current I Us / R flowing through the signal winding of the MMP 1, N is the measured magnetic field, those. projection of the external magnetic field vector on the sensitivity axis of the IMF 1.

In a magnetometric device, it is advisable to use a rectangular voltage generator, since in this case the shape of the pulses at the output of the signal winding of the MMP 1 is practically independent of the repetition period T (FIG. 2). This allows you to reduce the requirements for stability of the frequency of the generator and to expand the range of operating frequencies from several tens of hertz to several hundred kilohertz, as well as significantly expand the frequency range of the measured magnetic fields.

Note that when using a rectangular voltage generator, the duty cycle of the voltage pulses generated by the generator can be set over a wide range. In this case, it is enough only to prevent the overlap of positive and negative pulses at the output of the signal winding MMP 1.

 KKiAR R + KKiAB

Mer, amorphous alloys. This allows you to get such a sensitivity MMP 1, which makes it possible to use a magnetometric device for constructing sensitive magnetometers or orientation sensors of moving objects relative to the geomagnetic field, for example, magnetic azimuth sensors inclinometers. In the latter case, two or three magnetometric devices can be used, which is determined by the choice of the design of the azimuth sensor, and one common generator to excite all IMFs,

The proposed magnetometric device is implemented on the basis of widespread components manufactured by the domestic industry.

Claims (1)

A magnetometric device comprising a magnetomodulating transducer, including a ferromagnetic rod with an excitation winding and a signal winding, a generator connected to an excitation winding of the magnetomodulating transducer, as well as an adder and a first detector, characterized in that a second detector and a resistor are introduced into it, the outputs of the detectors are connected to the inputs of the adder, the output of which through a resistor is connected to the common connection point of the output of the signal winding of the magneto odulyatsionnogo converter and the inputs of detectors, the detectors are made by schemes providing rectification positive half cycles signal by a first detector and negative half-periods of the signal by the second detector, and the adder has a low-pass filter characteristics.