SU842648A1 - Digital magnetic field meter - Google Patents

Description

(54) DIGITAL MAGNETIC FIELD METER

The invention relates to magnetic measurements and can be used for precision measurements in a wide range of induction of constant magnetic fields. According to the main auth. No. 748305, digital meters for measuring a wide range of induction of permanent magnetic fields are known, consisting of a Hall sensor (DF), an alternating current supply source DF, an additional coil, in the field of which there is a DF, a source of direct current for supplying windings an additional coil connected in series with the Hall sensor of the controlled divider, voltage-code converter and reverser counter, dividing device connected between the converter and the digital reading device control unit connected to a digital reading device, a converter. Reference-code, reversible counter, splitter device, the second input of which is connected to the output of the reversible counter and a DC source, as well as a phase element whose Bko is connected to the DC and a controlled divider, and a polarity trigger connected to the second input of the controlled divider. The measurement cycle in a given device consists of two cycles. In the first cycle, two constant magnetic fields simultaneously act on the DF: the measured and the additional Vdd, created by the DC source of the additional coil in which the DF is located. The output signal of the sensor, proportional to the sum of the l. Magnitudes of the magnetic inductions (Viei + Vdop), is fed to a voltage-code converter, from which it is output to a reversible counter, counting in the forward direction, as a sequence of pulses. In the second cycle 1, only the measured magnetic field B acts on DH, the output signal of the sensor, proportional to the measured magnetic induction, BKSM /., Goes to the voltage-to-voltage transducers, from where it is output to a reversible counter counting in the opposite direction. As a result, after the second cycle, the reversible counting device records the number of pulses N, proportional to the additional magnetic field (Via 11 + WAOP) - BUS simultaneously in the output register of the voltage-code generator, the code N is set, corresponding to the measured induction. After two measurement cycles, the numbers N come from the output register of the converter and the voltage N and from the reversing counter to the inputs of the separating device. After the arrival of the control signal from the control device, the dividing device performs an operation of dividing the number N by a number. The result of dividing is N-5-K. Wiem .KO -BAon “AOn where S is the specific sensitivity of HF induction; K - circuit transfer coefficient; If the induction value of the additional magnetic field is taken as the unit of the measured value, then the result of the generation will be proportional to the measured magnetic induction Tl. The disadvantage of this device is the dependence of the measurement results on the direction of the measured magnetic field and the inaccuracy of the measurement results when the magnetic field of the measured and additional magnetic fields does not match in the direction, as well as if the additional magnetic field BQ it induces the measured magnetic field by induction. In this case, the reverse The area in the second measurement cycle is fixed. There is a result that will not be proportional to the additional magnetic field „,, (W-8ai) 5 sa W-55adt6 mggl in rezul After this operation, neither the instrument gives an unreliable measurement result. The purpose of the invention is to improve the measurement accuracy. The goal is achieved by the fact that in a digital meter containing DH, an alternating current source for DH feeding, an additional coil in the field of which is DH, a DC source for supplying the winding of an additional coil, a controlled divider, a phase element, a polarity trigger, . The transducer has a direct code, a reversible counter, a dividing device, a digital reading device and a control unit in which the DF is connected to the P-code converter, the first output of which is Connected to the first input of the dividing device, second output through a reversible counter to the second input of the dividing device, the output is connected to a digital reading device, the first input of the phase element is connected to the output of the Hall sensor, the second output is connected to the output of the AC source connected to the Hall sensor, and the outputs, respectively, are connected to the zero and single inputs of the hghepolarity, the output of which is connected to the control input of the controlled divider, the control unit is connected to the converter Voltage code, reversible counter / dividing device and DC source, additionally three triggers, an OR element, six AND elements and a trigger with a counting input, the output of which is connected to the reversible counter control input, a counting input through the first AND element - with a block control, zero input through the OR element and the second AND element - with zero polarity trigger input, single input through the third AND element - s. single input of the polarity trigger, single input of the first trigger through the fourth AND element It is connected to the single input of the polarity trigger, the single input of the second ‑ trigger via the fifth AND element is connected to the zero input of the polarity trigger, the sixth AND element is connected between the outputs of the first and second triggers and the single input of the third trigger, the first output of which is connected to the second input of OR, and the second output — with the second inputs of the first, second, and third elements AND, the control unit being connected to the zero inputs of three flip-flops, the second inputs of the fourth and fifth elements AND, and the third inputs of the second and third Ina elements of the drawing is a block diagram of a digital meter magnetic field. The device is compacted from Hall sensor 1, AC source 2, DC source 3, additional coil 4, controlled Healer 5, phase element b, polarity trigger 7, voltage-code converter 8, reversible counter 9, dividing device 10 , a digital reading device 11, a control unit 12, a trigger 13 with a counting input, an OR element 14 elements AND 15-20, a trigger 21-23. The device works in the following way. The phase element b, depending on the direction of the magnetic field acting on the Hall sensor 1, sets the trigger 7 of the polarity to a certain state. For example,

in the positive direction of the magnetic field, the control signal from the phase element b is fed to the single input of trigger 7. The trigger 7 of the polarity outputs to the controlled divider 5 a signal that sets it to the state corresponding to the positive direction of the magnetic field. In the negative direction the magnetic field is controlled The signal from the phase element 6 is fed to the steering input of the polarity trigger 7, sets the controlled divider 5 to the state corresponding to the negative direction of the magnetic field. If, with a negative magnetic field direction, the sensitivity of the Hall sensor is greater than with a positive one, then the transmission coefficient of the controlled divider with a negative direction will be less than one magnetic field, provided that with a positive direction it is taken as one. With the reverse ratio, the transmission coefficient with a negative direction of the magnetic field will be greater than one.

The operation of the device occurs in two cycles. In the first cycle, two permanent magnetic fields act simultaneously on the DF 1: measured by BHJM and an additional subdirectory. In the second cycle, only the measured field Vie1ch acts on the DF. Depending on the ratio of the measured and additional magnetic fields and their direction, four options are possible:

BIZM BAOVI, Wigm and Vdop coincide in direction;

Vizm B (, zm and coincide in direction;

Vzzm Vdop f Vizm and Vdop coincide in direction)

Vmzk Vdop; Vtsam and Vdop do not coincide in direction.

An analysis of these conditions shows that in the first, second and third cases the magnetic field in the first and second cycles does not change its direction. In the fourth case, the direction of the magnetic field acting on the DH in the first cycle does not coincide with the direction of the magnetic field in the second cycle. In the presence of the first and third conditions of the meter, the following occurs.

In the first cycle, two permanent magnetic fields of the high-voltage drive simultaneously act on the household current. Additional magnetic field ng le is created by an additional coil 4, in the field of which there is a household current 1. A current from the direct current source 3 flows through the winding of the additional coil. The output signal, DH 1, through a controlled divider 5, proportional to the sum of the wilicines (W (-)) is fed to the voltage-code converter 8, from where it arrives in the form of a sequence of pulses

reversible counter 9, which in the first cycle works on the addition. The operation mode of the reversible counter is determined by the state of the phase element b. When the magnetic fields X and HP are coincident in the direction (for example, if the additional magnetic field is positive, the initial setup signal arriving at the WH 15 and 16 elements passes through the AND 15 element, the OR 14 element to the zero input of the reverse trigger 13. In this case, the flip-flop trigger 13 outputs such a control signal to the reversible counter 9, at which it works on addition. The reversible counter 9 will fix a code proportional to the sum of the magnetic inductions of the measured ri magnetic fields

N (Vizm +% op) S-K-lm0 In the second cycle, only measured magnetic field B acts on DH 1, since control unit 12 turns off the source of direct current 3. The output signal DH 1 through controlled 5 divider 5, proportional to the magnetic induction of the Wigm / enters the voltage-code converter 8, from where as a sequence of pulses goes to the reversible counter 9. In the second cycle, the reversible counter 9 works on subtraction. The change of the counting direction occurs on the signal coming through the element And 17 to the counting input of the trigger 13 of the reverse. As a result, after the second cycle, the reversible counter 9 will record the number of pulses N / proportional to the induction of the additional magnetic field Vdc7P

n (.s-K-and-B jM-s-K 1gt, w

 Vddp-5-K-Irr,

After two measurement cycles, the numbers N3 from the output register of the voltage-code converter are fed to the inputs of the separator device 10

 8 and from the reversible counter 9. After the arrival of the control signal from the control unit 12, the dividing device 10 performs the operation of dividing the number N, Ha the number Nj.

0 division result equal to

N-a s-K-Jm-ftH lA & i-5m,

At 5-to-8dop WANP

55

does not depend on the specific sensitivity of the Hall sensor to induction, its current supply, circuit transfer coefficient. If the induction value of the additional magnetic field Vdcg is taken as a unit of the measured value, then the result of the division will be proportional to the measured magnetic induction, if this condition is present in the positive direction, add a magnetic field) signal start

Noah installation passes through the element 16 to a single input trigger 13 of the reverse. In this case, the trigger 13 of the reverse, in the first measurement cycle, issues a control signal, according to which the reversible counter 9 works on subtraction and fixes a negative number N., proportional to the difference of magnetic inductions of the measured and additional fields.

Ni. - (Viy - TSOP) 5 K. I. . In the second cycle, the reversible counter 9 works on addition and, as a result, after the second cycle, it will record the number of pulses N 2 t proportional to the additional magnetic field

(% s; p-wigm) B ".J" S.K-

N,

- VK “-5-К. |. about,. TO.

 Вддп К- Ifri ° y (ВАОП-S к-1,

Further operation of the device is no different from the previously described work in the presence of the first condition.

If the fourth condition is present (in the positive direction of the additional magnetic field), the initial installation signal passes through the AND 15 element and the OR 14 element to the zero input of the flip-flop 13 of the reverse. In this case, the trigger 13 of the reverse produces a control signal, according to which the reversible counter 9 works on addition. A reversible counter 9 will fix a code H proportional to the difference of the magnetic inductions of the additional and measured fields l (Vdc7n-Vi5m) 5KCh

In the second measurement cycle, the direction of the magnetic field changes, acting on the Hall sensor 1. In this case, the control signal from the phase element 6 passes through the element 18 on the single input of the trigger 21. This triggers the trigger 23, TeiK as its single input receives a signal from the element 20, triggered by the fact that the trigger 22 is in a single state on the signal that passed the first cycle from the phase element b through the element 19. And the control signal from the output of the trigger 23 prohibits the passage of signals through the elements 17, 15 and 16, and the signal coming through the element OR 14 on

the flip-flop 13 of the reverse sets it in such a state that the reversible counter 9 in the second cycle works on addition.

As a result, after the second clock cycle, the reversible counter 9 will record the number of pulses N / 2. ,: proportional to the additional magnetic field,

V (% n-aJ- - 3m-.M-5- -3m ydop-5- - t-0-5-m - 5, - 5- - t

Vdop-3-K-Lp1The further operation of the meter occurs in the same way as in the cases considered earlier.

Claims (1)

1. USSR author's certificate 748305, c. 01 R 33/02, 1978.