SU866516A1

SU866516A1 - Magnetic field measuring device

Info

Publication number: SU866516A1
Application number: SU792859370A
Authority: SU
Inventors: Виктор Евгеньевич Ефремов
Original assignee: Дальневосточный Ордена Трудового Красного Знамени Политехнический Институт Им.В.В.Куйбышева
Priority date: 1979-12-14
Filing date: 1979-12-14
Publication date: 1981-09-23

Description

Изобретение относится к магнитным измерениям и может быть использовано для прецизионных измерений постоянных магнитных полей.The invention relates to magnetic measurements and can be used for precision measurements of constant magnetic fields.

Известны устройства для измерения магнитных полей, содержащие датчик Хол- ® ла с концентраторами, магнитного поля, источник постоянного тока для питания датчика, усилитель выходных сигналов и измерительный прибор £13Недостатками устройства являются су- ¹⁰шественные ограничения по чувствительности и точности измерений.Known devices for measuring magnetic fields, comprising the Hall sensor ® la with concentrators, magnetic field, DC power supply for the sensor, the amplifier output signals and the meter devices are 13Nedostatkami £ Su- ¹⁰ shestvennye limit of sensitivity and measurement accuracy.

Наиболее близким по технической сущности к предлагаемому является измеритель магнитных полей, использующий принцип модуляции магнитного потока измеряемого поля, протекающего в концентраторах, дополнительным синусоидальным полем, которое создается обмоткой, намотанной на концентраторах и питаемой от специального генератора. Такая модуляция, осуществляемая с целью частотного разделения полезного сигнала и напряжения ’неэквипотенциальности, возможна благодаря гистерезисной характеристике материала концентраторов. На выходе датчика Холла образуется ряд гармоник, кратных частоте дополнительного поля. Причем информацию об измеряемом поле унесут только четные гармоники, одна из которых выделяется избирательным усилителем [2 Д.The closest in technical essence to the proposed one is a magnetic field meter, using the principle of modulation of the magnetic flux of the measured field flowing in the concentrators, with an additional sinusoidal field, which is created by a winding wound on the concentrators and powered by a special generator. Such modulation, carried out with the aim of frequency separation of the useful signal and voltage ’non-equipotentiality, is possible due to the hysteretic characteristic of the material of the concentrators. At the output of the Hall sensor, a series of harmonics are formed that are multiples of the frequency of the additional field. Moreover, information about the measured field will be carried away only by even harmonics, one of which is highlighted by a selective amplifier [2 D.

Однако в известном устройстве полностью исключено влияние напряжения неэквипотенциальности на результаты из- мерений.However, in the known device, the influence of non-equipotentiality voltage on the measurement results is completely excluded.

Цель изобретения - повышение точности измерения.The purpose of the invention is to improve the accuracy of measurement.

Поставленная цель достигается тем, что устройство для измерения магнитных полей, содержащее датчик Холла с концентраторами магнитного поля, обмотку, индуктивно связанную с концентраторами магнитного поля и связанную с генератором синусоидального тока, при этом выход датчика Холла через селективный усилитель соединен с измерительным прибором, снабжено вторым генератором синусоидального тока, связанным с датчиком Холла.This goal is achieved in that the device for measuring magnetic fields, comprising a Hall sensor with magnetic field concentrators, a winding inductively coupled to magnetic field concentrators and connected to a sinusoidal current generator, while the output of the Hall sensor through a selective amplifier is connected to a measuring device, equipped with a second a sinusoidal current generator associated with a Hall sensor.

. На чертеже приведена функциональная схема предлагаемого устройства.. The drawing shows a functional diagram of the proposed device.

Устройство содержит датчик .1 Холла с концентраторами 2 магнитного поля, обмотку 3 и генератор 4 синусоидального тока питания катушки, генератор 5 синусоидального тока для питания датчика 1, селективный усилитель 6 и измерительный прибор 7. Выход генератора 6 подключен ко входу датчика 1, выход которого, в свою очередь, соединен через усилитель 6 с измерительным прибором 7. Обмотка 3, индуктивно связанная с концентраторами 2. Недостаток известного устройства невысокая чувствительность магнитометра, связанная с низкой селективностью избирательного усилителя, подключена к выходу генератора 4. При этом усилитель выполнен с полосой пропускания, охватывающей резонансную частоту между одной из четных гармоник генератора питания катушки и частотой питания датчика Холла. Предпочтительно подбирать параметры элементов так, чтобы названная разностная частота совпадала с центральной частотой полосы пропускания усилителя.The device contains a Hall sensor .1 with magnetic field concentrators 2, a winding 3 and a sinusoidal current supply generator 4, a sinusoidal current generator 5 for supplying a sensor 1, a selective amplifier 6 and a measuring device 7. The output of the generator 6 is connected to the input of the sensor 1, the output of which in turn, is connected through an amplifier 6 to a measuring device 7. A winding 3 inductively coupled to concentrators 2. A disadvantage of the known device is the low sensitivity of the magnetometer due to the low selectivity of the selector ohm amplifier, connected to the output of the generator 4. In this case, the amplifier is made with a passband covering the resonant frequency between one of the even harmonics of the coil power generator and the power frequency of the Hall sensor. It is preferable to select the parameters of the elements so that the named difference frequency coincides with the center frequency of the passband of the amplifier.

Устройство работает следующим обра.зом.The device operates as follows.

При внесении датчика 1 в измеряемое поле концентраторы 2, выполненные из магнитомягкого материала, намагничиваются одновременно измеряемым постоянным полем и синусоидальным полем обмотки 3. В результате магнитное состояние материала концентраторов изменяется по несимметричной магнитнй петле. Переменная составляющая магнитной индукции содержит гармоники, кратные частоте генератора 4, причем четные из них имеют амплитуду, пропорциональную измеряемому полю. Возникая в объеме сердечника концентраторов, переменная составляющая магнитной индукции пронизывает зазор сердечника, в котором расположен датчик 1 Холла. В результате балансно-амплитудной модуляции в датчике, на его выходе образуется ряд гармоник. Причем, приближая частоту генератора 5 к одной из четных гармоник магнитной индукции, частоту биения данной гармоники и генератора питания датчика (т.е. упомянутую раз5 ностную частоту) можно существенно отодвинуть от мешающие помех. Эта разностная частота выделяется усилителем 6.When the sensor 1 is introduced into the measured field, the concentrators 2 made of soft magnetic material are magnetized at the same time by the measured constant field and the sinusoidal field of the winding 3. As a result, the magnetic state of the material of the concentrators changes along an asymmetric magnetic loop. The variable component of magnetic induction contains harmonics that are multiples of the frequency of the generator 4, and even of them have an amplitude proportional to the measured field. Arising in the volume of the core of concentrators, the variable component of magnetic induction permeates the gap of the core in which the Hall sensor 1 is located. As a result of balance-amplitude modulation in the sensor, a number of harmonics are formed at its output. Moreover, by approximating the frequency of generator 5 to one of the even harmonics of magnetic induction, the beat frequency of this harmonic and the sensor power generator (i.e., the difference frequency mentioned above) can be significantly removed from interfering interference. This difference frequency is allocated by amplifier 6.

Преследуя цель обеспечить с помощью предлагаемого устройства прецизионную 10 точность измерения слабых магнитных полей, разработчик аппаратуры здесь уже не связан требованиями селективности применяемых усилителей. Вместо сложных и дорогих схем прецизионных усилителей здесь 15 можно без ущерба для точности применять более простые, но зато и более компактные и надежные схемы усилителя. Кроме того, универсальность реализованного метода, заключающаяся в удобстве выделения лк>2о бой четной гармоники магнитной индукции, позволяет получать максимум магнитного усиления в концентраторах любой формы, что достигается в известном устройстве ценой больших затрат, выражающихся, 25 главным образом, в необходимости использования прецизионного усилителя.In pursuit of the goal of providing with the proposed device precision 10 the accuracy of measuring weak magnetic fields, the equipment designer is no longer bound by the selectivity requirements of the amplifiers used. Instead of complex and expensive precision amplifier circuits, here 15 it is possible, without sacrificing accuracy, to use simpler, but more compact and reliable amplifier circuits. In addition, the universality of the method implemented, which consists in the convenience of extracting lx> 2 even odd harmonics of magnetic induction, allows you to get maximum magnetic gain in concentrators of any shape, which is achieved in the known device at the cost of high costs, expressed mainly 25 by the need to use a precision amplifier .

Claims

(54) DEVICE FOR MEASURING MAGNETIC FIELDS The invention relates to magnetic measurements and can be used for precision measurements of constant magnetic fields. Apparatus for measuring magnetic fields are known, comprising a Hall sensor with concentrators, a magnetic field, a direct current source for powering the sensor, an output amplifier, and a measuring G13. The drawbacks of the device are significant limitations on the sensitivity and accuracy of measurements. The closest in technical terms to the present invention is a magnetic field meter, which uses a sinusoidal field created by a winding wound on the concentrators and fed from a special generator for magnetic field modulation of the magnetic flux of the measured field flowing in the concentrators. Such modulation, carried out for the purpose of frequency separation of the useful signal and the voltage of the FIELD of non-equipotentiality, is possible due to the hysteresis characteristic of the material of the concentrators. At the output of the Hall sensor, a series of harmonics is generated, multiples of the frequency of the additional field. Moreover, information about the measured field will be carried away only by even harmonics, one of which is allocated by a selective amplifier 2 D. However, in the known device, the effect of non-equipotential voltage on the measurement results is completely excluded. The purpose of the invention is to improve the measurement accuracy. The goal is achieved in that a device for measuring magnetic fields, comprising a Hall sensor with magnetic field concentrators, a winding connected inductively with a magnetic field concentrators and connected with a sinusoidal current generator, while the output of the Hall sensor through a selective amplifier is connected to a measuring device. 3s a1a6geno by a second sinusoidal current generator connected to a hall sensor. The drawing shows a functional diagram of the proposed device. The device contains a Hall sensor 1 with magnetic field concentrators 2, a winding 3 and a generator 4 of sinusoidal current supplying the coil, a generator 5 of sinusoidal current for supplying sensor 1, a selective amplifier 6 and measuring device 7. The output of generator 6 is connected to the input of sensor 1, the output of which in turn, connected through an amplifier b with a measuring device 7. Winding 3, inductively connected to the hubs

2. A disadvantage of the known device is the low sensitivity of the magnetometer associated with the low selectivity of the selective amplifier, connected to the output of the generator 4. In this case, the amplifier is made with a bandwidth covering 11 (its resonant frequency between the even and even harmonics of the coil power generator and the power supply of the Hall sensor, choose the parameters of the elements so that the named difference frequency coincides with the center frequency of the amplifier bandwidth, the device operates as follows. When the sensor 1 is inserted into the measured field, the concentrators 2 made of magnetically soft material are magnetized simultaneously by the measured constant field and the sinusoidal field of the winding 3. As a result, the magnetic state of the material of the concentrators changes along the same network. The recurrent component of the magnetic induction contains harmonics that are multiple to the frequency of the generator 4, and even of them have an amplitude proportional to the field being measured. Occurs in the volume of the core of the concentrators, the variable component of the magnetic duction penetrates the gap of the center, in which the Hall 1 sensor is located. As a result of the balance-amplitude modulation in the sensor, a number of harmonics are formed at its output. Moreover, by approximating the frequency of the generator 5 to one of the even harmonics of the magnetic induction, the beating frequency of this harmonic and the generator of the sensor power supply (i.e., the aforementioned difference frequency) can be significantly removed from the interference. This difference frequency is allocated by the amplifier 6. Following the goal of ensuring the precision accuracy of measuring weak magnetic fields with the proposed device, the designer of the equipment is no longer bound by the selectivity of the amplifiers used. Instead of complex and expensive precision amplifier circuits, here you can, without sacrificing accuracy, use simpler, but more compact and reliable amplifier circuits. In addition, the universality of the implemented method, which consists in the convenience of isolating any even harmonics of magnetic induction, makes it possible to obtain a maximum of magnetic amplification in concentrators of any shape, which is achieved in a known device at the cost of increasing costs, expressed mainly in the need to use a precision amplifier. Claims An apparatus for measuring magnetic fields, comprising a Hall sensor with magnetic field concentrators, a winding, inductively coupled to a magnetic field concentrators and associated with a sinusoidal current generator, the output of the Hall sensor through a selective amplifier connected to a measuring instrument, characterized in that , in order to improve measurement accuracy, it is equipped with a second sinusoidal current generator coupled to a Hall sensor. Sources of information taken into account during the examination 1. Yu. V. Afanasyev and others. Magnetometric converters, devices, installations. L., Energie, 1972, 2, USSR Copyright Certificate M 475572, cl. Ci O1 R 33/02, 1975.

Uj

You bc

Luj