Measuring device and measuring method for four-wire dual-port magneto-electric isolator

Abstract

The application belongs to the technical field of two-port electrical network elements, and relates to a measuring device of a four-wire two-port magneto-electric isolator, which comprises a magneto-electric isolator, an impedance analyzer, a static bias magnetic field applying device and a support; the magneto-electric isolator is fixed on the support and placed at the central position of the static bias magnetic field applying device; the impedance analyzer is used for measuring the current and voltage of the magneto-electric isolator in the sweep frequency process, and then the input end impedance and the output end impedance of the magneto-electric isolator are obtained to obtain the isolation degree of the magneto-electric isolator; the static bias magnetic field applying device is composed of a neodymium-iron-boron permanent magnet oppositely arranged on a guide rail. It is verified by the measuring device that the magneto-electric isolator can realize the signal isolation function in the low frequency field, and has potential application value in power transmission and signal isolation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of two-port electrical network elements, and relates to a measuring device and a measuring method for a four-wire two-port magneto-electric isolator. BACKGROUND

[0002] Generally, an electrical isolation device provides a seamless connection and a general medium for signal transmission (signal isolation) or power transmission (power isolation) for a two-port electrical network, and the circuits to be isolated can withstand a certain voltage difference, and is often used to isolate the ground potential difference and common-mode transient noise, and can better protect the electrical system from unpredictable surges and noise, and is currently widely used in occasions such as sensor interface modules, data communication, field bus isolation, peripheral interface and telecommunication circuits, and the like, which require an isolation device of a data interface and a power module to protect the core circuit and eliminate the reference voltage difference. Fundamentally, the electrical isolator is an interface circuit that provides current isolation between two-port electrical networks to ensure electrical insulation and isolation, but at the same time allows reliable data transmission between two modules, which helps to eliminate the ground loop and provide protection for high-voltage sensitive circuits.

[0003] Traditional isolation technologies are mainly divided into photoelectric isolation technology, capacitive isolation technology and transformer magnetic coupling isolation technology. The photoelectric isolator has high power consumption due to the energy conversion between photoelectricity, and the transmission rate is limited, but it is easy to be disturbed by noise when transmitting because it cannot generate a differential signal. The capacitive isolator realizes isolation transmission through the form of electric field, and adopts a differential channel composed of two channels, thereby solving the problem of no differential signal in single-channel transmission. Compared with magnetic coupling isolation, the outstanding advantage is strong anti-electromagnetic interference capability. The magnetic coupling isolator is usually realized by using a discrete transformer, which has a large volume and is not conducive to integration, and has weak anti-electromagnetic interference capability. The operational amplifier is often used in the magnetic coupling isolator, so that the bandwidth of the isolator is limited and the low-voltage application is limited. However, magnetic coupling isolation is currently the only integrated power transmission isolation technology. As a new type of magneto-electric isolation element, the magneto-electric composite structure has inherent characteristics of ordered magnetization under the action of an electric field or electric polarization under the action of a magnetic field, which can accompany the mutual conversion of magnetic field energy and electric field energy, so that it has potential application in the field of magnetic coupling isolation. SUMMARY

[0004] The application aims to provide a measuring device and a measuring method for a four-wire two-port magneto-electric isolator, which verifies that the magneto-electric isolator can realize signal isolation in the low-frequency field, and has potential application value in power transmission and signal isolation.

[0005] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0006] The application provides a measuring device of a four-wire dual-port magneto-electric isolator, comprising a magneto-electric isolator, an impedance analyzer, a static bias magnetic field applying device and a support; the magneto-electric isolator is fixed on the support and placed at the center position of the static bias magnetic field applying device; the impedance analyzer is used for measuring the current and voltage of the magneto-electric isolator in the frequency sweeping process, and then obtaining the input end impedance and output end impedance of the magneto-electric isolator to obtain the isolation degree of the magneto-electric isolator; the magneto-electric isolator is a four-wire dual-port element composed of a magneto-electric composite material and a coil uniformly surrounding the periphery of the magneto-electric composite material; the magneto-electric composite material is a symmetrical structure composed of a piezoelectric ceramic layer and magnetostrictive layers located on both sides of the piezoelectric ceramic layer; the coil end is connected with the impedance analyzer as an input end, and the magneto-electric composite material end is connected with the impedance analyzer as an output end; and the static bias magnetic field applying device is composed of Nd-Fe-B permanent magnets oppositely arranged on guide rails.

[0007] In one technical solution, the measuring device further comprises a lock-in amplifier and a 100Ω fixed resistor; the 100Ω fixed resistor is connected in series with the coil end or the magneto-electric composite material end; and the lock-in amplifier is used for measuring the output voltage of the coil end or the output voltage of the magneto-electric composite material end, and then obtaining the forward transfer impedance and reverse transfer impedance of the magneto-electric isolator to verify the non-reciprocity of the magneto-electric isolator.

[0008] In one technical solution, the magnetostrictive layer is a Ni 0.8 Zn 0.2 Fe2O4 nickel-zinc ferrite magnetostrictive layer, and the piezoelectric ceramic layer is a PZT-8 piezoelectric ceramic layer.

[0009] The application further provides a measuring method of the measuring device of the four-wire dual-port magneto-electric isolator, comprising the following steps:

[0010] manufacturing the four-wire dual-port magneto-electric isolator;

[0011] fixing the magneto-electric isolator on the support and placing it at the center position of the static bias magnetic field applying device;

[0012] connecting the coil end with the impedance analyzer as an input end, adjusting the distance between the two permanent magnets and the magneto-electric isolator to change the magnetic field applied on the magneto-electric isolator, and obtaining the variation curve of the modulus value of the input end impedance of the magneto-electric isolator with frequency and magnetic field;

[0013] connecting the magneto-electric composite material end with the impedance analyzer as an output end, adjusting the distance between the two permanent magnets and the magneto-electric isolator to change the magnetic field applied on the magneto-electric isolator, and obtaining the variation curve of the modulus value of the output end impedance of the magneto-electric isolator with frequency and magnetic field;

[0014] The isolation degree of the magnetoelectric isolator is calculated by the modulus of the input impedance of the magnetoelectric isolator and the modulus of the output impedance of the magnetoelectric isolator, and then the change curve of the isolation degree with the frequency and the magnetic field is obtained.

[0015] A 100Ω constant resistor is connected in series with the coil end, the magnetoelectric composite material end is connected with the lock-in amplifier, the voltage is applied at the coil end, the output voltage of the magnetoelectric composite material end is measured, the current flowing through the constant resistor is calculated, and then the forward transfer impedance of the magnetoelectric isolator is obtained.

[0016] A 100Ω constant resistor is connected in series with the coil end, the magnetoelectric composite material end is connected with the lock-in amplifier, the voltage is applied at the coil end, the output voltage of the magnetoelectric composite material end is measured, the current flowing through the constant resistor is calculated, and then the forward transfer impedance of the magnetoelectric isolator is obtained.

[0017] If the modulus of the forward transfer impedance of the magnetoelectric isolator is equal to the modulus of the reverse transfer impedance of the magnetoelectric isolator, the magnetoelectric isolator has non-reciprocity.

[0018] Compared with the prior art, the beneficial effects of the present application are that:

[0019] Compared with the traditional ferrite isolator, the three-layer symmetrical magnetoelectric isolator of the present application utilizes the magnetostriction effect of the ferromagnetic material and the piezoelectric effect of the piezoelectric material and realizes strong magnetoelectric coupling through interlayer strain transmission, realizes the conversion function between magnetic field energy and electric energy, through the advantages of the device itself, good forward transmission and reverse isolation functions are achieved, and the size of the device is further reduced, has the advantages of simple preparation process, low cost, low mechanical loss, etc., and has potential application value in power transmission and signal isolation. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is one of the structure schematic diagrams of the measuring device of the present application.

[0021] Figure 2 It is the second structure schematic diagram of the measuring device of the present application.

[0022] Figure 3 It is the change curve of the input impedance and the output impedance with the frequency and the magnetic field (0Oe~190Oe).

[0023] Figure 4 It is the change curve of the isolation degree of the magnetoelectric isolator designed by the present application with the frequency and the magnetic field.

[0024] In the drawings, 1 is a magnetoelectric isolator, 2 is an impedance analyzer, 3 is a static bias magnetic field applying device, 4 is a support, and 5 is a lock-in amplifier. DETAILED DESCRIPTION

[0025] The following examples are intended to illustrate the present application and are not intended to limit the scope of the present application. Unless otherwise indicated, the techniques employed in these examples are standard techniques commonly used in the art. The test methods used in the following examples are standard methods unless otherwise indicated.

[0026] Example 1

[0027] 1) Preparation of four-wire dual-port magneto-electric isolator

[0028] The four-wire dual-port magneto-electric isolator is composed of a magneto-electric composite material and a coil uniformly surrounding the periphery of the magneto-electric composite material. The three-layer symmetrical structure magneto-electric composite material is composed of a piezoelectric ceramic layer and magnetostrictive layers on both sides of the piezoelectric ceramic layer. The two magnetostrictive layers and the piezoelectric ceramic layer are combined into an M-P-M sandwich structure by an epoxy resin adhesive layer. The magnetostrictive layer used in this embodiment is a nickel-zinc ferrite Ni 0.8 Zn 0.2 Fe2O4, with a size of 38 mm x 5 mm x 1 mm; the piezoelectric ceramic layer is PZT-8, with a size of 40 mm x 5 mm x 1 mm.

[0029] The preparation method of the four-wire dual-port magneto-electric isolator is as follows: (1) select a polished Ni 0.8 Zn 0.2 Fe2O4 nickel-zinc ferrite sample and a piezoelectric ceramic PZT-8 sheet material, each with a thickness of 1 mm and a length of 40 mm; (2) polish the nickel-zinc ferrite sample using 600# fine sandpaper and clean it with acetone to remove the oxidation layer and attachments for use; (3) combine and bond the 40 mm long piezoelectric ceramic sample and the treated nickel-zinc ferrite sample with an epoxy resin adhesive layer, and then place them in an oven at a constant temperature of 120°C for 2 hours to obtain a three-layer symmetrical structure magneto-electric composite structure; (4) weld electrodes on the upper and lower surfaces of the prepared magneto-electric composite element using conductive copper wire, and check the continuity; (5) uniformly and densely wind an enameled wire with a wire diameter of 0.2 mm around the periphery of the magneto-electric composite element, leaving two wire ends as the input terminals of the device, and complete the preparation of the four-wire dual-port magneto-electric isolator.

[0030] Since there is no direct electrical connection between the coil and the magneto-electric composite material, the device itself has the characteristic of electrical isolation. In addition, due to the different sizes of the input impedance of the two ports of the device, the flow of signals is also affected differently. The end with larger impedance can hinder the flow of signals, while the end with smaller impedance allows the flow of signals.

[0031] The coil end is used as the input end and the magnetoelectric composite material end as the output end. The current signal passes through the outer winding coil to convert electrical energy into magnetic field energy. The nickel-zinc ferrite in the magnetoelectric composite material will vibrate with the changes in the surrounding magnetic field, that is, convert the magnetic field energy into vibrating mechanical energy, and then transmit the mechanical energy to the middle piezoelectric ceramic layer through the glue layer. The piezoelectric ceramic is affected by pressure and will generate voltage on the two poles, completing the conversion of mechanical energy to electrical energy. The voltage signal is then output backward to complete the signal transmission function.

[0032] On the contrary, when the voltage signal is input from the magnetoelectric composite material end, since the impedance of this end is very large (the value is 300~500 times that of the coil end), this end has a great obstruction effect on the flow of the signal, which can complete the signal isolation function.

[0033] 2) Build the measuring device

[0034] like Figure 1 As shown, the measurement setup includes a magnetoelectric isolator 1, an impedance analyzer 2, a static bias magnetic field applicator 3, and a bracket 4. The static bias magnetic field applicator 3, consisting of NdFeB permanent magnets positioned relative to each other on a guide rail, provides a static bias magnetic field for the magnetoelectric isolator. The prepared magnetoelectric isolator 1 is secured to the bracket and placed at the center of the static bias magnetic field applicator 3. The impedance analyzer used is a model E4990A, purchased from Keysight Technologies.

[0035] 3) Measuring isolation

[0036] Connect the coil end as the input end to the impedance analyzer 2, adjust the distance between the two permanent magnets and the magnetoelectric isolator to change the magnitude of the magnetic field applied to the magnetoelectric isolator, and obtain the modulus value of the input impedance of the magnetoelectric isolator 1 |Z 11 |The curve of the change with frequency f and magnetic field (0Oe~190Oe), such as Figure 3 -a. Figure 3 -a shows that as the frequency f increases, the modulus of the input impedance |Z 11 | gradually increases, and positive and negative resonances appear at the resonant frequency. At the same time, the modulus of the input impedance |Z 11 | reaches the maximum or minimum value; the modulus of the input impedance |Z 11 |With the increase of the external magnetic field, it shows a trend of first increasing, then decreasing, and finally tending to saturation.

[0037] Connect the magnetoelectric composite material end as the output end to impedance analyzer 2, adjust the distance between the two permanent magnets and the magnetoelectric isolator to change the magnetic field applied to the magnetoelectric isolator, and obtain the modulus value of the output end impedance of the magnetoelectric isolator 1 |Z 22 |The curve of the change with frequency f and magnetic field (0Oe~190Oe), such as Figure 3 -b.Figure 4 -b shows that as the frequency f increases, the modulus of the output impedance |Z 22 | gradually increases, the modulus of the output impedance at the resonant frequency |Z 22 | reaches the maximum value; the modulus of the output impedance |Z 22 |With the increase of the external magnetic field, it shows a trend of first increasing, then decreasing, and finally tending to saturation.

[0038] Use the modulus of input impedance |Z 11 | and the modulus of the output impedance |Z 22 The isolation of the magnetoelectric isolator 1 is defined by the ratio of ||. The larger the ratio, the better the isolation effect of the magnetoelectric isolator. The isolation of the magnetoelectric isolator 1 is calculated by the modulus of the input impedance and the modulus of the output impedance of the magnetoelectric isolator 1, and then the curve of the isolation changing with frequency f and magnetic field is obtained, as shown in Figure 4 As shown in the figure above, the upper right figure shows the curve of isolation changing with magnetic field. Figure 2 It can be seen that when the optimal bias magnetic field is 190Oe, the modulus of the input impedance |Z 11 | and the modulus of the output impedance |Z 22 The phase difference reaches the peak point (the modulus of the output impedance |Z 22 |Approximately the modulus of the input impedance|Z 11 |1220 times), proving that the design Ni selected in the present invention 0.8 Zn 0.2 The magnetoelectric isolator 1 composed of Fe2O4 nickel-zinc ferrite sample and PZT-8 piezoelectric ceramic material can play a good role in forward transmission and reverse isolation.

[0039] 4) Measure transfer impedance parameters

[0040] like ​ As shown in the figure, the forward measurement of transfer impedance is as follows: a fixed resistor of 100Ω is connected in series with the coil end, the magnetoelectric composite material end is connected to the lock-in amplifier 5, a voltage of U1=100mV is applied to the coil end, the output voltage U2 of the magnetoelectric composite material end is measured by the lock-in amplifier 5, and the current I1 flowing through the fixed resistor is calculated. According to the forward transfer impedance formula Z 21 =U2 / I1, the forward transfer impedance Z of the magnetoelectric isolator is calculated 21 .

[0041] Reverse measurement of transfer impedance: Connect a 100Ω fixed resistor in series with the end (input end) of the magnetoelectric composite material, connect the coil end (output end) to the lock-in amplifier 5, apply a voltage of U2 = 100mV to the end of the magnetoelectric composite material, use the lock-in amplifier 5 to measure the output voltage U1 of the coil end, calculate the current I2 flowing through the fixed resistor, and use the reverse transfer impedance formula Z 12=U1 / I2, the reverse transfer impedance Z of the magneto-electric isolator is calculated 12 .

[0042] By measuring forward and reverse, the modulus |Z 21 | of the forward transfer impedance and the modulus |Z 12 | of the reverse transfer impedance are calculated, and |Z 12 | is compared with |Z 21 |, so as to verify the non-reciprocity of the isolator with forward transmission and reverse isolation, and directly prove the rationality of the four-wire double-port magneto-electric isolator design scheme designed in the present application. Compared with the traditional ferrite isolator, the magneto-electric isolator with the three-layer symmetrical structure has a lower working frequency, is suitable for application in the electronic field, has a smaller size, has a higher space utilization rate, and compared with the traditional active circuit, since it is a passive device, it is more suitable for use in power electronic signal transmission. Therefore, the present application can replace the traditional ferrite isolator and active circuit and has potential application value in power transmission and signal isolation.

[0043] The above-described embodiments are only preferred embodiments of the present application, merely used to explain the present application, and are not intended to limit the scope of the present application. For those skilled in the art, of course, other embodiments can be easily made by substitution or change according to the technical content disclosed in the present application, and any changes and improvements made on the principle of the present application shall be included in the scope of the patent application of the present application.

Claims

1. A method for measuring the isolation of a four-wire dual-port magnetoelectric isolator, characterized in that: The following steps are involved: A four-wire, two-port magnetoelectric isolator is manufactured; the magnetoelectric isolator is a four-wire, two-port element composed of a magnetoelectric composite material and a coil uniformly surrounding the magnetoelectric composite material. The magnetoelectric composite material is a symmetrical structure composed of a piezoelectric ceramic layer and magnetostrictive layers located on both sides of the piezoelectric ceramic layer. Fixing the magnetoelectric isolator on a bracket and placing it at the center of a static bias magnetic field applying device; Connect the coil end as the input end to the impedance analyzer, adjust the distance between the two permanent magnets and the magnetoelectric isolator to change the magnetic field applied to the magnetoelectric isolator, and obtain the curve of the modulus of the input impedance of the magnetoelectric isolator as a function of frequency and magnetic field; The magnetoelectric composite material is connected to an impedance analyzer as the output end. The distance between the two permanent magnets and the magnetoelectric isolator is adjusted to change the magnitude of the magnetic field applied to the magnetoelectric isolator. The curve of the modulus of the output impedance of the magnetoelectric isolator as a function of frequency and magnetic field is obtained. The isolation of the magnetoelectric isolator is calculated by the modulus of the input impedance and the output impedance of the magnetoelectric isolator, and then the curve of the isolation varying with frequency and magnetic field is obtained; A 100Ω fixed resistor is connected in series with the coil end, and the magnetoelectric composite material end is connected to a lock-in amplifier. A voltage is applied to the coil end, and the output voltage of the magnetoelectric composite material end is measured. The current flowing through the fixed resistor is calculated, and the forward transfer impedance of the magnetoelectric isolator is obtained. A 100Ω fixed resistor is connected in series with the end of the magnetoelectric composite material, and the coil end is connected to a lock-in amplifier. A voltage is applied to the end of the magnetoelectric composite material, and the output voltage of the coil end is measured. The current flowing through the fixed resistor is calculated, and the reverse transfer impedance of the magnetoelectric isolator is obtained. If the modulus of the forward transfer impedance of the magnetoelectric isolator is equal to the modulus of the reverse transfer impedance of the magnetoelectric isolator, the magnetoelectric isolator is non-reciprocal.

2. The isolation measurement method according to claim 1, wherein: The static bias magnetic field applying device is composed of NdFeB permanent magnets arranged relatively on the guide rail.

3. The isolation measurement method according to claim 1, wherein: The magnetostrictive layer is Ni 0.8 Zn 0.2 The Fe2O4 nickel-zinc ferrite magnetostrictive layer is a piezoelectric ceramic layer. The piezoelectric ceramic layer is a PZT-8 piezoelectric ceramic layer.

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