Hysteresis loop measuring device and method based on bipolar SSLTD module circuit

Abstract

The invention discloses a hysteresis loop measuring device and method based on a bipolar SSLTD module circuit, and relates to the technical field of magnetization characteristic curve measurement of magnetic materials, the device comprises a controller, an excitation winding, a direct current power supply and a detection winding, the excitation winding comprises the bipolar SSLTD module circuit, and the circuit comprises two SSLTD modules and a magnetic core. The two SSLTD modules are a positive SSLTD module and a negative SSLTD module and share one magnetic core, each SSLTD module comprises a charging port and a plurality of unit groups formed by discharging switches and capacitors, the excitation winding is connected with the magnetic core to be tested through a closed wire, and the closed wire simultaneously penetrates through the magnetic core to be tested and a middle area of a bipolar SSLTD module circuit. The detection winding comprises an oscilloscope and is connected with the magnetic core to be detected through another wire, the other wire penetrates through the magnetic core to be detected, the two ends of the other wire are connected with a voltage probe of the oscilloscope, and the closed wire is connected with a current probe of the oscilloscope. The method has the advantages of being short in measurement period, high in measurement parameter adjustability and capable of supporting high voltage and large current.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring the magnetization characteristic curve of magnetic materials, and particularly to a magnetic hysteresis loop measuring device and method based on a bipolar SSLTD module circuit. Background Art

[0002] In the field of power circuits, ferromagnetic materials are widely used in components such as transformers, sensors, and power regulators. To improve the efficiency, safety, and reliability of power systems, it is necessary to accurately describe the magnetization characteristics of these components. The magnetic hysteresis loop is a key tool for characterizing the core properties, and important parameters such as the magnetic saturation point, remanent magnetization, and coercive force of the core can be determined through it. Currently, the commonly used magnetization characteristic measurement methods are the low-frequency AC measurement method and the impulse measurement method. However, these two methods have obvious limitations under high-frequency and high-voltage conditions.

[0003] The low-frequency measurement method is suitable for low-frequency conditions such as 50 Hz or 60 Hz, but it cannot reflect high-frequency characteristics such as eddy current loss and hysteresis loss at high frequencies. At low frequencies, the induced voltage is small, the signal noise is large, and the operating characteristics under high voltage cannot be accurately measured. In addition, the low-frequency measurement method mainly focuses on its quasi-static characteristics and cannot reflect the dynamic response of the core in high-frequency circuits (such as switching speed and changes in the magnetic hysteresis loop). The low-frequency measurement method has a long measurement time, which may cause the equipment to heat up and affect the test stability.

[0004] The impulse measurement method measures the dynamic magnetization characteristics by applying a high-voltage pulse and is suitable for high-frequency and high-voltage environments. However, its frequency range is limited and cannot cover the entire frequency band of the core. At extremely high frequencies (such as in the MHz range), impulse measurement may not accurately reflect the core performance. Impulse measurement usually uses a fixed pulse waveform and cannot simulate the complex voltage waveforms in actual operation, resulting in inaccurate measurement. In addition, impulse measurement cannot reflect the thermal loss characteristics of the core under high-frequency and high-voltage conditions, and these losses are crucial for long-term stable operation.

[0005] The above conventional measurement methods have the disadvantages of a long test cycle, being unable to measure the core under ultra-high frequency conditions, unable to measure under high voltage and large current, not having the ability to adjust core parameters (pulse width, voltage, pulse interval, positive and negative asymmetric voltage, etc.) in any output state, and being unable to measure under different working environments. Summary of the Invention

[0006] One of the objectives of the present invention is to provide a magnetic hysteresis loop measuring device based on a bipolar SSLTD module circuit to overcome the defect in the prior art that magnetization characteristic measurement cannot be performed under certain specific high-voltage and high-frequency conditions.

[0007] To achieve the above objective, the present invention adopts the following technical solutions:

[0008] A magnetic hysteresis loop measuring device based on a bipolar SSLTD module circuit, comprising a controller and an excitation winding connected thereto, further comprising a DC power supply for providing power energy to the excitation winding, and a detection winding. The excitation winding comprises a bipolar SSLTD module circuit, and the bipolar SSLTD module circuit comprises two unipolar SSLTD modules and a magnetic core. The two unipolar SSLTD modules are respectively a positive-polarity SSLTD module and a negative-polarity SSLTD module, and they share a magnetic core. Each unipolar SSLTD module comprises a charging port and a plurality of unit groups composed of discharge switches and capacitors. The excitation winding is connected to the magnetic core under test through a closed wire, and this closed wire passes through the middle region of the magnetic core under test and the bipolar SSLTD module circuit at the same time. The detection winding comprises an oscilloscope and is connected to the magnetic core under test through another wire. After passing through the magnetic core under test, both ends of this other wire are connected to the voltage probes of the oscilloscope, and the closed wire is connected to the current probe of the oscilloscope.

[0009] Further, one of the unipolar SSLTD modules is inverted and combined with the other unipolar SSLTD module, and the magnetic core shared by the two is located in the sandwich space between them.

[0010] Further, the output current and / or voltage of each unipolar SSLTD module are inductively superimposed on the output end through the transformer principle of the magnetic core.

[0011] Further, the following method is adopted to control the discharge of the unipolar SSLTD module:

[0012] S1. The controller issues a control signal, which is converted into an optical signal through an optical-electric converter, and then the optical signal is transmitted to the optical-electric transceiver of the discharge switch in each unipolar SSLTD module through an optical fiber;

[0013] S2. After receiving the optical signal, the optical-electric transceiver converts it into an electric signal and outputs it to the drive circuit of the corresponding discharge switch;

[0014] S3. After receiving the electric signal, the drive circuit generates a corresponding pulse signal for controlling the conduction and cut-off of the discharge switch;

[0015] S4. When the discharge switch receives the discharge control signal, it conducts, and the voltage is induced into the load through the magnetic core to achieve high-voltage output; when the control signal stops being provided, the discharge switch turns off, and the capacitor stops discharging the load.

[0016] Further, the bipolar output of the bipolar SSLTD module is output through two inverted unipolar SSLTD modules according to a certain time sequence, and then a positive and a negative voltage-current waveform can be output.

[0017] Another object of the present invention is to provide a method for measuring the hysteresis loop based on a bipolar SSLTD module circuit, which uses the above-described device for measuring the hysteresis loop based on a bipolar SSLTD module circuit, and includes the following steps:

[0018] (1) Keep the detection winding side of the magnetic core to be measured open, and let the DC power supply charge the energy storage element in the bipolar SSLTD module circuit; subsequently, the controller issues a corresponding control signal, which is converted into an optical signal via an optical-electric converter. This optical signal is transmitted to the optical-electric converter at the positive-polarity SSLTD module end according to a preset timing sequence and converted into an electrical signal for output. This electrical signal is then transmitted to the driver of the corresponding switch in the positive-polarity SSLTD module. When the drive circuit in the positive-polarity SSLTD module receives this electrical signal, a corresponding trigger control signal is generated to control the conduction of the switch in the positive-polarity SSLTD module circuit; in this state, record the current on the excitation winding side of the magnetic core to be measured and the voltage on the detection winding side; at this time, the state of the magnetic core to be measured is also in a saturated state;

[0019] (3) After the magnetic core to be measured reaches the saturated state, the controller turns off the switch in the positive-polarity SSLTD module circuit. Subsequently, the controller issues a control signal again, which is still converted into an optical signal via an optical-electric converter. This optical signal is transmitted to the optical-electric converter at the negative-polarity SSLTD module end according to a preset timing sequence and converted into an electrical signal for output. This electrical signal is then transmitted to the driver of the corresponding switch in the negative-polarity SSLTD module. When the drive circuit in the negative-polarity SSLTD module receives the electrical signal, a corresponding trigger control signal is generated to control the conduction of the switch in the negative-polarity SSLTD module circuit; in this case, record the current on the excitation winding side of the magnetic core to be measured and the voltage on the detection winding side again;

[0020] (4) Then, the controller turns off the switch in the negative-polarity SSLTD module circuit, and at the same time, turns on the switch in the positive-polarity SSLTD module circuit again; in this state, record the current on the excitation winding side of the magnetic core to be measured and the voltage on the detection winding side again;

[0021] (5) Obtain the voltage-current data of the magnetic core to be measured under a set of positive-polarity pulse voltages and negative-polarity pulse voltages respectively through at least one complete bipolar pulse voltage cycle, and then convert it into magnetic flux density B and magnetic field strength H data, and obtain the B-H magnetization characteristic curve of the magnetic core to be measured by connecting the vertices of the hysteresis loop.

[0022] Further, calculate the magnetic flux density and magnetic field strength according to the following formula:

[0023]

[0024] Among them, is the magnetic flux, with the unit of Wb; B is the magnetic flux density, with the unit of T; V is the voltage on the detection winding side of the magnetic core to be measured, with the unit of v; t is the magnetic flux change time of the magnetic core to be measured, with the unit of s; N 1 is the number of turns of the coil on the excitation winding side of the magnetic core to be measured; S is the cross-sectional area of the magnetic core to be measured, with the unit of m 2 ;

[0025]

[0026] Among them, H is the magnetic field strength, with the unit of A / m; L is the average path length of the magnetic core to be measured, with the unit of m; I is the current on the excitation winding side of the magnetic core to be measured, with the unit of A; N 1 is the number of turns of the coil on the excitation winding side of the magnetic core to be measured.

[0027] Furthermore, by performing a change operation on the parameter settings directly on the controller, the pulse width of the pulse output voltage and the loop frequency can be adjusted accordingly.

[0028] Furthermore, when converting the measured voltage and current data into magnetic flux density B and magnetic field strength H data, the current and voltage data obtained from the first group of measurements are discarded, and this group of data is used to ensure that the magnetic core to be measured is in a saturated state at the initial stage of the measurement.

[0029] Furthermore, the magnetic flux density and magnetic field strength of the magnetic core in the circuit sandwich of the bipolar SSLTD module need to be greater than those of the magnetic core to be measured.

[0030] Furthermore, the turn ratio of the coils on the excitation winding side and the detection winding side of the magnetic core to be measured is 1:1.

[0031] The present invention provides a rapid measurement device for magnetic hysteresis loops based on a bipolar SSLTD module circuit and a corresponding measurement method, which has the advantages of a short measurement period, strong adjustability of measurement parameters, support for high voltage and large current, and at the same time has the ability to test the magnetic core under different working environments, that is, the ability to arbitrarily change the applied voltage and working frequency when measuring the magnetic hysteresis loop of the magnetic core. Brief Description of the Drawings

[0032] Figure 1 is the schematic diagram of the principle of the magnetic hysteresis loop measurement device based on the bipolar SSLTD module circuit;

[0033] Figure 2 is the schematic diagram of the equivalent circuit for measuring the magnetic hysteresis loop by the magnetic hysteresis loop measurement device based on the bipolar SSLTD module circuit;

[0034] Figure 3It is a typical output waveform diagram of a bipolar SSLTD multi-module power system, which shows the waveforms of voltage and current;

[0035] Figure 4 It is a typical output waveform diagram of a bipolar SSLTD multi-module power system, which shows that the adjustable range of the pulse waveform width is 200 - 400 ns;

[0036] Figure 5 It is a typical output waveform diagram of a bipolar SSLTD multi-module power system, which shows the output waveform with the change of the pulse interval between the negative-polarity pulse and the positive-polarity pulse;

[0037] Figure 6 It is a typical output waveform diagram of a bipolar SSLTD multi-module power system, which shows 10 burst outputs at 1.25 MHz;

[0038] Figure 7 It is a waveform diagram of the bipolar SSLTD pulse asymmetric voltage output;

[0039] Figure 8 It is a schematic diagram of the waveforms of the typical voltage and current for core measurement;

[0040] Figure 9 It is a schematic diagram of the timing control principle of the bipolar SSLTD module circuit;

[0041] Figure 10 It is a schematic diagram of the test results for different core materials. Specific implementation manners

[0042] To better understand the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and specific implementation manners. See the attached Figures 1-10 .

[0043] The present invention aims to overcome the defect in the prior art that magnetization characteristics cannot be measured under certain specific high-voltage and high-frequency conditions, and thus provides a hysteresis loop measurement device and method based on a bipolar SSLTD module circuit, which mainly includes a controller, a DC power supply (such as an adjustable DC power supply device), a bipolar SSLTD pulse power supply excitation winding (i.e., a bipolar SSLTD module circuit excitation winding device), and a detection winding (including an oscilloscope, an oscilloscope voltage probe, and a current probe). Among them, the controller controls the pulse width and frequency of the output voltage of the bipolar SSLTD pulse power supply (bipolar SSLTD module circuit) by generating control signals. The adjustable DC power supply device provides power energy for the bipolar SSLTD module circuit excitation winding device. The bipolar SSLTD module circuit is mainly composed of two unipolar SSLTD modules, namely a positive-polarity SSLTD module and a negative-polarity SSLTD module. For a bipolar SSLTD module circuit, the positive- and negative-polarity SSLTD modules share the same magnetic core. Each SSLTD module includes a charging port and several unit groups composed of discharge switches and capacitors.

[0044] The control method for the discharge of the unipolar SSLTD module is as follows:

[0045] S1. The controller issues a control signal, which is converted into an optical signal through an optical-electric converter and then transmitted to the optical-electric transceiver of the discharge switch in each SSLTD module through an optical fiber;

[0046] S2. After receiving the optical signal, the optical-electric transceiver converts it into an electric signal and outputs it to the drive circuit of the corresponding discharge switch;

[0047] S3. After receiving the electric signal, the drive circuit generates a corresponding pulse signal to control the conduction and cut-off of the discharge switch;

[0048] S4. When the discharge switch receives the discharge control signal, it conducts, and the voltage is induced to the load through the magnetic core to achieve high-voltage output; when the control signal stops being provided, the discharge switch cuts off, and the capacitor stops discharging to the load.

[0049] Among them, the output current and / or voltage of each unipolar SSLTD module is inductively superimposed on the output end through the transformer principle of the magnetic core.

[0050] Since the modular structure of the SSLTD allows it to be assembled and adjusted according to specific application requirements, in order to achieve bipolar output of the SSLTD, one of the unipolar SSLTD modules is inverted and then combined with another unipolar SSLTD module. The common magnetic core is located in the interlayer space between the upper and lower modules of the bipolar SSLTD. By setting appropriate control signals through the controller, the bipolar SSLTD module circuit formed by the present invention can generate a bipolar output pulse waveform. The exciting winding device of the bipolar SSLTD module circuit passes a closed wire through the magnetic core under test and the middle area of the bipolar SSLTD module circuit at the same time, and this closed wire is connected to the current probe of the oscilloscope; the detecting winding device is formed by passing a wire through the magnetic core under test and connecting both ends to the voltage probes of the oscilloscope.

[0051] Among them, the working process of the loop formed by the exciting winding side and the detecting winding side of the bipolar SSLTD module circuit is divided into the following stages:

[0052] (1) The detecting winding side of the magnetic core under test remains open. The number of turns of the exciting winding side and the detecting winding side coils of the magnetic core under test are N 1 、N 2 respectively, and their turn ratio is 1:1. When the discharge switch S1 of the positive-polarity SSLTD module is turned on, the current I1 on the exciting winding side of the magnetic core under test and the voltage V1 on the detecting winding side are recorded;

[0053] (2) After the magnetic core is saturated, the discharge switch S1 of the positive-polarity SSLTD module is turned off, and the discharge switch S2 of the negative-polarity SSLTD module is turned on. Then, the current I2 on the exciting winding side of the magnetic core under test and the voltage V2 on the detecting winding side are recorded;

[0054] (3) Subsequently, the discharge switch S2 of the negative-polarity SSLTD module is turned off, and the discharge switch S1 of the positive-polarity SSLTD module is turned on again. Then, the current I3 on the exciting winding side of the magnetic core under test and the voltage V3 on the detecting winding side are recorded.

[0055] Among them, the magnetic flux density and magnetic field intensity of the magnetic core under test can be obtained in the following ways:

[0056]

[0057] First, according to Faraday's law, the magnetic flux in unit of Wb is derived in Equation (1), and the magnetic flux density B in unit of T is derived using Equation (2). V is the voltage on the detecting winding side of the magnetic core under test in unit of v. t is the magnetic flux change time of the magnetic core under test in unit of s. N 1 is the number of turns of the exciting winding side coil of the magnetic core under test. S is the cross-sectional area of the magnetic core under test in unit of m 2 .

[0058]

[0059] The magnetic field strength H, in A / m, is derived using Equation (3). L is the average path length of the magnetic core under test, in m. I is the current on the excitation winding side of the magnetic core under test, in A. N 1 is the number of turns of the coil on the excitation winding side of the magnetic core under test.

[0060] Among them, the voltage-current data of the magnetic core under test under a set of positive-polarity pulse voltages and negative-polarity pulse voltages can be obtained respectively through at least one complete bipolar pulse voltage cycle, and then converted into B and H data by the above-mentioned formulas (1), (2), and (3). The B-H magnetization characteristic curve of the magnetic core under test is obtained by connecting the vertices of the hysteresis loop.

[0061] Among them, by directly changing the parameter settings on the controller, the pulse width of the pulse output voltage can be changed and the frequency of the circuit can be adjusted.

[0062] The above-mentioned hysteresis loop measuring device and measuring method have the advantages of short measuring period, strong adjustability of measuring parameters, and support for high voltage and large current, and at the same time have the ability to test the magnetic core under different working environments. It should be noted that its measurement range depends on the BH range of the magnetic core used in the bipolar SSLTD module circuit, that is, the BH range of the magnetic core used in the bipolar SSLTD module circuit needs to be greater than the BH range of the magnetic core under test.

[0063] The following is further illustrated by specific examples.

[0064] As Figure 1 shown, this embodiment provides a magnetic core under test, which is respectively wound with an excitation winding and a detection winding. The entire measuring device includes an FPGA controller, an adjustable DC power supply device, a bipolar SSLTD module circuit excitation winding device, and a detection winding device (including an oscilloscope (LeCroy-WaveSurfer 454), an oscilloscope voltage probe (Tektronix-TPP0201), and a current probe (Pearson-PCM 110)). Among them, the adjustable DC power supply device provides the applied voltage for the bipolar SSLTD module pulse power supply device (the bipolar SSLTD module circuit excitation winding device); the bipolar SSLTD module circuit in the excitation winding device is a combination of two unipolar SSLTD modules. Since the modular structure of the SSLTD allows it to be assembled and adjusted according to specific application requirements, in order to achieve the bipolar output of the SSLTD, one of the unipolar SSLTD modules is inverted and then combined with the other unipolar SSLTD module. The magnetic core is located in the sandwich space between the upper and lower modules of the bipolar SSLTD.

[0065] The FPGA controller is used to set and generate control signals with a certain time sequence, enabling the bipolar SSLTD module circuit formed by the present invention to generate specific bipolar pulse output waveforms. The pulse output waveforms can be referred to Figure 9 as shown. The exciting winding device of the bipolar SSLTD module circuit passes a closed wire through the middle area of the magnetic core to be measured and the magnetic core of the bipolar SSLTD module circuit at the same time. This closed wire is connected to the current probe of the oscilloscope; the detecting winding device is composed of a wire that passes through the magnetic core to be measured and is connected to the voltage probes of the oscilloscope at both ends.

[0066] Figures 3-6 shows the typical output waveforms generated by charging two unipolar SSLTD modules to 80V in the bipolar SSLTD module power supply system (i.e., the hysteresis loop measuring device based on the bipolar SSLTD module circuit, also known as the hysteresis loop measuring device based on the bipolar SSLTD module power supply). Among them, Figure 3 shows the waveforms of voltage and current, while Figure 4 shows that the adjustable range of the pulse waveform width is 200 - 400ns, Figure 5 shows the output waveform of the pulse interval change between the negative pulse (pulse width of 400ns) and the positive pulse (pulse width of 400ns), Figure 6 shows 10 burst outputs at 1.25MHz. Although the first bipolar pulse output reaches ±160V, due to the small capacitance of the charging capacitor, the last bipolar output voltage drops to ±140V. Therefore, it can be known that when the capacitance is larger, it is believed that the bipolar SSLTD system can even output a stable voltage at 1.25MHz. As can be seen from the above, the shared-core bipolar SSLTD has the advantage of high-frequency output of the load, but all modules need to be switched synchronously. At the same time, the bipolar SSLTD can also perform asymmetric output of positive and negative pulse voltages, such as Figure 7 shown, the positive module is charged to 80V and the pulse width is set to 200ns; the negative module is charged to 40V and the pulse width is set to 400ns.

[0067] Figure 2 shows the equivalent circuit diagram of the device for measuring the hysteresis loop. Two mutually independent and opposite pulse circuits are used as the exciting winding circuit, which can apply opposite voltages to the magnetic core to be measured, and the detecting winding side remains open all the time. The number of turns of the coils on both the exciting winding side and the detecting winding side is 1, and their turn ratio is 1:1. As Figure 2 (a) shows, when S1 is turned on and S2 is turned off, the current on the exciting winding side and the voltage on the detecting winding side are recorded. As Figure 2 (b) shows, after the magnetic core to be measured is saturated, S1 is turned off and S2 is turned on, and then, the current on the exciting winding side and the voltage on the detecting winding side are recorded. As Figure 2(As shown in (a)), turn on S1 again and turn off S2, and then record the current on the excitation winding side and the voltage on the detection winding side. It should be noted that the first pulse data should be ignored, that is, the current and voltage of the first set of data should be discarded because it is used to ensure that the initial state of the magnetic core under test is in a saturated state. Taking the 1K107 magnetic core as an example, the obtained data waveform is as shown in Figure 8 . The applied voltage is 100V and the frequency is about 100kHz. In addition, by modifying the relevant code parameters on the FPGA, the pulse width, relative delay time, and operating frequency of the pulse voltage applied to the magnetic core under test can be changed.

[0068] In this embodiment, the circuit working process of the closed loop is divided into the following stages:

[0069] (1) Keep the detection winding side open. The number of turns of the coils on both the excitation winding side and the detection winding side is 1. S2N is turned off and S1N is turned on, and record the current i(t) on the excitation winding side as I1 and the voltage u(t) on the detection winding side as V1;

[0070] (2) After the magnetic core under test is saturated, turn off S1N and turn on S2N. Then, record the current i(t) on the excitation winding side as I2 and the voltage u(t) on the detection winding side as V2;

[0071] (3) Subsequently, turn off S2N and turn on S1N, and record the current i(t) on the excitation winding side as I3 and the voltage u(t) on the detection winding side as V3.

[0072] Next, calculate the magnetic induction intensity B(t), and then calculate the corresponding magnetic field intensity H(t) based on Ampere's circuital law, that is:

[0073]

[0074]

[0075] First, derive the magnetic flux in Equation (1) according to Faraday's law The unit is Wb. Use Equation (2) to derive the magnetic flux density B, and the unit is T. V is the voltage on the detection winding side of the magnetic core under test, and the unit is v. t is the magnetic flux change time of the magnetic core under test, and the unit is s. N 1 is the number of turns of the coil on the excitation winding side of the magnetic core under test. S is the cross-sectional area of the magnetic core under test, and the unit is m 2 .

[0076]

[0077] Use Equation (3) to derive the magnetic field intensity H, and the unit is A / m. L is the average path length of the magnetic core under test, and the unit is m. I is the current on the excitation winding side of the magnetic core under test, and the unit is A. N 1is the number of turns of the coil on the exciting winding side of the magnetic core to be measured.

[0078] Then, based on the obtained B(t) and H(t), plot points and the B-H curve of the magnetic core can be obtained.

[0079] In addition, by measuring the hysteresis loops of magnetic cores with different materials and different thicknesses respectively, the corresponding hysteresis loop curves are drawn. As Figure 10 shown, the saturation magnetic flux density of the FT-3H magnetic core is higher than that of the 1K107 magnetic core. Under the condition of the same thickness, the coercive force of the FT-3H magnetic core is smaller than that of the 1K107 magnetic core; for the same material, the saturation magnetic flux density is almost the same. However, increasing the thickness of the magnetic core is equivalent to increasing the unsaturated inductance, which will cause the coercive force to increase.

[0080] As described above, it is only the preferred embodiment of the present invention, and does not impose any formal limitations on the present invention. However, all contents that do not deviate from the technical solution of the present invention still fall within the patent scope of the technical solution of the present invention.

Claims

1. A hysteresis loop measurement device based on a bipolar SSLTD module circuit, characterized in that: It includes a controller and an excitation winding connected thereto, a DC power supply for providing power energy to the excitation winding, and a detection winding, wherein the excitation winding includes a bipolar SSLTD module circuit, the bipolar SSLTD module circuit includes two unipolar SSLTD modules and a magnetic core, the two unipolar SSLTD modules are a positive polarity SSLTD module and a negative polarity SSLTD module respectively, and they share a magnetic core, each unipolar SSLTD module includes a charging port and a plurality of unit groups consisting of a discharge switch and a capacitor, the excitation winding is connected to the magnetic core to be tested through a closed conductor, and the closed conductor simultaneously passes through the magnetic core to be tested and the middle area of ​​the bipolar SSLTD module circuit, the detection winding includes an oscilloscope and is connected to the magnetic core to be tested through another conductor, the other conductor passes through the magnetic core to be tested and the two ends are connected to the voltage probe of the oscilloscope, and the closed conductor is connected to the current probe of the oscilloscope.

2. The hysteresis loop measuring device based on the bipolar SSLTD module circuit according to claim 1, characterized in that: One of the unipolar SSLTD modules is inverted and combined with another unipolar SSLTD module, and the common magnetic core of the two is located in the sandwich space between them.

3. The hysteresis loop measuring device based on the bipolar SSLTD module circuit according to claim 1, characterized in that: The output current and / or voltage of each unipolar SSLTD module is induced and superimposed to the output terminal through the transformer principle of the magnetic core.

4. The hysteresis loop measuring device based on the bipolar SSLTD module circuit according to claim 1 is characterized in that: The discharge control of the unipolar SSLTD module is carried out in the following manner: S1, the controller sends a control signal, which is converted into an optical signal by a photoelectric converter, and then the optical signal is transmitted to the photoelectric transceiver of the discharge switch in each unipolar SSLTD module through an optical fiber; S2, after receiving the optical signal, the optoelectronic transceiver converts it into an electrical signal and outputs it to the driving circuit of the corresponding discharge switch; S3, after receiving the electrical signal, the driving circuit generates a corresponding pulse signal to control the on and off of the discharge switch; S4. When the discharge switch receives the discharge control signal, it is turned on, and the voltage is induced into the load through the magnetic core to achieve high voltage output; when the control signal stops being provided, the discharge switch is turned off, and the capacitor stops discharging to the load.

5. A hysteresis loop measurement method based on a bipolar SSLTD module circuit, characterized in that: A hysteresis loop measuring device based on a bipolar SSLTD module circuit according to any one of claims 1 to 4 is used, and comprises the following steps: (1) Keep the detection winding side of the magnetic core to be tested in an open circuit state, and allow the DC power supply to charge the energy storage element in the bipolar SSLTD module circuit; then the controller sends a corresponding control signal, which is converted into an optical signal via a photoelectric converter. This optical signal is transmitted to the photoelectric converter of the positive polarity SSLTD module according to a preset timing, and converted into an electrical signal output. The electrical signal is then transmitted to the driver of the corresponding switch in the positive polarity SSLTD module. When the driving circuit in the positive polarity SSLTD module receives this electrical signal, it generates a corresponding trigger control signal, thereby controlling the positive polarity SSLTD module circuit switch to turn on; in this state, the current on the excitation winding side and the voltage on the detection winding side of the magnetic core to be tested are recorded; at this time, the state of the magnetic core to be tested is also in a saturated state; (3) After the magnetic core to be tested reaches the saturation state, the controller turns off the circuit switch of the positive polarity SSLTD module. Subsequently, the controller sends a control signal again, and the control signal is still converted into an optical signal through the photoelectric converter. This optical signal is transmitted to the photoelectric converter of the negative polarity SSLTD module according to a preset timing and converted into an electrical signal for output. This electrical signal is then transmitted to the driver of the corresponding switch in the negative polarity SSLTD module. When the driving circuit in the negative polarity SSLTD module receives the electrical signal, it generates a corresponding trigger control signal to control the circuit switch of the negative polarity SSLTD module to turn on. In this case, the current on the excitation winding side and the voltage on the detection winding side of the magnetic core to be tested are recorded again. (4) Afterwards, the controller turns off the circuit switch of the negative polarity SSLTD module, and at the same time, turns on the circuit switch of the positive polarity SSLTD module again; in this state, the current on the exciting winding side of the magnetic core to be tested and the voltage on the detection winding side are recorded again; (5) The voltage and current data of the magnetic core to be tested under a set of positive polarity pulse voltage and negative polarity pulse voltage are obtained through at least one complete bipolar pulse voltage cycle, and then converted into magnetic flux density B and magnetic field intensity H data. The BH magnetization characteristic curve of the magnetic core to be tested is obtained by connecting the vertices of the hysteresis loop.

6. The hysteresis loop measurement method based on the bipolar SSLTD module circuit according to claim 5 is characterized in that: The magnetic flux density and magnetic field strength are calculated according to the following formula: in, is the magnetic flux, in units of Wb; B is the magnetic flux density, in units of T; V is the voltage on the detection winding side of the magnetic core to be tested, in units of v; t is the magnetic flux change time of the magnetic core to be tested, in units of s; N1 is the number of turns of the coil on the excitation winding side of the magnetic core to be tested; S is the cross-sectional area of ​​the magnetic core to be tested, in units of m 2 ; Wherein, H is the magnetic field strength, in A / m; L is the average path length of the magnetic core to be tested, in m; I is the current on the excitation winding side of the magnetic core to be tested, in A; N1 is the number of turns of the coil on the excitation winding side of the magnetic core to be tested.

7. The hysteresis loop measurement method based on the bipolar SSLTD module circuit according to claim 5, characterized in that: By directly changing the parameter settings on the controller, the pulse width of the pulse output voltage and the circuit frequency can be changed.

8. The hysteresis loop measurement method based on the bipolar SSLTD module circuit according to claim 5, characterized in that: When converting the measured voltage and current data into magnetic flux density B and magnetic field intensity H data, the first set of measured current and voltage data is discarded. This set of data is used to ensure that the magnetic core to be measured is in a saturated state at the beginning of the measurement.

9. The hysteresis loop measurement method based on the bipolar SSLTD module circuit according to claim 5, characterized in that: The magnetic flux density and magnetic field strength of the magnetic core in the circuit interlayer of the bipolar SSLTD module are greater than those of the magnetic core to be tested.

10. The hysteresis loop measurement method based on the bipolar SSLTD module circuit according to claim 5, characterized in that: The turns ratio of the coils on the excitation winding side and the detection winding side of the magnetic core to be tested is 1:1.

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