A method and system for non-contact measurement of magnetic material b-h characteristics

Abstract

The application discloses a kind of magnetic material B-H characteristic non-contact measurement method and system, including microcontroller, power amplifier circuit, magnetic field measurement module, first filter circuit, second filter circuit etc.;The application eliminates the interference of excitation coil and surrounding magnetic field to measuring coil by compensation coil, and measures the B-H curve shape of the measured material under different frequencies based on magnetic field induction non-contact. Based on this platform, the best working frequency of different magnetic materials can be determined quickly by sweeping frequency without contact. Compared with the contact measurement method, the measurement method can effectively avoid many problems caused by the contact between the measured material and the measuring instrument.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics and communication principles, and particularly relates to a non-contact measurement method and system for B-H characteristics of magnetic materials. BACKGROUND

[0002] The B-H characteristics of magnetic materials are an important factor in exploring the application fields of magnetic materials, and the rapid measurement of the B-H characteristics of magnetic materials can help various magnetic materials to play their best performance in various applications, and help to select appropriate working frequencies and reduce energy loss caused by magnetization.

[0003] In addition, although the contact measurement technology can also be applied to the detection of the B-H characteristics of different magnetic materials, the contact measurement method is limited by factors such as the shape of the magnetic material sample to be measured, surface oxides, and contaminated materials during the research on the B-H characteristics of different magnetic materials, and the contact measurement may contaminate the surface of the magnetic material to be measured. The contact measurement has undergone a quite long development stage, and the technology in all aspects has reached a bottleneck, and still cannot overcome the problems caused by the contact between the magnetic material to be measured and the measuring instrument. SUMMARY

[0004] In order to solve the shortcomings and deficiencies in the prior art, the present application provides a non-contact measurement method and system for B-H characteristics of magnetic materials.

[0005] The technical scheme adopted by the present application is as follows:

[0006] A non-contact measurement system for B-H characteristics of magnetic materials, the system comprising a microcontroller, a power amplifier circuit, a magnetic field measurement module, a first filter circuit, and a second filter circuit.

[0007] The magnetic field measurement module (3) comprises an excitation coil L1, a measurement coil L2, and a compensation transformer T1; the excitation coil L1 is connected in series with the primary side of the compensation transformer T1, and the two ends after series connection are connected with the power amplifier circuit; the measurement coil L2 is connected in series with the secondary side of the compensation transformer T1; the excitation coil L1 and the measurement coil L2 are wound in the same direction in the form of concentric circles on a plane to form an excitation-measurement coil pair, and the magnetic material to be measured is placed on the surface of the plane; the mutual inductance between the excitation coil L1 and the measurement coil L2 is the same as the inductance value of the primary and secondary sides of the compensation transformer T1.

[0008] The microcontroller controls output of a sine wave to a power amplifier circuit, the power amplifier circuit outputs an excitation signal to a magnetic field measurement module; an input end of the first filter circuit is connected with one side of the excitation coil L1, and an output end is connected with an input end of the microcontroller, for obtaining a current on the one side of the excitation coil L1 as an excitation current signal and inputting the excitation current signal to the microcontroller; an input end of the second filter circuit is connected with both ends of the series connection of the measurement coil L2 and the secondary side of the compensation transformer T1, and an output end is connected with an input end of the microcontroller, for obtaining an induced voltage signal and inputting the induced voltage signal to the microcontroller.

[0009] Further, the system further comprises a host computer, the microcontroller sends the detected current signal data and voltage signal data to the host computer, and the host computer completes data analysis to obtain the B-H characteristics of the magnetic material.

[0010] Further, the host computer is further used for setting a frequency and an amplitude of the sine signal output to the power amplifier circuit controlled by the microcontroller.

[0011] Further, the microcontroller realizes fast bidirectional communication with the host computer through Ethernet.

[0012] Further, the frequency range of the sine wave is 10 Hz-100 kHz.

[0013] A non-contact measurement method of B-H characteristics of a magnetic material based on the system, comprising the following steps:

[0014] The measured magnetic material is placed on the surface of the excitation-measurement coil pair, the microcontroller controls output of a sine wave to a power amplifier circuit, the power amplifier circuit outputs an excitation signal to a magnetic field measurement module; the magnetic field measurement module outputs an excitation current signal and an induced voltage signal, which are input to the microcontroller through the first filter circuit and the second filter circuit respectively;

[0015] Based on the excitation current signal and the induced voltage signal data obtained by the microcontroller, the induced voltage signal data is taken as an X axis, and the excitation current signal data is taken as a Y axis after being shifted by 90° phase according to the current frequency, an XY scatter plot is drawn, and after multiple point drawing, a B-H curve shape of the measured magnetic material at the corresponding frequency is obtained.

[0016] Further, the system further comprises:

[0017] The area surrounded by the B-H curve at each frequency is recorded by the sweep frequency method, the frequency corresponding to the minimum surrounding area is calculated, and the optimal working frequency of the measured magnetic material is obtained.

[0018] The application has the advantages that the application can control the frequency of the excitation signal through the MCU, and eliminate the interference of the excitation coil and the surrounding magnetic field on the measuring coil through the compensation coil, and measure the B-H curve shape of the measured material at different frequencies based on the magnetic field induction in a non-contact manner. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the present application, the drawings needed in the following embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 A system block diagram of a magnetic material B-H characteristic non-contact measurement system according to the present application is provided.

[0021] Figure 2 A structure top view, a structure center axis sectional view, and side views of the excitation coil L1 and the measuring coil L2 of an excitation-measuring coil pair in a typical embodiment of a magnetic material B-H characteristic non-contact measurement system according to the present application are provided.

[0022] Figure 3 A working schematic diagram of an excitation-measuring coil group and a compensation coil group in a magnetic material B-H characteristic non-contact measurement system according to the present application is provided.

[0023] Figure 4 A schematic diagram of the corresponding pins of the microcontroller connected to other modules in a typical embodiment of a magnetic material B-H characteristic non-contact measurement method and system according to the present application is provided.

[0024] Figure 5 A specific implementation circuit of a power amplification circuit in a typical embodiment of a magnetic material B-H characteristic non-contact measurement system according to the present application is provided.

[0025] Figure 6 A specific implementation circuit of a first filter circuit in a typical embodiment of a magnetic material B-H characteristic non-contact measurement system according to the present application is provided.

[0026] Figure 7 A specific implementation circuit of a second filter circuit in a typical embodiment of a magnetic material B-H characteristic non-contact measurement system according to the present application is provided.

[0027] Figure 8A placement schematic diagram of a measured magnetic material in a typical embodiment of a magnetic material B-H characteristic non-contact measurement system according to the present application;

[0028] Figure 9 A flowchart of a magnetic material B-H characteristic non-contact measurement method according to the present application;

[0029] Figure 10 Results of a typical embodiment of a magnetic material B-H characteristic non-contact measurement system according to the present application;

[0030] Figure 11 A flowchart of a typical embodiment of a magnetic material B-H characteristic non-contact measurement method according to the present application;

[0031] Figure 12 A flowchart of a typical embodiment of a magnetic material B-H characteristic non-contact measurement system according to the present application for exploring the optimal working frequency of a magnetic material; DETAILED DESCRIPTION

[0032] To make the structure and advantages of the present application clearer, the structure of the present application will be further described below in combination with the drawings:

[0033] As shown in Figure 1 , the present application provides a magnetic material B-H characteristic non-contact measurement system, which comprises a microcontroller 1, a power amplification circuit 2, a magnetic field measurement module 3, a first filter circuit 4, and a second filter circuit 5.

[0034] The magnetic field measurement module 3 comprises an excitation coil L1, a measurement coil L2, and a compensation transformer T1, as shown in Figure 2 . The primary side of the compensation transformer T1 serves as a compensation coil L 1p1 , and the secondary side of the compensation transformer T1 serves as a compensation coil L 1s1 . The excitation coil L1 and the measurement coil L2 are wound in the same direction in the form of concentric circles on a plane to form an excitation-measurement coil pair. The structure of the excitation-measurement coil pair is shown in a top view as Figure 2 (2) and a central axis cross-sectional view as Figure 2 (3). The side view of the excitation coil L1 and the measurement coil L2 is shown in Figure 2(4) shown; the excitation coil L1 and the primary side of the compensation transformer T1 are connected in series to form an excitation coil loop, the two ends of the excitation coil loop are connected with the output ports "OUT+" and "OUT-" of the power amplifier circuit 2 respectively, for receiving an excitation signal, and outputting the current on the side of the excitation coil L1 as a measurement current to the ports "current IN+" and "current IN-" of the first filter circuit 4; the measurement coil L2 and the secondary side of the compensation transformer T1 are connected in series to form a measurement coil loop, the two ends of the measurement coil loop are output ports of an induced voltage signal, and are output to the ports "voltage IN+" and "voltage IN-" of the second filter circuit 5; wherein the mutual inductance between the excitation coil L1 and the measurement coil L2 is the same as the inductance value of the primary and secondary sides of the compensation transformer T1;

[0035] The microcontroller 1 controls the output of a sine wave to the power amplifier circuit 2, and the power amplifier circuit 2 outputs an excitation signal to the magnetic field measurement module 3; the input end of the first filter circuit 4 is connected with the side of the excitation coil L1, and the output end is connected with the input end of the microcontroller 1, for obtaining the current on the side of the excitation coil L1 as an excitation current signal and inputting the excitation current signal to the microcontroller 1; the input end of the second filter circuit 5 is connected with the two ends of the measurement coil L2 and the secondary side of the compensation transformer T1 connected in series, and the output end is connected with the input end of the microcontroller 1, for obtaining an induced voltage signal and inputting the induced voltage signal to the microcontroller 1.

[0036] The current signal in the excitation coil loop and the voltage signal in the measurement coil loop obtained by the microcontroller 1 can analyze the shape of the B-H curve of the measured magnetic material, and the principle is as follows:

[0037] As shown in Figure 3 , the excitation coil L1 and the compensation coil L 1p1 are connected in series to form an excitation coil loop; the measurement coil L2 and the compensation coil L 1s1 are connected in series to form a measurement coil loop; wherein the mutual inductance between the "excitation-measurement coil pair" is M 12 .

[0038] The excitation coil loop current value is defined as I e .

[0039] The voltage generated by the electromagnetic induction between the two ends of the measurement coil L2 in the measurement coil loop and the excitation coil L1 is equal to: U 12 = jωM 12 I e ; wherein ω represents the frequency of the excitation signal, i e represents the instantaneous current in the excitation coil loop;

[0040] Since the compensation transformer T1, i.e. the compensation coil L 1p1 in the excitation coil loop and the compensation coil L 1s1Mutual inductance M wound in opposite directions on an iron core s1p1 With M 12 Same size; compensation coil L in the measuring coil circuit 1s1 Voltage U at both ends s1p1 Equal to the compensation coil L in the excitation coil circuit 1p1 Voltage U at both ends p1s1 , represented as: U s1p1 =U p1s1 =-jωM 12 I e ;

[0041] The magnetic material under test is equivalent to an inductor and a resistor connected in series, where the inductance is L3 and the resistance is R3.

[0042] When the magnetic material under test is placed on the excitation-measuring coil pair, the inductance L3 in the magnetic material under test and the excitation coil L1 in the excitation circuit will generate mutual inductance. The voltage generated by the mutual inductance between the inductance L3 and the excitation coil L1 in the magnetic material under test is equal to U. 13 , represented as: U 13 =jωM 13 I e ;

[0043] The inductance L3 in the magnetic material being tested and the measuring coil L2 in the measuring circuit will generate mutual inductance. Assume that the magnitude of their mutual inductance is M. 23 The voltage generated by electromagnetic induction between the measuring coil L2 and the inductor L3 in the magnetic material being measured in the measuring circuit is equal to U. 32 , represented as: U 32 =jωM 23 I3; where I3 represents the current in the inductance L3 of the magnetic material being tested;

[0044] From the above, we can conclude that the voltage U2 across the measuring coil L2 in the measuring coil circuit is equal to: U2 = U 12 +U 32 =jωM 12 I e +jωM 23 I3;

[0045] From the above, the total voltage Us in the measuring coil circuit can be obtained. ig1 Equal to: U sig1 =U2+U s1p1 =jωM 23 I3;

[0046] Since the current in the measuring coil circuit is very small, the mutual inductance voltage generated by it to other coils can be ignored. Therefore, the induced voltage U3 across the inductor L3 in the magnetic material being measured is equal to: U3 = U 13 =jωM 13 Ie ;

[0047] From the above argument, it can be concluded that the current I3 in the tested magnetic material is proportional to the total voltage U in the measuring coil circuit. sig1 The induced voltage U3 across the inductor L3 in the tested magnetic material is proportional to the current I in the excitation coil circuit. e ;

[0048] According to the law of magnetic induction And U3=U 13 =jωM 13 I e The relationship between magnetic induction intensity B and excitation coil circuit current I can be derived. e Relationship: S represents the area of ​​the magnetic field surrounded by the inductance L3 in the tested magnetic material;

[0049] According to Ampere's circuital law The conclusion is definition When the unit magnetic field strength H The value; and because Therefore, we can deduce that the magnetic field strength H is related to the total voltage U in the measuring coil circuit. sig1 Relationship:

[0050] The magnetic induction intensity B and the excitation circuit current I e Relationship The magnetic field strength H and the total voltage U in the measuring coil circuit sig1 Relationship The BH relationship can be derived:

[0051] Given that the material to be tested and the signal frequency are constants, then... The shape can reflect the shape of the BH curve;

[0052] Similarly, the BH relationship can also be represented as:

[0053] Given that the material to be tested is a constant, then The shape can reflect the shape of the BH curve, and The area enclosed by the shape is proportional to the area enclosed by the BH curve of the magnetic material at that frequency, that is, proportional to the energy loss of the magnetic material in one cycle of magnetization at that frequency.

[0054] As an optional embodiment, a host PC is further included, the microcontroller 1 sends the detected current signal data and voltage signal data to the host PC, and the host PC completes data analysis to obtain the B-H characteristics of the magnetic material. Further, as shown in Figure 4 The microcontroller 1 can adopt STM32G431 / 48, internally programmed to output a sine excitation signal of a set frequency by a sine function, convert the digital signal into an analog signal, and output the sine excitation signal DAC by the PA4 port; convert the filtered current signal ADIN1 in the first filter circuit 4 into an analog signal by the PA0 / ADC12_IN1, and input the digital signal into the microcontroller 1; convert the filtered voltage signal ADIN2 in the second filter circuit 5 into an analog signal by the PA1, and input the digital signal into the microcontroller 1; and then transmit the current signal and the voltage signal in the controller to the host PC through Ethernet.

[0055] Figure 5 The power amplifier circuit 2 is provided by an embodiment of the present application, which comprises a signal amplification circuit 501 and an amplification filter circuit 502.

[0056] In an embodiment of the present application, as shown in Figure 5 The signal amplification circuit 501 comprises resistors R1, R2, R3, R4, and a first operational amplifier MCP6022. The signal amplification circuit 501 plays a role of signal amplification. Two ends of the resistor R1 are coupled with the pin PA4 of the microcontroller 1, i.e. the port DAC_IN, and the positive input end of the first operational amplifier MCP6022, respectively, and the signal is input by the port DAC_IN. Two ends of the resistor R2 are coupled with the positive input end of the first operational amplifier MCP6022 and the ground, respectively. Two ends of the resistor R3 are coupled with the reverse input end of the first operational amplifier MCP6022 and the ground, respectively. Two ends of the resistor R4 are coupled with the reverse input end of the first operational amplifier MCP6022 and the output end of the first operational amplifier MCP6022, respectively, playing a role of signal amplification and isolation. The output end of the first operational amplifier MCP6022 serves as the output end of the signal amplification circuit 501, and is coupled with the input end of the amplification filter circuit 502.

[0057] In an embodiment of the present application, as shown in Figure 5As shown in the figure, the amplification filter circuit 502 includes: a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a capacitor C2, a capacitor C3, and a second operational amplifier OPA541. The amplification filter circuit 502 functions as a power amplifier and a filter. One end of the resistor R5 is connected in series with one end of the capacitor C1, the other end of the capacitor C1 is connected to the output end of the signal amplification circuit 501, the other end of the resistor R5 is coupled to the inverting input end of the second operational amplifier OPA541, the two ends of the resistor R6 are coupled to the non-inverting output end of the second operational amplifier OPA541 and the inverting input end of the second operational amplifier OPA541 respectively, one end of the resistor R7 is grounded, and the other end serves as the inverting output end “OUT-” of the power amplifier circuit 2. One end of the capacitor C2 is coupled to the output end of the second operational amplifier OPA541, and the other end serves as the non-inverting output end “OUT+” of the power amplifier circuit 2. The two ends of the capacitor C3 are coupled to the ground and the non-inverting output end “OUT+” of the power amplifier circuit 2 respectively. The signal is output by the ports “OUT+” and “OUT-” after power amplification and filtering.

[0058] Figure 6 The filter circuit provided by the embodiment of the present application is used as a first filter circuit 4, which includes: an operational-following circuit 601, an amplification filter circuit 602, and an operational-following circuit 603.

[0059] In an embodiment of the present application, as shown in the figure, Figure 6 The operational-following circuit 601 includes: a sampling resistor R8 and a third operational amplifier MCP6022. The operational-following circuit 601 functions as a sampler, an isolator, and an impedance matcher. The two ends of the sampling resistor R8 are coupled to the “current IN+” port and the “current IN-” port, and the current signal is input by the magnetic field measurement module 3. One end of the resistor R8 is coupled to the non-inverting input end of the third operational amplifier MCP6022. The inverting input end of the third operational amplifier MCP6022 is coupled to the output end to form an operational-following circuit, which functions as an isolator and an impedance matcher. The output end of the third operational amplifier MCP6022 serves as the output end of the operational-following circuit 601 and is coupled to the input end of the amplification filter circuit 602.

[0060] In an embodiment of the present application, as shown in the figure, Figure 6As shown in the figure, the amplification filter circuit 602 comprises: a resistor R9, a resistor R10, a capacitor C4 and a fourth operational amplifier MCP6022. The amplification filter circuit 602 functions as a filter and signal amplifier. Two ends of the resistor R9 are coupled with the output end of the third operational amplifier MCP6022 and the reverse input end of the fourth operational amplifier MCP6022 respectively. Two ends of the resistor R10 are coupled with the output end of the fourth operational amplifier MCP6022 and the reverse input end of the fourth operational amplifier MCP6022 respectively. Two ends of the capacitor C4 are coupled with the output end of the fourth operational amplifier MCP6022 and the reverse input end of the fourth operational amplifier MCP6022 respectively. The output end of the fourth operational amplifier MCP6022 serves as the output end of the amplification filter circuit 602 and is coupled with the input end of the operational-following circuit 603.

[0061] In an embodiment of the present application, as shown in the figure, Figure 6 As shown in the figure, the operational-following circuit 603 comprises: a resistor R11, a resistor R12 and a fifth operational amplifier MCP6022. The fifth operational amplifier MCP6022 constitutes an operational-following circuit and functions as an isolation and impedance matching. Two ends of the resistor R11 are coupled with the output end of the fourth operational amplifier MCP6022 and the forward input end of the fifth operational amplifier MCP6022 respectively. The output end of the fifth operational amplifier MCP6022 is coupled with the reverse input end of the fifth operational amplifier MCP6022. Two ends of the resistor R12 are coupled with the forward input end of the fifth operational amplifier MCP6022 and the ground respectively. The output end of the fifth operational amplifier MCP6022 serves as the output end of the operational-following circuit 603 and is output to the pin PA0 / ADC12_IN1 of the microcontroller 1 through the ADIN1 port.

[0062] Referring to Figure 7 The present application provides a filter circuit as a second filter circuit 5, comprising: a signal amplification circuit 701, an adjustable amplification circuit 702, an amplification filter circuit 703, an operational-following circuit 704, wherein:

[0063] In an embodiment of the present application, as shown in the figure, Figure 7As shown in the figure, the signal amplification circuit 701 comprises a resistor R13, a resistor R14 and a sixth operational amplifier MCP6022. The input end of the signal amplification circuit 701 collects the voltage signal in the magnetic field measurement module 3 from the port "voltage IN+" and the port "voltage IN-". The signal amplification circuit 701 functions to isolate and amplify the voltage signal. The two ends of the resistor R13 are coupled with the "voltage IN+" port and the reverse input end of the sixth operational amplifier MCP6022 respectively. The two ends of the resistor R14 are coupled with the reverse input end of the sixth operational amplifier MCP6022 and the output end of the sixth operational amplifier MCP6022 respectively. The forward input end of the sixth operational amplifier MCP6022 is coupled with the "voltage IN-" port. The output end of the sixth operational amplifier MCP6022 serves as the output end of the signal amplification circuit 701 and is coupled with the input end of the adjustable amplification circuit 702.

[0064] In an embodiment of the present application, as shown in the figure, Figure 7 As shown in the figure, the adjustable amplification circuit 702 comprises a resistor R15, an adjustable resistor R16, a resistor R17 and a seventh operational amplifier TLV2376. The input end of the signal amplification circuit 702 is coupled with the output end of the signal amplification circuit 701. The resistor R15 is in series with the adjustable resistor R16 and the two ends thereof are coupled with the reverse input end of the seventh operational amplifier TLV2376 and the output end of the sixth operational amplifier MCP6022 respectively. The two ends of the resistor R17 are coupled with the reverse input end of the seventh operational amplifier TLV2376 and the output end of the seventh operational amplifier TLV2376 respectively. The signal amplification gain of the adjustable amplification circuit 702 can be adjusted by adjusting the access value of the adjustable resistor R16. The output end of the seventh operational amplifier TLV2376 serves as the output end of the adjustable amplification circuit 702 and is coupled with the input end of the amplification and filtering circuit 703.

[0065] In an embodiment of the present application, as shown in the figure, Figure 7As shown in the figure, the amplification filter circuit 703 includes: resistance R18, resistance R19, capacitor C5 and eighth operational amplifier TLV2376. The amplification filter circuit 703 plays a role of filtering and signal amplification, two ends of the resistance R18 are respectively coupled with the reverse input end of the eighth operational amplifier TLV2376 and the output end of the seventh operational amplifier TLV2376, two ends of the resistance R19 are respectively coupled with the reverse input end of the eighth operational amplifier TLV2376 and the output end of the eighth operational amplifier TLV2376, two ends of the capacitor C5 are respectively coupled with the reverse input end of the eighth operational amplifier TLV2376 and the output end of the eighth operational amplifier TLV2376, and the output end of the eighth operational amplifier TLV2376 serves as the output end of the amplification filter circuit 703 and is coupled with the input end of the operational-following circuit 704.

[0066] In an embodiment of the present application, as shown in the figure, Figure 7 As shown in the figure, the operational-following circuit 704 includes: resistance R20, resistance R21, ninth operational amplifier MCP6022. One end of the resistance R20 is coupled with the output end of the eighth operational amplifier TLV2376 in the amplification filter circuit 703, two ends of the resistance R21 are respectively coupled with the positive input end of the ninth operational amplifier MCP6022 and the ground, the reverse input end of the ninth operational amplifier MCP6022 is coupled with the output end of the ninth operational amplifier MCP6022, the resistance R20 and the resistance R21 adjust the gain of the voltage signal, the ninth operational amplifier MCP6022 constitutes an operational-following circuit and plays a role of isolation and impedance matching, and the output end of the ninth operational amplifier MCP6022 serves as the output end of the operational-following circuit 704 and is output to the pin PA1 of the microcontroller 1 through the ADIN2 port.

[0067] Figure 8 As shown in the figure, it is a placement schematic diagram of a measured magnetic material in a typical embodiment of a magnetic material B-H characteristic non-contact measurement system proposed by the present application. The measured magnetic material 6 is placed on the excitation-measuring coil pair to generate electromagnetic induction, and then the non-contact measurement is performed through the platform. Generally, the measured magnetic material is placed on the upper excitation-measuring coil pair, and the relative position of the measured material and the excitation-measuring coil pair remains unchanged during a measurement process.

[0068] Figure 9 As shown in the figure, it is a flowchart of a magnetic material B-H characteristic non-contact measurement method using a magnetic material B-H characteristic non-contact measurement system proposed by the present application, which specifically includes the following steps: Figure 9 As shown in the figure, it is a flowchart of a magnetic material B-H characteristic non-contact measurement method using a magnetic material B-H characteristic non-contact measurement system proposed by the present application, which specifically includes the following steps:

[0069] The to-be-tested magnetic material 6 is placed on the excitation-measurement coil pair, and the host computer PC sets various data of the output sinusoidal signal, including amplitude and frequency;

[0070] The data is transmitted to the microcontroller 1 through Ethernet;

[0071] After the microcontroller 1 acquires the data, the digital signal is converted into an analog signal through the DA function, and a 10Hz-100kHz sinusoidal wave is output;

[0072] The sinusoidal wave obtains an excitation signal through the power amplification circuit 2;

[0073] The excitation signal is input into the excitation coil loop;

[0074] The current signal in the excitation coil loop and the voltage signal in the measurement coil loop are detected;

[0075] The detected signals are filtered and transmitted back to the microcontroller 1;

[0076] The microcontroller 1 converts the analog signal into a digital signal through the AD function;

[0077] The digital measurement signal is transmitted back to the host computer PC;

[0078] The host computer PC obtains the voltage signal U sig1 as the x-axis, and the frequency ω and the current signal I e are multiplied by the result of the forward shift of 90° as the y-axis, and an XY scatter plot is drawn, so that the B-H curve shape of the to-be-tested magnetic material at the frequency can be analyzed, and the shape area is proportional to the energy loss of the magnetic material in the one-cycle magnetization at the frequency;

[0079] Finally, the B-H curve shape of the to-be-tested magnetic material is as shown in Figure 10 .

[0080] The area surrounded by the B-H curve at the frequency is obtained, and the area surrounded by the B-H hysteresis loop is proportional to the energy loss in the one-cycle magnetization;

[0081] Further, the method of the present application can also obtain the frequency at which the energy loss is minimum during the magnetization of the magnetic material, i.e., the optimal working frequency, and the flow is as shown in Figure 11 The area surrounded by the B-H curve at each frequency is recorded by the sweep frequency method, and the frequency corresponding to the minimum surrounding area is obtained, i.e., the optimal working frequency of the to-be-tested magnetic material, and the detection method as shown in Figure 12 is used to perform step-by-step sweep detection of the optimal working frequency:

[0082] In the first step, the minimum frequency in the working range is set to f MIN , and the maximum frequency in the working range is set to f MAX ;

[0083] Second step, let f1=f MIN , f 20 =f MAX , (i=2,3,…,19);

[0084] Third step, each frequency stability work 10 cycles, get the shape of B-H curve, calculate the area surrounded by B-H curve hysteresis loop, respectively, S1, S2,…,S 20 ; select the minimum area of three frequencies from small to large order recorded as f min , f mid , f max (where f min <f mid <f max );

[0085] Fourth step, judge the size of f max -f min whether the frequency range contained meets the required accuracy, if it meets the requirements, the minimum area is recorded as S min , the minimum area corresponding to the frequency f min is the best working frequency f best ; otherwise, the accuracy has not reached the requirements, repeat the second step, the third step to further improve the frequency scanning accuracy, until the accuracy meets the requirements, output f best .

[0086] From the above process, the area surrounded by the B-H hysteresis loop is the minimum corresponding to the signal frequency f best , thus analyzing the energy loss of the magnetic material corresponding to the minimum working frequency.

[0087] The above only for the embodiment of the present application, and not to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application, should be included in the protection scope of the present application.

Claims

1. A non-contact system for measuring the B-H properties of a magnetic material, comprising: The system comprises a microcontroller (1), a power amplifier circuit (2), a magnetic field measurement module (3), a first filter circuit (4), and a second filter circuit (5). The magnetic field measurement module (3) comprises an excitation coil L1, a measurement coil L2, and a compensation transformer T1; the excitation coil L1 is connected in series with the primary side of the compensation transformer T1, and the two ends of the series connection are connected to the power amplifier circuit (2); the measurement coil L2 is connected in series with the secondary side of the compensation transformer T1; the excitation coil L1 and the measurement coil L2 are wound in the same direction in the form of concentric circles on a plane to form an excitation-measurement coil pair, and the measured magnetic material is placed on the surface of the plane; the mutual inductance between the excitation coil L1 and the measurement coil L2 is the same as the inductance value of the primary and secondary sides of the compensation transformer T1. The microcontroller (1) controls the output of a sine wave to the power amplifier circuit (2), and the power amplifier circuit (2) outputs an excitation signal to the magnetic field measurement module (3); the input end of the first filter circuit (4) is connected to the side of the excitation coil L1, and the output end is connected to the input end of the microcontroller (1), which is used to obtain the current on the side of the excitation coil L1 as an excitation current signal and input it to the microcontroller (1); the input end of the second filter circuit (5) is connected to the two ends of the series connection of the measurement coil L2 and the secondary side of the compensation transformer T1, and the output end is connected to the input end of the microcontroller (1), which is used to obtain an induced voltage signal and input it to the microcontroller (1).

2. The system of claim 1, wherein: Further comprising a host computer (PC), the microcontroller (1) sends the detected current signal data and voltage signal data to the host computer (PC), and the host computer (PC) completes data analysis to obtain the B-H characteristics of the magnetic material.

3. The system of claim 2, wherein: The host computer (PC) is also used to set the frequency and amplitude of the sine signal output to the power amplifier circuit (2) controlled by the microcontroller (1).

4. The system of claim 2, wherein: The microcontroller (1) realizes fast bidirectional communication with the host computer (PC) through Ethernet.

5. The system of claim 1, wherein: The frequency range of the sine wave is 10 Hz to 100 kHz.

6. A method for non-contact measurement of magnetic material B-H characteristics based on the system of any one of claims 1-5, characterized in that, The method comprises the following steps: The measured magnetic material is placed on the surface of the excitation-measurement coil pair, the microcontroller (1) controls the output of a sine wave to the power amplifier circuit (2), and the power amplifier circuit (2) outputs an excitation signal to the magnetic field measurement module (3); the magnetic field measurement module (3) outputs an excitation current signal and an induced voltage signal, which are input to the microcontroller (1) through the first filter circuit (4) and the second filter circuit (5), respectively; Based on the excitation current signal and the induced voltage signal data obtained by the microcontroller (1), the induced voltage signal data is taken as the X-axis, and the excitation current signal data is taken as the Y-axis after being shifted by 90° phase according to the current frequency, an XY scatter plot is drawn, and after multiple points are drawn, the B-H curve shape of the measured magnetic material at the corresponding frequency is obtained.

7. The method of claim 6, wherein, Further comprising: The area enclosed by the B-H curve at each frequency is recorded by the sweep frequency method, the frequency corresponding to the minimum enclosed area is calculated, and the optimal working frequency of the measured magnetic material is obtained.

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