Magnetic material magnetic property measurement system based on LLC resonance circuit and construction method

Abstract

The invention provides a magnetic material magnetic property measurement system based on an LLC resonance circuit and a construction method, and belongs to the technical field of switching converters. The measuring system comprises a direct-current power supply Vin, a square-wave generator, a resonant capacitor Cr, a resonant inductor Lr, a magnetic ring, a magnetic ring primary winding Lp, a magnetic ring secondary winding Ls, a rectifier, a filter capacitor C0, a load Lo and a power analyzer. Wherein the magnetic ring is made of a to-be-tested magnetic material; wherein the direct-current power supply Vin, the square-wave generator, the resonant capacitor Cr and the resonant inductor Lr are connected in sequence and are connected to the magnetic ring primary winding Lp; the resonant capacitor Cr, the resonant inductor Lr and the excitation inductor Lm of the magnetic ring primary winding Lp form a resonant circuit; the rectifier is connected with a secondary winding Ls of the magnetic ring; two ends of the rectifier are connected in parallel with a filter capacitor C0 and a load Lo; and the power analyzer is used for acquiring the primary side current and the secondary side voltage of the magnetic ring to determine the magnetic characteristic parameters of the magnetic material to be detected. The invention can reduce the error of the magnetic property measurement result of the magnetic material.

Description

Technical Field

[0001] The present invention relates to the technical field of switching converters, and in particular to a magnetic material magnetic property measurement system based on an LLC resonant circuit and a construction method thereof. Background Art

[0002] In recent years, with the development of new energy, flexible DC transmission, energy storage and other technologies, new power electronic transformers and other equipment have become the current research hotspots. New soft magnetic materials represented by amorphous and nanocrystalline materials have gradually become a popular choice for electrical equipment due to their magnetic properties such as low loss, low coercivity and high magnetic permeability. Research on the magnetic properties of nanocrystalline materials is of great significance for improving the power density, reducing losses and reducing the volume of electrical equipment.

[0003] Currently, soft magnetic material measurement experimental platforms mostly use a signal generator with a power amplifier to provide the excitation waveform required for measurement. However, since the excitation signals provided are mostly ideal waveforms, it is difficult to effectively simulate the voltage and current characteristics of actual working conditions, and the measurement results of the magnetic properties of magnetic materials are subject to large errors. Summary of the invention

[0004] The embodiment of the present invention provides a magnetic material magnetic property measurement system based on LLC resonant circuit and a construction method thereof, so as to solve the problem of how to reduce the error of the magnetic property measurement result of the magnetic material.

[0005] In a first aspect, an embodiment of the present invention provides a magnetic material magnetic property measurement system based on an LLC resonant circuit, comprising: a DC power supply V in , square wave generator, resonant capacitor C r , resonant inductor L r , magnetic ring, magnetic ring primary winding L p , secondary winding L s , rectifier and filter capacitor C0, load L o and a power analyzer; wherein the magnetic ring is made based on the magnetic material to be measured;

[0006] Wherein, the DC power supply V in , the square wave generator, the resonant capacitor C r and the resonant inductor L r Connect in sequence and connect to the primary winding L of the magnetic ring p ; The resonant capacitor C r , resonant inductor L r and the primary winding L of the magnetic ring p The excitation inductance L m To form a resonant circuit;

[0007] The rectifier is connected to the secondary winding L of the magnetic ring sThe two ends of the rectifier are connected in parallel to the filter capacitor C0 and the load L o The power analyzer is used to collect the primary current and secondary voltage of the magnetic ring to determine the magnetic characteristic parameters of the magnetic material to be tested.

[0008] In a possible implementation, the square wave generator is a full-bridge structure, including: a first switch tube S1, a second switch tube S2, a third switch tube S3 and a fourth switch tube S4;

[0009] The duty cycle of the driving signal of each switch tube is 0.5; the phase difference between the driving signal of the first switch tube S1 and the second switch tube S2 and the third switch tube S3 is 180°;

[0010] The phase difference between the driving signal of the fourth switch tube S4 and the second switch tube S2 and the third switch tube S3 is 180°.

[0011] In a possible implementation, the rectifier is a full-bridge structure, including: a first rectifier diode D5, a second rectifier diode D6, a third rectifier diode D7 and a fourth rectifier diode D8.

[0012] In a possible implementation, the measurement system further includes: a digital sampler;

[0013] The input end of the digital sampler is used to collect the primary current and the secondary voltage of the magnetic ring respectively, and the output end is used to connect to the power analyzer.

[0014] In a possible implementation, the measurement system further includes: a current probe and a voltage probe connected to the input end of the digital sampler;

[0015] The current probe and the voltage probe respectively collect the primary current and the secondary voltage of the magnetic ring.

[0016] In a possible implementation manner, the magnetic material to be tested is ferrite, amorphous, nanocrystalline or magnetic powder core.

[0017] In a possible implementation, the magnetic rings made of different magnetic materials to be tested have the same shape and size.

[0018] In a second aspect, an embodiment of the present invention provides a method for constructing a magnetic material magnetic property measurement system based on an LLC resonant circuit for use in the first aspect or any possible implementation of the first aspect, including:

[0019] Obtain the input and output parameters, resonant frequency and working areas corresponding to different resonant states of the resonant circuit, and calculate the primary-secondary transformation ratio, resonant component value and working frequency range; wherein the resonant component value includes the resonant capacitor, resonant inductor and excitation inductor values;

[0020] Calculating the transformation ratio of the primary winding of the magnetic ring and the secondary winding of the magnetic ring according to the value of the resonant element, and determining the number of turns on the primary side and the number of turns on the secondary side;

[0021] Connecting a magnetic ring made of the primary side turns, the secondary side turns and the magnetic material to be measured to a measurement system;

[0022] The power analyzer collects the primary current and the secondary voltage of the magnetic ring, and draws a hysteresis loop of the magnetic material according to the primary current and the secondary voltage, so as to calculate the loss and the magnetic permeability according to the hysteresis loop of the magnetic material.

[0023] In a possible implementation manner, the input and output parameters include an input voltage range, a rated input voltage, a rated output voltage, and a rated output power.

[0024] In a possible implementation, the calculating the primary-secondary transformation ratio, the resonant component value and the operating frequency range includes:

[0025] The primary-secondary transformation ratio is determined according to the ratio of the input voltage to the secondary clamping voltage;

[0026] Calculate the maximum input voltage gain and the minimum input voltage gain according to the secondary side clamping voltage, the input voltage range and the primary-to-secondary side transformation ratio, and calculate the load resistance and the primary side equivalent resistance according to the primary-to-secondary side transformation ratio, the secondary side clamping voltage and the rated output power;

[0027] determining an inductance, and calculating a maximum quality factor based on the inductance and the highest input voltage gain;

[0028] Calculate the maximum frequency and the minimum frequency according to the highest input voltage gain and the lowest input voltage gain, and determine the operating frequency range;

[0029] The resonance element value is determined according to the primary side equivalent resistance, the maximum quality factor and the resonance frequency.

[0030] The embodiment of the present invention provides a magnetic material magnetic property measurement system and construction method based on LLC resonant circuit, and a resonant circuit is constructed by resonant capacitor, resonant inductor and the excitation inductance of the primary winding of the magnetic ring, and a magnetic material magnetic property measurement system is constructed based on this. The system replaces the traditional function generator and power amplifier through the circuit structure composed of its components, thereby getting rid of the dependence on expensive experimental equipment and effectively simulating the excitation characteristics under actual working conditions. In the system, a DC power supply, a square wave generator, a resonant capacitor and a resonant inductor are connected in sequence and connected to the primary winding of the magnetic ring. The rectifier is connected to the secondary winding of the magnetic ring, and the filter capacitor and the load are connected in parallel at both ends. The square wave generator converts the input DC voltage into a square wave voltage as the input of the resonant network, driving the resonant circuit to operate under different working conditions to simulate the actual working conditions. The primary current and secondary voltage of the magnetic ring are collected by the power analyzer to determine the magnetic property parameters of the magnetic material to be measured. Such measurement results are based on the voltage and current characteristics under actual working conditions, which helps to reduce the error of the magnetic property measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a structural schematic diagram of a magnetic material magnetic property measurement system based on LLC resonant circuit provided by an embodiment of the present invention;

[0033] Figure 2 yes Figure 1 The equivalent schematic diagram of the magnetic material magnetic property measurement system based on LLC resonant circuit is shown;

[0034] Figure 3 is a schematic structural diagram of a magnetic material magnetic property measurement system based on an LLC resonant circuit provided by another embodiment of the present invention;

[0035] Figure 4 yes Figure 3 The equivalent schematic diagram of the magnetic material magnetic property measurement system based on LLC resonant circuit is shown;

[0036] Figures 5a to 5d yes Figure 4 The equivalent schematic diagram of the magnetic material magnetic property measurement system based on LLC resonant circuit is shown in FIG.

[0037] Figure 6is a flow chart of a method for constructing a magnetic material magnetic property measurement system based on an LLC resonant circuit provided by an embodiment of the present invention,

[0038] Figure 7 It is a flow chart of a method for designing LLC resonant circuit parameters of a magnetic material magnetic property measurement system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0040] In view of the fact that the excitation signals provided by the current soft magnetic material measurement experimental platform are mostly ideal waveforms, it is difficult to effectively simulate the voltage and current characteristics of actual working conditions. Therefore, establishing an actual circuit to provide excitation signals is of great significance for accurately measuring the magnetic properties of materials.

[0041] LLC resonant circuit can use the resonant network to realize soft switching characteristics under various working conditions such as no-load, half-load, and full-load. Its switch tube voltage can automatically return to zero before the driving voltage comes, realizing zero voltage opening of the switch tube in the converter. When LLC resonance occurs in the converter, the electric energy cannot be transmitted through the transformer, and the rectifier diode is reverse-biased and cut off, realizing zero current shutdown. The use of soft switching characteristics can reduce the high switching loss caused by high frequency and non-ideal devices, making the circuit have the characteristics of high stability, low loss, and high efficiency, and is therefore widely used in electrical equipment.

[0042] This application aims to use the improved LLC resonant circuit topology as a measurement platform to establish an actual circuit to provide an excitation signal and improve the accuracy of measuring the magnetic properties of the material.

[0043] The improved LLC resonant circuit topology is used as a measurement platform. It only needs to be matched with an input DC power supply to replace the function generator and power amplifier. By changing the on-off frequency of the switching tube and the replaceable resonant inductor, capacitor and magnetic surround group, the magnetic properties of nanocrystalline materials under the excitation of LLC circuits at different frequencies can be tested. The magnetic properties of small-power nanocrystalline transformers based on LLC circuits can be detected and simulated, which not only meets the experimental test requirements, but also greatly reduces the equipment cost and avoids the measurement errors caused by ideal test conditions.

[0044] In addition, the current soft magnetic material measurement experimental platform has higher bandwidth requirements for instruments adapted at high frequencies, which undoubtedly greatly increases the cost of the equipment. This application proposes a magnetic property measurement system based on LLC resonant circuit, which can replace function generators and power amplifiers to work, get rid of the dependence on expensive experimental equipment, and can effectively simulate the excitation characteristics under actual working conditions.

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

[0046] Figure 1 The structure diagram of the magnetic material magnetic property measurement system based on LLC resonant circuit provided by one embodiment of the present invention. Figure 1 As shown, the magnetic material magnetic property measurement system based on LLC resonant circuit includes: a DC power supply V in , square wave generator, resonant capacitor C r , resonant inductor L r , magnetic ring, magnetic ring primary winding L p , secondary winding L s , rectifier and filter capacitor C0, load L o and a power analyzer; wherein the magnetic ring is made based on the magnetic material to be measured.

[0047] like Figure 1 As shown, the magnetic ring passes through L p1 ~L p4 and L s1 ~L s4 Access to the measurement system. Figure 2 yes Figure 1 The equivalent circuit diagram of the structure of the measurement system shown in Figure 1 is shown in Figure 2. m is the excitation inductance of the magnetic ring. Among them, the DC power supply V in , square wave generator, resonant capacitor C r and resonant inductor L r Connect in sequence and connect to the primary winding L of the magnetic ring p ; Resonant capacitor C r , resonant inductor L r and the primary winding L p To avoid unnecessary details that hinder the description of the present invention, in the embodiments of the present application, LLC is the resonant capacitor C if not explicitly stated. r , resonant inductor L r and the primary winding L p The resonant circuit composed of the excitation inductance.

[0048] The square wave generator converts the input DC voltage into a square wave voltage as the input of the resonant network. The resonant network consists of a resonant capacitor Cr , resonant inductor L r and the excitation inductance L of the magnetic ring m Composition, resonant capacitor C r At the same time, it also plays a role in blocking direct current.

[0049] In the traditional solution, a square wave voltage is applied to the magnetic material through a signal generator and a power amplifier to excite the magnetic material, and the magnetic material generates a triangular wave current. However, in the embodiment of the present application, under the LLC resonant working condition, the excitation signal is a square wave voltage and the current is a trapezoidal current. Compared with the traditional triangular wave current, the peak current of the trapezoidal current is more concentrated and controllable, which is conducive to the precise regulation and measurement of the characteristics of the magnetic material. In addition, due to the high efficiency of the LLC resonant circuit, the required voltage and current amplitudes can be reduced while producing the same excitation effect, which is conducive to reducing energy consumption and costs.

[0050] Rectifier connected to the secondary winding L s , the two ends of the rectifier are connected in parallel with the filter capacitor C0 and the load L o ; Power analyzer, used to collect the primary current and secondary voltage of the magnetic ring to determine the magnetic characteristic parameters of the magnetic material to be tested.

[0051] The voltage output by the rectifier is filtered by capacitor C0 to obtain a stable DC output for the load L. o use.

[0052] The power analyzer collects the primary current and secondary voltage of the magnetic ring and performs parameter analysis. Based on the parameters, the hysteresis loop of the magnetic material is drawn and the magnetic characteristic parameters such as loss and permeability are calculated.

[0053] In the specific implementation process, according to specific test requirements, the magnetic ring made based on the magnetic material to be tested is connected to the magnetic material magnetic property measurement system, and comparative testing of different magnetic materials to be tested can be achieved under the same working conditions.

[0054] In the present embodiment, a resonant circuit is constructed by resonant capacitor, resonant inductor and the excitation inductance of the primary winding of the magnetic ring, and a magnetic material magnetic property measurement system is constructed based on this. The system replaces the traditional function generator and power amplifier through the circuit structure composed of its components, thereby getting rid of the dependence on expensive experimental equipment and effectively simulating the excitation characteristics under actual working conditions. In the system, a DC power supply, a square wave generator, a resonant capacitor and a resonant inductor are connected in sequence and connected to the primary winding of the magnetic ring. The rectifier is connected to the secondary winding of the magnetic ring, and the filter capacitor and the load are connected in parallel at both ends. The square wave generator converts the input DC voltage into a square wave voltage as the input of the resonant network, driving the resonant circuit to operate under different working conditions to simulate the actual working conditions. The primary current and secondary voltage of the magnetic ring are collected by the power analyzer to determine the magnetic property parameters of the magnetic material to be measured. Such a measurement result is based on the voltage and current characteristics under actual working conditions, which helps to reduce the error of the magnetic property measurement result.

[0055] Figure 3 A schematic structural diagram of a magnetic material magnetic property measurement system based on an LLC resonant circuit provided in another embodiment of the present invention.

[0056] In one possible implementation, Figure 3 As shown, the square wave generator is a full-bridge structure, including: a first switch tube S1, a second switch tube S2, a third switch tube S3 and a fourth switch tube S4;

[0057] The duty cycle of the driving signal of each switch tube is 0.5; the phase difference between the driving signal of the first switch tube S1 and the second switch tube S2 and the third switch tube S3 is 180°;

[0058] The phase difference between the driving signal of the fourth switch tube S4 and the second switch tube S2 and the third switch tube S3 is 180°.

[0059] Among them, the square wave generator, that is, the inverter module, is carefully constructed by four MOSFET devices and adopts an efficient full-bridge structure. MOSFET is selected as the switch tube, thanks to its excellent switching speed, extremely low on-resistance and excellent thermal stability, which together improves the precise control ability of the test process. Through the duty cycle and phase difference design of the drive signal of the switch tube, a certain dead time is guaranteed to prevent the two switch tubes in the same bridge arm from being directly connected.

[0060] In one possible implementation, Figure 3 As shown, the rectifier is a full-bridge structure, including: a first rectifier diode D5, a second rectifier diode D6, a third rectifier diode D7 and a fourth rectifier diode D8.

[0061] exist Figure 3Also shown are a control circuit and a drive circuit, where the control circuit and the drive circuit cooperate to control the states of the switching tubes of the square-wave generator, thereby controlling the operating state of the LLC and simulating the actual working conditions.

[0062] As Figure 3 shown, assume that the switching frequency of the MOSFET is f s , L r and C r have a resonant frequency of f r , L r and L m and C r have a resonant frequency of f m , then there are:

[0063]

[0064]

[0065] The operating state of the LLC is divided into three types.

[0066] ① When f r < f, the LLC operates in the resonance state of L r and C r , which is called LC resonance at this time. Although the primary-side MOSFET can achieve soft switching, the secondary-side diode operates in the continuous conduction mode and cannot achieve soft switching;

[0067] ② When f r < f < f m , the LLC operates in the resonance state of L r , L m , C r , which is called LLC resonance at this time. The circuit can achieve zero-voltage switching (ZVS) of the primary-side switching tube and zero-current switching (ZCS) of the secondary-side rectifier diode, which is the ideal frequency range for the LLC resonant converter to work.

[0068] ③ When f = f m , operating in this working frequency range, the equivalent input impedance of the resonant network presents capacitive, which is the ZCS working area of the LLC resonant converter and cannot achieve ZVS of the switching tube. Although achieving ZCS can also reduce the switching loss of the switching tube to a certain extent, for the MOSFET, its turn-off loss is much smaller than the turn-on loss.

[0069] Based on the measurement system provided by the embodiments of the present application, the above three working conditions can be simulated and designed. Since the second working condition is more commonly used in industry, when constructing the measurement system, the design is mainly carried out for the full soft-switching characteristics of the LLC circuit.

[0070] In order to understand the specific working principle of the magnetic material magnetic property measurement system based on LLC resonant circuit, Figure 3 The structural schematic diagram is shown for explanation. Figure 3 The magnetic ring passes through L p1 ~L p4 and L s1 ~L s4 Access to the measurement system. Figure 4 yes Figure 3 The equivalent circuit diagram of the structure of the measurement system shown in the figure, where L m is the magnetizing inductance of the magnetic ring.

[0071] When the LLC circuit works in the positive half cycle of the switch tube, the LLC mode includes four modes, namely: Figure 5a , 5b , 5c and 5d.

[0072] exist Figure 5a In the mode shown, the resonant current is less than zero, the parasitic capacitance of the switch has completed charging and discharging, and the voltage of capacitors C2 and C4 increases to the input voltage V in , the voltage across capacitors C1 and C3 is reduced to zero, creating conditions for zero-voltage turning on of switches S1 and S3.

[0073] exist Figure 5b In the second mode shown, the switches S1 and S3 are turned on with zero voltage, and the magnetizing inductor L in the resonant network on the primary side is m No longer participates in resonance, but the resonant inductor L r and resonant capacitor C r The two components resonate. The secondary voltage clamp of the magnetic ring is located at V o , the primary clamp voltage of the magnetic ring is nV o . Excitation inductance current i Lm and the resonant inductor current i Lr starts to rise, where the excitation current i Lm Linear rise, resonant current i Lr The rising voltage is fast. The rectifier diodes D5 and D8 are forward-conducting, and energy is transferred from the primary side to the secondary side.

[0074] exist Figure 5c In the third mode shown, the excitation current i Lm rises to the resonant current i Lr Equal, excitation inductance L m No longer clamped, the magnetizing inductance L in the resonant network m Participate in the resonance process, the excitation inductance L m , resonant inductor L r and the resonant capacitor participate in the resonance.m If the excitation current is large and the duration is short, it can be considered that the excitation current does not change during this period. Lm With the resonant current i Lr The primary input current of the magnetic ring gradually decreases to zero, and the current of the rectifier diodes D5 and D8 also decreases to zero accordingly. D5 and D8 are turned off to separate the primary and secondary sides. The rectifier diodes D5 and D8 are turned off with zero current, and there is no reverse recovery process. During this period of time, there is no energy transfer from the primary side to the secondary side, and the output filter capacitor on the secondary side transfers energy to the load.

[0075] exist Figure 5d In mode 4, S1 and S3 are turned off and the circuit enters the dead zone. Lr While charging capacitors C1 and C3, capacitors C2 and C4 are also discharged. The parasitic capacitance of the switch tube has completed charging and discharging, and the voltage of capacitors C1 and C3 increases to the input voltage V in , the voltage across capacitors C2 and C4 is reduced to zero, creating conditions for the zero voltage turn-on of switches S2 and S4. This process lasts for a short time and approximately reduces the excitation inductor current i Lm and the resonant inductor current i Lr In this process, the magnetic ring no longer participates in energy transmission, and the output filter capacitor C o is the load L o Transfer energy.

[0076] When the converter enters the negative half cycle, the switching modes are the same as those in the positive cycle, but in the opposite direction.

[0077] In summary, in the embodiments of the present application, an LLC resonant circuit is constructed, and excitation signals under various working conditions are applied to the magnetic ring through the actual circuit, so that the tested magnetic properties are more accurate, and the ability to perform magnetic property tests in a wide frequency range of 20kHz to 200kHz is achieved. The test system is suitable for comparative testing of different soft magnetic materials under the same working conditions, without the need to repeatedly build the test system, thereby significantly improving the efficiency of magnetic property testing and greatly reducing the cost of test equipment.

[0078] Based on any of the foregoing embodiments, in a possible implementation manner, the measurement system further includes: a digital sampler;

[0079] The input end of the digital sampler is used to collect the primary current and the secondary voltage of the magnetic ring respectively, and the output end is used to connect to the power analyzer.

[0080] Based on any of the foregoing embodiments, in a possible implementation manner, as Figure 3 As shown, the measurement system also includes: a current probe and a voltage probe connected to the input end of the digital sampler;

[0081] The current probe and voltage probe collect the primary current and secondary voltage of the magnetic ring respectively.

[0082] The current probe and voltage probe have high sensitivity and low interference characteristics, and can accurately capture the fluctuations of the primary current and secondary voltage of the magnetic ring, providing accurate data support for evaluating the magnetic characteristics of the magnetic ring. After the initial signal acquisition is completed, the output end of the digital sampler transmits the data to the power analyzer for in-depth analysis and processing.

[0083] In a possible implementation, the magnetic material to be tested is ferrite, amorphous, nanocrystalline or magnetic powder core.

[0084] In a possible implementation, the magnetic rings made of different magnetic materials to be tested have the same shape and size.

[0085] Among them, the magnetic rings made of different magnetic materials to be tested have the same shape and size, which ensures that when different magnetic materials to be tested are compared and analyzed, the primary current and secondary voltage data of the magnetic rings collected are highly comparable, thereby improving the accuracy and reliability of the test.

[0086] The following is a method embodiment of the present invention. For details not described in detail therein, reference may be made to the corresponding method embodiment described above.

[0087] Figure 6 A flow chart of a method for constructing a magnetic material magnetic property measurement system based on an LLC resonant circuit according to an embodiment of the present invention is shown. For ease of explanation, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0088] like Figure 6 As shown, the method comprises the following steps:

[0089] S601, obtaining input and output parameters, resonant frequency and working areas corresponding to different resonant states of the resonant circuit, and calculating the primary-secondary transformation ratio, resonant component value and working frequency range; wherein the resonant component value includes the resonant capacitor, resonant inductor and excitation inductor values.

[0090] S602, calculating the transformation ratio of the primary winding of the magnetic ring and the secondary winding of the magnetic ring according to the value of the resonant element, and determining the number of turns on the primary side and the number of turns on the secondary side.

[0091] S603, connecting a magnetic ring made of a primary side turn number, a secondary side turn number and a magnetic material to be measured to a measurement system.

[0092] S604, the power analyzer collects the primary current and the secondary voltage of the magnetic ring, and draws a hysteresis loop of the magnetic material according to the primary current and the secondary voltage, so as to calculate the loss and the magnetic permeability according to the hysteresis loop of the magnetic material.

[0093] In a possible implementation, the input and output parameters include an input voltage range, a rated input voltage, a rated output voltage, and a rated output power.

[0094] In a possible implementation, calculating the primary-secondary transformation ratio, the resonant component value, and the operating frequency range includes:

[0095] The primary-secondary transformation ratio is determined according to the ratio of the input voltage to the secondary clamping voltage;

[0096] The maximum input voltage gain and the minimum input voltage gain are calculated based on the secondary side clamping voltage, input voltage range and primary-to-secondary transformation ratio. The load resistance and primary side equivalent resistance are calculated based on the primary-to-secondary transformation ratio, secondary side clamping voltage and rated output power.

[0097] Determine the inductance and calculate the maximum quality factor based on the inductance and the highest input voltage gain;

[0098] Calculate the maximum frequency and the minimum frequency according to the gain of the highest input voltage and the gain of the lowest input voltage to determine the operating frequency range;

[0099] Determine the resonant component value based on the primary side equivalent resistance, maximum quality factor and resonant frequency.

[0100] Figure 7 The following is a flow chart of a method for designing LLC resonant circuit parameters of a magnetic material magnetic property measurement system provided by an embodiment of the present invention. The LLC resonant circuit parameter design is based on the fundamental wave analysis method (First-Harmonic Approximation, FHA). The flow chart is as follows:

[0101] 1. Determine the input voltage range V in-min ~V in-max , rated input voltage V in ; Rated output voltage, rated output power P o .

[0102] 2. Select the resonant frequency f r and working area, when rated input and output, the circuit operates at the resonant frequency f r .

[0103] 3. Calculate the magnetic ring transformation ratio and resonant component values.

[0104] 3.1. Theoretical transformation ratio n, and find the integral of n.

[0105]

[0106] 3.2. Maximum input voltage gain G max and minimum input voltage gain Gmin .

[0107]

[0108]

[0109] 3.3. Load resistance R0 and primary side equivalent resistance R ac .

[0110]

[0111]

[0112] 3.4. Determine the inductance coefficient K value. Generally speaking, the larger the K value, the smaller the maximum voltage gain and the flatter the voltage gain curve, and the lower the frequency adjustment ability.

[0113] 3.5. Calculate the quality factor Q, first calculate the maximum quality factor Q max Generally, a maximum margin of 5% is reserved during calculation.

[0114]

[0115] 3.6. Maximum frequency f max and minimum frequency f min .

[0116]

[0117]

[0118] 3.7. Resonant inductor L r , resonant capacitor C r , Excitation inductance L p .

[0119]

[0120]

[0121] L m =kLr

[0122] 3.8. Calculation of maximum current I m and the excitation current I p If I is not satisfied m >I p , need to reduce Q or increase L r +L p Among them, C oss is the parasitic capacitance of the switching device, C stray is the equivalent parasitic capacitance in parallel with the resonant network.

[0123]

[0124]

[0125] 4. Magnetic ring design

[0126] 4.1. Actual transformation ratio of magnetic ring n real .

[0127]

[0128] 4.2. Primary side turns N p and the secondary side turns N s , and need to be rounded, where B w is the working magnetic flux density, A e is the cross-sectional area of ​​the magnetic ring, V D It needs to be rounded to the forward conduction voltage drop of the rectifier diode.

[0129]

[0130]

[0131] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0132] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A magnetic material magnetic property measurement system based on LLC resonant circuit, characterized in that: include: DC power supply V in , square wave generator, resonant capacitor C r , resonant inductor L r , magnetic ring, magnetic ring primary winding L p , secondary winding L s , rectifier and filter capacitor C0, load L o and a power analyzer; wherein the magnetic ring is made based on the magnetic material to be measured; Wherein, the DC power supply V in , the square wave generator, the resonant capacitor C r and the resonant inductor L r Connect in sequence and connect to the primary winding L of the magnetic ring p ; The resonant capacitor C r , resonant inductor L r and the primary winding L of the magnetic ring p The excitation inductance L m To form a resonant circuit; The rectifier is connected to the secondary winding L of the magnetic ring s The two ends of the rectifier are connected in parallel to the filter capacitor C0 and the load L o The power analyzer is used to collect the primary current and secondary voltage of the magnetic ring to determine the magnetic characteristic parameters of the magnetic material to be tested.

2. The magnetic material magnetic property measurement system based on LLC resonant circuit according to claim 1, characterized in that: The square wave generator is a full-bridge structure, including: a first switch tube S1, a second switch tube S2, a third switch tube S3 and a fourth switch tube S4; The duty cycle of the driving signal of each switch tube is 0.5; the phase difference between the driving signal of the first switch tube S1 and the second switch tube S2 and the third switch tube S3 is 180°; The phase difference between the driving signal of the fourth switch tube S4 and the second switch tube S2 and the third switch tube S3 is 180°.

3. The magnetic material magnetic property measurement system based on LLC resonant circuit according to claim 1, characterized in that: The rectifier is a full-bridge structure, including: a first rectifier diode D5, a second rectifier diode D6, a third rectifier diode D7 and a fourth rectifier diode D8.

4. The magnetic material magnetic property measurement system based on LLC resonant circuit according to claim 1, characterized in that: Also includes: Digital sampler; The input end of the digital sampler is used to collect the primary current and the secondary voltage of the magnetic ring respectively, and the output end is used to connect to the power analyzer.

5. The magnetic material magnetic property measurement system based on LLC resonant circuit according to claim 4, characterized in that: Also includes: A current probe and a voltage probe connected to the input terminal of the digital sampler; The current probe and the voltage probe respectively collect the primary current and the secondary voltage of the magnetic ring.

6. The magnetic material magnetic property measurement system based on LLC resonant circuit according to claim 1, characterized in that: The magnetic material to be tested is ferrite, amorphous, nanocrystalline or magnetic powder core.

7. The magnetic material magnetic property measurement system based on LLC resonant circuit according to claim 1, characterized in that: The magnetic rings made of different magnetic materials to be tested have the same shape and size.

8. A method for constructing a magnetic material magnetic property measurement system based on an LLC resonant circuit as claimed in any one of claims 1 to 7, characterized in that: include: Obtain the input and output parameters, resonant frequency and working areas corresponding to different resonant states of the resonant circuit, and calculate the primary-secondary transformation ratio, resonant component value and working frequency range; wherein the resonant component value includes the resonant capacitor, resonant inductor and excitation inductor values; Calculating the transformation ratio of the primary winding of the magnetic ring and the secondary winding of the magnetic ring according to the value of the resonant element, and determining the number of turns on the primary side and the number of turns on the secondary side; Connecting a magnetic ring made of the primary side turns, the secondary side turns and the magnetic material to be measured to a measurement system; The power analyzer collects the primary current and the secondary voltage of the magnetic ring, and draws a hysteresis loop of the magnetic material according to the primary current and the secondary voltage, so as to calculate the loss and the magnetic permeability according to the hysteresis loop of the magnetic material.

9. The method for measuring magnetic properties of magnetic materials based on LLC resonant circuit according to claim 8, characterized in that: The input and output parameters include input voltage range, rated input voltage, rated output voltage and rated output power.

10. The method for measuring magnetic properties of magnetic materials based on LLC resonant circuit according to claim 8, characterized in that: The calculation of the primary-to-secondary transformation ratio, the resonant component value and the operating frequency range includes: The primary-secondary transformation ratio is determined according to the ratio of the input voltage to the secondary clamping voltage; Calculate the maximum input voltage gain and the minimum input voltage gain according to the secondary side clamping voltage, the input voltage range and the primary-to-secondary side transformation ratio, and calculate the load resistance and the primary side equivalent resistance according to the primary-to-secondary side transformation ratio, the secondary side clamping voltage and the rated output power; determining an inductance, and calculating a maximum quality factor based on the inductance and the highest input voltage gain; Calculate the maximum frequency and the minimum frequency according to the highest input voltage gain and the lowest input voltage gain, and determine the operating frequency range; The resonance element value is determined according to the primary side equivalent resistance, the maximum quality factor and the resonance frequency.

Images