Construction Method of Magnetic Material Magnetic Property Measurement System Based on LLC Resonant Circuit

Abstract

This invention provides a method for constructing a magnetic property measurement system for magnetic materials based on an LLC resonant circuit, belonging to the field of switching converter technology. The measurement system includes: a DC power supply. V in Square wave generator, resonant capacitor C r Resonant inductor L r Magnetic ring, primary winding of magnetic ring L p Secondary winding of magnetic ring L s rectifier and filter capacitor C 0. Load L o And a power analyzer; wherein, the magnetic ring is made based on the magnetic material to be tested; wherein, a DC power supply V in Square wave generator, resonant capacitor C r and resonant inductor L r Connect sequentially and connect to the primary winding of the magnetic ring. L p resonant capacitor C r Resonant inductor L r and the primary winding of the magnetic ring L p excitation inductor L m Forming a resonant circuit; the rectifier is connected to the secondary winding of the magnetic ring. L s A filter capacitor is connected in parallel across the rectifier. C 0 and load L o A power analyzer is used to collect the primary-side current and secondary-side voltage of a magnetic ring to determine the magnetic characteristic parameters of the magnetic material under test. This invention can reduce the error in the measurement results of the magnetic characteristics of magnetic materials.

Description

Technical Field

[0001] This invention relates to the field of switching converter technology, and in particular to a method for constructing a magnetic material magnetic property measurement system based on LLC resonant circuit. Background Technology

[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 a research hotspot. New soft magnetic materials, represented by amorphous and nanocrystalline materials, have gradually become popular choices for electrical equipment due to their low loss, low coercivity and high permeability. Researching the magnetic properties of nanocrystalline materials is of great significance for improving the power density, reducing losses, and minimizing the size of electrical equipment.

[0003] Currently, most experimental platforms for measuring soft magnetic materials use signal generators paired with power amplifiers to provide the excitation waveforms required for measurement. However, since the provided excitation signals are mostly ideal waveforms, they are difficult to effectively simulate the voltage and current characteristics under actual working conditions, resulting in large errors in the measurement results of the magnetic properties of magnetic materials. Summary of the Invention

[0004] This invention provides a method for constructing a magnetic property measurement system based on LLC resonant circuits to address the problem of reducing the error in the measurement results of magnetic properties of magnetic materials.

[0005] In a first aspect, embodiments of the present invention provide a magnetic property measurement system for magnetic materials 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, primary winding of magnetic ring L p Secondary winding of magnetic ring L s rectifier and filter capacitor C 0. Load L o A power analyzer; wherein the magnetic ring is made based on the magnetic material to be tested;

[0006] Among them, the DC power supply V in The square wave generator and the resonant capacitor C r and the resonant inductor L r Connect sequentially and connect to the primary winding of the magnetic ring. L p The resonant capacitor C rResonant inductor L r and the primary winding of the magnetic ring L p excitation inductor L m Form a resonant circuit;

[0007] The rectifier is connected to the secondary winding of the magnetic ring. L s The filter capacitor is connected in parallel across the two ends of the rectifier. C 0 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 under test.

[0008] In one possible implementation, the square wave generator is a full-bridge structure, including: a first switching transistor. S 1. Second switching transistor S 2. Third switching transistor S 3 and the fourth switching transistor S 4;

[0009] The duty cycle of the drive signal for each switching transistor is 0.5; the first switching transistor S 1. The phase difference between the drive signals of the second switch S2 and the third switch S3 is 180°.

[0010] The fourth switching transistor S 4 has a phase difference of 180° with the drive signals of the second switch S2 and the third switch S3, respectively.

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

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

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

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

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

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

[0017] In one possible implementation, magnetic rings made of different magnetic materials being tested are identical in shape and size.

[0018] Secondly, embodiments of the present invention provide a method for constructing a magnetic property measurement system for magnetic materials based on an LLC resonant circuit, as described in the first aspect or any possible implementation of the first aspect, comprising:

[0019] Obtain the input and output parameters, resonant frequency, and operating regions corresponding to different resonant states of the resonant circuit, and calculate the primary-to-secondary turns ratio, resonant element values, and operating frequency range; wherein, the resonant element values ​​include the values ​​of resonant capacitor, resonant inductor, and magnetizing inductor.

[0020] Calculate the turns ratio of the primary winding and the secondary winding of the magnetic ring based on the resonant element values, and determine the number of turns on the primary side and the number of turns on the secondary side.

[0021] The measurement system is connected based on the number of turns on the primary side, the number of turns on the secondary side, and the magnetic ring made of the magnetic material to be tested;

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

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

[0024] In one possible implementation, the calculation of the primary-to-secondary transformer ratio, resonant element value, and operating frequency range includes:

[0025] The primary-to-secondary turns ratio is determined based on the ratio of the input voltage to the secondary clamping voltage.

[0026] The maximum input voltage gain and the minimum input voltage gain are calculated based on the secondary-side clamping voltage, the input voltage range, and the primary-secondary-side turns ratio. The load resistance and the primary-side equivalent resistance are calculated based on the primary-secondary-side turns ratio, the secondary-side clamping voltage, and the rated output power.

[0027] Determine the inductance coefficient, and calculate the maximum quality factor based on the inductance coefficient and the highest input voltage gain;

[0028] The maximum and minimum frequencies are calculated based on the gains of the highest and lowest input voltages to determine the operating frequency range;

[0029] The value of the resonant element is determined based on the primary-side equivalent resistance, the maximum quality factor, and the resonant frequency.

[0030] This invention provides a method for constructing a magnetic material magnetic property measurement system based on an LLC resonant circuit. A resonant circuit is constructed using a resonant capacitor, a resonant inductor, and the magnetizing inductance of the primary winding of a magnetic ring, and a magnetic material magnetic property measurement system is built upon this circuit. This system, through its component-based circuit structure, replaces the traditional function generator and power amplifier, thus eliminating reliance on expensive experimental equipment and effectively simulating excitation characteristics under actual operating conditions. In this system, a DC power supply, a square wave generator, a resonant capacitor, and a resonant inductor are connected sequentially and connected to the primary winding of the magnetic ring. A rectifier is connected to the secondary winding of the magnetic ring, with a filter capacitor and a load connected in parallel across its two ends. The square wave generator converts the input DC voltage into a square wave voltage, which serves as the input to the resonant network, driving the resonant circuit to operate under different conditions to simulate actual operating conditions. The primary current and secondary voltage of the magnetic ring are collected using a power analyzer to determine the magnetic property parameters of the magnetic material under test. This measurement result, based on the voltage and current characteristics under actual operating conditions, helps reduce errors in the magnetic property measurement results. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of a magnetic material magnetic property measurement system based on an LLC resonant circuit according to an embodiment of the present invention;

[0033] Figure 2 yes Figure 1 The diagram shows an equivalent schematic of a magnetic material magnetic property measurement system based on an LLC resonant circuit.

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

[0035] Figure 4 yes Figure 3 The diagram shows an equivalent schematic of a magnetic material magnetic property measurement system based on an LLC resonant circuit.

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

[0037] Figure 6This is a flowchart illustrating a method for constructing a magnetic property measurement system for magnetic materials based on an LLC resonant circuit, according to an embodiment of the present invention.

[0038] Figure 7 This is a flowchart illustrating the LLC resonant circuit parameter design method for a magnetic material magnetic property measurement system according to an embodiment of the present invention. Detailed Implementation

[0039] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0040] Given that the excitation signals provided by current experimental platforms for measuring soft magnetic materials are mostly ideal waveforms, which are difficult to effectively simulate the voltage and current characteristics under actual working conditions, it is of great significance to establish an actual circuit to provide the excitation signal for accurately measuring the magnetic properties of materials.

[0041] LLC resonant circuits can achieve soft-switching characteristics under various operating conditions, including no-load, half-load, and full-load. The voltage of the switching transistor can automatically return to zero before the drive voltage arrives, achieving zero-voltage turn-on of the switching transistor in the converter. When LLC resonance occurs in the converter, electrical current cannot be transmitted through the transformer, and the rectifier diodes are reverse-biased and cut off, achieving zero-current turn-off. Using soft-switching characteristics reduces the high switching losses caused by high frequencies and non-ideal components, resulting in circuits with high stability, low loss, and high efficiency, thus making them widely used in electrical equipment.

[0042] This application aims to use an improved topology of LLC resonant circuit as a measurement platform to establish an actual circuit that provides an excitation signal, thereby improving the accuracy of measuring the magnetic properties of materials.

[0043] Using an improved topology of the LLC resonant circuit as a measurement platform, it can replace the function generator and power amplifier simply by adding an input DC power supply. By changing the switching frequency of the switching transistors and replacing the resonant inductor, capacitor, and magnetic winding assembly, the magnetic properties of nanocrystalline materials excited by LLC circuits at different frequencies can be tested. Magnetic property detection and simulation of low-power nanocrystalline transformers based on LLC circuits can be performed, which not only meets the experimental testing requirements but also greatly reduces equipment costs and avoids measurement errors caused by ideal testing conditions.

[0044] Furthermore, current experimental platforms for measuring soft magnetic materials require instruments adapted for high frequencies with higher bandwidth requirements, which undoubtedly increases the cost of the equipment significantly. This application proposes a magnetic characteristic measurement system based on an LLC resonant circuit. This system can replace function generators and power amplifiers, eliminating dependence on expensive experimental equipment and effectively simulating excitation characteristics under actual working conditions.

[0045] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0046] Figure 1 This is a schematic diagram of a magnetic material magnetic property measurement system based on an LLC resonant circuit, provided as an embodiment of the present invention. Figure 1 As shown, the magnetic property measurement system for magnetic materials based on LLC resonant circuits includes: a DC power supply. V in Square wave generator, resonant capacitor C r Resonant inductor L r Magnetic ring, primary winding of magnetic ring L p Secondary winding of magnetic ring L s rectifier and filter capacitor C 0. Load L o And a power analyzer; wherein, the magnetic ring is made based on the magnetic material to be tested.

[0047] like Figure 1 As shown, the magnetic ring passes through L p1 ~ L p4 and L s1 ~ L s4 Connect to the measurement system. Figure 2 yes Figure 1 The equivalent circuit diagram of the measurement system shown is provided. L m This is the magnetizing inductance of the magnetic ring. The DC power supply is also included. V in Square wave generator, resonant capacitor C r and resonant inductor L r Connect sequentially and connect to the primary winding of the magnetic ring. L p resonant capacitor C r Resonant inductor L rand the primary winding of the magnetic ring L p The magnetizing inductance forms a resonant circuit. To avoid unnecessary details from obscuring the description of the invention, in the embodiments of this application, unless otherwise explicitly stated, LLC refers to the resonant capacitor. C r Resonant inductor L r and the primary winding of the magnetic ring L p A resonant circuit composed of magnetizing inductors.

[0048] The square wave generator converts the input DC voltage into a square wave voltage, which serves as the input to the resonant network. The resonant network consists of a resonant capacitor. C r Resonant inductor L r Magnetizing inductance of magnetic ring L m Composition, resonant capacitor C r It also serves to block direct current.

[0049] In traditional methods, a square wave voltage is applied to the magnetic material via a signal generator and power amplifier, generating a triangular wave current. However, in this embodiment, under LLC resonant operation, the excitation signal is a square wave voltage, and the current is a trapezoidal current. Compared to the traditional triangular wave current, the trapezoidal current has a more concentrated and controllable peak current, which is beneficial for achieving precise control and measurement of the magnetic material's properties. Furthermore, due to the high efficiency of the LLC resonant circuit, the required voltage and current amplitudes can be reduced to achieve the same excitation effect, thereby reducing energy consumption and cost.

[0050] Rectifier connecting magnetic ring secondary winding L s A filter capacitor is connected in parallel across the rectifier. C 0 and load L o A power analyzer is used to collect the primary-side current and secondary-side voltage of a magnetic ring to determine the magnetic characteristic parameters of the magnetic material under test.

[0051] The voltage output from the rectifier passes through a capacitor. C After 0 filtering, a stable DC output is obtained to supply the load. L o use.

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

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

[0054] In this embodiment, a resonant circuit is constructed using a resonant capacitor, a resonant inductor, and the magnetizing inductance of the primary winding of a magnetic ring. Based on this circuit, a magnetic material magnetic property measurement system is built. This system, through its component-based circuit structure, replaces the traditional function generator and power amplifier, thus eliminating reliance on expensive experimental equipment and effectively simulating excitation characteristics under actual operating conditions. In this system, a DC power supply, a square wave generator, a resonant capacitor, and a resonant inductor are connected sequentially and connected to the primary winding of the magnetic ring. A rectifier is connected to the secondary winding of the magnetic ring, with a filter capacitor and a load connected in parallel across its two ends. The square wave generator converts the input DC voltage into a square wave voltage, which serves as the input to the resonant network, driving the resonant circuit to operate under different conditions to simulate actual operating conditions. By acquiring the primary current and secondary voltage of the magnetic ring using a power analyzer, the magnetic property parameters of the magnetic material under test are determined. This measurement result, based on the voltage and current characteristics under actual operating conditions, helps reduce errors in the magnetic property measurement results.

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

[0056] In one possible implementation, such as Figure 3 As shown, the square wave generator is a full-bridge structure, including: a first switching transistor. S 1. Second switching transistor S 2. Third switching transistor S 3 and the fourth switching transistor S 4;

[0057] The duty cycle of the drive signal for each switching transistor is 0.5; the first switching transistor... S 1. The phase difference between the drive signals of the second switch S2 and the third switch S3 is 180°.

[0058] Fourth switching transistor S 4 has a phase difference of 180° with the drive signals of the second switch S2 and the third switch S3, respectively.

[0059] The square wave generator, or inverter module, is meticulously constructed from four MOSFET devices, employing a highly efficient full-bridge structure. MOSFETs were chosen as the switching transistors due to their superior switching speed, extremely low on-resistance, and excellent thermal stability, which collectively enhance the precise control capabilities of the testing process. The duty cycle and phase difference of the drive signals for the switching transistors are designed to ensure a certain dead time to prevent shoot-through between two switches on the same bridge arm.

[0060] In one possible implementation, such as 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 3 The diagram also shows the control circuit and drive circuit, which work together to control the state of each switch in the square wave generator, thereby controlling the working state of the LLC and simulating actual working conditions.

[0062] like Figure 3 As shown, assume the switching frequency of the MOSFET is... f s , L r and C r The resonant frequency is f r , L r and L m and C r The resonant frequencies of the three are: f m Then we have:

[0063]

[0064]

[0065] LLCs have three working statuses.

[0066] ① f r < f At that time, LLC worked in L r and C r The resonant state, at this time is called LC Resonance occurs because although the primary-side MOSFET can achieve soft-switching, the secondary-side diode operates in continuous conduction mode and cannot achieve soft-switching.

[0067] ② fr < f < f m At that time, LLC worked in L r , L m , C r The resonant state, also known as LLC resonance, allows the circuit to achieve zero-voltage switching (ZVS) of the primary-side switching transistor and zero-current switching (ZCS) of the secondary-side rectifier diode. This is the ideal frequency range for the operation of the LLC resonant converter.

[0068] ③ f = f m When operating within this frequency range, the equivalent input impedance of the resonant network exhibits capacitive characteristics, constituting the ZCS operating region of the LLC resonant converter, and ZVS of the switching transistor cannot be achieved. Although achieving ZCS can reduce the switching losses of the switching transistor to some extent, for MOSFETs, the turn-off loss is much smaller than the turn-on loss.

[0069] Based on the measurement system provided in this application embodiment, simulation design can be performed for the above three working conditions. Since the second working condition is more commonly used in industry, the measurement system is mainly designed for the fully soft-switching characteristics of LLC circuits.

[0070] To facilitate understanding of the specific working principle of the magnetic property measurement system for magnetic materials based on LLC resonant circuits, Figure 3 The structural diagram shown is used for illustration. Figure 3 The image shows the magnetic ring passing through L p1 ~ L p4 and L s1 ~ L s4 Connect to the measurement system. Figure 4 yes Figure 3 The equivalent circuit diagram of the measurement system structure shown is given, where, L m It is the magnetizing inductance of the magnetic ring.

[0071] When the LLC circuit operates during the positive half-cycle of the switching transistor, the LLC mode includes four modes, as follows: Figure 5a , 5b As shown in 5c and 5d.

[0072] exist Figure 5aIn the mode shown, the resonant current is less than zero, and the parasitic capacitance of the switching transistor has completed charging and discharging. C 2 and C The voltage of 4 is increased to the input voltage. V in ,capacitance C 1 and C The voltage across terminals 3 is reduced to zero, creating conditions for zero-voltage turn-on of switching transistors S1 and S3.

[0073] exist Figure 5b In the second mode shown, switches S1 and S3 are turned on with zero voltage, and the magnetizing inductor in the primary side resonant network... L m It no longer participates in resonance, but is a 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 side of the magnetic ring is clamped. nV o Magnetizing inductor current i Lm and resonant inductor current i Lr It begins to rise, in which the excitation current i Lm Linear increase, resonant current i Lr The rise is relatively rapid. Rectifier diode. D 5 and D 8. Forward conduction allows energy to be transferred from the primary side to the secondary side.

[0074] exist Figure 5c Under the third mode shown, the excitation current i Lm Rise to resonant current i Lr Equal, magnetizing inductance L m No longer clamped, the magnetizing inductor in the resonant network L m The magnetizing inductor participates in the resonance process. L m Resonant inductor L r Together with the resonant capacitor, they participate in resonance. Due to the magnetizing inductance... L m Since the excitation current is relatively large and the duration is short, it can be assumed that the excitation current remains unchanged during this period. Because the excitation current... i Lm With resonant current i LrAs the primary input current of the magnetic ring gradually decreases to zero, the rectifier diode... D 5 and D The current at 8 also decreases to zero accordingly. D 5 and D 8. Turn off the primary and secondary sides to separate. Rectifier diode. D 5 and D 8 represents zero-current turn-off with no reverse recovery process. During this period, there is no energy transfer from the primary side to the secondary side, while the output filter capacitor on the secondary side transfers energy to the load.

[0075] exist Figure 5d In the fourth mode shown, S1 and S3 are turned off, entering the dead zone. Resonant inductor current... i Lr When supplying capacitors C 1 and C 3. While charging, it is also supplying power to the capacitor. C 2 and C 4. Discharge. The parasitic capacitance of the switching transistor has completed charging and discharging. C 1 and C The voltage of 3 is increased to the input voltage. V in ,capacitance C 2 and C The voltage across terminals 4 decreases to zero, creating conditions for the zero-voltage turn-on of switches S2 and S4. This process is relatively short, approximately reducing the magnetizing inductor current. i Lm and resonant inductor current i Lr Assuming it remains unchanged, the magnetic ring no longer participates in energy transfer during this process, and the output filter capacitor... C o For load L o Transfer energy.

[0076] When the converter enters the negative half-cycle, the switching modes of each switch are the same as those in the positive cycle, only in the opposite direction.

[0077] In summary, the embodiments of this application constructed an LLC resonant circuit and applied excitation signals under various operating conditions to the magnetic ring through the actual circuit, making the tested magnetic properties more accurate and enabling magnetic property testing within a wide frequency range of 20kHz to 200kHz. This testing system is suitable for comparative testing of different soft magnetic materials under the same operating conditions, eliminating the need to repeatedly construct the testing system, thereby significantly improving the efficiency of magnetic property testing and greatly reducing the cost of testing equipment.

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

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

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

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

[0082] Current and voltage probes possess high sensitivity and low interference characteristics, enabling them to accurately capture fluctuations in the primary-side current and secondary-side voltage of the magnetic ring, providing accurate data support for evaluating the magnetic characteristics of the ring. After initial signal acquisition, the output of the digital sampler transmits the data to the power analyzer for in-depth analysis and processing.

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

[0084] In one possible implementation, magnetic rings made of different magnetic materials being tested are identical in shape and size.

[0085] Among them, the magnetic rings made of different magnetic materials to be tested are the same in 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 are highly comparable, thereby improving the accuracy and reliability of the test.

[0086] The following are method embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0087] Figure 6 A flowchart illustrating a method for constructing a magnetic property measurement system for magnetic materials based on an LLC resonant circuit according to an embodiment of the present invention is shown. For ease of explanation, only the parts relevant to the embodiment of the present invention are shown, and are described in detail below:

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

[0089] S601, obtain the input and output parameters, resonant frequency, and operating regions corresponding to different resonant states of the resonant circuit, and calculate the primary-to-secondary turns ratio, resonant element values, and operating frequency range; wherein, the resonant element values ​​include the values ​​of resonant capacitor, resonant inductor, and magnetizing inductor.

[0090] S602, calculate the turns ratio of the primary winding and the secondary winding of the magnetic ring based on the resonant element values, and determine the number of turns on the primary side and the number of turns on the secondary side.

[0091] S603, a magnetic ring made of primary-side turns, secondary-side turns, and the magnetic material to be tested is connected to the measurement system.

[0092] The S604 power analyzer collects the primary current and secondary voltage of the magnetic ring and plots the hysteresis loop of the magnetic material based on the primary current and secondary voltage, so as to calculate the loss and permeability based on the hysteresis loop.

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

[0094] In one possible implementation, calculating the primary-to-secondary winding ratio, resonant element values, and operating frequency range includes:

[0095] The primary-to-secondary turns ratio is determined based on the ratio of the input voltage to the secondary clamping voltage.

[0096] Calculate the maximum input voltage gain and the minimum input voltage gain based on the secondary clamping voltage, input voltage range, and primary-secondary turns ratio; calculate the load resistance and primary-side equivalent resistance based on the primary-secondary turns ratio, secondary clamping voltage, and rated output power.

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

[0098] The maximum and minimum frequencies are calculated based on the gain of the highest and lowest input voltages to determine the operating frequency range.

[0099] The value of the resonant element is determined based on the primary side equivalent resistance, maximum quality factor, and resonant frequency.

[0100] Figure 7 A flowchart illustrating the LLC resonant circuit parameter design method for a magnetic material magnetic property measurement system according to an embodiment of the present invention is shown. The LLC resonant circuit parameter design is based on the fundamental frequency analysis method (First-Harmonic Approximation, FHA). The process 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 rWithin the operating range, at rated input and output, the circuit operates at the resonant frequency. f r .

[0103] 3. Calculate the magnetic ring turns ratio and resonant element values.

[0104] 3.1. Theoretical Variation n and to n Please make it whole.

[0105]

[0106] 3.2. Maximum Input Voltage Gain G max and the gain of the lowest input voltage G min .

[0107]

[0108]

[0109] 3.3. Load Resistance R 0 and primary side equivalent resistance R ac .

[0110]

[0111]

[0112] 3.4. Determine the inductance coefficient K Value, generally speaking K The larger the value, the smaller the maximum voltage gain and the flatter the voltage gain curve, and the lower its frequency regulation capability.

[0113] 3.5. Calculate the quality factor Q First calculate the maximum quality factor. Q max Generally, a 5% margin is left during calculations to obtain the maximum margin.

[0114]

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

[0116]

[0117]

[0118] 3.7. Resonant Inductor Lr Resonant capacitor C r Magnetizing inductor L p .

[0119]

[0120]

[0121]

[0122] 3.8. Calculate the maximum current I m and excitation current I p If not satisfied I m > I p It needs to be reduced Q or increase L r + L p .in, C oss For parasitic capacitance of switching devices, C stray This is the equivalent parasitic capacitance connected in parallel with the resonant network.

[0123]

[0124]

[0125] 4. Magnetic ring design

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

[0127]

[0128] 4.2. Number of primary side turns N p and number of secondary side turns N s And it needs to be rounded down, where B w For working magnetic flux density, A e For the cross-sectional area of ​​the magnetic ring, V D It needs to be rounded up to the forward voltage drop of the rectifier diode.

[0129]

[0130]

[0131] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0132] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for constructing a magnetic property measurement system for magnetic materials based on LLC resonant circuits, characterized in that, 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, primary winding of magnetic ring L p Secondary winding of magnetic ring L s rectifier and filter capacitor C 0. Load L o A power analyzer; wherein the magnetic ring is made based on the magnetic material to be tested; the square wave generator is a full-bridge structure, including: a first switching transistor. S 1. Second switching transistor S 2. Third switching transistor S 3 and the fourth switching transistor S 4; Among them, the DC power supply V in The square wave generator and the resonant capacitor C r and the resonant inductor L r Connect sequentially and connect to the primary winding of the magnetic ring. L p The resonant capacitor C r Resonant inductor L r and the primary winding of the magnetic ring L p excitation inductor L m Form a resonant circuit; The rectifier is connected to the secondary winding of the magnetic ring. L s The filter capacitor is connected in parallel across the two ends of the rectifier. C 0 and the load L o The power analyzer is used to collect the primary side current and secondary side voltage of the magnetic ring to determine the magnetic characteristic parameters of the magnetic material under test. In the LLC resonant condition, the excitation signal is a square wave voltage and the current is a trapezoidal current. By changing the switching frequency of the switch and replacing the resonant inductor, capacitor and magnetic ring, the magnetic characteristic test of the nanocrystalline material under LLC circuit excitation at different frequencies is completed. The method includes: Obtain the input and output parameters, resonant frequency, and operating regions corresponding to different resonant states of the resonant circuit, and calculate the primary-to-secondary turns ratio, resonant element values, and operating frequency range; wherein, the resonant element values ​​include the values ​​of resonant capacitor, resonant inductor, and magnetizing inductor. Calculate the turns ratio of the primary winding and the secondary winding of the magnetic ring based on the resonant element values, and determine the number of turns on the primary side and the number of turns on the secondary side. The measurement system is connected based on the number of turns on the primary side, the number of turns on the secondary side, and the magnetic ring made of the magnetic material to be tested; The power analyzer collects the primary current and secondary voltage of the magnetic ring, and plots the hysteresis loop of the magnetic material based on the primary current and secondary voltage, so as to calculate the loss and permeability based on the hysteresis loop of the magnetic material; wherein, under LLC resonant condition, the excitation signal is a square wave voltage and the current is a trapezoidal current.

2. The method for constructing a magnetic material magnetic property measurement system based on LLC resonant circuits according to claim 1, characterized in that, The duty cycle of the drive signal for each switching transistor is 0.5; the first switching transistor S 1. The phase difference between the drive signals of the second switch S2 and the third switch S3 is 180°. The fourth switching transistor S 4 has a phase difference of 180° with the drive signals of the second switch S2 and the third switch S3, respectively.

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

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

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

7. The method for constructing a magnetic material magnetic property measurement system based on LLC resonant circuits according to claim 1, characterized in that, The magnetic rings made of different magnetic materials being tested have the same shape and size.

8. The method for constructing a magnetic material magnetic property measurement system based on LLC resonant circuits according to claim 1, characterized in that, The input and output parameters include the input voltage range, rated input voltage, rated output voltage, and rated output power.

9. The method for constructing a magnetic material magnetic property measurement system based on LLC resonant circuits according to claim 8, characterized in that, The calculation of the primary-to-secondary winding ratio, resonant element value, and operating frequency range includes: The primary-to-secondary turns ratio is determined based on the ratio of the input voltage to the secondary clamping voltage. The maximum input voltage gain and the minimum input voltage gain are calculated based on the secondary-side clamping voltage, the input voltage range, and the primary-secondary-side turns ratio. The load resistance and the primary-side equivalent resistance are calculated based on the primary-secondary-side turns ratio, the secondary-side clamping voltage, and the rated output power. Determine the inductance coefficient, and calculate the maximum quality factor based on the inductance coefficient and the highest input voltage gain; The maximum and minimum frequencies are calculated based on the gains of the highest and lowest input voltages to determine the operating frequency range; The value of the resonant element is determined based on the primary-side equivalent resistance, the maximum quality factor, and the resonant frequency.

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