Inductance saturation evaluation method and device, medium and equipment

Abstract

The invention provides an inductance saturation evaluation method and device, a medium and equipment, and the method comprises the steps: carrying out the current measurement of electronic equipment, and obtaining a fundamental current and a multiple harmonic current; according to the fundamental current and the multiple harmonic current, primary selection of inductor models is carried out, and at least one primary selection inductor is determined; carrying out saturation current measurement on the primary selection inductor under the working frequency and each harmonic frequency to obtain saturation current under the working frequency and saturation current under multiple harmonic frequencies; and comparing the fundamental current with the saturation current under the working frequency, comparing the multiple harmonic current with the saturation current under the multiple harmonic frequency, and evaluating whether the primary inductance is taken as the target inductance or not according to comparison results. The inductance saturation evaluation accuracy can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of inductance measurement, and in particular to an inductance saturation evaluation method, device, medium and equipment. Background Art

[0002] Inductors are one of the most common passive components in circuits. They store electrical energy by generating a magnetic field. In an inductor, as the current flowing into it gradually increases, the current that the inductor can withstand will also be limited. When the current reaches a certain value, the inductor will enter a saturated state, resulting in current saturation of the inductor. Accurately measuring the saturation current of an inductor is of great significance for the circuit design and component selection of electronic equipment. Summary of the invention

[0003] In view of this, the present application provides an inductor saturation evaluation method, device, medium and equipment, the main purpose of which is to design a suitable inductor for an electronic device by performing saturation evaluation on the inductor.

[0004] According to one aspect of the present application, a method for evaluating inductance saturation is provided for selecting a target inductance for electronic device design, the method comprising:

[0005] Measuring the current of the electronic device to obtain the fundamental current and multiple harmonic currents;

[0006] Performing a preliminary selection of inductor models according to the fundamental current and the multiple harmonic currents, and determining at least one preliminary selected inductor;

[0007] Measuring the saturation current of the primary inductor at the operating frequency and each harmonic frequency to obtain the saturation current at the operating frequency and the saturation current at multiple harmonic frequencies;

[0008] The fundamental current is compared with the saturation current at the operating frequency, and the multiple harmonic currents are compared with the saturation currents at the multiple harmonic frequencies, and whether to use the primary inductance as the target inductance is evaluated according to the comparison results.

[0009] In one implementation, measuring the current of the electronic device to obtain the fundamental current and multiple harmonic currents includes:

[0010] The electronic device is connected to a line impedance stabilization network LISN as a device under test, and the current at the output end of the LISN is measured by a current probe of a measuring receiver to calculate the fundamental current and multiple harmonic currents.

[0011] In one implementation,

[0012] The inductor is a common mode inductor;

[0013] The electronic device is connected to the LISN as a device under test, and the LISN power line data is measured by a current probe of a measuring receiver to calculate the fundamental current and multiple harmonic currents, including the following steps:

[0014] (1) Powering on the electronic device for preheating and achieving a stable working state;

[0015] (2) Connecting the current probe to a power line to be tested on the LISN to obtain data of one end of the power line to be tested;

[0016] (3) Set the measurement receiver bandwidth and measurement time according to the measurement frequency range, and scan the corresponding frequency band;

[0017] (4) Repeat steps (2)-(3) to obtain the data of the power line to be tested at the other end;

[0018] (5) Read the fundamental current value and each harmonic current value on the two power lines respectively;

[0019] (6) determining the absolute value of the difference between the fundamental currents of the two power lines as the fundamental current;

[0020] (7) Determine the absolute value of the difference between the harmonic currents of the two power lines as multiple harmonic currents.

[0021] In one implementation,

[0022] The inductor is a differential mode inductor;

[0023] The electronic device is connected to the LISN as the device under test, and the LISN power line data is measured by the current probe of the measuring receiver to calculate the fundamental current and multiple harmonic currents, including the following steps:

[0024] (1) Powering on the electronic device to preheat and reach a stable working state;

[0025] (2) connecting the current probe to a power line to be tested;

[0026] (3) setting the measurement receiver bandwidth and measurement time according to the measurement frequency range, and scanning in the corresponding frequency band;

[0027] (4) determining that the measurement data of the current probe at the fundamental frequency is the fundamental current;

[0028] (5) Determine that the measurement data of the current probe at each harmonic frequency is multiple harmonic current.

[0029] In one implementation, the inductor model is preliminarily selected based on the fundamental current and the multiple harmonic currents to determine a preliminarily selected inductor;

[0030] Determine a preset fundamental saturation current value and a preset harmonic saturation current value according to the fundamental current and the multiple harmonic currents;

[0031] A preliminary model selection is performed based on the saturation current parameters of the candidate inductors, wherein an inductor having a fundamental saturation current parameter greater than or equal to a preset saturation current value and a harmonic saturation current parameter greater than or equal to a preset harmonic saturation current value is determined as the preliminary selected inductor.

[0032] In one implementation, the step of evaluating whether to use the preliminary selected inductance as the target inductance according to the comparison result includes:

[0033] Determine whether the saturation current at the operating frequency is greater than the fundamental current, and whether the saturation current at the multiple harmonic frequencies is greater than the multiple harmonic currents. If so, select and determine the target inductance from the at least one preliminary inductance. If not, determine that the saturation evaluation fails, and reselect the inductance.

[0034] In one implementation,

[0035] The inductor is a common mode inductor;

[0036] The method also includes: building a common-mode inductor saturation current measurement circuit, the measurement circuit including an adjustable resistor R, a common-mode inductor L to be measured, a function signal generator, a capacitor C, a bandpass filter, a digital bridge and a spectrum analyzer, wherein the current is changed by the adjustable resistor, and then the inductance is measured to infer whether the inductance has reached saturation.

[0037] In one implementation, the common-mode inductor saturation current measurement circuit performs measurement through the following steps:

[0038] (1) Adjust the adjustable resistor R so that the common-mode inductor L to be measured works at a certain amplitude of saturation current A1, and record the value of A1 through the spectrum analyzer;

[0039] (2) Adjust the output signal frequency of the function signal generator to a certain fixed frequency;

[0040] (3) Select a corresponding bandpass filter according to the output signal frequency of the function signal generator to filter out the influence of harmonic components;

[0041] (4) After the spectrum analyzer is connected to the current detection probe, set the spectrum analyzer to maximum hold;

[0042] (5) After pressing the output key of the function signal generator, the current A2 and the inductance value L1 are recorded on the spectrum analyzer and the digital bridge respectively;

[0043] (6) Obtain the line unbalanced current A=A2-A1 of the common mode inductor L to be measured;

[0044] (7) changing the output size of the function signal generator, repeating operations (5)-(6), obtaining an unbalanced saturation current curve between lines of the common-mode inductor LA to be measured at a fixed frequency, and obtaining a saturation current at the operating frequency;

[0045] (8) Changing the output frequency of the function signal generator, repeating operations (2)-(6), obtaining the line-to-line unbalanced saturation current curve of the common-mode inductor LA to be measured at the corresponding frequency, and obtaining the saturation current at the multiple harmonic frequencies.

[0046] In one implementation,

[0047] The inductor is a differential mode inductor;

[0048] The method also includes: building a differential mode inductor saturation current measurement circuit, the measurement circuit including a differential mode inductor to be measured, a function signal generator, a bandpass filter, a digital bridge and a spectrum analyzer, and obtaining corresponding inductance values ​​under different currents by changing the function signal generator, and inferring whether the inductance has reached saturation.

[0049] In one implementation, the differential mode inductor saturation current measurement circuit performs measurement through the following steps:

[0050] (1) Use wire L1 to connect the positive terminal of the function signal generator and pin A of the inductor;

[0051] (2) Select a corresponding bandpass filter according to the output signal frequency of the function signal generator to filter out the influence of harmonic components;

[0052] (3) One end of the wire L2 is connected to the negative terminal of the function signal generator;

[0053] (4) Connect the spectrum analyzer to the current probe to monitor the frequency domain current on L2. At the same time, set the spectrum analyzer to maximum hold.

[0054] (5) The two measurement ports of the digital bridge are connected to the A and B pins of the inductor respectively;

[0055] (6) Press the output key of the function signal generator, hold the other end of wire L2, make the wire tip touch the B end of the inductor, then remove wire L2 to make the wire tip and the B end of the inductor lose contact;

[0056] (7) Observe the spectrum analyzer and digital bridge readings, and record the current magnitude and inductance at the current frequency;

[0057] (8) Change the output frequency of the function signal generator, repeat operations (2)-(7), draw the saturation curve of the inductor LI, and obtain the saturation current at the operating frequency and the saturation current at multiple harmonic frequencies.

[0058] According to one aspect of the present application, there is provided an inductor saturation evaluation device for selecting a target inductance for electronic device design, the device comprising:

[0059] The fundamental harmonic current measurement unit is used to measure the current of the electronic equipment to obtain the fundamental current and multiple harmonic currents;

[0060] An inductor preliminary screening unit, used to perform preliminary selection of inductor models according to the fundamental current and the multiple harmonic currents, and determine a preliminary selected inductor;

[0061] The saturation current measuring unit is used to measure the saturation current of the primary selected inductor at the working frequency and each harmonic frequency to obtain the saturation current at the working frequency and the saturation current at multiple harmonic frequencies; the saturation judging unit is used to compare the fundamental current with the saturation current at the working frequency, and the multiple harmonic current with the saturation current at the multiple harmonic frequencies, and evaluate whether to use the primary selected inductor as the target inductor according to the comparison result.

[0062] According to one aspect of the present application, a storage medium is provided, in which a computer program is stored, wherein the computer program is configured to execute the above-mentioned inductor saturation evaluation method when running.

[0063] According to one aspect of the present application, an electronic device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to run the computer program to execute the above-mentioned inductor saturation evaluation method.

[0064] By means of the above technical scheme, the present application provides an inductor saturation evaluation method, device, medium and equipment, which first measures the fundamental current and each harmonic current of the electronic device, and performs a preliminary selection of the inductor device based on the measurement results, and then measures the saturation current at the working frequency of the inductor and the saturation current at each harmonic frequency, and finally compares the fundamental current with the saturation current at the working frequency, and each harmonic current with the saturation current at each harmonic frequency, respectively, to perform a saturation evaluation of the inductor. In the evaluation scheme of the present application, in addition to considering the influence of the fundamental current, the influence of each harmonic current is also fully considered, and the saturation state of the inductor can be fully and accurately evaluated to protect the inductor and the system in which it is located, and prevent the inductor from entering the saturation state and making the system unstable. It can be seen that the present application fully evaluates and selects the saturation current in the inductor selection stage to avoid safety accidents such as product failure, local inductor heating and burning due to improper consideration of the saturation current problem in the later stage.

[0065] At the same time, this application introduces specific methods of current measurement for common-mode inductors and differential-mode inductors, respectively, so this application can be applied to the selection and evaluation of inductors for electronic devices that select different types of inductors. For common-mode inductors, a comprehensive evaluation of the unbalanced fundamental current and harmonic components between lines is used as the basis for the selection of common-mode inductors. Then, the electronic products are operated under the expected working conditions to observe whether the functional status of the products is normal, and confirm that the common-mode inductors are working in an unsaturated state, thereby evaluating whether the unbalanced saturation current between the common-mode inductors meets the requirements. This can effectively solve the problem of instability or even heat and burnout of common-mode inductors during system operation due to insufficient early design selection and evaluation, and ensure that the common-mode inductors and the system in which they are located work normally and stably. For differential-mode inductors, a comprehensive evaluation of the fundamental current and harmonic components is performed as the basis for selecting differential-mode inductors. Then the electronic products are operated at full load to observe whether the functional status of the products is normal. Simultaneously, relevant parameters such as inductance value and heat generation are measured to confirm that the inductor is working in an unsaturated state, thereby evaluating the inductor saturation current. This can effectively solve the problem of instability or even heat and burnout of the inductor when the system is working, and ensure the normal and stable operation of the inductor and the system in which it is located.

[0066] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0068] Figure 1 A flow chart of an inductor saturation evaluation method provided in an embodiment of the present application is shown;

[0069] Figure 2 A measurement circuit diagram of fundamental current and multiple harmonic current of an electronic device provided in an embodiment of the present application is shown;

[0070] Figure 3 A measurement circuit diagram for measuring common-mode inductor saturation current provided in an embodiment of the present application is shown;

[0071] Figure 4 A curve chart showing the measurement results of measuring the common-mode inductor saturation current provided by an embodiment of the present application is shown;

[0072] Figure 5 A measurement circuit diagram for measuring the differential mode inductor saturation current provided in an embodiment of the present application is shown;

[0073] Figure 6 A curve chart showing the measurement results of measuring the differential-mode inductor saturation current provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0074] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only embodiments of a part of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0075] Inductors are often used in electronic devices for energy storage, and inductors with different specifications and parameters need to be selected according to different application scenarios. For an inductor with a magnetic core, when the current flowing through it increases to a certain level, the magnetic field strength in the magnetic core will no longer increase with the increase of current. This is called the inductor saturation state, and the current that causes the inductor to enter the saturation state is called the saturation current of the inductor. The saturation of the inductor will cause a sharp drop in inductance and a sharp increase in current. The drop in inductance will cause the system containing the inductor to work unstably. In actual applications, the inductor often becomes saturated before reaching the preset saturation current value, resulting in performance degradation or even heat and burning. Because the system contains various electronic devices and the electromagnetic environment is complex, it is difficult to obtain the cause of inductor saturation through actual measurement or calculation.

[0076] Most manufacturers define: the minimum current that causes the inductance value to decay to less than 70% of the original no-load value at a certain frequency point is the saturation current of the inductor. When the current reaches the saturation current, the inductance performance decays significantly. As the current continues to increase, the inductance performance decays seriously, and eventually it cannot play the role of an inductor. The inventors of this application found in the research process that in the actual use scenario of the inductor, there are very few working conditions at a single frequency, and the saturation of the inductor is not only caused by the current at a single frequency point. In the actual use of inductors, the electronic products often contain switching devices such as MOS tubes and IGBTs with a large number of harmonic components. Therefore, for electronic products, especially high-power electronic products, the inductor often decays when the working current does not reach the saturation current evaluated when the device is selected, or even loses its function. Therefore, when selecting the inductor, while considering the working current, it is also necessary to consider the fundamental and harmonic currents, and it is necessary to consider multiple harmonic problems at the same time.

[0077] See also Figure 1 , is an inductor saturation evaluation method provided in an embodiment of the present application, the method is used to select a target inductance for electronic device design, and includes the following steps S101-S104.

[0078] S101: Measure the current of the electronic device to obtain the fundamental current and multiple harmonic currents.

[0079] The electronic device in the embodiment of the present application refers to the currently designed electronic products, including various types of plug-in devices. As long as the equipment involves control and power conversion, it is necessary to design interference and anti-interference filters, so inductor selection and design are required.

[0080] In S101, a comprehensive evaluation of the fundamental current and multiple harmonic currents of the electronic device is performed, wherein each harmonic current can be understood as a harmonic current component. Generally speaking, there are many power modules in actual electronic products, and the harmonic components are difficult to obtain through simple prediction or calculation. Therefore, actual measurements can be performed on the electronic device prototype (for example, the following combination can be used). Figure 2 The actual fundamental current and harmonic current components are obtained by measuring the fundamental current and harmonic current components. For example, when the product is working, the fundamental current is defined as X, and the multiple harmonic currents are X. a , X b , X c ….

[0081] S102: Preliminary selection of inductor models is performed based on the fundamental current and multiple harmonic currents to determine a preliminary selected inductor.

[0082] After measuring the fundamental current and multiple harmonic currents, the saturation current preset value for device selection is determined, where the preset value is greater than the measured value. For example, the model is initially selected based on the saturation current parameters of the candidate inductors, where the inductors with fundamental saturation current parameters greater than or equal to the saturation current preset value and harmonic saturation current parameters greater than or equal to the harmonic saturation current preset value are determined as the primary inductors. That is, it is necessary to ensure that the device saturation current parameter is greater than the fundamental current and multiple harmonic current measurement values ​​selected from the candidate devices. As in the previous example, if the measured fundamental current is X, and the multiple harmonic currents are X respectively. a , X b , X c …, then, select the fundamental saturation current parameter greater than X, the harmonic saturation current parameter greater than X a , X b , X c The inductance of ... is used as the primary inductance.

[0083] S103: measuring the saturation current of the primary selected inductor at the operating frequency and each harmonic frequency to obtain the saturation current at the operating frequency and the saturation current at multiple harmonic frequencies.

[0084] Measure or select the inductor to obtain the fundamental saturation current X′ and the saturation current X at each harmonic frequency. A , X B , XC …. For specific measurement methods, please refer to Figure 3-4 , Figure 5-6 example.

[0085] S104: respectively comparing the fundamental current with the saturation current at the operating frequency, and the multiple harmonic currents with the saturation currents at the multiple harmonic frequencies, and evaluating whether to use the primary selected inductor as the target inductor based on the comparison results.

[0086] Determine the saturation current value of all required frequencies to meet the requirements of X, X a , X b , X c ...the requirement within the value, that is, X′>X, X A >X a , X B >X b , X C >X c , and then finally recommend the target inductor, for example, recommend an inductor with a saturation current value that is at least a certain amplitude (for example, more than 30%) higher than the actual product fundamental and harmonic current value as the target inductor. After that, the selected inductor can be installed in the designed product for functional verification. Run the product under full load working state, observe whether the functional status of the product is normal, and simultaneously carry out calorific value parameter measurement (which can be measured using a thermocouple instrument) to confirm that the inductor is working in an unsaturated state (the temperature will rise abnormally quickly when the inductor is saturated).

[0087] It can be seen that the embodiment of the present application proposes a method for evaluating inductor saturation, firstly, the fundamental current and each harmonic current of the electronic device are measured, and the inductor device is preliminarily selected based on the measurement results, and then the saturation current at the working frequency of the inductor and the saturation current at each harmonic frequency are measured, and finally the fundamental current is compared with the saturation current at the working frequency, and each harmonic current is compared with the saturation current at each harmonic frequency to evaluate the saturation of the inductor. In the evaluation scheme of the present application, in addition to considering the influence of the fundamental current, the influence of each harmonic current is also fully considered, and the saturation state of the inductor can be fully and accurately evaluated to protect the inductor and the system in which it is located, and prevent the inductor from entering the saturation state and making the system unstable. It can be seen that the present application fully evaluates and selects the saturation current in the inductor selection stage to avoid safety accidents such as product failure, local inductor heating and burning due to improper consideration of the saturation current problem in the later stage.

[0088] Those skilled in the art understand that inductors can be divided into common-mode inductors and differential-mode inductors.

[0089] Common-mode inductors are two-wire bidirectional, with two windings connected to the neutral line and the live line respectively. The two windings have the same input and output, and the common-mode signal is filtered out. Since common-mode inductors are two-wire bidirectional, the currents of the two lines will be different, that is, there will be saturation caused by unbalanced currents due to the current difference between the lines. Therefore, for common-mode inductors, in some practical applications, the difference in unbalanced current between the equipment lines is very large, which can easily lead to saturation of the common-mode inductors. Therefore, when selecting common-mode inductors, in addition to considering the operating current, it is also necessary to consider the unbalanced current between the lines, and the problem of multiple harmonic differences between the unbalanced currents between the lines needs to be considered at the same time.

[0090] Differential mode inductance is unidirectional. The differential mode is a filter inductor with one winding connected separately to the neutral line and the live line, which can only filter out differential mode interference.

[0091] There are different measurement methods for common-mode inductance and differential-mode inductance when measuring current, which are exemplified below.

[0092] First, the principle and method of measuring fundamental current and multiple harmonic currents (specific implementation method of S101) are introduced.

[0093] Figure 2 The schematic diagram of the measurement circuit for measuring fundamental current and multiple harmonic currents is shown in FIG. In the measurement circuit, an electronic device is connected to a line impedance stabilization network (LISN) as a device under test (EUT), wherein a load (e.g., a 50-ohm load) is connected to the signal output terminal of each LISN, and the LISN output terminal circuit is measured by a power probe of a measuring receiver (e.g., the current probe is placed 5 cm away from the LISN), and the measurement results are provided to a data recording device, so that the fundamental current and multiple harmonic currents are calculated based on the measurement records.

[0094] Among them, the specific steps are different for common-mode inductors and differential-mode inductors.

[0095] 1. Common mode inductor

[0096] For electronic devices that use common-mode inductors, the steps for measuring fundamental current and multiple harmonic currents include:

[0097] (1) The electronic equipment is used as the EUT, and is powered on for preheating and reaches a stable working state;

[0098] (2) Place the current probe on a power line to be tested;

[0099] (3) Set the receiver bandwidth and measurement time according to the measurement frequency range and scan the corresponding frequency band;

[0100] (4) Repeat steps (2)-(3) to obtain data of another power line to be tested;

[0101] (5) Read the fundamental current and harmonic current values ​​on the two power lines respectively;

[0102] (6) The unbalanced fundamental current between lines is the absolute value of the difference between the fundamental currents of the two power lines;

[0103] (7) The line-to-line unbalanced harmonic current is the absolute value of the difference between the corresponding harmonic currents of the two power lines.

[0104] For example, the measurement data unit is dBμA, according to the unit conversion formula A=10 (dBμA-120) / 20 The fundamental wave and harmonic currents on each power line can be obtained, and the corresponding unbalanced fundamental wave current and harmonic current between lines can be obtained by taking the absolute value of the difference.

[0105] For example, Table 1 is a record table of neutral line measurement results, and Table 2 is a record table of live line measurement results.

[0106] Table 1

[0107]

[0108] Table 2

[0109]

[0110] From the measurement results, we can see that the live and neutral currents at the operating frequency are 153.76dBμA and 151.67dBμA respectively. (dBμA-120) / 20 After conversion, the fundamental currents of the live line and the neutral line are 48.75A and 38.33A respectively, and the line-to-line unbalanced fundamental current = |48.75-38.33| = 10.42A. The line-to-line unbalanced 3rd, 5th, 7th, 11th, and 13th harmonic currents are 0.049A, 0.272A, 0.074A, 0.034A, and 0.059A respectively.

[0111] 2. Differential mode inductance

[0112] For electronic devices that use differential mode inductors, the steps for measuring fundamental current and multiple harmonic currents include:

[0113] (1) The EUT is powered on, preheated and reaches a stable working state;

[0114] (2) Place the current probe on a power line to be tested;

[0115] (3) Set the receiver bandwidth and measurement time according to the measurement frequency range and scan the corresponding frequency band;

[0116] (4) The magnitude of the fundamental current can be directly measured using the measurement data of the above current probe at the fundamental frequency;

[0117] (5) The magnitude of the harmonic current can be directly measured using the measurement data of the above current probe at the harmonic frequency.

[0118] The measurement data unit can be dBμA. According to the unit conversion, we get A=10 (dBμA-120) / 20 .

[0119] In one example, the measurement result record is shown in Table 3.

[0120] Table 3

[0121]

[0122] As can be seen from the measurement results, the current measurement result at the operating frequency is 140.69dBμA, the current measurement result at 150Hz (third harmonic) is 96.78dBμA, and the current measurement result at 250Hz (fifth harmonic) is 98.33dBμA. (dBμA-120) / 20 After conversion, the fundamental current is 10.83A, the third harmonic current is 0.07A, and the fifth harmonic current is 0.08A.

[0123] Next, the principle and steps (specific implementation of S103 ) of measuring the saturation current of an inductor (common mode inductor or differential mode inductor) at the operating frequency and the saturation current at each harmonic frequency are introduced.

[0124] 1. Common mode inductor

[0125] Those skilled in the art understand that inductor saturation refers to a phenomenon in which the inductor loses its performance after the current passing through the inductor is too large. For example, a 10mH inductor is measured as 10mH under 0A conditions, but if it is under 10A current conditions, it may be saturated. At this time, the measured inductance value may be 1mH, losing 90% of its performance. Accordingly, in the embodiment of the present application, the principle adopted by the common-mode inductor saturation current measurement circuit is to change the current through an adjustable resistor, and then measure the inductance value to infer whether the inductor is saturated.

[0126] See also Figure 3, is the circuit schematic diagram of the common-mode inductor line-to-line unbalanced saturation current measurement method. Among them, the adjustable resistor R is adjusted to make the common-mode inductor L to be measured work under a certain amplitude (for example, about 30%) of the saturation current A1, ensuring that the common-mode inductor L to be measured will not be saturated in this state. The function of the capacitor C is to block the influence of the DC power supply on the function signal generator. The function signal generator is used to inject a radio frequency current of the corresponding frequency into one of the coils of the common-mode inductor to be measured (the radio frequency current is the line-to-line unbalanced current of the common-mode inductor L to be measured), and the bandpass filter is used to eliminate the influence of the harmonic component of the radio frequency current itself, and the common-mode inductance value is obtained through the digital bridge, and the current A2 size at the current frequency is read through the spectrum analyzer, and the output amplitude of the function generator is changed to obtain the corresponding common-mode inductance value under different output currents, and the line-to-line unbalanced saturation current curve of the common-mode inductor L to be measured is drawn. Finally, the output frequency of the function signal generator is changed, and the above operation is repeated to comprehensively obtain the line-to-line unbalanced saturation current value of the common-mode inductor L to be measured at different frequencies.

[0127] The measurement steps are as follows:

[0128] (1) Press Figure 3 Measurement connection: Build a measurement link, adjust the adjustable resistor R so that the common mode inductor L to be measured works at 30% of the saturation current A1, and record the value of A1 through the spectrum analyzer;

[0129] (2) Adjust the output signal frequency of the function signal generator to a certain fixed frequency;

[0130] (3) Select a corresponding bandpass filter according to the output signal frequency of the function signal generator to filter out the influence of harmonic components;

[0131] (4) After the spectrum analyzer is connected to the current detection probe, set the spectrum analyzer to maximum hold;

[0132] (5) After pressing the output key of the function signal generator, the current A2 and the inductance value L1 are recorded on the spectrum analyzer and the digital bridge respectively;

[0133] (6) Obtain the line unbalanced current A=A2-A1 of the common mode inductor L to be measured;

[0134] (7) Change the output size of the function signal generator and repeat operations (5)-(6) to draw the unbalanced saturation current curve between the lines of the common mode inductor LA to be tested at a fixed frequency;

[0135] (8) By changing the output frequency of the function signal generator and repeating operations (2) to (6), the line-to-line unbalanced saturation current curve of the common-mode inductor LA to be measured at the corresponding frequency can be plotted.

[0136] For example, the line unbalanced saturation curve of a certain type of common mode inductor is as follows: Figure 4 shown. Figure 4 The graph shows the change of the inductance of a certain type of common mode inductor with the line unbalanced current at a frequency of 50Hz. The coordinates of the points in the graph are the line unbalanced current when the inductance decays to 70%, that is, the line unbalanced saturation current is 1.6A.

[0137] 2. Differential mode inductance

[0138] For example, function signal generators, digital bridges, and spectrum analyzers can be used to perform measurements, such as Figure 5 As shown. By injecting RF current of corresponding frequency into the inductor, using a bandpass filter to eliminate the influence of the harmonic component of the RF current itself, the inductance value at the corresponding frequency is obtained through a digital bridge, the current size at the current frequency is read through a spectrum analyzer, the output amplitude of the function generator is changed, the corresponding inductance value under different output currents is obtained, and the inductance saturation curve is drawn. Finally, the output frequency of the function signal generator is changed, and the above operations are repeated to comprehensively obtain the saturation current value of the inductor at different frequencies.

[0139] The measurement steps are as follows:

[0140] (1) Press Figure 5 Measurement connection Build the measurement link and connect the positive terminal of the function signal generator and the pin A of the inductor with wire L1. ;

[0141] (2) Select a corresponding bandpass filter according to the output signal frequency of the function signal generator to filter out the influence of harmonic components;

[0142] (3) One end of the wire L2 is connected to the negative terminal of the function signal generator;

[0143] (4) Connect the spectrum analyzer to the current probe to monitor the frequency domain current on L2. At the same time, set the spectrum analyzer to maximum hold.

[0144] (5) The two measurement ports of the digital bridge are connected to the A and B pins of the inductor respectively;

[0145] (6) Press the output key of the function signal generator, hold the other end of wire L2 with your hand, let the wire tip touch the B end of the inductor, then quickly remove wire L2 to break contact between the wire tip and the B end of the inductor.

[0146] (7) Observe the spectrum analyzer and digital bridge readings, and record the current magnitude and inductance at the current frequency;

[0147] (8) Change the output frequency of the function signal generator, repeat operations (2) to (7), and draw the saturation curve of the inductor LI.

[0148] For example, the saturation curve of a certain type of differential mode inductor is as follows: Figure 6 shown. Figure 6The graph shows the curve of inductance changing with current. The X coordinate of the point in the graph is the current when the inductance decays to 70%, that is, the saturation current is 0.18A.

[0149] In summary, the inductor saturation evaluation method provided in the embodiment of the present application, in addition to considering the working current, also fully considers the influence of the fundamental current and the harmonic current on the inductor saturation, so that the inductor saturation evaluation is more accurate; at the same time, for common-mode inductors and differential-mode inductors, specific methods of current measurement are introduced respectively, so the present application can be applied to the inductor selection and evaluation of electronic devices that select different types of inductors.

[0150] For common-mode inductors, a comprehensive evaluation of the unbalanced fundamental current and harmonic components between lines is performed as the basis for the selection of common-mode inductors. Then, the electronic products are operated under the expected working conditions to observe whether the functional status of the products is normal and confirm that the common-mode inductors are working in an unsaturated state. This can effectively solve the problem of common-mode inductors being unstable or even overheating and burning when the system is working due to insufficient evaluation in the early design selection, thereby ensuring that the common-mode inductors and the system they are in work normally and stably.

[0151] For differential-mode inductors, a comprehensive evaluation of the fundamental current and harmonic components is performed as the basis for selecting differential-mode inductors. Then the electronic products are operated at full load to observe whether the functional status of the products is normal. Simultaneously, relevant parameters such as inductance value and heat generation are measured to confirm that the inductor is working in an unsaturated state, thereby evaluating the inductor saturation current. This can effectively solve the problem of instability or even heat and burnout of the inductor when the system is working, and ensure the normal and stable operation of the inductor and the system in which it is located.

[0152] Corresponding to the above method, an embodiment of the present application further provides an inductor saturation evaluation device for selecting a target inductance for electronic device design, the device comprising:

[0153] The fundamental harmonic current measurement unit is used to measure the current of the electronic equipment to obtain the fundamental current and multiple harmonic currents;

[0154] An inductor preliminary screening unit, used to perform preliminary selection of inductor models according to the fundamental current and the multiple harmonic currents, and determine a preliminary selected inductor;

[0155] The saturation current measuring unit is used to measure the saturation current of the primary selected inductor at the working frequency and each harmonic frequency to obtain the saturation current at the working frequency and the saturation current at multiple harmonic frequencies; the saturation judging unit is used to compare the fundamental current with the saturation current at the working frequency, and the multiple harmonic current with the saturation current at the multiple harmonic frequencies, and evaluate whether to use the primary selected inductor as the target inductor according to the comparison result.

[0156] An embodiment of the present application further provides a storage medium, in which a computer program is stored, wherein the computer program is configured to execute the steps of any of the above method embodiments when running.

[0157] Optionally, in this embodiment, the storage medium may be configured to store a computer program for performing the following steps:

[0158] Measuring the current of the electronic device to obtain the fundamental current and multiple harmonic currents;

[0159] Performing a preliminary selection of inductor models according to the fundamental current and the multiple harmonic currents, and determining at least one preliminary selected inductor;

[0160] Measuring the saturation current of the primary inductor at the operating frequency and each harmonic frequency to obtain the saturation current at the operating frequency and the saturation current at multiple harmonic frequencies;

[0161] The fundamental current is compared with the saturation current at the operating frequency, and the multiple harmonic currents are compared with the saturation currents at the multiple harmonic frequencies, and whether to use the primary inductance as the target inductance is evaluated according to the comparison results.

[0162] Optionally, in this embodiment, the above-mentioned storage medium may include but is not limited to: a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk, and other media that can store computer programs.

[0163] An embodiment of the present application further provides an electronic device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to run the computer program to execute the steps in any one of the above method embodiments.

[0164] Optionally, the electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor, and the input / output device is connected to the processor.

[0165] Optionally, in this embodiment, the processor may be configured to perform the following steps through a computer program:

[0166] Measuring the current of the electronic device to obtain the fundamental current and multiple harmonic currents;

[0167] Performing a preliminary selection of inductor models according to the fundamental current and the multiple harmonic currents, and determining at least one preliminary selected inductor;

[0168] Measuring the saturation current of the primary inductor at the operating frequency and each harmonic frequency to obtain the saturation current at the operating frequency and the saturation current at multiple harmonic frequencies;

[0169] The fundamental current is compared with the saturation current at the operating frequency, and the multiple harmonic currents are compared with the saturation currents at the multiple harmonic frequencies, and whether to use the primary inductance as the target inductance is evaluated according to the comparison results.

[0170] Optionally, the specific examples in this embodiment may refer to the examples described in the above embodiments and optional implementation modes, and this embodiment will not be described in detail here.

[0171] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0172] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0173] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0174] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0175] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0176] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, disk or optical disk and other media that can store program codes.

[0177] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for evaluating inductor saturation, characterized in that: For selecting a target inductance for an electronic device design, the method comprises: Measuring the current of the electronic device to obtain the fundamental current and multiple harmonic currents; Performing a preliminary selection of inductor models according to the fundamental current and the multiple harmonic currents, and determining at least one preliminary selected inductor; Measuring the saturation current of the primary inductor at the operating frequency and each harmonic frequency to obtain the saturation current at the operating frequency and the saturation current at multiple harmonic frequencies; The fundamental current is compared with the saturation current at the operating frequency, and the multiple harmonic currents are compared with the saturation currents at the multiple harmonic frequencies, and whether to use the primary inductance as the target inductance is evaluated according to the comparison results.

2. The method according to claim 1, characterized in that The step of measuring the current of the electronic device to obtain the fundamental current and multiple harmonic currents includes: The electronic device is connected to a line impedance stabilization network LISN as a device under test, and the current at the output end of the LISN is measured by a current probe of a measuring receiver to calculate the fundamental current and multiple harmonic currents.

3. The method according to claim 2, characterized in that The inductor is a common mode inductor; The electronic device is connected to the LISN as a device under test, and the LISN power line data is measured by a current probe of a measuring receiver to calculate the fundamental current and multiple harmonic currents, including the following steps: (1) Powering on the electronic device for preheating and achieving a stable working state; (2) Connecting the current probe to a power line to be tested on the LISN to obtain data of one end of the power line to be tested; (3) Set the measurement receiver bandwidth and measurement time according to the measurement frequency range, and scan the corresponding frequency band; (4) Repeat steps (2)-(3) to obtain the data of the power line to be tested at the other end; (5) Read the fundamental current value and each harmonic current value on the two power lines respectively; (6) determining the absolute value of the difference between the fundamental currents of the two power lines as the fundamental current; (7) Determine the absolute value of the difference between the harmonic currents of the two power lines as multiple harmonic currents.

4. The method according to claim 2, characterized in that: The inductor is a differential mode inductor; The electronic device is connected to the LISN as the device under test, and the LISN power line data is measured by the current probe of the measuring receiver to calculate the fundamental current and multiple harmonic currents, including the following steps: (1) Powering on the electronic device to preheat and reach a stable working state; (2) connecting the current probe to a power line to be tested; (3) setting the measurement receiver bandwidth and measurement time according to the measurement frequency range, and scanning in the corresponding frequency band; (4) determining that the measurement data of the current probe at the fundamental frequency is the fundamental current; (5) Determine that the measurement data of the current probe at each harmonic frequency is multiple harmonic current.

5. The method according to claim 1, characterized in that The inductor model is preliminarily selected according to the fundamental current and the multiple harmonic currents to determine the preliminarily selected inductor; Determine a preset fundamental saturation current value and a preset harmonic saturation current value according to the fundamental current and the multiple harmonic currents; A preliminary model selection is performed based on the saturation current parameters of the candidate inductors, wherein an inductor having a fundamental saturation current parameter greater than or equal to a preset saturation current value and a harmonic saturation current parameter greater than or equal to a preset harmonic saturation current value is determined as the preliminary selected inductor.

6. The method according to claim 1, characterized in that The step of evaluating whether to use the preliminary selected inductance as the target inductance according to the comparison result includes: Determine whether the saturation current at the operating frequency is greater than the fundamental current, and whether the saturation current at the multiple harmonic frequencies is greater than the multiple harmonic currents. If so, select and determine the target inductance from the at least one preliminary inductance. If not, determine that the saturation evaluation fails, and reselect the inductance.

7. The method according to any one of claims 1-3, 5-6, characterized in that: The inductor is a common mode inductor; The method also includes: building a common-mode inductor saturation current measurement circuit, the measurement circuit including an adjustable resistor R, a common-mode inductor L to be measured, a function signal generator, a capacitor C, a bandpass filter, a digital bridge and a spectrum analyzer, wherein the current is changed by the adjustable resistor, and then the inductance is measured to infer whether the inductance has reached saturation.

8. An inductor saturation evaluation device, characterized in that: For selecting a target inductance for an electronic device design, the apparatus comprises: The fundamental harmonic current measurement unit is used to measure the current of the electronic equipment to obtain the fundamental current and multiple harmonic currents; An inductor preliminary screening unit, used to perform preliminary selection of inductor models according to the fundamental current and the multiple harmonic currents, and determine a preliminary selected inductor; The saturation current measuring unit is used to measure the saturation current of the primary selected inductor at the working frequency and each harmonic frequency to obtain the saturation current at the working frequency and the saturation current at multiple harmonic frequencies; the saturation judging unit is used to compare the fundamental current with the saturation current at the working frequency, and the multiple harmonic current with the saturation current at the multiple harmonic frequencies, and evaluate whether to use the primary selected inductor as the target inductor according to the comparison result.

9. A storage medium, characterized in that: The storage medium stores a computer program, wherein the computer program is configured to execute the method according to any one of claims 1 to 7 when executed.

10. An electronic device comprising a memory and a processor, characterized in that: A computer program is stored in the memory, and the processor is configured to run the computer program to perform the method according to any one of claims 1 to 7.

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