Method for creating a DC superposition model of a magnetic core for a noise filter and method for providing a DC superposition model of a magnetic core for a noise filter

Abstract

This document provides a method for creating a DC superposition model for simulation using SPICE (Simulation Program with Integrated Circuit Emphasis) when a magnetic core is used as a noise filter, and a method for providing that model. [Solution] The method for simulating the circuit characteristics when a DC superimposed current is applied to a magnetic core involves representing the magnetic core with an equivalent circuit using passive elements consisting of R, L, and C, measuring the frequency characteristics of the impedance by changing the DC current when a DC current is superimposed, calculating the resistance value of R, the inductance value of L, and the capacitance value of C from the frequency characteristics of the impedance at each current, constructing a DC superimposed model using a behavioral power supply based on the equivalent circuit, and setting table functions for R, L, and C as element constants of the elements used in the model, based on the obtained resistance, inductance, and capacitance values.

Description

Technical Field

[0001] The present invention relates to a method for creating a DC superposition model and a method for providing a DC superposition model for simulating the electrical characteristics of a magnetic core used in a noise filter by a circuit simulator using SPICE (Simulation Program with Integrated Circuit Emphasis).

Background Art

[0002] As the requirements for electronic devices for higher speed, larger capacity, smaller size and lower power consumption increase, shortening the development period and reducing costs of electronic devices have become essential for improving competitiveness. Therefore, a highly accurate simulation model is required to reduce the number of prototype experiments. In electronic circuit design, circuit simulators such as SPICE (Simulation Program with Integrated Circuit Emphasis) are used.

[0003] The inductance of a magnetic core used in a noise filter or the like changes depending on the DC bias voltage or DC current applied in superposition, and this change cannot be ignored when performing circuit simulation for noise countermeasures.

[0004] Ferrites widely used in magnetic cores are ceramics mainly composed of iron oxide, and most magnetic cores are often used in a ring shape. By passing a conductor through the hole of the ring, an inductor is formed by the conductor and the ferrite core. This inductor has a higher impedance as the frequency becomes higher. Therefore, it acts as a low-pass filter that blocks high-frequency currents and can attenuate high-frequency noise. Also, part of the noise current passing through the conductor is lost as magnetic loss, which has the effect of removing noise.

[0005] The increasing digitalization and high-current capabilities of equipment are driving a growing demand for noise suppression in the high-frequency range. Setting the optimal magnetic core for noise suppression is a complex, time-consuming, and labor-intensive process, requiring highly accurate circuit simulation techniques. Therefore, SPICE simulations that consider DC superposition characteristics are also required for noise suppression.

[0006] Various simulation methods that take into account the DC superposition characteristics of capacitors and inductors have been developed, mainly by companies that manufacture and sell electronic components, and many of these methods are provided free of charge.

[0007] For example, the following method is disclosed as a method for constructing a superimposed equivalent circuit. This method constructs the superimposed equivalent circuit of a passive element in a superimposed state where current or voltage is superimposed, using the reference state equivalent circuit of the passive element in a reference state where no current or voltage is superimposed. This method includes the step of supplying a current or voltage corresponding to the difference between the non-superimposed characteristics in the reference state of the passive element and the superimposed characteristics in the superimposed state to correct the difference. More specifically, this method involves connecting a voltage source and a current sensor between the external terminals of the superimposed equivalent circuit, and connecting the reference state equivalent circuit, a current source, and a voltage sensor to an independent closed-loop circuit not connected between the external terminals of the superimposed equivalent circuit. The current between the external terminals is detected by the current sensor, and a current dependent on this detection result is supplied from the current source to the reference state equivalent circuit. The voltage generated in the reference state equivalent circuit by this supply of current is detected by the voltage sensor, and a voltage dependent on this result is output from the voltage source to perform the correction (see, for example, Patent Document 1).

[0008] Furthermore, a simulation model for an inductor is disclosed that ensures the simulation results of a circuit including an inductor do not deviate significantly from the actual operation of the circuit. Specifically, it is a simulation model for an inductor when a triangular wave current superimposed with a DC current flows through it, and the equivalent circuit of the inductor is a series circuit of the DC resistance and the apparent AC resistance and inductance adjusted for AC losses, and the DC resistance of the inductor is a first function of the amplitude of the triangular wave and the DC current superimposed on the triangular wave, the apparent AC resistance of the inductor is a second function of the amplitude of the triangular wave, the DC current superimposed on the triangular wave and the frequency of the triangular wave, and the inductance of the inductor is a second function of the amplitude of the triangular wave, the DC current superimposed on the triangular wave and the frequency of the triangular wave The third function is defined as a first behavioral current source controlled by a formula obtained by dividing the voltage across its terminals by the value obtained by the first function, the apparent AC resistance is defined as a second behavioral current source controlled by a formula obtained by dividing the voltage across the AC resistance by the value obtained by the second function, the inductance is defined as a third behavioral current source controlled by a formula obtained by dividing the integral of the voltage across its inductance by the value obtained by the third function, and the DC superimposed current of the triangular wave is obtained by smoothing the current flowing through the first behavioral current source using a smoothing circuit. This simulation model determines the amplitude of the triangular wave by subtracting the value of the superimposed current of the triangular wave from the current value flowing through the first behavioral current source and then peak-holding the result in a peak-hold circuit. The frequency of the triangular wave is determined by subtracting the value of the DC superimposed current of the triangular wave from the current value flowing through the first behavioral current source, converting the result into a pulse wave in a waveform conversion circuit, and then counting the pulse wave in a counter circuit (see, for example, Patent Document 2).

[0009] Furthermore, for example, a simulation method and a nonlinear equivalent circuit model for an inductor that can dynamically simulate the nonlinear characteristics of an inductor with high accuracy when a DC current is superimposed are disclosed. Specifically, the equivalent circuit of the inductor is represented using a passive circuit element, the rate of change of the characteristics of the passive circuit element when a DC current is superimposed is represented as an approximate function with current as a variable based on measured values, the current flowing through the inductor is referenced, and based on the rate of change of the characteristics calculated by the approximate function corresponding to the referenced current, and the voltage generated in the passive circuit element when no DC current is superimposed, a control voltage source connected in series with the passive circuit element whose characteristics change due to the superposition of a DC current generates a difference voltage between the superimposed voltage and the unsupervised voltage generated in the passive circuit element when a DC current is superimposed, and the nonlinear characteristics of the inductor when a DC current is superimposed are simulated by superimposing the difference voltage on the unsuperimposed voltage (see, for example, Patent Document 3).

[0010] Furthermore, for example, a method for analyzing the circuit constants of an equivalent circuit model is disclosed, aimed at effectively suppressing the occurrence of errors between circuit design using a circuit simulator and actual circuit performance. Specifically, a series circuit of inductance L1 and resistance R1, considering the skin effect of the internal conductor, is connected in parallel with the mutual inductance Lm between the DC inductance L0 and inductance L1, and the DC resistance Rdc1 of the internal conductor is connected in series to this. Next, the parasitic inductance Ls of the external electrode is connected in series with the equivalent inductance L0, and the DC resistance Rdc2 of the external electrode is connected in series with the DC resistance Rdc1 of the internal conductor. In addition, an equivalent circuit model is used in which a series circuit in which parasitic capacitance Cp and resistance Rp representing the loss of the dielectric constituting the chip are connected in series is connected in parallel inside the equivalent elements Ls and Rdc2 of the external electrode (see, for example, Patent Document 4). [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2018-160132 [Patent Document 2] Japanese Patent Publication No. 2017-091346 [Patent Document 3] International Publication Number WO2014 / 185294 [Patent Document 4] Japanese Patent Publication No. 2010-204869 [Overview of the project] [Problems that the invention aims to solve]

[0012] The invention described in Patent Document 1 is characterized by its ability to accurately represent the characteristics when current or voltage is superimposed, by adding a power supply circuit that represents the characteristic change when current or voltage is superimposed, based on an equivalent circuit where current or voltage is in a reference state. To achieve this, a current sensor or voltage sensor is used to make it dependent on the current of the current source or the voltage of the voltage source, resulting in a complex configuration.

[0013] The invention described in Patent Document 2 is a simulation model for an inductor when a triangular wave current superimposed with a DC current flows, and is intended for simulation when a large amplitude current flows under certain conditions, such as in a power inductor used in a DC-DC converter, and is difficult to apply to the field of noise filters using magnetic cores such as ferrite cores.

[0014] The invention described in Patent Document 3 is a simulation method for inductors, specifically for inductors used in power supply circuits such as DC-DC converters. Therefore, its application to the noise filter field is difficult. The invention described in Patent Document 4 concerns a simulation method for multilayer chip inductors, and is difficult to apply to the field of noise filters.

[0015] When using magnetic cores such as ferrite cores as noise filters, an inductor is constructed by passing or winding wires around the magnetic core. It is known that the inductance of an inductor rapidly decreases when the DC saturation current is exceeded. When used as a noise filter, not only can the noise level and noise frequency not be set in advance, but the inductance (L) decreases as the current increases (DC superposition characteristic), and the core's permeability (μ) and saturation magnetic flux density (Bs) also change due to heat generation.

[0016] This invention provides a method for simulating with SPICE when using a magnetic core including a ferrite core as a noise filter. Magnetic core for noise filter Method for creating a DC superposition model and Magnetic core for noise filter The purpose is to present a method for providing the DC superposition model to users. [Means for solving the problem]

[0017] To solve the above-mentioned conventional problems, the present invention Magnetic core for noise filter The DC superposition model creation method is a method for creating a model for simulating the circuit characteristics when a DC superposition current is applied to a magnetic core used as a noise filter, using SPICE (Simulation Program with Integrated Circuit Emphasis), and the magnetic core is represented by an equivalent circuit using passive elements consisting of a resistor (R), an inductor (L), and a capacitor (C). Furthermore, a circuit model for use within SPICE was constructed, in which the values ​​of resistance (R) and capacitor (C) are determined using a table function with the DC superimposed current value as a variable, the inductor (L) is represented by a behavioral current source, and the DC superimposed current applied to the magnetic core is determined by a behavioral voltage source that acts as an ammeter. The provider's computer then... The frequency characteristics of the impedance are measured by changing the DC current when a DC current is superimposed, and the resistance value of the resistor (R), the inductance value of the inductor (L), and the capacitance value of the capacitor (C) are calculated from the frequency characteristics of the impedance at each DC current. 1 The steps and the element constants of the elements used in the DC superposition model are as follows: Calculated for each DC superimposed current Based on resistance, inductance, and capacitance values, a table function is used for resistance (R), capacitance (C), and inductance (L). Ensure that it does not contain undefined variables. The setting2 and the step of This process simulates the circuit characteristics when a DC superimposed current is applied. is characterized in that.

[0018] Furthermore, in the 1 step, The provider's computer, the resistance value may be calculated from the resistance value at the resonance frequency, the inductance value may be calculated from the slope on the low-frequency side of the resonance frequency, and the capacitance value may be calculated from the resonance frequency. Note that the method for obtaining the resistance value, inductance value, and capacitance value is not limited to the above and other methods may be used.

[0019] Also, in the above method, the magnetic core is composed of different materials and / or shapes In the case , The provider's computer and for each magnetic core composed of different materials and / or shapes, the 1 step and the 2 step may be performed to create a DC superposition model for each magnetic core composed of different materials and / or shapes. In the above, the expression "different materials and / or shapes" means the case where the materials are different, the case where the shapes are different, and the case where the materials and shapes are different from each other.

[0020] As the material of the magnetic core, ferrite is often used, but in addition, dust materials, amorphous, nanocrystals, etc. are also used as the core. Since their magnetic properties are different from each other, it is necessary to create a DC superposition model, especially a table function, individually. Also, since the magnetic properties of the magnetic core vary depending on the shape, for example, the ring diameter and width, etc., it may be necessary to create a DC superposition model, especially a table function, individually for these. However, when the shapes are different but the same resistance value, inductance value, and capacitance value can be used, the same DC superposition model may be used.

[0021] The inductance of a magnetic core decreases as the current increases; this is known as the DC superposition characteristic. Furthermore, as the current increases and heat is generated, the permeability and saturation magnetic flux density of the core change. Therefore, high accuracy cannot be obtained with static simulation methods. However, in the DC superposition model of the present invention, the table functions of resistance, inductance, and capacitance are set for the magnetic core based on measured data, making high-accuracy simulation possible even when the DC superposition current changes.

[0022] Next, the present invention Magnetic core for noise filter The method for providing a DC superposition model is a method for simulating the circuit characteristics when a DC superposition current is applied to a magnetic core used as a noise filter, using SPICE, wherein the magnetic core is represented by an equivalent circuit using passive elements consisting of a resistor (R), an inductor (L), and a capacitor (C). A circuit model for use within SPICE was constructed, in which the values ​​of resistance (R) and capacitor (C) are determined using a table function with the DC superimposed current value as a variable, the inductor (L) is represented by a behavioral current source, and the DC superimposed current applied to the magnetic core is determined by a behavioral voltage source that acts as an ammeter. The provider's computer then... The frequency characteristics of the impedance are measured by changing the DC current when a DC current is superimposed, and the resistance value of the resistor (R), the inductance value of the inductor (L), and the capacitance value of the capacitor (C) are calculated from the frequency characteristics of the impedance at each DC current, and these are used as the element constants of the elements used in the DC superposition model. Calculated for each DC superimposed current Based on resistance, inductance, and capacitance values, a table function is used for resistance (R), capacitance (C), and inductance (L). Ensure that it does not contain undefined variables. setting A DC superposition model is created to simulate the circuit characteristics when a DC superposition current is superimposed. Stores information about the step, the DC superposition model, and the magnetic core. B The steps and information regarding the magnetic core will be made public via the internet. C If a user who performs noise reduction using a magnetic core after completing the steps wishes to obtain information about the magnetic core, The user's computer I would like to access information about magnetic cores via the internet and obtain that information. If the user enters the information into the provider's computer, the provider's computer will request user registration from the user's computer, and once user registration is completed from the user's computer, the provider's computer will then... In contrast, it is characterized by allowing the download of information regarding magnetic cores, including DC superposition models.

[0023] Furthermore, in calculating resistance, inductance, and capacitance values, The provider's computer, The resistance value may be calculated from the resistance value at the resonant frequency, the inductance value from the slope on the low-frequency side of the resonant frequency, and the capacitance value from the resonant frequency.

[0024] Furthermore, if the magnetic core is composed of different materials and / or shapes, The provider's computer The above A In the first step, resistance, inductance, and capacitance values ​​are calculated for each magnetic core composed of different materials and / or shapes, and a DC superposition model is created for each magnetic core composed of different materials and / or shapes. In step B, Information regarding these DC superposition models and magnetic cores may be stored.

[0025] By using the above provision method, the provider of the magnetic core can represent the magnetic core, which functions as an inductor, with a behavioral power supply. The provider's computer By setting table functions based on measured values ​​for resistance, inductance, and capacitor represented by the equivalent circuit, high-precision simulations can be performed even when the DC superimposed current changes. As a result, the user The computer on the other side This allows for easy circuit simulation using SPICE in simulations involving magnetic cores. [Effects of the Invention]

[0026] The method for providing a simulation model of a magnetic core according to the present invention can be widely used by users who perform noise countermeasures using magnetic cores, and will have a significant effect in various noise countermeasure fields. [Brief explanation of the drawing]

[0027] [Figure 1] This figure shows the equivalent circuit of the magnetic core according to this embodiment. [Figure 2]This diagram shows the basic circuit configuration of a magnetic core that functions as an inductor. [Figure 3] This figure shows the first basic model used to mathematically demonstrate that the DC superposition model shown in Figure 5 is valid. [Figure 4] This figure shows a second basic model used to mathematically demonstrate that the DC superposition model shown in Figure 5 is valid. [Figure 5] This diagram illustrates a method for determining the table function of a DC superposition model. (a) shows the resistance, inductance, and capacitance values ​​that change with the DC superposition current in the equivalent circuit, and (b) is a diagram illustrating the DC superposition model and its table function. [Figure 6] Figure 5 shows the frequency characteristics of each impedance in the equivalent circuit and the simulation results of the impedance frequency characteristics obtained by setting a table function in the DC superposition model. (a) is the simulation result obtained in Figure 5(a), and (b) is the simulation result obtained using the DC superposition model in Figure 5(b). [Figure 7] This is the result of determining the correlation between frequency and impedance using the DC superposition model of the present invention, with the DC superposition current as a parameter. [Figure 8] Figure 7 shows the device configuration used to obtain the measured values. [Figure 9] This shows the result of determining the change in inductance (Ls) due to DC superimposed current when using a MnZn core (E04RM251512: manufactured by Seiwa Electric Co., Ltd.) as the magnetic core. [Figure 10] This shows the result of determining the change in inductance (Ls) due to DC superimposed current when using a nanocrystal core (E04RK254015: manufactured by Seiwa Electric Co., Ltd.). [Figure 11] This is a simple diagram illustrating a configuration in which a user places a magnetic core model between an inverter (INV) and a motor (Motor) as a noise countermeasure in a power circuit and evaluates its noise characteristics. [Figure 12]This diagram shows the steps for a user to download a DC superposition model of a magnetic core, incorporate it into a circuit they are designing, and simulate it. [Modes for carrying out the invention]

[0028] (Embodiment) A method for creating a DC superposition model and a method for providing a DC superposition model according to embodiments of the present invention will be described in detail.

[0029] Figure 1 shows the equivalent circuit of the magnetic core according to this embodiment. In Figure 1, L1 is the inductor of the magnetic core, C1 is the capacitor representing the parasitic capacitance of the magnetic core, and R1 and R2 are the resistive components of the magnetic core. Figure 2 shows the basic circuit configuration of a magnetic core that functions as an inductor. Figure 3 shows the first basic model used to mathematically demonstrate that the DC superposition model shown in Figure 5 is valid. Figure 4 shows a second basic model used to mathematically demonstrate that the DC superposition model shown in Figure 5 is valid.

[0030] Figure 5 illustrates a method for determining the table function of the DC superposition model. (a) shows the resistance, inductance, and capacitance values ​​that change with the DC superposition current in the equivalent circuit, and (b) is a diagram illustrating the DC superposition model and the table function. The method for creating a DC superposition model according to this embodiment will be described in detail below using these figures.

[0031] relating to this embodiment Magnetic core for noise filter The DC superposition model creation method is a method for creating a model for simulating the circuit characteristics when a DC superposition current is applied to a magnetic core used as a noise filter, using SPICE, wherein the magnetic core is represented by an equivalent circuit using passive elements consisting of a resistor (R), an inductor (L), and a capacitor (C). The circuit model used within SPICE is constructed in which the values ​​of resistor (R) and capacitor (C) are determined using a table function with the DC superimposed current value as a variable, the inductor (L) is represented by a behavioral current source, and the DC superimposed current applied to the magnetic core is determined by a behavioral voltage source that acts as an ammeter. The provider's computer then...The frequency characteristics of the impedance are measured by varying the DC current when a DC current is superimposed, and the resistance value of the resistor (R), the inductance value of the inductor (L), and the capacitance value of the capacitor (C) are calculated from the frequency characteristics of the impedance at each DC current. 1 The steps and the element constants of the elements used in the DC superposition model are as follows: Calculated for each DC superimposed current Based on resistance, inductance, and capacitance values, a table function is used for resistance (R), capacitance (C), and inductance (L). Ensure that it does not contain undefined variables. The setting 2 The steps and This process simulates the circuit characteristics when a DC superimposed current is applied. It is characterized by the following:

[0032] In this embodiment, the first method described above is 1 In the step, The provider's computer, The resistance value is calculated from the resistance value at the resonant frequency, the inductance value is calculated from the slope on the low-frequency side of the resonant frequency, and the capacitance value is calculated from the resonant frequency. However, the method for determining the resistance value, inductance value, and capacitance value is not limited to the above and other methods may be used. Also, although there are various types of magnetic cores with different materials and shapes, this embodiment will describe the case using a ferrite core as an example. The following explains in detail how to create and provide the simulation model.

[0033] The characteristics of a magnetic core can be represented by an equivalent circuit using passive elements R, L, and C, as shown in Figure 1. However, even if a simulation is performed using LT-SPICE with DC superimposed on the magnetic core using such an equivalent circuit, only static characteristics can be represented if the constants of the R, L, and C elements are set to constant values. However, since the characteristics of a magnetic core change with current, this equivalent circuit cannot provide an accurate evaluation.

[0034] Therefore, as shown in Figure 5(b), we constructed a DC superposition model incorporating a behavioral power supply and decided to use a table function with measured values ​​for the element constants of the passive elements. Below, the validity of this DC superposition model will be explained using mathematical formulas based on the first basic model shown in Figure 3. (First basic model)

[0035] The magnetic core used for noise suppression acts as an inductor, either by passing a wire through it or winding it around it. The basic circuit configuration is shown in Figure 2. Figure 3 shows the first basic model of the DC superposition model shown in Figure 5(b). In the DC superposition model shown in Figure 5(b), a behavioral voltage source (V0) is placed and used as an ammeter, so that the table function does not contain undefined variables, eliminating the need for the user to set variables each time. In addition, the inductor, which is the magnetic core, is represented as a behavioral current source, so that the user can respond to the DC current superposition by using the set table function without having to worry about variables.

[0036] In Figure 2, when DC is applied to the inductor (L1), the voltage (VL) across the inductor is proportional to the rate of change of the current (ΔIL / Δt), and is expressed by Equation 1.

[0037]

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[0038] In Figure 3, B1 and B2 are behavioral voltage sources; B1 outputs VL, and B2 outputs v2 depending on V. B3 is a behavioral current source. In this case, VL is represented by equation 2.

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[0042] Here, R3 in Figure 3 is set to 1 mΩ, which is a very small value, so it can be approximated as 0. In that case, R3iL can be considered as 0. Also, since L1 is set to a constant of 1 (H), 1 / L1 = 1 in equation 4. Therefore, equation 4 is finally obtained. Next, since i and iL shown in Figure 3 are the same, equation 5 holds true.

[0043]

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[0048] From the above results, we can make equation 3 true by outputting the value obtained from B2 using equation 10. Therefore, we can simulate the magnetic core constituting the inductor using the first basic model shown in Figure 3.

[0049]

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[0050] The second basic model is shown in Figure 4. Compared to the first basic model shown in Figure 3, the second basic model shown in Figure 4 consists of a behavioral voltage source B3 and a behavioral current source B2. The output VL1 of the behavioral power supply B1 can be expressed in the same way as in the first basic model. This is shown in Equation 11.

[0051]

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[0052] For the behavioral power supply B3 shown in Figure 4 to behave as an inductor with inductance (f(i)), it is required to satisfy equation 12 from equation 1. This is the same as the first SPICE model.

[0053]

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[0054] Next, we will explain how using the second basic model yields a formula equivalent to equation 12. Using equation 1 obtained from Figure 2, the inductor (L1) can be represented by equation 13.

[0055]

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[0060] As shown in Figure 1, the magnetic core was represented by an equivalent circuit using passive elements consisting of a resistor (R), an inductor (L), and a capacitor (C). Next, the frequency characteristics of the impedance were measured by varying the DC current when a DC current was superimposed on the magnetic core, and the resistance, inductance, and capacitance values ​​were calculated from the frequency characteristics of the impedance at each DC current. In this embodiment, the resistance value was calculated from the resistance value at the resonant frequency, the inductance value was calculated from the slope on the low-frequency side of the resonant frequency, and the capacitance value was calculated from the resonant frequency.

[0061] Figure 5 shows specific examples of resistance, inductance, and capacitance values ​​calculated according to the superimposed DC current. In Figure 5, (a-1) is the case when the superimposed DC current is 0A, (a-2) is the case when the superimposed DC current is 1A, (a-3) is the case when the superimposed DC current is 5A, and (a-4) is the case when the superimposed DC current is 10A. For example, in (a-1) when the superimposed DC current is 0A, R1=37.8Ω, R2=41.3Ω, C1 (capacitance value)=1.3nF, and L1 (inductance value)=6.7μH. In (a-4) when the superimposed DC current is 10A, R7=17.3Ω, R8=22.6Ω, C4 (capacitance value)=1.5nF, and L1 (inductance value)=0.16μH. Thus, as the DC superimposed current increases, the resistance and inductance values ​​decrease, but the capacitance value does not change much. Note that the equivalent circuits for resistance, inductance, and capacitance are the same, but their values ​​differ depending on the DC superimposed current, so they are distinguished by their signs.

[0062] Figure 5(b) is a DC superposition model based on the first basic model. In this DC superposition model, the table function is set based on the values ​​obtained in Figure 5(a). The capacitance value of C5 is shown in Equation 18. The values ​​of R9 and R10 are shown in Equations 19 and 20. The output of B1 is shown in Equation 21.

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[0067] By using the equivalent circuit to determine the values ​​for each DC current, creating table functions using these values, and setting table functions (Equations 18-21) when running this DC superposition model in SPICE, it became possible to perform accurate simulations even when a DC superposition current is applied.

[0068] Figure 6 shows the simulation results for the frequency characteristics of each impedance in the equivalent circuit shown in Figure 5, and the frequency characteristics of the impedance obtained by setting a table function in the DC superposition model. Figure 6(a) shows the simulation results obtained in Figure 5(a), and Figure 6(b) shows the simulation results obtained using the DC superposition model in Figure 5(b). Both show similar behavior, and it was confirmed that the DC superposition model can provide sufficiently high-accuracy simulations even when the DC superposition current changes.

[0069] In Figure 5(a), the DC currents are set to 0A, 1A, 5A, and 10A, but in practice, it is preferable to apply a wider range of current values ​​to obtain the values ​​and reflect them in the table function. Furthermore, it is preferable to extend the maximum current value to an even wider range. (Comparison of simulation results and actual measurements)

[0070] Figure 7 shows the results of determining the correlation between frequency and impedance using the DC superposition model of the present invention, with the DC superposition current as a parameter. A MnZn core (E04RM251512: manufactured by Seiwa Electric Co., Ltd.) was used as the magnetic core. The simulation is displayed using SIM, and the measured values ​​are displayed using MEAS. (a) shows the results when the DC superposition current is 0A, (b) is 1A, (c) is 5A, (d) is 8A, (e) is 10A, and (f) is 15A. It can be seen that the measured values ​​and the simulation values ​​using the DC superposition model agree well even when the DC superposition current changes from 1A to 15A. The measured values ​​were measured using the apparatus configuration shown in Figure 8.

[0071] Figure 9 shows the results of determining the change in inductance (Ls) due to DC superimposed current when using a MnZn core (E04RM251512: manufactured by Seiwa Electric Co., Ltd.) as the magnetic core. (a) shows the case when the frequency is 10 kHz, and (b) shows the case when the frequency is 100 kHz. The simulation is displayed using SIM, and the measured values ​​are displayed using MEAS. As can be seen from the figure, the simulation data and measured values ​​show good agreement up to a DC superimposed current of 15 A.

[0072] Figure 10 shows the results of determining the change in inductance (Ls) due to DC superimposed current when using a nanocrystal core (E04RK254015: manufactured by Seiwa Electric Co., Ltd.). (a) shows the case when the frequency is 10 kHz, and (b) shows the case when the frequency is 100 kHz. The simulation is displayed using SIM, and the measured values ​​are displayed using MEAS. As can be seen from the figure, the simulation data and measured values ​​show good agreement up to a DC superimposed current of 2 A. As described above, the simulation model of the present invention shows good agreement with measured values ​​for a magnetic core superimposed with a DC current. (Method for providing a DC superposition model)

[0073] The method for providing a DC superposition model for magnetic cores is a method for simulating the circuit characteristics when a DC superposition current is applied to a magnetic core used as a noise filter, using SPICE.

[0074] Specifically, the magnetic core is represented by an equivalent circuit using passive elements consisting of a resistor (R), an inductor (L), and a capacitor (C). The circuit model used within SPICE is constructed in which the values ​​of resistor (R) and capacitor (C) are determined using a table function with the DC superimposed current value as a variable, the inductor (L) is represented by a behavioral current source, and the DC superimposed current applied to the magnetic core is determined by a behavioral voltage source that acts as an ammeter. The provider's computer then... The frequency characteristics of the impedance are measured by varying the DC current when a DC current is superimposed, and the resistance, inductance, and capacitance values ​​are calculated from the frequency characteristics of the impedance at each DC current. Next, the element constants of the elements used in the DC superposition model are determined as follows: Calculated for each DC superimposed current Based on resistance, inductance, and capacitance values, a table function is used for resistance (R), capacitance (C), and inductance (L). Ensure that it does not contain undefined variables. setting Then, simulate the circuit characteristics when a DC superimposed current is applied. Create a DC superposition model. Next, we store information about the created DC superposition model and magnetic core.

[0075] moreover, Provider side computer teeth, Information regarding magnetic cores will be made publicly available via the internet. In this case, the information regarding magnetic cores includes data necessary for users to select a magnetic core, such as frequency bandwidth, availability of a DC superposition model compatible with SPICE, impedance map, applicable cable diameter, and product shape.

[0076] Next, if a user who uses magnetic cores for noise reduction wants to obtain information about magnetic cores... The user's computer I would like to access information about magnetic cores via the internet and obtain that information. If the user enters the information into the provider's computer, the provider's computer will request user registration from the user's computer, and once user registration is completed from the user's computer, the provider's computer will then request user registration from the user's computer. It is preferable to allow the download of information regarding magnetic cores, including the DC superposition model.

[0077] This allows the user to select the optimal magnetic core from the information related to the magnetic core, download the DC superposition model for that magnetic core, incorporate it into the circuit they intend to design, and perform a simulation. The DC superposition model of the magnetic core in this invention has a table function set up, and since there is no need to deal with undefined variables, simulation can be easily performed.

[0078] The computer used in this embodiment may be a regular personal computer. However, in this case, since it is necessary to store a large amount of information about magnetic cores, it is preferable to store this information on a server and allow the computer to access the server. A regular personal computer can also be used by the user.

[0079] This document describes an example of using the DC superposition model of the present invention using SPICE. Figure 11 is a simple configuration diagram in which a user places a magnetic core model between an inverter (INV) and a motor (Motor) as a noise countermeasure in a power circuit and evaluates its noise characteristics. In such a case, the user downloads the DC superposition model of the magnetic core using the procedure shown in Figure 12, incorporates it into the circuit to be designed, and simulates it. First, the user downloads the SPICE software from the internet. Next, the downloaded SPICE software and symbols are stored in a designated folder in LTspice. Then, the DC superposition model of the present invention is placed in the circuit to be simulated. After this state is reached, the circuit simulation is started. This allows the user to very easily simulate noise countermeasures using a magnetic core.

[0080] Furthermore, in calculating resistance, inductance, and capacitance values, the resistance value may be calculated from the resistance value at the resonant frequency, the inductance value from the slope on the low-frequency side of the resonant frequency, and the capacitance value from the resonant frequency. However, this is not the only way to do so.

[0081] Furthermore, if the magnetic core is composed of different materials and / or shapes, The provider's computer is A In the first step, resistance, inductance, and capacitance values ​​are calculated for each magnetic core composed of different materials and / or shapes, and a DC superposition model is created for each different material and / or magnetic core. In step B, The system may also store information about the DC superposition model and the magnetic core.

[0082] In addition to LTspice (Analog Devices), which was used in this invention, other circuit simulators such as Pspice (Texas Instruments), ADC (Keysight Advanced Design Systems), CST (AET), Ansys (Ansys), QucsStudio (developer: Michael Margraf), and MicroCAP (Toyo Technica) are also available, and this invention can be applied to these as well. [Industrial applicability]

[0083] The method for creating a simulation model of a magnetic core and the method for providing such a simulation model according to the present invention will have a significant effect on electrical and electronic fields where noise countermeasures are required, such as power supply circuits, motor drive circuits, and high-frequency circuits. [Explanation of symbols]

[0084] C1 Capacitor R1, R2, R resistance L1 Inductor (1H) SW Switch IL current VL Voltage B1, B2, B3 Behavioral Power Supply i, iL current R3 resistance (1mΩ) C1, C2, C3, C4, C5 Capacitors R1, R2, R3, R4, R5, R6, R7, R8, R9, R10 resistance L1, L2, L3, L4 Inductors L6 Inductor (1H) INV Inverter Motor

Claims

1. A method for creating a DC superposition model for simulating the circuit characteristics when a DC superposition current is applied to a magnetic core used as a noise filter, using SPICE (Simulation Program with Integrated Circuit Emphasis), A circuit model for use within SPICE is constructed, in which the magnetic core is represented by an equivalent circuit using passive elements consisting of a resistor (R), an inductor (L), and a capacitor (C), the values ​​of the resistor (R) and the capacitor (C) are determined using a table function with the DC superimposed current value as a variable, the inductor (L) is represented by a behavioral current source, and the DC superimposed current applied to the magnetic core is determined by a behavioral voltage source that operates as an ammeter. The provider's computer, The first step involves varying the DC current when a DC current is superimposed and measuring the frequency characteristics of the impedance, and calculating the resistance value of the resistor (R), the inductance value of the inductor (L), and the capacitance value of the capacitor (C) from the frequency characteristics of the impedance at each DC current. A method for creating a DC superposition model for a magnetic core for a noise filter, characterized by performing a second step of setting the resistance (R), capacitor (C), and inductor (L) values ​​in the table function so as element constants for the elements used in the DC superposition model, based on the resistance value, inductance value, and capacitance value calculated for each DC superposition current, so as not to include any undefined variables, and simulating the circuit characteristics when a DC superposition current is superimposed.

2. In the first step described above, The method for creating a DC superposition model of a magnetic core for a noise filter according to claim 1, characterized in that the computer on the providing side calculates the resistance value from the resistance value at the resonant frequency, the inductance value from the slope on the low-frequency side of the resonant frequency, and the capacitance value from the resonant frequency.

3. If the magnetic core is composed of different materials and / or shapes, The method for creating a DC superposition model of a magnetic core for a noise filter according to claim 1, characterized in that the computer on the providing side performs the first step and the second step for each of the magnetic cores made of different materials and / or shapes to create a DC superposition model for each of the magnetic cores made of different materials and / or shapes.

4. A method for providing a DC superposition model for simulating the circuit characteristics when a DC superposition current is applied to a magnetic core used as a noise filter, using SPICE (Simulation Program with Integrated Circuit Emphasis), A circuit model for use within SPICE is constructed, in which the magnetic core is represented by an equivalent circuit using passive elements consisting of a resistor (R), an inductor (L), and a capacitor (C), the values ​​of the resistor (R) and the capacitor (C) are determined using a table function with the DC superimposed current value as a variable, the inductor (L) is represented by a behavioral current source, and the DC superimposed current applied to the magnetic core is determined by a behavioral voltage source that operates as an ammeter. The provider's computer, The frequency characteristics of the impedance are measured by changing the DC current when a DC current is superimposed, and the resistance value of the resistor (R), the inductance value of the inductor (L), and the capacitance value of the capacitor (C) are calculated from the frequency characteristics of the impedance at each DC current. Step A involves creating a DC superposition model that simulates the circuit characteristics when a DC superposition current is superimposed, by setting the element constants of the elements used in the DC superposition model so that the table function does not contain any undefined variables for the resistor (R), capacitor (C), and inductor (L), based on the resistance, inductance, and capacitance values ​​calculated for each DC superposition current, and Step B involves storing information about the DC superposition model and the magnetic core, Step C is performed, in which information regarding the aforementioned magnetic core is made public via the internet. If a user who uses the magnetic core to perform noise countermeasures wishes to obtain information about the magnetic core, If the user's computer accesses information about the magnetic core via the internet and inputs a request to the provider's computer to obtain the information, A method for providing a DC superposition model of a magnetic core for a noise filter, characterized in that the provider's computer requests user registration from the user's computer, and when user registration is performed from the user's computer, the provider's computer allows the user's computer to download information about the magnetic core, including the DC superposition model of the magnetic core for the noise filter.

5. In calculating the aforementioned resistance value, inductance value, and capacitance value, The method for providing a DC superposition model of a magnetic core for a noise filter according to claim 4, characterized in that the computer on the providing side calculates the resistance value from the resistance value at the resonant frequency, the inductance value from the slope on the low-frequency side of the resonant frequency, and the capacitance value from the resonant frequency.

6. If the magnetic core is composed of different materials and / or shapes, The aforementioned provider's computer, In step A, the resistance, inductance, and capacitance values ​​are calculated for each magnetic core composed of different materials and / or shapes, and a DC superposition model is created for each magnetic core composed of different materials and / or shapes. The method for providing a DC superposition model for a magnetic core for a noise filter according to claim 4, characterized in that, in step B, information relating to the DC superposition model and the magnetic core is stored.

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