Method and apparatus for measuring magnetic properties

Abstract

The present invention provides a magnetic properties measurement method and a magnetic properties measurement apparatus that can determine either or both of the magnetic permeability (true magnetic permeability) and iron loss (true iron loss) of a sample under test when the capacitance of the input section of the voltage measurement circuit of the magnetic properties measurement apparatus is zero. [Solution] Based on the voltage measured by the voltage measurement circuit 32 and the current measured by the current measurement circuit 8, the control calculation unit 9 acquires at least two or more permeability values ​​and at least two or more iron losses of the sample under test 2, corresponding to at least two or more set values ​​of the variable capacitor 33, or both. By extrapolating the acquired numerical data of at least two or more permeability values ​​and at least two or more iron losses, the control calculation unit 9 calculates the capacitance C, including the parasitic capacitance of the input section of the voltage measurement circuit 32. m and the capacitance C of the variable capacitor 33 connected in parallel to the secondary winding 4. n Determine either the permeability and / or iron loss of the sample 2 under measurement when the sum of the two is zero.

Description

[Technical Field]

[0001] This invention relates to a method for measuring magnetic properties and a device for measuring magnetic properties. [Background technology]

[0002] Soft magnetic materials are widely used in electrical equipment as the core of coil components such as motors, transformers, and inductors. To measure the magnetic properties such as permeability and iron loss of soft magnetic materials and magnetic components such as coils using them, the two-coil method, which measures the magnetic properties of the magnetic material with primary and secondary windings or the soft magnetic material sample to be measured, is widely employed (for example, Patent Document 1).

[0003] Figure 1 is a block diagram illustrating the schematic configuration of a conventional magnetic property measuring device that measures magnetic properties using the two-coil method. In the magnetic property measuring device 1 shown in Figure 1, a toroidal (ring-shaped) sample 2 made of a soft magnetic material to be measured has a primary winding 3 with N1 windings that functions as an excitation winding and a secondary winding 4 with N2 windings that functions as an induced voltage detection winding.

[0004] The magnetic properties measuring device 1 is connected to a signal generator 5 and includes a shunt resistor 6, a voltage measuring circuit 7, a current measuring circuit 8, and a control calculation unit 9.

[0005] The signal generator 5 supplies an excitation current (AC current) to the primary winding 3 at a measurement frequency f. By flowing the excitation current through the primary winding 3, a voltage is induced across the ends of the secondary winding 4. The shunt resistor 6 is connected in series with the primary winding 3, and both ends of the shunt resistor 6 are connected to the current measurement circuit 8, and it has a resistance value of r.

[0006] The voltage measurement circuit 7 is connected in parallel to the secondary winding 4 and measures the voltage induced across the secondary winding 4 when an excitation current is passed through the primary winding 3, thereby inducing a voltage across the secondary winding 4. The voltage measurement circuit 7 includes an amplifier 11, an AD converter 12, and a memory 12.

[0007] One input of amplifier 11 is connected to one end, and the other input of amplifier 11 is connected to the other end of the secondary winding 4. The input of AD converter 12 is connected to the output of amplifier 11. Memory 12 is connected to the output of AD converter 12 and the control calculation unit 9, and stores the digital data of the voltage induced between the two ends of the secondary winding 4.

[0008] The portion of the conductor 14 between one input of the amplifier 11 and one end of the secondary winding 4, and the portion of the conductor 15 between the other input of the amplifier 11 and the other end of the secondary winding 4 that is included in the voltage measurement circuit 7, form the input of the voltage measurement circuit 7.

[0009] The input section of the voltage measurement circuit 7 has a unique capacitance C greater than zero. m and a predetermined resistance R greater than zero m This occurs. More specifically, capacitance C occurs between the conductors 14 and 15 at the input of the voltage measurement circuit 7. m and resistor R m This occurs. Capacitance C m This includes parasitic capacitance unintended in the circuit design of the voltage measurement circuit 7.

[0010] The current measurement circuit 8 measures the current flowing through the shunt resistor 6 when an excitation current is passed through the primary winding 3, which induces a voltage across the terminals of the secondary winding 4. The current flowing through the shunt resistor 6 corresponds to the current i1(t) flowing through the primary winding 3. The current measurement circuit 8 includes an amplifier 21, an AD converter 22, a divider 23, and a memory 24.

[0011] One input of amplifier 21 is connected to one end of shunt resistor 6, and the other input of amplifier 21 is connected to the other end of shunt resistor 6. The input of AD converter 22 is connected to the output of amplifier 21. Divide 23 divides the voltage across the shunt resistor 6 supplied from the output of AD converter 22 by the resistance value r of the shunt resistor 6. Memory 24 is connected to the output of divider 23 and control calculation unit 9, and stores the digital data of the current flowing through the primary winding 3 obtained by dividing the voltage across the shunt resistor 6 by the resistance value r of the shunt resistor 6.

[0012] The control arithmetic unit 9 has a CPU, a memory, etc., controls the voltage measurement circuit 7 and the current measurement circuit 8, performs data storage and data processing such as numerical calculations, and calculates the magnetic permeability and iron loss of the measured sample 2. Specifically, the control arithmetic unit 9 reads out the digital data stored in the memory 13 and the digital data stored in the memory 24, and obtains one or both of the magnetic permeability and iron loss of the measured sample 2 based on these digital data.

[0013] In the magnetic characteristic measuring apparatus 1 of FIG. 1, a resonance circuit is constituted by an inductance and a capacitance. FIG. 2 is a block diagram showing the resonance circuit constituted by an inductance and a capacitance in the magnetic characteristic measuring apparatus of FIG. 1. When the parasitic capacitance between the primary winding 3 and the secondary winding 4 is C w and the inductance of the primary winding 3 is L1, the equivalent circuit seen from the primary winding 3 side in FIG. 2 is represented by FIG. 3.

[0014] The resonance frequency f m determined by the inductance L2 and the capacitance C C of the secondary winding 4 is calculated by the following formula (1). (For example, Non-Patent Document 1).

Equation

[0015] When a current flows through the secondary winding 4, accurate measurement of the magnetic permeability and iron loss of the measured sample 2 becomes impossible due to the influence of the magnetic field generated by the current. When the measurement frequency f coincides with the resonance frequency f C the current flowing through the secondary winding 4 becomes maximum. The influence of the current flowing through the secondary winding 4 on the measurement results of the magnetic permeability and iron loss of the measured sample 2 becomes particularly significant.

[0016] The two-coil method for measuring the permeability and iron loss of sample 2 assumes that there is no current flowing through the secondary winding 4 and that the secondary winding 4 does not generate a magnetic field inside sample 2. If current flows through the secondary winding 4 and a magnetic field is generated inside sample 2, accurate measurement of the permeability and iron loss of sample 2 cannot be performed.

[0017] The measured frequency f is the resonant frequency f C As the frequency decreases below a certain level, the current flowing through the secondary winding 4 decreases, and the effect of the magnetic field generated by the current flowing through the secondary winding 4 decreases. Generally, the measurement frequency f is equal to the resonant frequency f. C If it is less than 1 / 10 of this value, the current flowing through the secondary winding 4 becomes small, and it is said that the effect on the measurement results of the permeability and iron loss of the sample 2 under test becomes negligible. Therefore, the resonant frequency f C It is recommended to determine the permeability and iron loss of the sample under test 2 using an excitation current with a measurement frequency f that is 1 / 10 or less of the above (for example, Non-Patent Document 1).

[0018] In recent years, the increasing demand for miniaturization and power saving in devices has led to the use of higher frequencies in soft magnetic materials. In this context of increasing high frequencies in soft magnetic materials, the resonant frequency f C The limitation on the upper limit of the measurement frequency f, which is imposed by using an excitation current with a measurement frequency f that is less than 1 / 10 of the upper frequency, to determine the permeability and iron loss of the sample under test 2, is a major challenge.

[0019] In equation (1), capacitance C m This value is specific to the magnetic property measuring device 1 and therefore cannot be changed. Thus, the resonant frequency f C Methods to increase this include reducing the number of turns N2 in the secondary winding 4 and reducing the parasitic capacitance C w There is a way to make it smaller.

[0020] Figure 4 is a diagram illustrating the inductance of the secondary winding wound around a toroidal sample under test. When the permeability of the sample under test 2 is μ, the inductance L2 of the secondary winding 4 can be expressed by the following equation (2) (for example, Non-Patent Document 1).

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[0021] In equation (2), the magnetic permeability μ of the sample under test 2 cannot be changed because it is a value unique to the sample under test 2. Therefore, methods to reduce the inductance L2 of the secondary winding 4 include reducing the number of turns N2 of the secondary winding 4, reducing the thickness h of the sample under test 2, and reducing the ratio a / b of the inner and outer diameters of the sample under test 2.

[0022] resonance frequency f C As a method to increase the magnetic permeability, the inductance L2 is usually reduced by decreasing the number of turns N2 of the secondary winding 4, for ease of implementation. However, it has been reported that when the number of turns N2 of the secondary winding 4 is reduced, the variation in the measurement of the magnetic permeability and iron loss of the sample under test 2 increases (for example, Non-Patent Literature 2). [Prior art documents] [Patent Documents]

[0023] [Patent Document 1] Special Publication No. 3-221886

[0024] [Non-Patent Document 1] Development of high-output motors and related materials for next-generation EVs / HEVs, Technical Information Association, January 31, 2022 (1st edition), Chapter 10, Section 2, pp. 570-577. [Non-Patent Document 2] Yamamoto, Narita, Ishiyama, Transactions of the Institute of Electrical Engineers of Japan, Vol. 143, No. 6, pp. 216-221 (2023) [Overview of the project] [Problems that the invention aims to solve]

[0025] As mentioned above, when the measurement frequency is 1 / 10 or less of the resonant frequency, the current flowing through the secondary winding becomes small, and it is said that the effect on the measurement results of the permeability and iron loss of the sample under test becomes negligible. However, in reality, minute measurement errors occur in the measurement of the permeability and iron loss of the sample under test due to the current flowing through the secondary winding via the capacitance of the input section of the voltage measurement circuit of the magnetic property measuring device. Since the measurement errors in the measurement of the permeability and iron loss of the sample under test are caused by the capacitance of the input section of the voltage measurement circuit of the magnetic property measuring device, in order to eliminate the measurement errors in the measurement of the permeability and iron loss of the sample under test, it is necessary to set the capacitance of the input section of the voltage measurement circuit of the magnetic property measuring device to zero. However, as mentioned above, the capacitance of the input section of the voltage measurement circuit of the magnetic property measuring device includes parasitic capacitance that is not intended in the circuit design, so it is difficult to set the capacitance of the input section of the voltage measurement circuit of the magnetic property measuring device to zero. Therefore, it is difficult to determine either or both of the permeability (true permeability) and iron loss (true iron loss) of the sample under test when the capacitance of the input section of the voltage measurement circuit of the magnetic property measuring device is zero.

[0026] The object of the present invention is to provide a magnetic properties measurement method and a magnetic properties measurement apparatus that can determine one or both of the magnetic permeability (true magnetic permeability) and iron loss (true iron loss) of a sample under test when the capacitance of the input section of the voltage measurement circuit of the magnetic properties measurement apparatus is zero. [Means for solving the problem]

[0027] The magnetic properties measurement method according to the present invention is a method for measuring the magnetic properties of a sample under test, which is wound with a primary winding of a first number of turns and a secondary winding of a second number of turns. Each time the capacitance of a variable capacitance unit connected in parallel to the secondary winding is switched to at least two different set values, an excitation current of a predetermined frequency is supplied from a signal generator to the primary winding, thereby maintaining the maximum magnetic flux density or maximum magnetic field of the sample under test at a predetermined value and inducing a voltage across the ends of the secondary winding. At that time, a voltage measurement circuit connected in parallel to the secondary winding measures the voltage induced across the ends of the secondary winding. The current measurement circuit measures the current flowing through the primary winding, and the control calculation unit acquires, based on the voltage and current, one or both of at least two permeability values ​​and at least two iron losses of the sample under test corresponding to at least two set values, respectively. The control calculation unit also performs an extrapolation step in which it determines, by extrapolating numerical data of one or both of at least two permeability values ​​and at least two iron losses, the case in which the sum of the capacitance including the parasitic capacitance of the input part of the voltage measurement circuit and the capacitance of the variable capacitance part is zero.

[0028] Preferably, the acquisition step includes a preparation step of switching the capacitance of the variable capacitance unit to a setting value to be switched from at least two or more set values ​​in preparation for measuring voltage by a voltage measurement circuit and measuring current by a current measurement circuit, and a calculation step in which, with the capacitance of the variable capacitance unit switched to the setting value to be switched, the voltage measurement circuit measures the voltage and the current measurement circuit measures the current, and the control calculation unit calculates one or both of the permeability and iron loss of the sample to be measured corresponding to the setting value to be switched, based on the voltage and current, and the preparation step and the calculation step are repeated until the capacitance of the variable capacitance unit is switched to all of at least two or more set values. Preferably, the control calculation unit performs the extrapolation step.

[0029] The magnetic properties measuring device according to the present invention is a magnetic properties measuring device for measuring the magnetic properties of a sample under test, which has a primary winding of a first number of turns and a secondary winding of a second number of turns wound around it, comprising: a variable capacitance unit connected in parallel to the secondary winding and having capacitances that can be switched to at least two different set values; a voltage measuring circuit connected in parallel to the secondary winding, which, each time the capacitance of the variable capacitance unit is switched to at least two different set values, supplies an excitation current of a predetermined frequency from a signal generator to the primary winding, thereby maintaining the maximum magnetic flux density or maximum magnetic field of the sample under test at a predetermined value and measuring the voltage induced between the ends of the secondary winding when a voltage is induced between the ends of the secondary winding; and the capacitance of the variable capacitance unit has at least two or more set values The device is characterized by comprising: a current measurement circuit that measures the current flowing through the primary winding when an excitation current is supplied from a signal generator to the primary winding each time the set value is switched, thereby maintaining the magnetic flux density or magnetic field of the sample under test at a predetermined value and inducing a voltage across the ends of the secondary winding; and a control calculation unit that, based on the voltage and current, acquires one or both of at least two permeability values ​​and at least two iron losses of the sample under test corresponding to at least two set values, and extrapolates the numerical data of at least two permeability values ​​and at least two iron losses to determine one or both of the permeability values ​​and iron losses of the sample under test when the sum of the capacitance including the parasitic capacitance of the input section of the voltage measurement circuit and the capacitance of the variable capacitance section is zero.

[0030] Preferably, in preparation for measuring voltage by the voltage measurement circuit and measuring current by the current measurement circuit, the capacitance of the variable capacitance unit is switched to a setting value to be switched from at least two or more set values. With the capacitance of the variable capacitance unit switched to the setting value to be switched, the voltage measurement circuit measures the voltage and the current measurement circuit measures the current. The control calculation unit calculates one or both of the permeability and iron loss of the sample to be measured corresponding to the setting value to be switched, based on the voltage and current. The switching to the setting value to be switched and the calculation of one or both of the permeability and iron loss of the sample to be measured corresponding to the setting value to be switched are repeated until the capacitance of the variable capacitance unit is switched to all of at least two or more set values.

[0031] Preferably, the control calculation unit automatically performs at least one of the following: switching the capacitance of the variable capacitance unit to each of at least two or more set values; calculating one or both of the magnetic permeability and iron loss of the sample to be measured corresponding to the set value to be switched; and extrapolating numerical data. [Effects of the Invention]

[0032] The permeability of the sample under test when the sum of the capacitance including the parasitic capacitance of the input section of the voltage measurement circuit and the capacitance of the variable capacitance section is zero corresponds to the permeability of the sample under test when the capacitance including the parasitic capacitance of the input section of the voltage measurement circuit is zero (true permeability). Similarly, the iron loss when the sum of the capacitance including the parasitic capacitance of the input section of the voltage measurement circuit and the capacitance of the variable capacitance section is zero corresponds to the iron loss of the sample under test when the capacitance including the parasitic capacitance of the input section of the voltage measurement circuit is zero (true iron loss). Therefore, according to the present invention, it is possible to determine either or both of the permeability (true permeability) and iron loss (true iron loss) of the sample under test when the capacitance including the parasitic capacitance of the input section of the voltage measurement circuit is zero. [Brief explanation of the drawing]

[0033] [Figure 1] This block diagram shows the schematic configuration of a conventional magnetic property measuring device that measures magnetic properties using the two-coil method. [Figure 2] Figure 1 is a block diagram showing a resonant circuit composed of inductance and capacitance in a magnetic properties measurement device. [Figure 3] Figure 2 shows an example of an equivalent circuit of the resonant circuit viewed from the primary winding side. [Figure 4] This diagram illustrates the inductance of a secondary winding wound around a toroidal specimen under test. [Figure 5] This is a block diagram showing the schematic configuration of a magnetic property measuring device according to the present invention. [Figure 6] This is a flowchart showing the process according to an embodiment of the magnetic property measurement method according to the present invention. [Figure 7] Figure 5 is a block diagram showing a resonant circuit composed of inductor and capacitance in a magnetic properties measurement device. [Figure 8] Figure 7 shows an example of an equivalent circuit of the resonant circuit viewed from the primary winding side. [Figure 9] Figure 9A is a graph of the permeability of the sample under test as a function of the capacitance of the input section of the voltage measurement circuit, and Figure 9B is a graph of the iron loss of the sample under test as a function of the capacitance of the input section of the voltage measurement circuit. [Figure 10] This diagram illustrates the case where current flows only through the primary winding when both the primary and secondary windings are wound around the sample under test. [Figure 11] This diagram illustrates the case where current flows only through the secondary winding when the primary and secondary windings are wound around the sample under test. [Figure 12] This diagram illustrates the case where current flows through both the primary and secondary windings while they are wound around the sample under test. [Figure 13] This figure shows the sample under test and a portion of the voltage measurement circuit, around which the primary and secondary windings are wound. [Figure 14] This shows the current flowing through the primary and secondary windings wound around the sample under test, and the voltage induced by them. [Figure 15] This is a diagram showing the equivalent circuit of an ideal transformer. [Figure 16] This figure adds the resistance representing the copper loss in the primary and secondary windings, the iron loss of the sample under test, and the capacitance of the input section of the voltage measurement circuit to Figure 15. [Figure 17] Figure 17A is a graph showing the measurement results of magnetic permeability according to an embodiment of the magnetic property measurement method according to the present invention, and Figure 17B is a graph showing the measurement results of iron loss according to an embodiment of the magnetic property measurement method according to the present invention. [Figure 18] Figure 18A is a graph of relative permeability with respect to capacitance at the input of a voltage measurement circuit when both the number of turns of the primary and secondary windings are 16 and the measurement frequency is 500 kHz. Figure 18B is a graph of iron loss with respect to capacitance at the input of a voltage measurement circuit when both the number of turns of the primary and secondary windings are 16 and the measurement frequency is 500 kHz. [Figure 19] Figure 19A is a graph of relative permeability with respect to capacitance at the input of a voltage measurement circuit when both the number of turns of the primary and secondary windings are 16 and the measurement frequency is 1000 kHz. Figure 19B is a graph of iron loss with respect to capacitance at the input of a voltage measurement circuit when both the number of turns of the primary and secondary windings are 16 and the measurement frequency is 1000 kHz. [Figure 20] Figure 20A is a graph of relative permeability with respect to capacitance at the input of a voltage measurement circuit when both the number of turns of the primary and secondary windings are 16 or 32 and the measurement frequency is 1000 kHz. Figure 20B is a graph of iron loss with respect to capacitance at the input of a voltage measurement circuit when both the number of turns of the primary and secondary windings are 16 or 32 and the measurement frequency is 1000 kHz. [Figure 21] This figure shows an example of extrapolating a higher-order function to the measurement results of relative permeability with respect to capacitance at the input section of a voltage measurement circuit. [Modes for carrying out the invention]

[0034] Embodiments of the magnetic property measurement method and magnetic property measurement apparatus according to the present invention will be described in detail with reference to the drawings and using symbols. Figure 5 is a block diagram illustrating the schematic configuration of a magnetic properties measuring device according to the present invention. The magnetic properties measuring device 31 is connected to a signal generator 5 and includes a shunt resistor 6, a voltage measurement circuit 32, a current measurement circuit 8, and a control calculation unit 9.

[0035] The voltage measurement circuit 32 is connected in parallel to the secondary winding 4 and includes a variable capacitor 33, an amplifier 11, an AD converter 12, and a memory 12. The variable capacitor 33 is connected in parallel to the secondary winding 4 and has a capacitance C that can be switched to at least two different set values. n In this embodiment, the variable capacitor 33 is placed at the input of the voltage measurement circuit 32. The variable capacitor 33 is an example of a variable capacitance unit.

[0036] The voltage measurement circuit 32 generates an excitation current at frequency f from the signal generator 5 to the primary winding 3, thereby measuring the maximum magnetic flux density B of the sample 2 under test. m or maximum magnetic field H m When the voltage is held at a predetermined value and a voltage is induced across the terminals of the secondary winding 4, the voltage induced across the terminals of the secondary winding 4 is measured. In this embodiment, the voltage measurement by the voltage measurement circuit 32 is performed by measuring the capacitance C of the variable capacitor 33. n This is performed each time the setting is switched to at least two or more different values. Frequency f is an example of a predetermined frequency for the excitation current.

[0037] The voltage measurement circuit 32 uses the capacitance C of the variable capacitor 33. n It may also have a capacitance setting unit (not shown) for switching between at least two or more set values. Furthermore, the capacitance C of the variable capacitor 33 may also be included. n The control calculation unit 9 may automatically switch between at least two or more set values.

[0038] The current measurement circuit 8 generates an excitation current at frequency f from the signal generator 5 to the primary winding 3, thereby measuring the maximum magnetic flux density B of the sample 2 under test. m or maximum magnetic field H m The current flowing through the shunt resistor 6 is measured when the voltage is maintained at a predetermined value and a voltage is induced across the terminals of the secondary winding 4. The current flowing through the shunt resistor 6 corresponds to the current i1(t) flowing through the primary winding 3. In this embodiment, the current measurement by the current measurement circuit 8 is measured by the capacitance C of the variable capacitor 33. n This occurs each time you switch to at least two different settings.

[0039] In this embodiment, the control calculation unit 9 calculates the capacitance C of the variable capacitor 33 based on the measured voltage and current. n The control calculation unit 9 then obtains one or both of the permeability of at least two or more samples under test and at least two or more iron losses, corresponding to at least two or more set values. m and the capacitance C of the variable capacitor 33 n The control calculation unit 9 extrapolates numerical data of at least two permeability values ​​and at least two iron loss values ​​(one or both) to the sum of at least two set values. m and the capacitance C of the variable capacitor 33 n Determine either the permeability and / or iron loss of the sample 2 under measurement when the sum of the two is zero.

[0040] Figure 6 is a flowchart showing the process according to an embodiment of the magnetic property measurement method according to the present invention. First, in preparation step S1, the capacitance C of the variable capacitor 33 is measured. n The capacitance C of the variable capacitor 33 n The measurement system is prepared by switching to the appropriate setting from at least two or more set values.

[0041] Next, in calculation step S2, the capacitance C of the variable capacitor 33 is calculated.n The capacitance C of the variable capacitor 33 n With the setting switched to the desired setting from at least two or more of the settings, an excitation current is supplied from the signal generator 5 to the primary winding 3 at frequency f. This allows the maximum magnetic flux density B of the sample under test 2 to be determined. m or maximum magnetic field H m When the voltage is maintained at a predetermined value and a voltage is induced across the ends of the secondary winding 4, the voltage measurement circuit 32 measures the voltage and the current measurement circuit 8 measures the current. The control calculation unit 9 then calculates one or both of the permeability and iron loss of the sample under test 2, corresponding to the setting value to be switched for the variable capacitor 33, based on the measured voltage and current.

[0042] Next, in the determination step S3, it is determined whether the preparation step S1 and the calculation step S2 have been repeated a predetermined number of times (for example, 3 times). That is, in the determination step S3, the capacitance C of the variable capacitor 33 is determined. n It is determined whether at least two or more setting values ​​have been switched to all of them. If the preparation step S1 and the calculation step S2 have not been repeated a predetermined number of times (No. in the determination step S3), the process returns to the preparation step S1.

[0043] In contrast, if the preparation step S1 and calculation step S2 are repeated a predetermined number of times (Yes in the determination step S3), the control calculation unit 9 performs extrapolation of the numerical data in the extrapolation step S4. The numerical data includes the capacitance C, which includes the parasitic capacitance of the input section of the voltage measurement circuit 32. m and the capacitance C of the variable capacitor 33 n This is numerical data of either or both of the permeability and iron loss calculated in calculation step S2 for the sum of at least one of two or more set values. The capacitance C including the parasitic capacitance of the input part of the voltage measurement circuit 32 is calculated by extrapolation by the control calculation unit 9. m and the capacitance C of the variable capacitor 33 n Determine either the permeability and / or iron loss of the sample 2 under measurement when the sum of the two is zero.

[0044] Preparation step S1 and calculation step S2 involve calculating the capacitance C of the variable capacitor 33. n This is an example of an acquisition process that acquires at least two or more permeability values ​​and at least two or both of the iron loss values ​​of the sample 2 to be measured, corresponding to at least two or more set values. At least one of the preparation process S1, calculation process S2, determination process S3, and extrapolation process S4 may be performed automatically by the control calculation unit 9.

[0045] Here, the resonant frequency in the measurement system prepared in preparation step S1 will be explained. Figure 7 is a block diagram showing the resonant circuit composed of inductance and capacitance in the magnetic property measurement device of Figure 5. Similar to Figure 3, the equivalent circuit viewed from the primary winding 3 side of Figure 7 is shown in Figure 8. The resonant frequency f in this case is Cn This is expressed by the following equation (3).

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[0046] Furthermore, the inductance L1 of the primary winding 3 is proportional to the square of the number of turns N1 of the primary winding 3, and the inductance L2 of the secondary winding 4 is proportional to the square of the number of turns N2 of the secondary winding 4. Therefore, the following equation (4) holds true.

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[0047] From the above, equation (3) can be expressed as equation (5) below.

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[0048] Capacitance C at the input of the voltage measurement circuit 32 s The reactance component X of the circuit generated by this Cs At the measurement frequency f, it is expressed by the following equation (6).

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[0049] Figure 9A is a graph of the permeability of the sample under test against the capacitance of the input section of the voltage measurement circuit. In Figure 9A, the horizontal axis represents the capacitance C of the input section of the voltage measurement circuit 32. s The vertical axis represents the measurement frequency f and the maximum magnetic flux density B of the sample under test 2. m or maximum magnetic field H m This is the permeability calculated in calculation step S2 in Figure 6, assuming the same conditions.

[0050] In Figure 9A, capacitance C mThis is the intrinsic capacitance of the input section of the voltage measurement circuit 32 that exceeds zero. Therefore, when using the same voltage measurement circuit 32, the capacitance C of the input section of the voltage measurement circuit 32 is... S capacitance C m It cannot be less than [amount].

[0051] Also, in Figure 9A, C c The resonant frequency is fc n This shows the capacitance of the input section of the voltage measurement circuit 32 when the measurement frequency f is equal to the capacitance C of the input section of the voltage measurement circuit 32 with respect to at least two or more permeability μ (in Figure 9A, two or more permeability μ1, μ2,...) calculated in calculation step S2 of Figure 6. S When is close to zero, a linear function extrapolation can be performed, as shown by the solid line α in Figure 9A. By such linear function extrapolation, the capacitance C at the input of the voltage measurement circuit 32 can be calculated. S The permeability μ of the sample under measurement 2 can be determined when the value is zero.

[0052] Furthermore, using at least two permeability μs calculated in calculation step S2 in Figure 6, extrapolation to a higher-order function, which will be explained in detail later, can be performed, as shown by the solid line β in Figure 9A. Through such extrapolation to a higher-order function, the capacitance C of the input section of the voltage measurement circuit 32 can be calculated. S The permeability μ of the sample under measurement 2 can be determined when the value is zero.

[0053] Figure 9B is a graph of the iron loss of the sample under test in relation to the capacitance of the input section of the voltage measurement circuit. In Figure 9B, the horizontal axis represents the capacitance C of the input section of the voltage measurement circuit 32. s The vertical axis represents the measurement frequency f and the maximum magnetic flux density B of the sample under test 2. m or maximum magnetic field H m When the conditions are the same, the iron loss P calculated in calculation step S2 in Figure 6 is c Let's assume that.

[0054] At least two or more iron losses P calculated in calculation step S2 in Figure 6 c (In Figure 9B, there are two or more iron losses P c1 ,Pc2 Capacitance C at the input of the voltage measurement circuit 32 related to ,...) S Regarding this, as shown by the solid line γ in Figure 9B, a linear function extrapolation can be performed. By such linear function extrapolation, the capacitance C at the input of the voltage measurement circuit 32 can be obtained. S Iron loss P of the sample 2 under measurement when it is zero c It is possible to find this.

[0055] (Capacitance C including parasitic capacitance at the input of the voltage measurement circuit 32) m (Regarding the permeability of sample 2 under measurement (true permeability) when it is zero) Next, the capacitance C, including the parasitic capacitance at the input of the voltage measurement circuit 32. m This explains why the permeability of sample 2 (true permeability) can be determined when the value is zero.

[0056] (When current flows only through primary winding 3) Figure 10 illustrates the case where current flows only through the primary winding when both the primary and secondary windings are wound around the sample under test. In Figure 10, the permeability of the sample under test 2 is μ, and the magnetic path length of the sample under test 2 is

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[0057] The electromotive force v1 generated in the primary winding 3 due to the change in magnetic flux Φ1 is expressed by the following equation (8), assuming the direction of the arrow in Figure 10 is positive.

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[0058] Equation (8) can be expressed by the following equation (9).

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[0059] On the one hand, when a part (or all) of the magnetic flux Φ1 created by the primary winding 3, i.e., the magnetic flux kΦ1 (0 < k ≤ 1), links with the secondary winding 4, the electromotive force v2 generated in the secondary winding 4 is expressed by the following equation (10) when the direction of the arrow in Fig. 10 is taken as positive.

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[0060] Here, the mutual inductance M between the primary winding 3 and the secondary winding 4 is expressed by the following equation (11).

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[0061] (When current flows only in the secondary winding 4) Fig. 11 is a diagram for explaining the case where current flows only in the secondary winding while the primary winding and the secondary winding are wound around the measured sample. The magnetic flux Φ2 created by the current i2 flowing in the secondary winding 4 is expressed by the following equation (13).

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[0062] The electromotive force v2 generated in the secondary winding 4 by the magnetic flux Φ2 is expressed by the following equation (14) when the direction of the arrow in Fig. 11 is taken as positive.

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[0063] Here, the inductance L2 of the secondary winding 4 is expressed by the following equation (15).

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[0064] On the other hand, the electromotive force v1 generated in the primary winding 3 by linking a portion of the magnetic flux kΦ2 created by the secondary winding 4 with the primary winding 3 is expressed by the following equation (17), assuming the direction of the arrow in Figure 11 is positive.

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[0065] (When current flows through both the primary winding 3 and the secondary winding 4) Figure 12 illustrates the case where current flows through both the primary and secondary windings when they are wound around the sample under test. Next, when current i1 flows through the primary winding 3 and current i2 flows through the secondary winding 4, the electromotive force v1 generated in the primary winding 3 and the electromotive force v2 generated in the secondary winding 4 are expressed by equations (19) and (20), respectively.

number

[0066] Here, we calculate the electromotive force v2 in equation (20) using a different solution method. In Figure 12, let Φ1 and Φ2 be the magnetic fluxes created by currents i1 and i2, respectively. If a portion of the magnetic flux Φ1, kΦ1, links with the secondary winding 4, and a portion of the magnetic flux Φ2, kΦ2, links with the primary winding 3, then the magnetic flux Φ that links with the secondary winding 4 is expressed by the following equation (21).

number

[0067] When the magnetic permeability of the sample under test 2 is μ, the electromotive force v2 generated in the secondary winding 4 is expressed by the following equation (22).

number

number

[0068] According to this embodiment, when obtaining the permeability and iron loss of the sample 2 under measurement, the maximum magnetic flux density B m or maximum magnetic field H m While the value is kept at a predetermined level, the electromotive force v2 of the secondary winding 4 is generally used to measure the magnetic flux density. The magnetic flux density B using the electromotive force v2 is expressed by the following equation (24).

number

[0069] By applying equations (23), (11), and (15) to equation (24), we obtain the following equation (25).

number

[0070] Meanwhile, the current i1 flowing through the primary winding 3 is measured, and the magnetic field strength H is determined from the following equation (26).

number

[0071] FIG. 13 is a diagram showing a measurement sample around which a primary winding and a secondary winding are wound and an input section of a voltage measurement circuit. As shown in FIG. 13, a circuit including a capacitor C m and a resistor R m is configured at the input section of the voltage measurement circuit 32. Also, a variable capacitor 33 is connected in parallel to the capacitor C m and the resistor R m at the input section of the voltage measurement circuit 3s2. Usually, the resistor R m has a very high value of about several hundred kΩ to 1 MΩ, and the capacitor C m is also about 18.5 pF (about 80 kΩ at a frequency of 100 kHz). Therefore, when the capacitance C n of the variable capacitor 33 is zero, the current i2 flowing through the secondary winding 4 becomes almost zero when the measurement frequency f is sufficiently low. Assuming k = 1, the magnetic field strength H is accurately measured in Equation (26), and from Equations (25) and (26), the magnetic permeability μ of the measurement sample 2 is accurately measured in the following Equation (27).

Equation

[0072] As the measurement frequency f increases and the impedance of the capacitor C m decreases, the current i2 flowing through the secondary winding 4 becomes a magnitude that cannot be ignored in Equation (25). Therefore, with respect to the magnetic field strength H measured by the magnetic property measurement device 31 according to Equation (26), the magnetic flux density B generated by Equation (25) will have an error only due to the difference caused by i2 in the second term of Equation (25). This error increases as the capacitance C n of the variable capacitor 33 increases.

[0073] Here, paying attention to the directions of the currents i1, i2 and the electromotive voltages v1, v2 shown in FIG. 13, and assuming that the current flowing through the resistor R<00s0094>is zero, the electromotive voltage v2 of the secondary winding 4 is expressed by the following Equation (28).

Equation

[0074] According to equation (28), the current i2 is expressed by the following equation (29).

number

[0075] Furthermore, by substituting equation (29) into equation (20), we obtain the following equation (30).

number

[0076] Here, the peak value of current i1 is I m In this case, we assume that the instantaneous value i1(t) of the current i1 is a sine wave represented by the following equation (31).

number

[0077] In a steady state, the transformation shown in equation (32) below holds true using the complex notation of electrical circuit theory.

number

[0078] Therefore, when the electromotive force v2 and current i1 are expressed in vector form, taking equation (32) into consideration, equation (30) can be expressed as the following equation (33).

number

[0079] According to equation (33),

number

number

[0080] Therefore, the electromotive force v2 is expressed by the following equation (35).

Equation

[0081] When substituting equation (35) into equation (29) here, the following equation (36) is obtained.

Equation

[0082] Moreover, when substituting equations (31) and (36) into equation (25), the following equation (37) is obtained.

Equation

[0083] Here, the following equation (38) represents the magnetic field generated by the current i1 flowing through the primary winding 3.

Equation

[0084] When all the magnetic fluxes do not leak outside the measured sample 2, k = 1. Therefore, the magnetic permeability (apparent magnetic permeability) is expressed by the following equation (39).

Equation

[0085] According to equation (39), the magnetic permeability (apparent magnetic permeability) is the capacitance C of the input section of the voltage measurement circuit 32 s when it is zero, and is the capacitance C including the parasitic capacitance of the input section of the voltage measurement circuit 32 m when it is zero, and coincides with the magnetic permeability (true magnetic permeability) μ of the measured sample 2.

[0086] Furthermore, at the resonance point where equation (40) is given below, the permeability (apparent permeability) becomes infinite.

number

[0087] According to equation (39), the capacitance C at the input of the voltage measurement circuit 32 is s While changing the measurement frequency f and the maximum magnetic flux density B, m or maximum magnetic field H m By extrapolating the results of multiple permeability measurements taken under the same conditions for the number of turns N1 of the primary winding and the number of turns N2 of the secondary winding, C s The permeability of the sample 2 under measurement can be determined when = 0. s When = 0, the permeability is the capacitance C including the parasitic capacitance of the input section of the voltage measurement circuit 32. m This corresponds to the permeability of the sample under measurement 2 (true permeability) when it is zero. Therefore, the capacitance C including the parasitic capacitance of the input section of the voltage measurement circuit 32. m The permeability of sample 2 under measurement (true permeability) can be determined when the value is zero.

[0088] Here, equation (39) is C s When performing a Taylor expansion around =0, we obtain the following equation (41), which is an approximation of equation (39).

number

[0089] According to equation (41), C s Near =0, the permeability (apparent permeability) is C s It can be seen that it increases smoothly with increasing , and that it can be approximated using a linear function or a higher-order function.

[0090] (Capacitance C including parasitic capacitance at the input of the voltage measurement circuit 32) m (Regarding the iron loss (true iron loss) of sample 2 when the value is zero) Next, the capacitance C, including the parasitic capacitance at the input of the voltage measurement circuit 32.m The reason for being able to obtain the iron loss (true iron loss) of the measured sample 2 when it becomes zero will be explained.

[0091] FIG. 14 shows the currents flowing through the primary winding and the secondary winding wound around the measured sample and the voltages induced thereby. In FIG. 14, all the currents and voltages are in vector notation, and their polarities are positive in the direction of the arrows. The voltages induced in the primary winding 3 and the voltages induced in the secondary winding 4 can be expressed by the following equations (42) and (43), respectively.

Number

[0092] The inductance L1 of the primary winding 3 and the inductance L2 of the secondary winding 4 are expressed by the following equations (44) and (45), respectively.

Number

[0093] Here, the mutual inductance M between the primary winding 3 and the secondary winding 4 is expressed by the following equation (46).

Number

[0094] Here, the equivalent circuit of the transformer that satisfies equations (44), (45) and (46) is represented in FIG. 15.

[0095] If the transformer in FIG. 15 is an ideal transformer, when the following equation (47) is used, for FIG. 15

Number

Number

Number

[0096] According to FIG. 15,

Number

Number

[0097] Here, when using formula (49), formula (44), formula (47) and formula (46), formula (50) can be expressed by the following formula (51).

Number

[0098] Also, according to FIG. 15,

Number

Number

[0099] Substituting formula (51) into formula (52),

Number

Number

[0100] Similarly, according to FIG. 15,

Number

Number

[0101] Here, when formulas (44), (45), (46), (47), (48), and (51) are used,

number

number

[0102] Figure 16 is a modified version of Figure 15, with the addition of the resistance components representing the copper loss in the primary and secondary windings, the iron loss of the sample under test, and the capacitance of the voltage measurement circuit. In Figure 16, the resistance component representing the copper loss in the primary winding 3 is represented by r1, the resistance component representing the copper loss in the secondary winding 4 is represented by r2, the resistance component representing the iron loss in the sample under test 2 is represented by r0, and the capacitance of the input section of the voltage measurement circuit 32 is represented by C. s (=C m +C n It is represented by ). Resistance R m Since it is relatively high, in the following calculations, the resistor R m We will explain this assuming that the current flowing through it is zero.

[0103] The copper loss of the primary winding 3, the copper loss of the secondary winding 4, and the iron loss of the sample under test 2 are expressed by the following equations (56), (57), and (58), respectively.

number

[0104] In the circuit diagram in Figure 16

number

number

[0105] According to equations (60) and (62), in the circuit diagram of Figure 16

number

number

[0106] According to equation (63), in the circuit diagram of Figure 16

number

number

[0107] According to equations (48) and (64),

number

number

[0108] Also, in the circuit diagram in Figure 16

number

number

[0109] By equation (65), equation (66) can be expressed as the following equation (67).

number

[0110] According to equations (49) and (62),

number

number

[0111] According to equations (61), (67), and (68),

number

number

[0112] In the circuit diagram of Figure 16, the real part of the following equation (70) represents the measurement result of the iron loss by the magnetic property measuring device 31.

number

[0113] Here,

number

number

number

number

[0114] In Figure 16, C s When = 0, I2 = 0, so by equations (60) and (48),

number

number

[0115] Therefore, C s When = 0, iron loss P core The measurement result is given by the following equation (74).

number

[0116] Here, if the number of turns N1 of the primary winding 3 is the same as the number of turns N2 of the secondary winding 4, then by equation (48) a=1, and therefore equation (74) becomes equal to the iron loss of the sample 2 under test in equation (58).

[0117] Next, C s If ≠ 0, for example, the maximum magnetic flux density B m When measured while keeping the following constant, assuming the measurement frequency f, the number of turns N1 of the primary winding 3, and the number of turns N2 of the secondary winding 4 are the same,

number

[0118] Based on the above, the capacitance C of the input section of the voltage measurement circuit 32 s While changing the measurement frequency f and the maximum magnetic flux density B, m or maximum magnetic field H m By extrapolating the measurement results of multiple iron losses measured under the same conditions for the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding 4, Cs The iron loss can be calculated when = 0. s When = 0, the iron loss is the capacitance C including the parasitic capacitance of the input section of the voltage measurement circuit 32. m This corresponds to the true iron loss of the sample under measurement 2 when it is zero. Therefore, the capacitance C, including the parasitic capacitance of the input section of the voltage measurement circuit 32, is included. m The iron loss (true iron loss) of sample 2 can be determined when the value is zero.

[0119] (First embodiment of the magnetic property measurement method according to the present invention) Next, the measurement results obtained by the first embodiment of the magnetic property measurement method according to the present invention will be described. In the first embodiment of the magnetic property measurement method according to the present invention, the capacitance C of the variable capacitor 33 is set. n These values ​​are 0pF, 10pF, 20pF, 50pF, 100pF, 200pF, and 500pF, as shown in Table 1 below. In Table 1 below, capacitance C n Capacitance C when set to 0pF, 10pF, 20pF, 50pF, 100pF, 200pF, and 500pF s The resonant frequency f corresponding to the value of c This is also shown. [Table 1]

[0120] In the first embodiment of the magnetic property measurement method according to the present invention, the resonance frequency f shown in Table 1 c This was calculated using equation (5) under the first condition where the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding 4, both wound around the Chang Sung Sendust toroidal core CS234125 used as the sample under measurement, were both set to 16.

[0121] The inherent capacitance C is determined by the circuit design of the voltage measurement circuit 7. m Set this to 18.5pF, and this value represents the capacitance C of the variable capacitor 33. n The capacitance C at the input of the voltage measurement circuit 32 is the value obtained by adding this to the capacitance C. sThe values ​​are also shown in Table 1. The resonant frequency f is generally considered to have little effect from the current flowing through the secondary winding 4. c 1 / 10th of the frequency (f c The results for / 10) are also shown in Table 1.

[0122] Figure 17A is a graph showing the measurement results of magnetic permeability according to an embodiment of the magnetic property measurement method according to the present invention. In Figure 17A, the magnetic flux density is fixed at 1 mT under the first condition described above, and the capacitance C at the input of the voltage measurement circuit 32 is... s The permeability measurement results are shown when the measurement frequency f is changed from 10 kHz to 5 MHz each time the value of is switched to the values ​​shown in Table 1. In the graph of Figure 17A, the relative permeability is μ. r This shows (μ / μ0). Here, μ0 represents the permeability of vacuum and is an inherent value, so the relative permeability μ r This is equal to the value obtained by dividing the magnetic permeability μ by a constant.

[0123] In Figure 17A, the white rectangle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the magnetic permeability with respect to the measurement frequency f obtained when the value was switched to 0pF are shown. In Figure 17A, the black rectangle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the magnetic permeability against the measurement frequency f obtained when the value was switched to 10pF are shown.

[0124] In Figure 17A, the white circle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the magnetic permeability against the measurement frequency f obtained when the value was switched to 20pF are shown. In Figure 17A, the black circle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the magnetic permeability against the measurement frequency f obtained when the value was switched to 50pF are shown.

[0125] In Figure 17A, the white triangle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. nThe coordinates of the magnetic permeability against the measurement frequency f obtained when the value was switched to 100pF are shown. In Figure 17A, the black triangle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the magnetic permeability against the measurement frequency f obtained when the value was switched to 200pF are shown. In Figure 17A, the black inverted triangle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the magnetic permeability against the measurement frequency f obtained when the value was switched to 500pF are shown.

[0126] In Figure 17A, the white diamond represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the magnetic permeability against the measurement frequency f obtained when the value was switched to 1000pF are shown. In Figure 17A, the black diamond represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the magnetic permeability against the measurement frequency f obtained when the value was switched to 2500pF are shown.

[0127] Figure 17B is a graph showing the measurement results of iron loss according to an embodiment of the magnetic property measurement method according to the present invention. In Figure 17B, the magnetic flux density is fixed at 1 mT under the first condition described above, and the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32 is... n The measurement results of iron loss are shown when the measurement frequency f is changed from 10 kHz to 5 MHz each time the value of is switched. In the graph of Figure 17B, iron loss P is shown as iron loss. c P used in the evaluation c This shows / f. Here, the measurement frequency f is a fixed value, so P c / f is iron loss P c It is equal to the value obtained by dividing by a constant.

[0128] In Figure 17B, the white rectangle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the iron loss against the measurement frequency f obtained when the value was switched to 0pF are shown. In Figure 17B, the black rectangle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32.n The coordinates of the iron loss against the measurement frequency f obtained when the value was switched to 10pF are shown.

[0129] In Figure 17B, the white circle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the iron loss against the measurement frequency f obtained when the value was switched to 20pF are shown. In Figure 17B, the black circle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the iron loss against the measurement frequency f obtained when the value was switched to 50pF are shown.

[0130] In Figure 17B, the white triangle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the iron loss against the measurement frequency f obtained when the value was switched to 100pF are shown. In Figure 17B, the black triangle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the iron loss against the measurement frequency f obtained when the value was switched to 200pF are shown. In Figure 17B, the black inverted triangle represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the iron loss against the measurement frequency f obtained when the value was switched to 500pF are shown.

[0131] In Figure 17B, the white diamond represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the iron loss against the measurement frequency f obtained when the value was switched to 1000pF are shown. In Figure 17B, the black diamond represents the capacitance C of the variable capacitor 33 at the input of the voltage measurement circuit 32. n The coordinates of the iron loss against the measurement frequency f obtained when the value was switched to 2500pF are shown.

[0132] Figure 18A is a graph of the relative permeability with respect to capacitance at the input section of a voltage measurement circuit when both the number of turns of the primary and secondary windings are 16 and the measurement frequency is 500 kHz. In the graph of Figure 18A, the relative permeability μ is when both the number of turns of the primary winding N1 and the number of turns of the secondary winding N2 are 16 and the measurement frequency f is 500 kHz. r The measurement results were obtained from the graph in Figure 17A. C under the first condition described above. s The relative permeability when = 0 is the capacitance C of the input section of the voltage measurement circuit 32 obtained under the first condition described above. s Relative permeability μ for the value r It can be obtained by extrapolating the numerical data into a linear function. C under the first condition above s Relative permeability μ of sample 2 when = 0 r The capacitance C of the input section of the voltage measurement circuit 32 obtained under the above first condition was 125.96. s Relative permeability μ for the value r This was obtained using equation (41). This gives C s Relative permeability μ of sample 2 when = 0 r C corresponding to m We were able to determine the relative permeability (true relative permeability) of sample 2 when the result is 0.

[0133] Figure 18B is a graph of iron loss against capacitance at the input of a voltage measurement circuit when both the number of turns of the primary and secondary windings are 16 and the measurement frequency is 500 kHz. In the graph of Figure 18B, the iron loss P is when both the number of turns of the primary winding N1 and the number of turns of the secondary winding N2 are 16 and the measurement frequency f is 500 kHz. c The measurement results were obtained from the graph in Figure 17B. C under the first condition described above. s When = 0, the iron loss is the capacitance C of the input section of the voltage measurement circuit 32 obtained under the first condition described above. s Iron loss P for the value c It can be obtained by extrapolating the numerical data into a linear function. C under the first condition above s Iron loss P when = 0 cThe capacitance C at the input of the voltage measurement circuit 32 was obtained under the above first condition. s Iron loss P for the value c This was obtained using equation (72). This gives C s Iron loss P of the sample 2 under measurement when = 0 c C corresponding to m We were able to determine the iron loss (true iron loss) of sample 2 when the value is 0.

[0134] Figure 19A is a graph of the relative permeability with respect to capacitance at the input section of a voltage measurement circuit when both the number of turns of the primary and secondary windings are 16 and the measurement frequency is 1000 kHz. In the graph of Figure 19A, the relative permeability μ is when both the number of turns of the primary winding N1 and the number of turns of the secondary winding N2 are 16 and the measurement frequency f is 1000 kHz. r The measurement results were obtained from the graph in Figure 17A. In the graph shown in Figure 19A, C under the first condition described above s The relative permeability when = 0 is the capacitance C of the input section of the voltage measurement circuit 32 obtained under the first condition described above. s Relative permeability μ for the value r It can be obtained by extrapolating the numerical data into a linear function. C under the first condition above s Relative permeability μ when = 0 r The capacitance C of the input section of the voltage measurement circuit 32 obtained under the above first condition was 123.8. s Relative permeability μ for the value r This was obtained using equation (41). This gives C s Relative permeability μ of sample 2 when = 0 r C corresponding to m We were able to determine the relative permeability (true relative permeability) of sample 2 when the result is 0.

[0135] Figure 19B is a graph of iron loss against capacitance at the input of a voltage measurement circuit when both the number of turns of the primary and secondary windings are 16 and the measurement frequency is 1000 kHz. In the graph of Figure 19B, the iron loss P when both the number of turns of the primary winding N1 and the number of turns of the secondary winding N2 are 16 and the measurement frequency f is 1000 kHz. c The measurement results were obtained from the graph in Figure 17B. C under the first condition described above. s When = 0, the iron loss is the capacitance C of the input section of the voltage measurement circuit 32 obtained under the first condition described above. s Iron loss P for the value c It can be obtained by extrapolating the numerical data into a linear function. C under the first condition above s Iron loss P when = 0 c The capacitance C at the input of the voltage measurement circuit 32 was obtained under the above first condition. s Iron loss P for the value c This was obtained using equation (72). This gives C s Iron loss P of the sample 2 under measurement when = 0 c C corresponding to m We were able to determine the iron loss (true iron loss) of sample 2 when the value is 0.

[0136] (Second embodiment of the magnetic property measurement method according to the present invention) Next, the measurement results obtained by the second embodiment of the magnetic property measurement method according to the present invention will be described. In the second embodiment of the magnetic properties measurement method according to the present invention, the capacitance C of the variable capacitor 33 is set. n These values ​​are 0pF, 10pF, 20pF, 50pF, 100pF, 200pF, and 500pF, as shown in Table 2 below. In Table 2 below, capacitance C n Capacitance C when set to 0pF, 10pF, 20pF, 50pF, 100pF, 200pF, and 500pF s The resonant frequency f corresponding to the value of c This is also shown. [Table 2]

[0137] In a second embodiment of the magnetic property measurement method according to the present invention, the resonant frequency f shown in Table 2 is used. c This was calculated using formula (5) under the condition that the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding 4, both wound around a Chang Sung Sendust toroidal core CS234125 as the sample under measurement 2, were both 32.

[0138] The inherent capacitance C is determined by the circuit design of the voltage measurement circuit 7. m The capacitance C of the variable capacitor 33 is set to 18.5pF. n The capacitance C at the input of the voltage measurement circuit 32 is the value obtained by adding this to the capacitance C. s The values ​​are also shown in Table 2. The resonant frequency f is generally considered to have little effect from the current flowing through the secondary winding 4. c 1 / 10th of the frequency (f c The results for / 10) are also shown in Table 2.

[0139] Figure 20A is a graph of the relative permeability with respect to capacitance at the input section of a voltage measurement circuit when both the number of turns of the primary and secondary windings are 16 or 32, and the measurement frequency is 1000 kHz. In the graph of Figure 20A, the black circles represent the relative permeability μ obtained when the measurement frequency f is 1000 kHz under the first condition described above. r The measurement results are shown and are identical to the black circles in the graph in Figure 19A.

[0140] In the graph of Figure 20A, the X marks represent the relative permeability μ obtained when the measurement frequency f under the second condition described above is 1000 kHz. r The measurement results are shown below. The relative permeability μ obtained when the measurement frequency f under the second condition above is 1000 kHz. r The measurement results were obtained from a graph created in the same way as the graph in Figure 17A, under the second condition described above. s Relative permeability μ when = 0 r The capacitance C of the input section of the voltage measurement circuit 32, obtained under the second condition described above, is shown. s Relative permeability μ for the valuer It can be obtained by extrapolating the numerical data into a linear function. C under the second condition above s Relative permeability μ when = 0 r The capacitance C of the input section of the voltage measurement circuit 32 obtained under the second condition described above. s Relative permeability μ for the value r This was obtained using equation (41). Ultimately, C s The relative permeability when = 0 is given by C under the first condition above. s Relative permeability μ when = 0 r and C under the second condition above s Relative permeability μ when = 0 r Let's use the average of these values, which is 123.725. This means that C s Relative permeability μ of sample 2 when = 0 r C corresponding to the average m We were able to determine the relative permeability (true relative permeability) of sample 2 when the result is 0.

[0141] Figure 20B is a graph of iron loss against capacitance at the input of a voltage measurement circuit when both the number of turns of the primary and secondary windings are 16 or 32, and the measurement frequency is 1000 kHz. In the graph of Figure 20B, the black circles represent the iron loss P obtained when the measurement frequency f is 1000 kHz under the first condition described above. c The measurement results are shown and are identical to the black circles in the graph in Figure 19B.

[0142] Iron loss P when the measurement frequency f is 1000 kHz under the second condition described above. c The measurement results were obtained from a graph created in the same way as the graph in Figure 17B, under the second condition described above. s When = 0, the iron loss is the capacitance C of the input section of the voltage measurement circuit 32 obtained under the second condition above. s Iron loss P for the value c It can be obtained by extrapolating the numerical data into a linear function. C under the second condition above s Iron loss P when = 0 cThe capacitance C of the input section of the voltage measurement circuit 32 obtained under the second condition described above. s Iron loss P for the value c This was obtained using equation (72). C under the first condition above s Iron loss P when = 0 c and C under the second condition above s Iron loss P when = 0 c Since they are identical, ultimately, C s The permeability when = 0 is set to 0.0028W. This gives C s C corresponding to the magnetic permeability of the sample 2 under measurement when = 0 m We were able to determine the iron loss (true iron loss) of sample 2 when the value is 0.

[0143] (Regarding extrapolation of higher-order functions) Figure 21 shows an example of extrapolation of a higher-order function for the measurement results of relative permeability with respect to capacitance at the input section of a voltage measurement circuit. For the measurement, a Sendust toroidal core CS234125 manufactured by Chang Sung was used as the sample under measurement 2.

[0144] In the graph in Figure 21, the white circles represent the capacitance C at the input of the voltage measurement circuit 32, obtained when the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding, both wound around the sample 2 under test, are set to 16. s Relative permeability μ r The coordinates are shown.

[0145] In the graph in Figure 21, the black circles represent the capacitance C at the input of the voltage measurement circuit 32, obtained when the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding, both wound around the sample 2 under test, are set to 12. s Relative permeability μ r The coordinates are shown.

[0146] In the graph in Figure 21, the white rectangle represents the capacitance C at the input of the voltage measurement circuit 32, obtained when the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding, both wound around the sample 2 under test, are set to 10. s Relative permeability μr The coordinates are shown.

[0147] In the graph in Figure 21, the white triangle represents the capacitance C at the input of the voltage measurement circuit 32, obtained when the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding, both wound around the sample 2 under test, are set to 8. s Relative permeability μ r The coordinates are shown.

[0148] The following example shows the use of a cubic function as the higher-order function. When the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are both 16, C s Relative permeability μ of sample 2 when = 0 r This refers to the capacitance C at the input of the acquired voltage measurement circuit 32. s Relative permeability μ for the value r It can be obtained by extrapolating the numerical data to a cubic function. C when the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are both 16. s Relative permeability μ of sample 2 when = 0 r The result was 120.481. The capacitance C at the input of the voltage measurement circuit 32 when both the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are 16. s Relative permeability μ for the value r This was obtained using equation (41).

[0149] When the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are both 12, C s Relative permeability μ of sample 2 when = 0 r This refers to the capacitance C at the input of the acquired voltage measurement circuit 32. s Relative permeability μ for the value r It can be obtained by extrapolating the numerical data into a cubic function. C when the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are both 12. s Relative permeability μ of sample 2 when = 0 r The result was 120.201. The capacitance C at the input of the voltage measurement circuit 32 when the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are both 12. s Relative permeability μ for the valuer This was obtained using equation (41).

[0150] When the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are both 10, C s Relative permeability μ of sample 2 when = 0 r This refers to the capacitance C at the input of the acquired voltage measurement circuit 32. s Relative permeability μ for the value r It can be obtained by extrapolating the numerical data into a cubic function. C when the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are both 10. s Relative permeability μ of sample 2 when = 0 r The result was 120.458. The capacitance C at the input of the voltage measurement circuit 32 when the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are both 10. s Relative permeability μ for the value r This was obtained using equation (41).

[0151] When the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are both 8, C s Relative permeability μ of sample 2 when = 0 r This refers to the capacitance C at the input of the acquired voltage measurement circuit 32. s Relative permeability μ for the value r It can be obtained by extrapolating the numerical data into a cubic function. C when the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are both 8. s Relative permeability μ of sample 2 when = 0 r The result was 122.11. The capacitance C at the input of the voltage measurement circuit 32 when the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are both 8. s Relative permeability μ for the value r This was obtained using equation (41).

[0152] Ultimately, C s The relative permeability of the sample under test 2 when = 0 is obtained from all acquired C s Relative permeability μ of sample 2 when = 0 r Let's use the average of these values, which is 121.0625. This means that Cs Relative permeability μ of sample 2 when = 0 r C corresponding to the average m We were able to determine the relative permeability (true relative permeability) of the sample 2 under test when = 0. As described above, even when the number of turns N1 of the primary winding 3 and the number of turns N2 of the secondary winding are different, C s Relative permeability μ of sample 2 when = 0 r The difference falls within the error range of the magnetic property measuring device 31.

[0153] (Effects of this embodiment) According to this embodiment, the capacitance C of the input section of the voltage measurement circuit 32 S The permeability μ(C) of the sample under measurement 2 when is zero. S (=0) and iron loss P c (C S It is possible to determine one or both of the values ​​(=0). Capacitance C at the input of the voltage measurement circuit 32 S The permeability μ(C) of the sample under measurement 2 when is zero. S (=0) is the capacitance C including the parasitic capacitance of the input section of the voltage measurement circuit 32. m This corresponds to the permeability (true permeability) of the sample under measurement 2 when it is zero. Also, the capacitance C at the input of the voltage measurement circuit 32. S Iron loss P of the sample 2 under measurement when it is zero c (C S (=0) is the capacitance C including the parasitic capacitance of the input section of the voltage measurement circuit 32. m This corresponds to the iron loss (true iron loss) of the sample under measurement 2 when it is zero. Therefore, according to this embodiment, the capacitance C including the parasitic capacitance of the input section of the voltage measurement circuit 32 is m When the value is zero, it is possible to determine either or both of the magnetic permeability (true magnetic permeability) and iron loss (true iron loss) of the sample 2 under measurement.

[0154] Furthermore, according to this embodiment, the capacitance C of the input section of the voltage measurement circuit 32 S The capacitance C at the input of the voltage measurement circuit 32 was measured when the capacitance was not zero. SThe measurement results can be calculated when the value is zero. Therefore, in order to avoid the current flowing through the secondary winding 4 becoming large, the measurement frequency f is set to the resonant frequency f. c It is not necessary to limit it to less than 1 / 10 of the above. That is, the permeability μ and iron loss P of the sample 2 being measured. c To find the resonant frequency f over a wider frequency range c This eliminates the need to increase the resonant frequency f. c By increasing the value, it is possible to avoid changes in the shape of the winding N1 of the primary winding 3, the winding N2 of the secondary winding 4, and the shape of the sample under measurement 2, as well as limitations on measurement conditions and the occurrence of suboptimal excitation conditions.

[0155] Furthermore, the measurement frequency f is the resonant frequency f c Since there is no need to limit it to 1 / 10 or less, the magnetic property measuring device and magnetic property measuring method according to this embodiment are useful for the development of high-frequency materials such as soft magnetic materials and the development of coil components using them.

[0156] Furthermore, the measurement frequency f is the resonant frequency f c Since there is no need to limit it to less than 1 / 10 of the above, there is no need to reduce the number of windings N2 of the secondary winding 4. As a result, the permeability μ and iron loss P of the sample 2 under measurement can be determined. c This method prevents large variations in measurements and makes it easier to measure at the desired magnetic flux density.

[0157] (modified version) The present invention is not limited to the above embodiment, and numerous modifications and variations are possible. For example, the variable capacitor 33 may be placed outside the voltage measurement circuit 32. Alternatively, a computer device wired to the control calculation unit 9 of the magnetic property measurement device 31 in Figure 5 may perform the extrapolation step S4 of the flowchart in Figure 6. In this case, numerical data of at least two or more permeability values ​​and at least two or more iron loss values ​​of the sample under measurement 2 acquired by the control calculation unit 9 in Figure 5 are automatically supplied to the computer device via the wired connection. The computer device then performs the extrapolation step S4 of the flowchart in Figure 6 using a spreadsheet computer program or the like stored in the computer device's memory. Note that the numerical data may also be supplied to the computer device by an operator's operation, such as manually, in which case the computer device does not need to be wired to the control calculation unit 9 of the magnetic property measurement device 31 in Figure 5. Furthermore, in the above embodiment, the capacitance C of the variable capacitor 33 n Each time the settings are switched, the permeability μ of the sample under measurement 2 and the iron loss P are measured. c One or both of the values ​​were calculated, but the capacitance C of the variable capacitor 33 was... n After all switching, the permeability μ and iron loss P of the sample 2 under measurement are measured. c You may calculate one or both of them.

[0158] Alternatively, a set of multiple capacitors having different inherent capacitances and relays connected in series with them may be used instead of the variable capacitor 33. Furthermore, a mechanism that can accommodate one of the multiple capacitors having different inherent capacitances may be used instead of the variable capacitor 33. [Explanation of Symbols]

[0159] 1.31 Magnetic property measuring device 2 Sample to be measured 3 Primary winding 4. Secondary winding 5. Signal Generator 6 Shunt resistors 7.32 Voltage Measurement Circuit 8 Current measurement circuit 9 Control and Calculation Unit 11,21 Amplifier 12,22 AD converter 13.24 memory 23. Divider 33 Variable Capacitor C m Capacitance R m resistance

Claims

1. A method for measuring the magnetic properties of a sample to be measured, which is wound with a primary winding of a first number of turns and a secondary winding of a second number of turns, Each time the capacitance of the variable capacitance unit connected in parallel to the secondary winding is switched to at least two different set values, an excitation current of a predetermined frequency is supplied from the signal generator to the primary winding so that the maximum magnetic flux density or maximum magnetic field of the sample under test is maintained at a predetermined value and a voltage is induced across the ends of the secondary winding. At the same time, a voltage measurement circuit connected in parallel to the secondary winding measures the voltage induced across the ends of the secondary winding, and a current measurement circuit measures the current flowing through the primary winding. Based on the voltage and the current, the control calculation unit obtains at least two or more permeability values ​​and at least two or more iron losses of the sample under test, or both, corresponding to the at least two or more set values. An extrapolation step to determine the permeability and iron loss of the sample to be measured when the sum of the capacitance including the parasitic capacitance of the input section of the voltage measurement circuit and the capacitance of the variable capacitance section becomes zero, by extrapolating the numerical data of one or both of the above at least two permeability values ​​and the above at least two iron loss values, A method for measuring magnetic properties, characterized by comprising the following features.

2. The acquisition process described above is: Preparation for measuring the voltage by the voltage measuring circuit and measuring the current by the current measuring circuit, a preparation step of switching the capacitance of the variable capacitance unit to a setting value to be switched from among the at least two or more setting values, With the capacitance of the variable capacitance unit switched to the set value to be switched, the voltage measurement circuit measures the voltage and the current measurement circuit measures the current, and the control calculation unit calculates one or both of the permeability and iron loss of the sample to be measured, corresponding to the set value to be switched, based on the voltage and the current, in a calculation step, The magnetic property measurement method according to claim 1, wherein the preparation step and the calculation step are repeated until the capacitance of the variable capacitance unit is switched to all of the at least two or more set values.

3. The magnetic property measurement method according to claim 1 or 2, wherein the control calculation unit performs the extrapolation step.

4. A magnetic properties measuring device for measuring the magnetic properties of a sample to be measured, which is wound with a primary winding of a first number of turns and a secondary winding of a second number of turns, A variable capacitance unit connected in parallel to the secondary winding and having capacitances that can be switched to at least two different set values, A voltage measuring circuit is connected in parallel to the secondary winding, and each time the capacitance of the variable capacitance unit is switched to at least two or more set values, an excitation current of a predetermined frequency is supplied from the signal generator to the primary winding, thereby maintaining the maximum magnetic flux density or maximum magnetic field of the sample under test at a predetermined value, and measuring the voltage induced across the ends of the secondary winding when a voltage is induced across the ends of the secondary winding. Each time the capacitance of the variable capacitance unit is switched to at least two or more set values, the excitation current is supplied from the signal generator to the primary winding, thereby maintaining the magnetic flux density or magnetic field of the sample under test at a predetermined value and inducing a voltage across the ends of the secondary winding. A current measuring circuit measures the current flowing through the primary winding. A control calculation unit that, based on the voltage and current, obtains one or both of at least two permeability values ​​and at least two iron losses of the sample to be measured, corresponding to at least two or more set values, and extrapolates the numerical data of one or both of the at least two permeability values ​​and at least two or more iron losses to determine one or both of the permeability values ​​and iron losses of the sample to be measured when the sum of the capacitance including the parasitic capacitance of the input section of the voltage measurement circuit and the capacitance of the variable capacitance section is zero. A magnetic property measuring device characterized by comprising the following features.

5. In preparation for measuring the voltage by the voltage measuring circuit and measuring the current by the current measuring circuit, the capacitance of the variable capacitance unit is switched to one of the at least two set values ​​to be switched to. With the capacitance of the variable capacitance unit switched to the set value to be switched, the voltage measurement circuit measures the voltage and the current measurement circuit measures the current, and the control calculation unit calculates one or both of the permeability and iron loss of the sample to be measured corresponding to the set value to be switched, based on the voltage and the current. The magnetic property measuring apparatus according to claim 4, wherein the switching to the setting value to be switched and the calculation of one or both of the permeability and iron loss of the sample to be measured corresponding to the setting value to be switched are repeated until the capacitance of the variable capacitance unit is switched to all of the at least two or more setting values.

6. The magnetic property measuring apparatus according to claim 5, wherein the control calculation unit automatically performs at least one of the following: switching the capacitance of the variable capacitance unit to each of the at least two or more set values; calculating one or both of the magnetic permeability and iron loss of the sample to be measured corresponding to the set value to be switched; and extrapolating the numerical data.

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