JP7372540B2 - Magnetic flux density measurement method and magnetic flux density measurement device - Google Patents

Description

The present invention relates to a magnetic flux density measuring method and a magnetic flux density measuring device.

The magnetic flux density within the magnetic core of the magnetic material is not uniform throughout the magnetic core, but differs depending on the location of the magnetic core, depending on the shape of the magnetic core, the presence or absence of air gaps formed in the magnetic core, and the like. At locations in the magnetic core where the magnetic flux density is relatively high, temperature increases due to increased core loss and noise increases due to increased magnetostriction. Furthermore, at locations where the saturation magnetic flux density specific to the magnetic core is exceeded, inductance and the like decrease due to a decrease in magnetic permeability.

When used in magnetic components such as transformers, reactors, choke coils, etc. that use magnetic cores, which cause temperature increases due to increased core loss, increased noise due to increased magnetostriction, and decreased inductance due to decreased magnetic permeability, etc. The performance of magnetic components is significantly reduced.

As a means of predicting the local magnetic flux density within a magnetic core, there is a simulation using magnetic field analysis software using the finite element method or the like. However, the simulation results are only predicted results, and in order to determine whether the predicted results are correct, it is necessary to actually measure the local magnetic flux density within the magnetic core.

Search coil methods and probe methods are generally well known as methods for measuring local magnetic flux density (for example, the magnetic flux density sensor disclosed in Patent Document 1).

JP2013-238453A

FIG. 1 is a diagram illustrating a magnetic flux density measuring method using a general search coil method. In the search coil method, a search coil 2 is formed at a location where the magnetic flux density is to be measured in a sheet-shaped magnetic core 1 extending in the y-axis direction of a three-dimensional orthogonal coordinate system shown in FIG. This method measures the local magnetic flux density within the sheet-shaped magnetic core 1 based on the induced voltage _Vc generated in the magnetic core 1. According to the search coil method, it is possible to measure the local magnetic flux density within the magnetic core, which is sufficiently suitable for practical use. However, the search coil method has a drawback in that the work of forming search coils 2 at each location of the sheet-shaped magnetic core 1 to be measured is very complicated.

FIG. 2 is a diagram illustrating a general magnetic flux density measurement method using a probe method. In the probe method, two probes are placed in parallel at a distance d at the location where the magnetic flux density is to be measured in a conductive sheet-shaped magnetic core 1 extending in the y-axis direction of the three-dimensional orthogonal coordinate system shown in Figure 2. The two probes 3a, 3b are brought into contact with each other, and based on the voltage V _n between the two probes 3a, 3b generated by the eddy current flowing within the cross section of the sheet-shaped magnetic core 1, local This method measures magnetic flux density.

According to the probe method, measurement results equivalent to the search coil method, which corresponds to 1/2 turn when the search coil is formed through a hole made at the point where the two probes 3a and 3b are in contact, can be obtained. can get. In addition, according to the probe method, in order to measure the magnetic flux density, it is only necessary to touch the two probes 3a and 3b to the part of the sheet-shaped magnetic core 1 where the magnetic flux density is to be measured. In comparison, the local magnetic flux density within the sheet-shaped magnetic core 1 can be measured very easily.

However, in order to obtain measurement results equivalent to the 1/2-turn search coil method, the probe method must satisfy the following first and second application conditions in terms of measurement principle. The first application condition relates to the thickness h of the sheet-shaped magnetic core 1. That is, the first application condition is that the distance d is sufficiently larger than the thickness h of the sheet-shaped magnetic core 1 (d>>h). The second application condition relates to the surface shape of the sheet-shaped magnetic core 1 with which the probe comes into contact. That is, the second application condition is that the surface shape of the sheet-shaped magnetic core 1 that brings the two parallel probes 3a and 3b into contact is not a curved surface but a flat surface.

Therefore, the probe method has the disadvantage that it cannot be applied to anything other than conductive sheet-shaped magnetic cores 1 in which the distance d is sufficiently larger than the thickness h of the sheet-shaped magnetic core 1 and the surface shape is flat.

Manganese zinc ferrite is a soft magnetic material with electrical conductivity. In addition, manganese zinc ferrite has high magnetic permeability, high saturation magnetic flux when the frequency of the excitation current supplied to the wound excitation coil is below 1MHz to allow time-varying magnetic flux to pass through. It has density and low core loss. Therefore, manganese zinc ferrite is widely commonly used in magnetic components. When manganese zinc ferrite is used as an electromagnetic shielding material, sheet-shaped manganese zinc ferrite is used. On the other hand, when manganese-zinc ferrite is used as the magnetic core of magnetic components such as transformers, reactors, choke coils, etc., block-shaped manganese-zinc ferrite magnetic cores with rectangular or circular cross sections called EE cores, UU cores, ring cores, etc. are used. It will be done.

When the block-shaped manganese zinc ferrite magnetic core has a rectangular cross section, the first application condition and the second application condition are not satisfied. On the other hand, if the magnetic core of block-shaped manganese-zinc ferrite has a circular cross section, the second application condition described above is satisfied, but the distance between the two probes cannot be made sufficiently larger than the thickness of the magnetic core of block-shaped manganese-zinc ferrite. Since this is not possible, the first application condition described above is not satisfied. Therefore, the local magnetic flux density of the block-shaped manganese-zinc ferrite core cannot be measured using the probe method.

The object of the present invention is to provide a magnetic flux density measuring method and a magnetic flux density measuring method that can extremely easily measure the local magnetic flux density within a magnetic core, regardless of whether the cross section of the magnetic core of a conductive magnetic material is a rectangular cross section or a circular cross section. An object of the present invention is to provide a magnetic flux density measuring device.

The magnetic flux density measuring method according to the present invention includes a first electrode, a second electrode, a jig for moving the first electrode and the second electrode, and a point contact with a magnetic core of a conductive magnetic material. Magnetic flux density measurement that measures magnetic flux density in a magnetic core by using a magnetic flux density measuring device that includes a voltage measurement circuit that measures the voltage generated between a first electrode and a second electrode, and a control calculation unit. The method includes an electrode placement step of using a jig to place a first electrode and a second electrode in point contact with the magnetic core while facing each other across the center of the cross section of the magnetic core; and A voltage measurement step in which the measurement circuit measures the voltage generated between the first electrode and the second electrode after the electrode arrangement step, and a control calculation unit measures the magnetic flux density in the magnetic core in the voltage measurement step. and a step of calculating a magnetic flux density based on the voltage determined by the magnetic flux density.

Preferably, the first electrode and the second electrode are needle electrodes, and the jig points the tip of the first electrode to the midpoint of the first side of the rectangular cross section of the magnetic core. At the same time, the tip of the second electrode is brought into point contact with the midpoint of the second side parallel to the first side of the rectangular cross section.

Preferably, the first electrode and the second electrode are needle electrodes, and the jig is configured to attach the first electrode to the magnetic core while facing each other across the center of the circular cross section of the magnetic core. The tip and the tip of the second electrode are brought into point contact, respectively.

Preferably, the first electrode and the second electrode are rod electrodes, and the jig brings the side part of the first electrode into point contact with the first vertex of the rectangular cross section of the magnetic core having a rectangular cross section. At the same time, the side portion of the second electrode is brought into point contact with a second vertex opposite to the first vertex of the rectangular cross section with the center of the rectangular cross section in between.

Preferably, the first electrode and the second electrode are rod electrodes, and the jig is configured to attach the first electrode to the magnetic core while facing each other across the center of the circular cross section of the magnetic core. The side portion and the side portion of the second electrode are respectively brought into point contact.

The magnetic flux density measuring device according to the present invention includes a first electrode and a second electrode, and a state in which the first electrode and the second electrode are opposed to each other across the center of a cross section of a magnetic core of a conductive magnetic material. A first electrode and a second electrode are placed in point contact with the magnetic core while facing each other across the center of the cross section of the magnetic core. It includes a voltage measurement circuit that measures the voltage generated between the electrodes, and a control calculation unit that calculates the magnetic flux density within the magnetic core based on the voltage measured by the voltage measurement circuit.

According to the present invention, the local magnetic flux density within the magnetic core can be extremely easily measured regardless of whether the cross section of the magnetic core of a conductive magnetic material is a rectangular cross section or a circular cross section.

FIG. 2 is a diagram illustrating a magnetic flux density measuring method using a general search coil method. FIG. 2 is a diagram illustrating a magnetic flux density measurement method using a general probe method. 1 is a diagram illustrating a first embodiment of a magnetic flux density measuring method according to the present invention. FIG. 4 is a detailed diagram of a portion of FIG. 3; FIG. 5 is an enlarged view of the II cross section in FIG. 4. FIG. 3 is a flowchart showing processing according to the first embodiment of the magnetic flux density measuring method according to the present invention. FIG. 3 is a diagram illustrating an example of measuring the magnetic flux density of a magnetic core having a rectangular cross section using a magnetic flux density measuring method using a search coil method as a first comparative example. 8 is an enlarged view of the II-II cross section in FIG. 7. FIG. It is a figure explaining the 2nd embodiment of the magnetic flux density measuring method by this invention. 10 is a detailed diagram of a portion of FIG. 9; FIG. 11 is an enlarged view of the III-III cross section in FIG. 10. FIG. It is a flowchart which shows the process by 2nd Embodiment of the magnetic flux density measuring method by this invention. FIG. 7 is a diagram illustrating, as a second comparative example, an example of measuring the magnetic flux density of a magnetic core having a circular cross section using a magnetic flux density measuring method using a search coil method. 14 is an enlarged view of the IV-IV cross section in FIG. 13. FIG. It is a figure explaining the 3rd embodiment of the magnetic flux density measuring method by this invention. 16 is a detailed diagram of a portion of FIG. 15; FIG. 17 is an enlarged view of the VV cross section in FIG. 16. FIG. It is a flowchart which shows the process by 3rd Embodiment of the magnetic flux density measuring method by this invention. It is a figure explaining the 4th embodiment of the magnetic flux density measuring method by this invention. 20 is a detailed diagram of a portion of FIG. 19; FIG. 21 is an enlarged view of the VI-VI cross section in FIG. 20. FIG. It is a flowchart which shows the process by the 4th embodiment of the magnetic flux density measuring method by this invention. FIG. 7 is a diagram illustrating an example of measuring the magnetic flux density of a magnetic core having a rectangular cross section using a magnetic flux density measuring method using a probe method as a third comparative example. FIG. 7 is a diagram illustrating another example of measuring the magnetic flux density of a magnetic core having a rectangular cross section using a magnetic flux density measuring method using a probe method as a fourth comparative example. It is a figure showing the magnetization curve obtained by the 1st embodiment of the magnetic flux density measurement method by the present invention, and the magnetization curve obtained by the 1st comparative example. It is a figure which shows the magnetization curve obtained by the 3rd embodiment of the magnetic flux density measuring method by this invention, and the magnetization curve obtained by a 1st comparative example. It is a figure which shows the magnetization curve obtained by a 1st comparative example, the magnetization curve obtained by a 3rd comparative example, and the magnetization curve obtained by a 4th comparative example. It is a figure which shows the magnetization curve obtained by the 2nd embodiment of the magnetic flux density measuring method by this invention, and the magnetization curve obtained by a 2nd comparative example. It is a figure which shows the magnetization curve obtained by the 4th embodiment of the magnetic flux density measuring method by this invention, and the magnetization curve obtained by a 2nd comparative example.

Embodiments of the magnetic flux density measuring method and magnetic flux density measuring apparatus according to the present invention will be described in detail using symbols with reference to the drawings. In the drawings, the same components are given the same reference numerals.
FIG. 3 is a diagram explaining the first embodiment of the magnetic flux density measuring method according to the present invention, FIG. 4 is a detailed diagram of a part of FIG. 3, and FIG. It is an enlarged view of I section. The magnetic flux density measuring device 11 shown in FIG. 3 includes needle electrodes 21a and 21b whose tips face each other, and a jig 22. The magnetic flux density measuring device 11 is connected to a signal generator 23 and further includes a shunt resistor 24, a current measuring circuit 25, a voltage measuring circuit 26, a control calculation section 27, and a display device 28. The needle electrodes 21a and 21b are an example of a first electrode and a second electrode.

In the first embodiment, a UU core 29 having a rectangular cross section with vertices A, B, C, and D is fixed to the jig 22, and an excitation coil 30 is wound around the UU core 29. The length of the side DA side BC of the rectangular cross section of the UU core 29 extending in the x-axis direction of the three-dimensional orthogonal coordinate system shown in FIG. The lengths of sides AB and CD of the rectangular cross section of the UU core 29 extending in the direction are b. The side DA is an example of a first side, and the side BC is an example of a second side. The UU core 29 is an example of a magnetic core made of a magnetic material having electrical conductivity, and is also an example of a magnetic core having a rectangular cross section.

The needle electrodes 21a, 21b are connected to a voltage measurement circuit 26. As shown in FIG. 4, the jig 22 includes support parts 22a and 22b that support the needle electrodes 21a and 21b, and moves the support parts 22a and 22b in the direction of the y-axis of the three-dimensional orthogonal coordinate system shown in FIG. and a groove 22d for fixing the UU core 29. The positions of the support parts 22a and 22b, the width of the groove 22d, and the position of the UU core 29 disposed in the groove 22d are appropriately adjusted by a drive mechanism (not shown) of the jig 22.

In the first embodiment, as shown in FIG. 3, FIG. 4, and _FIG . Place it in point contact with the magnetic core. Specifically, a fixing member (not shown) of the jig 22 fixes the UU core 29 to the groove 22d whose width is adjusted to be b. Then, by appropriately moving the supporting parts 22a and 22b in the direction of the y-axis of the three-dimensional orthogonal coordinate system shown in FIG. The tip of the needle electrode 21b is brought into point contact with the center point Q of the side BC of the rectangular cross section of the UU core 29, and the tip of the needle electrode 21a is brought into point contact.

The signal generator 23 supplies an exciting current I ₁ to the exciting coil 30 in order to cause the magnetic flux Φ whose magnitude changes over time to pass through the UU core 29 . Both ends of the shunt resistor 24 are connected to the current measurement circuit 25.

The current measurement circuit 25 and the voltage measurement circuit 26 each include, for example, an amplifier, a DA converter, a storage device, and the like. The current measuring circuit 25 measures the current I ₁ flowing through the shunt resistor 24 corresponding to the current I ₁ flowing through the UU core 29 while the exciting current I ₁ is being supplied to the exciting coil 30 . In the voltage measurement circuit 26, the tip of the needle electrode 21b makes point contact with the midpoint P of the side DA of the rectangular cross section of the UU core 29, and the tip of the needle electrode 21a contacts the midpoint Q of the side BC of the rectangular cross section of the UU core 29. The voltage _Vs generated between the needle electrodes 21a and 21b in a point-contact state is measured.

The control calculation unit 27 includes a CPU, a memory, etc., and controls the current measurement circuit 25 and the voltage measurement circuit 26, and also performs data processing such as data storage and numerical calculation. The display device 28 displays results of data processing, information and instructions to the operator, and the like.

FIG. 6 is a flowchart showing processing according to the first embodiment of the magnetic flux density measuring method according to the present invention. First, in the UU core and needle electrode arrangement step S1, the UU core 29 is fixed in the groove 22d, and the tip of the needle electrode 21b is brought into point contact with the midpoint P of the side DA of the rectangular cross section of the UU core 29. The tip of the needle electrode 21a is brought into point contact with the midpoint Q of the side BC of the rectangular cross section. The UU core and needle electrode arrangement step S1 is an example of an electrode arrangement step.

Next, in the voltage measurement step S2, the signal generator 23 supplies a sinusoidal exciting current _I1 to the exciting coil 30 in order to cause the magnetic flux Φ whose magnitude changes over time to pass through the UU core 29. do. Then, the voltage measuring circuit 26 causes the tip of the needle electrode 21b to make point contact with the midpoint P of the side DA of the rectangular cross section of the UU core 29, and the tip of the needle electrode 21b comes into point contact with the midpoint Q of the side BC of the rectangular cross section of the UU core 29. The voltage V _s generated between the needle electrodes 21a and 21b is measured with their tips in point contact.

When the magnetic flux Φ whose magnitude changes over time passes through the UU core 29, an eddy current is generated within the UU core 29 because the UU core 29 has electrical conductivity. The strength of the electric field in the x-axis direction of the three-dimensional orthogonal coordinate system shown in FIG. If the electric field strengths in the y-axis direction of the three-dimensional orthogonal coordinate system shown in FIG. 5 on side AB (side CD) of the rectangular cross section are E _x and E _y , respectively, then The voltage V _s obtained is expressed by the following formula.

Due to the symmetry of the electric field strength E _x in the x-axis direction of the three-dimensional orthogonal coordinate system shown in FIG. 5 with respect to the x-axis of the three-dimensional orthogonal coordinate system shown in FIG. V _s is expressed by the following formula.

Furthermore, due to the symmetry of the electric field strength E _x in the x-axis direction of the three-dimensional orthogonal coordinate system shown in FIG. 5 with respect to the y-axis of the three-dimensional orthogonal coordinate system shown in FIG. The voltage V _s obtained is expressed by the following formula.

Next, in the magnetic flux density calculation step S3, the control calculation unit 27 calculates the magnetic flux density B based on the voltage V _s generated between the needle electrodes 21a and 21b, as will be explained in detail later.

FIG. 7 is a diagram illustrating an example of measuring the magnetic flux density of a magnetic core having a rectangular cross section using the magnetic flux density measuring method using the search coil method as a first comparative example. It is an enlarged view of a cross section. In FIGS. 7 and 8, a search coil 31 is formed around the outer periphery of the rectangular cross section of the UU core 29, and has one turn, with the winding start and winding end being a vertex D.

When the exciting current I ₁ is supplied to the exciting coil 30 in order to cause the magnetic flux Φ whose magnitude changes over time to pass through the inside of the UU core 29, since the UU core 29 has conductivity, the inside of the UU core 29 eddy currents occur. E _x and Assuming E _y , the voltage V _c between both ends of the search coil 31 is expressed by the following equation, which is the integral of the electric field along one turn of the search coil 31 .

Symmetry of electric field strength E _x in the x-axis direction of the three-dimensional orthogonal coordinate system shown in Fig. 8 with respect to the x-axis of the three-dimensional orthogonal coordinate system shown in Fig. From the symmetry of the axial electric field strength E _y with respect to the y-axis of the three-dimensional orthogonal coordinate system shown in FIG. 8, the voltage V _c between both ends of the search coil 31 is expressed by the following equation.

Further, if the area of the rectangular cross section of the UU core 29 is S (=a×b), the following equation holds true for the voltage V _c between both ends of the search coil 31 from Faraday's law.

Here, when comparing the right side of equation (3) and the right side of equation (5), the relational expression between the voltage V _s generated between the needle electrodes 21a and 21b and the voltage V _c between both ends of the search coil 31 is , becomes as follows.

Equation (7) is the same relational expression as ``the measurement result of the probe method is equivalent to the measurement result of the search coil method corresponding to 1/2 turn.'' However, by the time the equation (7), which is the relation between the voltage V _s generated between the needle electrodes 21a and 21b and the voltage V _c between both ends of the search coil 31, is derived, the needle electrodes 21a and 21b and the UU core 29 There are no structural dimensional constraints at all. This is because, when applying the first embodiment, the first application condition of the probe method is that the distance d is sufficiently larger than the thickness h of the sheet-shaped magnetic core 1 (d>>h). This indicates that there are no restrictions such as "Yes".

Therefore, if equation (6) is applied to the voltage V _c across the search coil 31 expressed by equation (7), the following equation is obtained.

If equation (8) is solved for magnetic flux density B, the following equation is obtained.

Therefore, the magnetic flux density B can be determined from the voltage _Vs generated between the needle electrodes 21a and 21b.

FIG. 9 is a diagram explaining the second embodiment of the magnetic flux density measuring method according to the present invention, FIG. 10 is a detailed diagram of a part of FIG. 9, and FIG. It is an enlarged view of the III section. In the second embodiment, an EER core 32 having a circular cross-section middle leg with a radius r is fixed to the jig 22, and an excitation coil 30 is wound around the EER core 32. The EER core 32 is an example of a magnetic core made of a magnetic material that has electrical conductivity, and is also an example of a magnetic core that has a circular cross section.

In the second embodiment, as shown in FIG. 9, FIG. 10, and _FIG . They are placed at points Q' and P' on the circular cross section of the EER core 32 so as to face each other and make point contact with the magnetic core. That is, points P' and Q' of the circular cross section of the middle leg of the EER core 32 are the diameter ends of the circular cross section of the middle leg of the EER core 32, and are located on both sides of the center O ₂ of the circular cross section of the middle leg of the EER core 32. facing each other. Specifically, the fixing member of the jig 22 fixes the EER core 32 to the groove 22d whose width is adjusted to 2r. Then, by appropriately moving the supporting parts 22a and 22b in the direction of the y-axis of the three-dimensional orthogonal coordinate system shown in FIG _. The tips of the needle electrodes 21a and 21b are brought into point contact with points Q' and P' on the circular cross section of the middle leg of the EER core 32, respectively, while facing each other with the electrodes in between.

FIG. 12 is a flowchart showing processing according to the second embodiment of the magnetic flux density measuring method according to the present invention. First, in the EER core and needle electrode arrangement step S11, the EER core 32 is fixed in the groove 22d, and the tips of the needle electrodes 21a and 21b are placed facing each other across the center O ₂ of the circular cross section of the middle leg of the EER core 32. are brought into point contact with points Q' and P' on the circular cross section of the middle leg of the EER core 32, respectively.

Next, in the voltage measurement step S12, the signal generator 23 supplies an excitation current _I1 to the excitation coil 30 in order to cause the magnetic flux Φ whose magnitude changes over time to pass through the EER core 32. Then, the voltage measurement circuit 26 connects the tips of the needle electrodes 21a and 21b to a point Q' on the circular cross section of the middle leg of the EER core 32 while facing each other across the center _O2 of the circular cross section of the middle leg of the EER core 32. , P', and measure the voltage _Vs generated between the needle electrodes 21a and 21b.

When the magnetic flux Φ whose magnitude changes over time passes through the EER core 32, eddy currents are generated within the EER core 32 because the EER core 32 is electrically conductive. If the strength of the electric field in the tangential direction on the circumference of the circular cross section of the middle leg of the EER core 32 caused by the eddy current generated in this way is E _l , then the voltage V _s generated between the needle electrodes 21a and 21b is , is expressed by the following formula.

Next, in the magnetic flux density calculation step S13, the control calculation unit 27 calculates the magnetic flux density B based on the voltage V _s generated between the needle electrodes 21a and 21b, as will be explained in detail later.

FIG. 13 is a diagram illustrating, as a second comparative example, an example of measuring the magnetic flux density of a magnetic core having a circular cross section using the magnetic flux density measuring method using the search coil method. It is an enlarged view of a cross section. In FIGS. 13 and 14, a search coil 31 having one turn is formed around the outer periphery of the circular cross section of the middle leg of the EER core 32, and the winding start and winding end are points P'.

When a sinusoidal excitation current I ₁ is supplied to the excitation coil 30 in order to cause the magnetic flux Φ whose magnitude changes over time to pass through the EER core 32, the EER Eddy currents are generated within the core 32. If the strength of the electric field in the tangential direction on the outer circumference of the circular section of the middle leg of the EER core 32 caused by the eddy current generated in this way is E _l , then the voltage V _c between both ends of the search coil 31 is equal to It is expressed by the following equation, which is the circuit integral of the electric field along the search coil 31.

The strength of the electric field in the tangential direction on the outer circumference of the circular cross section of the middle leg of the EER core 32 is calculated from the symmetry of E _l with respect to the center O ₂ of the circular cross section of the middle leg of the EER core 32, and the voltage between both ends of the search coil 31 is V _c is expressed by the following formula.

Further, if the area of the circular cross section of the middle leg of the EER core 32 is S (=π×r ² ), the following equation holds true for the voltage V _c between both ends of the search coil 31 from Faraday's law.

Here, when comparing the right side of equation (10) and the right side of equation (12), the relational expression between the voltage V _s generated between the needle electrodes 21a and 21b and the voltage V _c between both ends of the search coil 31 is , becomes as follows.

Equation (14) is the same as Equation (7) for the first embodiment, which is the second application condition of the probe method when applying the second embodiment. This shows that there is no restriction such as "the surface shape of the sheet-shaped magnetic core 1 that brings the two parallel probes 3a and 3b into contact is not a curved surface but a flat surface".

Therefore, if equation (13) is applied to the voltage V _c across the search coil 31 expressed by equation (14), the following equation is obtained.

If equation (15) is solved for magnetic flux density B, the following equation is obtained.

Therefore, the magnetic flux density B can be determined from the voltage _Vs generated between the needle electrodes 21a and 21b.

FIG. 15 is a diagram illustrating a third embodiment of the magnetic flux density measuring method according to the present invention, FIG. 16 is a detailed diagram of a part of FIG. 15, and FIG. It is an enlarged view of the V cross section. The magnetic flux density measuring device 41 shown in FIG. 15 includes round bar electrodes 51a and 51b that are parallel to each other and a jig 42. The round bar electrodes 51a and 51b are an example of a first electrode and a second electrode, and are also an example of a bar electrode. The magnetic flux density measuring device 41 is connected to a signal generator 23 and further includes a shunt resistor 24, a current measuring circuit 25, a voltage measuring circuit 26, a control calculation section 27, and a display device 28.

In the third embodiment, a UU core 29 is fixed to the jig 42, and an excitation coil 30 is wound around the UU core 29. The round bar electrodes 51a and 51b are connected to the voltage measurement circuit 26. As shown in FIG. 16, the jig 42 includes support parts 42a and 42b that support the round bar electrodes 51a and 51b, and a groove 42c for moving the support part 42a in the direction of arrow α or β shown in FIG. and a groove 42d for fixing the UU core 29. The positions of the supports 42a and 42b, the width of the groove 42d, and the position of the UU core 29 disposed in the groove 42d are appropriately adjusted by a driving mechanism (not shown) of the jig 42.

In the third embodiment, as shown in FIG. 15, FIG. 16, and _FIG . Place it so that it makes point contact with the magnetic core. Specifically, the UU core 29 is fixed in the groove 42d by a fixing member (not shown) of the jig 42 with the side part of the round bar electrode 51b in point contact with the vertex D of the rectangular cross section of the UU core 29. . By appropriately moving the support portion 42a in the direction of the arrow β shown in FIG. make point contact. Vertex D is an example of a first vertex, and vertex B is an example of a second vertex.

FIG. 18 is a flowchart showing processing according to the third embodiment of the magnetic flux density measuring method according to the present invention. First, in the UU core and round bar electrode arrangement step S21, the UU core 29 is fixed in the groove 42d with the side part of the round bar electrode 51b in point contact with the vertex D of the rectangular cross section of the UU core 29. The side of the round bar electrode 51a is brought into point contact with the vertex B of the rectangular cross section. The UU core and round bar electrode arrangement step S21 is an example of an electrode arrangement step.

Next, in the voltage measurement step S22, the signal generator 23 supplies the exciting current _I1 to the exciting coil 30 in order to cause the magnetic flux Φ whose magnitude changes over time to pass through the UU core 29. Then, the voltage measurement circuit 26 brings the side part of the round bar electrode 51b into point contact with the vertex D of the rectangular cross section of the UU core 29, and also brings the side part of the round bar electrode 51a into point contact with the vertex B of the rectangular cross section of the UU core 29. In this state, the voltage V _r generated between the round bar electrodes 51a and 51b is measured.

Next, in the magnetic flux density calculation step S23, the control calculation unit 27 calculates the magnetic flux density B based on the voltage V _r generated between the round bar electrodes 51a and 51b. Since the voltage V _r generated between the round bar electrodes 51a and 51b is equivalent to the voltage V _s generated between the needle electrodes 21a and 21b in the first embodiment, the following equation can be expressed similarly to equation (9). The formula holds true.

Therefore, the magnetic flux density B can be determined from the voltage V _r generated between the round bar electrodes 51a and 51b.

FIG. 19 is a diagram for explaining the fourth embodiment of the magnetic flux density measuring method according to the present invention, FIG. 20 is a detailed diagram of a part of FIG. 19, and FIG. It is an enlarged view of the VI section. The magnetic flux density measuring device 41' shown in FIG. 19 includes round bar electrodes 51a and 51b that are parallel to each other and a jig 42'. The magnetic flux density measuring device 41' is connected to a signal generator 23, and further includes a shunt resistor 24, a current measuring circuit 25, a voltage measuring circuit 26, a control calculation section 27, and a display device 28.

In the fourth embodiment, an EER core 32 is fixed to a jig 42', and an excitation coil 30 is wound around the middle leg of the EER core 32. The round bar electrodes 51a and 51b are connected to the voltage measurement circuit 26. As shown in FIG. 20, the jig 42' includes support parts 42a' and 42b' that support the round bar electrodes 51a and 51b, and a support part 42a' that extends in the direction of the x-axis of the three-dimensional orthogonal coordinate system shown in FIG. It has a groove 42c' for moving the EER core 32, and a groove 42d' for fixing the EER core 32. The positions of the support parts 42a' and 42b', the width of the groove 42d', and the position of the EER core 32 disposed in the groove 42d' are appropriately adjusted by a driving mechanism (not shown) of the jig 42'.

In the fourth embodiment, as shown in FIG. 19, FIG. 20, and _FIG . They are placed at points P' and Q' on the circular cross section of the middle leg of the EER core 32 so as to make point contact with the magnetic core. That is, points P' and Q' of the circular cross section of the middle leg of the EER core 32 face each other across the center O ₂ of the circular cross section of the middle leg of the EER core 32 . Specifically, first, the distance between the central axis of the round bar electrode 51a and the central axis of the round bar electrode 51b is the radius of each of the round bar electrodes 51a, 51b and the diameter of the circular cross section of the middle leg of the EER core 32. The support portion 42a' is appropriately moved by the drive mechanism of the jig 42' in the x-axis direction of the three-dimensional orthogonal coordinate system shown in FIG. Next, the side of the round bar electrode 51b is brought into point contact with the point Q' of the circular cross section of the middle leg of the EER core 32, and the side of the round bar electrode 51a is brought into point contact with the point P' of the circular cross section of the middle leg of the EER core 32. The EER core 32 is moved over the groove 42d' whose width is appropriately adjusted by a drive mechanism (not shown) of the jig 42' so that the EER core 32 is brought into point contact. Then, the EER core 32 is fixed to the groove 42d' by a fixing member (not shown) of the jig 42'.

FIG. 22 is a flowchart showing processing according to the fourth embodiment of the magnetic flux density measuring method according to the present invention. First, in the EER core and round bar electrode arrangement step S31, the side part of the round bar electrode 51b is brought into point contact with the point Q' of the circular cross section of the middle leg of the EER core 32, and the point Q' of the circular cross section of the middle leg of the EER core 32 is brought into point contact. The EER core 32 is moved over the groove 42d' whose width is appropriately adjusted and fixed in the groove 42d' so that the side part of the round bar electrode 51a is brought into point contact with P'. The EER core and round bar electrode arrangement step S31 is an example of an electrode arrangement step.

Next, in the voltage measurement step S32, the signal generator 23 supplies a sinusoidal excitation current _I1 to the excitation coil 30 in order to cause the magnetic flux Φ whose magnitude changes over time to pass through the EER core 32. do. Then, the voltage measurement circuit 26 brings the side part of the round bar electrode 51b into point contact with a point Q' on the circular cross section of the middle leg of the EER core 32, and brings the round bar electrode 51b into point contact with a point P' on the circular cross section of the middle leg of the EER core 32. The voltage V _r generated between the round bar electrodes 51 a and 51 b is measured with the sides of the electrode 51 a in point contact.

Next, in the magnetic flux density calculation step S33, the control calculation unit 27 calculates the magnetic flux density B based on the voltage V _r generated between the round bar electrodes 51a and 51b. Since the voltage V _r generated between the round bar electrodes 51 a and 51 b is equivalent to the voltage V _s generated between the needle electrodes 21 a and 21 b in the second embodiment, similarly to equation (16), ( 17) Equation is established.

Therefore, the magnetic flux density B can be determined from the voltage V _r generated between the round bar electrodes 51a and 51b.

In order to explain the magnetization curves obtained by the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment, a third comparative example and a fourth comparative example will be described. I will explain further.

FIG. 23 is a diagram illustrating, as a third comparative example, an example of measuring the magnetic flux density of a magnetic core having a rectangular cross section using the magnetic flux density measuring method using the probe method. In FIG. 23, an exciting current I ₁ is supplied to the exciting coil 30 in order to cause the magnetic flux Φ whose magnitude changes over time to pass through the UU core 29 . Then, the two probes 52a and 52b, which are arranged side by side with an interval d, are brought into contact with the surface including the side CD of the rectangular cross section of the UU core 29 shown in FIGS. 5 and 8.

FIG. 24 is a diagram illustrating another example of measuring the magnetic flux density of a magnetic core having a rectangular cross section using the magnetic flux density measuring method using the probe method as a fourth comparative example. In FIG. 24, an excitation current I ₁ is supplied to the excitation coil 30 in order to cause the magnetic flux Φ whose magnitude changes over time to pass through the UU core 29 . Then, the two probes 52a and 52b, which are arranged side by side with an interval d, are brought into contact with the surface including the side BC of the rectangular cross section of the UU core 29 shown in FIGS. 5 and 8.

Note that since the surface shape of the middle leg of the EER core 32 is a curved surface, the second compliance condition of the probe method is not satisfied. Magnetic flux density B cannot be measured. Therefore, an example of measuring the magnetic flux density B in the middle leg of the EER core 32 using the magnetic flux density measuring method using the probe method was not shown as a comparative example.

Next, examples of the magnetization curves obtained by the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment are shown in the first comparative example and the second comparative example. , a third comparative example, and a fourth comparative example.

The UU core 29 used in the first embodiment, the third embodiment, the first comparative example, the third comparative example, and the fourth comparative example is made of conductive manganese zinc ferrite. A UU core (a=2.1 mm, b=10 mm, S=21 mm ² ) with magnetic path length L=52.6 mm was used.

The excitation coil 30 used in the first embodiment, the third embodiment, the first comparative example, the third comparative example, and the fourth comparative example, and the search coil 31 used in the first comparative example. The number of turns was 5 for each. The distance d between the probes 52a and 52b used in the third comparative example and the fourth comparative example was 1.6 mm.

In the first embodiment, the frequency and amplitude of the sinusoidal excitation current I ₁ supplied to the excitation coil 30 are 50 kHz and 0.5 A, respectively, and the distance between the needle electrodes 21 a and 21 b in one cycle of the excitation current I ₁ is set to 50 kHz and 0.5 A, respectively. The resulting voltage V _s was measured.

In the third embodiment, the frequency and amplitude of the sinusoidal excitation current I ₁ supplied to the excitation coil 30 are 50 kHz and 0.5 A, respectively, and the distance between the round bar electrodes 51 a and 51 b in one cycle of the excitation current I ₁ is set to 50 kHz and 0.5 A, respectively. The voltage V _r generated at was measured.

In the first comparative example, the frequency and amplitude of the sinusoidal excitation current I ₁ supplied to the excitation coil 30 are 50 kHz and 0.5 A, respectively, and the voltage V between both ends of the search coil ₃₁ during one period of the excitation current I 1 _c was measured.

In the third comparative example and the fourth comparative example, the frequency and amplitude of the sinusoidal excitation current I ₁ supplied to the excitation coil 30 are 50 kHz and 0.5 A, respectively, and the probe 52a in one period of the excitation current I ₁ is , 52b was _measured .

In the first embodiment, the third embodiment, the first comparative example, the third comparative example, and the fourth comparative example, the strength H of the magnetic field generated in the UU core 29 is determined by the measured current I ₁ It was calculated from a well-known relational expression based on .

In the first embodiment, the magnetic flux density B was determined from equation (9) based on the measured voltage V _s . In the third embodiment, the magnetic flux density B was determined from equation (17) based on the measured voltage V _r .

In the first comparative example, the magnetic flux density B was determined from a well-known relational expression based on the measured voltage V _c . In the third comparative example and the fourth comparative example, the magnetic flux density B was determined from a well-known relational expression based on the measured voltage V _n .

As the EER core 32 used in the second embodiment, the fourth embodiment, and the second comparative example, an EER core (middle leg A cross-sectional area S=179mm ² ) was used.

The number of turns of the excitation coil 30 used in the second embodiment, the fourth embodiment, and the second comparative example was 10. The number of turns of the search coil 31 used in the second comparative example was three.

In the second embodiment, the frequency and amplitude of the sinusoidal excitation current I ₁ supplied to the excitation coil 30 are 10 kHz and 1.0 A, respectively, and between the needle electrodes 21 a and 21 b in one period of the excitation current I ₁ . The resulting voltage V _s was measured.

In the fourth embodiment, the frequency and amplitude of the sinusoidal excitation current I ₁ supplied to the excitation coil 30 are 10 kHz and 1.0 A, respectively, and the distance between the round bar electrodes 51 a and 51 b in one cycle of the excitation current I ₁ is set to 10 kHz and 1.0 A, respectively. The voltage V _r generated at was measured.

In the second comparative example, the frequency and amplitude of the sine wave excitation current I ₁ supplied to the excitation coil 30 are 10 kHz and 1.0 A, respectively, and the voltage V between both ends of the search coil ₃₁ in one cycle of the excitation current I 1 is _c was measured.

In the second embodiment, the fourth embodiment, and the second comparative example, the strength H of the magnetic field generated in the EER core 32 was determined from a well-known relational expression based on the measured current _I1 . In the second embodiment, the magnetic flux density B was determined from equation (16) based on the measured voltage V _s . In the fourth embodiment, the magnetic flux density B was determined from equation (17) based on the measured voltage V _r . In the second comparative example, the magnetic flux density B was determined from a well-known relational expression based on the measured V _c .

FIG. 25 is a diagram showing a magnetization curve obtained by the first embodiment of the magnetic flux density measuring method according to the present invention and a magnetization curve obtained by the first comparative example. The magnetization curve obtained according to the first embodiment is drawn using the magnetic field strength H and magnetic flux density B obtained as described above, and is shown as a solid line in FIG. 25. The magnetization curve obtained in the first comparative example is drawn using the magnetic field strength H and magnetic flux density B obtained as described above, and is indicated by a broken line in FIG. 25. As shown in FIG. 25, it can be seen that the magnetization curve obtained by the first embodiment is extremely similar to the magnetization curve obtained by the first comparative example.

FIG. 26 is a diagram showing a magnetization curve obtained by the third embodiment of the magnetic flux density measuring method according to the present invention and a magnetization curve obtained by the first comparative example. The magnetization curve obtained according to the third embodiment is drawn using the magnetic field strength H and magnetic flux density B obtained as described above, and is shown as a solid line in FIG. 26. The magnetization curve obtained in the first comparative example is drawn using the magnetic field strength H and the magnetic flux density B obtained as described above, and is indicated by a broken line in FIG. 26. As shown in FIG. 26, it can be seen that the magnetization curve obtained by the third embodiment is extremely similar to the magnetization curve obtained by the first comparative example.

FIG. 27 is a diagram showing a magnetization curve obtained by the first comparative example, a magnetization curve obtained by the third comparative example, and a magnetization curve obtained by the fourth comparative example. The magnetization curve obtained in the first comparative example is drawn using the magnetic field strength H and the magnetic flux density B obtained as described above, and is indicated by a broken line in FIG. 27. The magnetization curve obtained in the third comparative example is drawn using the magnetic field strength H and magnetic flux density B obtained as described above, and is indicated by a dashed line in FIG. 27. The magnetization curve obtained in the fourth comparative example is drawn using the magnetic field strength H and magnetic flux density B obtained as described above, and is shown as a solid line in FIG. 27. The magnetization curve obtained by the third comparative example and the magnetization curve obtained by the fourth comparative example are different from the magnetization curve obtained by the first comparative example, that is, the magnetization curve obtained by the probe method is different from the magnetization curve obtained by the first comparative example. It can be seen that the magnetization curve is different from the magnetization curve obtained by the search coil method. Such a difference is caused by the fact that the width d (1.6 mm) of the probes 52a and 52b is not sufficiently larger than the length a (2.1 mm) of the side BC or the length b (10 mm) of the side CD of the rectangular cross section of the UU core 29. This shows that the first application condition of the probe method is not satisfied.

Magnetization curve obtained by the first comparative example, magnetization curve obtained by the first embodiment, magnetization curve obtained by the third embodiment, magnetization curve obtained by the third comparative example, and fourth comparison Table 1 shows the residual magnetic flux density B _r and maximum magnetic flux density B _m of the magnetization curves obtained in the examples. The numerical values in parentheses in Table 1 are the respective errors (in %) with respect to the residual magnetic flux density B _r and the maximum magnetic flux density B _m of the magnetization curve obtained by the first comparative example (search coil method).

By referring to Table 1, the approximation of the magnetization curve obtained by the first embodiment, the magnetization curve obtained by the third embodiment, and the magnetization curve obtained by the first comparative example can be quantitatively determined. can be determined.

As shown in Table 1, the residual magnetic flux density B _r and the maximum magnetic flux density B _m of the magnetization curve obtained by the first embodiment and the magnetization curve obtained by the third embodiment are different from those of the first comparison. The error is less than 3% with respect to the residual magnetic flux density B _r and the maximum magnetic flux density B _m of the magnetization curve obtained by the example, and the accuracy is sufficient for practical use.

On the other hand, as shown in Table 1, the residual magnetic flux density B _r and the maximum magnetic flux density B _m of the magnetization curve obtained by the third comparative example are the same as the residual magnetic flux density B r and the maximum magnetic flux density B _m of the magnetization curve obtained by the first comparative example. There is a maximum error of about 9% with respect to the maximum magnetic flux density B _m .

Furthermore, as shown in Table 1, the residual magnetic flux density B _r and the maximum magnetic flux density B _m of the magnetization curve obtained by the fourth comparative example are the same as the residual magnetic flux density B r and the maximum magnetic flux density B _m of the magnetization curve obtained by the first comparative example. The error is about 80% with respect to the maximum magnetic flux density B _m .

Furthermore, although the difference between the third comparative example and the fourth comparative example is only in the surface of the UU core 29 that the probes 52a and 52b contact, the magnetization curve obtained by the third comparative example The residual magnetic flux density B _r and the maximum magnetic flux density B _m are significantly different from the residual magnetic flux density B _r and the maximum magnetic flux density B _m of the magnetization curve obtained by the fourth comparative example. Therefore, the third comparative example and the fourth comparative example are not suitable for practical use at all.

FIG. 28 is a diagram showing a magnetization curve obtained by the second embodiment of the magnetic flux density measuring method according to the present invention and a magnetization curve obtained by the second comparative example. The magnetization curve obtained according to the second embodiment is drawn using the magnetic field strength H and magnetic flux density B obtained as described above, and is shown as a solid line in FIG. 28. The magnetization curve obtained in the second comparative example is drawn using the magnetic field strength H and the magnetic flux density B obtained as described above, and is indicated by a broken line in FIG. 28. As shown in FIG. 28, it can be seen that the magnetization curve obtained by the second embodiment is extremely similar to the magnetization curve obtained by the second comparative example.

FIG. 29 is a diagram showing a magnetization curve obtained by the fourth embodiment of the magnetic flux density measuring method according to the present invention and a magnetization curve obtained by the second comparative example. The magnetization curve obtained according to the fourth embodiment is drawn using the magnetic field strength H and magnetic flux density B obtained as described above, and is shown as a solid line in FIG. 29. The magnetization curve obtained in the second comparative example is drawn using the magnetic field strength H and magnetic flux density B obtained as described above, and is shown by a broken line in FIG. 29. As shown in FIG. 29, it can be seen that the magnetization curve obtained by the fourth embodiment is extremely similar to the magnetization curve obtained by the second comparative example.

Record the residual magnetic flux density B _r and maximum magnetic flux density B _m of the magnetization curve obtained by the second comparative example, the magnetization curve obtained by the second embodiment, and the magnetization curve obtained by the fourth embodiment. The results are shown in Table 2. The numerical values in parentheses in Table 2 are the respective errors (unit: %) with respect to the residual magnetic flux density B _r and the maximum magnetic flux density B _m of the magnetization curve obtained by the second comparative example (search coil method).

By referring to Table 2, the approximation of the magnetization curve obtained by the second embodiment, the magnetization curve obtained by the fourth embodiment, and the magnetization curve obtained by the second comparative example can be quantitatively determined. can be determined.

As shown in Table 2, the residual magnetic flux density B _r and the maximum magnetic flux density B _m of the magnetization curve obtained by the second embodiment and the magnetization curve obtained by the fourth embodiment are different from those of the second comparison. The error is less than 3% with respect to the residual magnetic flux density B _r and the maximum magnetic flux density B _m of the magnetization curve obtained by the example, and the accuracy is sufficient for practical use.

According to the first embodiment, as in the first comparative example, it is possible to measure the local magnetic flux density within the UU core 29 sufficiently suitable for practical use. Further, according to the first embodiment, unlike the search coil method, it is not necessary to form a search coil for each location of the UU core 29 to be measured, and the above-mentioned first method required for the probe method is not required. It is not necessary to satisfy the applicable condition and the second applicable condition above. Therefore, the local magnetic flux density within the UU core 29 having a rectangular cross section can be measured very easily.

According to the second embodiment, as in the second comparative example, it is possible to measure the local magnetic flux density within the EER core 32 sufficiently for practical use. Further, according to the second embodiment, unlike the search coil method, it is not necessary to form a search coil for each location of the EER core 32 to be measured, and the above-mentioned first method required for the probe method is not required. It is not necessary to satisfy the applicable condition and the second applicable condition above. Therefore, the local magnetic flux density within the EER core 32 having the middle leg of a circular cross section can be measured very easily.

According to the third embodiment, as in the first comparative example, the local magnetic flux density within the UU core 29 can be measured sufficiently for practical use. Further, according to the third embodiment, unlike the search coil method, it is not necessary to form a search coil for each location of the UU core 29 to be measured, and the above-mentioned first method required for the probe method is not required. It is not necessary to satisfy the applicable condition and the second applicable condition above. Therefore, the local magnetic flux density within the UU core 29 having a rectangular cross section can be measured very easily. Furthermore, the round bar electrodes 51a and 51b can easily make point contact with the UU core 29 while facing each other with the center O ₁ of the rectangular cross section of the UU core 29 interposed therebetween.

According to the fourth embodiment, as in the second comparative example, it is possible to measure the local magnetic flux density within the EER core 32 sufficiently suitable for practical use. Further, according to the fourth embodiment, unlike the search coil method, it is not necessary to form a search coil for each location of the EER core 32 to be measured, and the above-mentioned first method required for the probe method is not required. It is not necessary to satisfy the applicable condition and the second applicable condition above. Therefore, the local magnetic flux density within the EER core 32 having the middle leg of a circular cross section can be measured very easily. Furthermore, the round bar electrodes 51a and 51b can easily make point contact with the middle leg of the EER core 32 while facing each other across the center _O2 of the circular cross section of the middle leg of the EER core 32.

The present invention is not limited to the first embodiment, second embodiment, third embodiment, and fourth embodiment described above, and numerous changes and modifications are possible. . For example, in the first embodiment and the second embodiment, a jig having a different configuration from the jig 22 may be used, and in the third embodiment, a jig having a different configuration from the jig 42 may be used. In the fourth embodiment, a jig having a different configuration from the jig 42' may be used.

Further, in the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment, a current probe is used instead of the shunt resistor 24 to detect the current _I1 . Good too. In the first embodiment and the third embodiment, the magnetic flux density inside the magnetic core other than the UU core 29 may be measured. The magnetic flux density within a magnetic core other than the above (for example, a ring core) may also be measured. For example, in the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment, the magnetic flux density in the ring core or the magnetic flux density in the magnetic core having a cross section other than a rectangle or a circle. Magnetic flux density may also be measured.

1 sheet-shaped magnetic core 2, 31 search coil 3a, 3b, 52a, 52b probe 11, 41, 41' magnetic flux density measuring device 21a, 21b needle electrode 22, 42, 42' jig 22a, 22b, 42a, 42b, 42a', 42b' Support part 22c, 22d, 42c, 42d, 42c', 42d' Groove 23 Signal generator 24 Shunt resistor 25 Current measurement circuit 26 Voltage measurement circuit 27 Control calculation unit 28 Display device 29 UU core 30 Excitation coil 32 EER core 51a, 51b round rod electrode

Claims (6)

a first electrode and a second electrode, a jig for moving the first electrode and the second electrode, the first electrode in point contact with a magnetic core of a conductive magnetic material, and the first electrode and the A magnetic flux density measuring method for measuring magnetic flux density in a magnetic core by using a magnetic flux density measuring device comprising a voltage measuring circuit that measures the voltage generated between the second electrodes and a control calculation unit, the method comprising:
an electrode arrangement step of arranging the first electrode and the second electrode so as to be in point contact with the magnetic core while facing each other across the center of the cross section of the magnetic core using the jig;
In order to cause a magnetic flux whose magnitude varies with time to pass through the magnetic core, an excitation current is supplied to the excitation coil by a signal generator connected to an excitation coil wound around the magnetic core, and then by the voltage measuring circuit. , a voltage measurement step of measuring the voltage generated between the first electrode and the second electrode arranged in the electrode arrangement step;
a magnetic flux density calculation step in which the control calculation unit calculates the magnetic flux density in the magnetic core based on the voltage measured in the voltage measurement step;
A magnetic flux density measurement method comprising: The first electrode and the second electrode are needle electrodes,
The jig brings the tip of the first electrode into point contact with the midpoint of the first side of the rectangular cross section of a magnetic core having a rectangular cross section, and the second side parallel to the first side of the rectangular cross section. 2. The magnetic flux density measuring method according to claim 1, wherein the tip of the second electrode is brought into point contact with the midpoint of . The first electrode and the second electrode are needle electrodes,
1 . The jig is configured to bring a tip of the first electrode and a tip of the second electrode into point contact with the magnetic core while facing each other across the center of the circular section of the magnetic core. The magnetic flux density measurement method described in . The first electrode and the second electrode are rod electrodes,
The jig brings the side part of the first electrode into point contact with the first vertex of the rectangular cross section of the magnetic core having a rectangular cross section, and contacts the first vertex of the rectangular cross section across the center of the rectangular cross section. 2. The magnetic flux density measuring method according to claim 1, wherein a side portion of the second electrode is brought into point contact with the opposing second vertex. The first electrode and the second electrode are rod electrodes,
The jig is configured to bring a side portion of the first electrode and a side portion of the second electrode into point contact with the magnetic core while facing each other across the center of the circular cross section of the magnetic core. Item 1. The method for measuring magnetic flux density according to item 1. a first electrode and a second electrode;
a jig for arranging the first electrode and the second electrode so as to be in point contact with the magnetic core while facing each other across the center of the cross-section of the magnetic core of a conductive magnetic material;
In order to cause a magnetic flux whose magnitude changes over time to pass through the magnetic core, an excitation current is supplied to the excitation coil by a signal generator connected to an excitation coil wound around the magnetic core, and then the magnetic core is a voltage measurement circuit that measures the voltage generated between the first electrode and the second electrode, which are arranged in point contact with the magnetic core while facing each other across the center of the cross section;
a control calculation unit that calculates the magnetic flux density within the magnetic core based on the voltage measured by the voltage measurement circuit;
A magnetic flux density measuring device equipped with.

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