JP6137922B2 - L load - Google Patents

Description

  The present invention relates to an L load used when evaluating dynamic characteristics of a power device (switching element).

  When measuring the switching characteristics that are the dynamic characteristics of the power device, a half-bridge circuit having an L load is used.

  Power devices need to be confirmed not only for rated current characteristics but also for a wide range from small currents to large currents. At this time, the voltage Vcc applied to the power device from the bank capacitor circuit provided in the half bridge circuit is fixed and cannot be changed. Also, from the viewpoint of work efficiency at the time of measurement, the L load is not normally exchanged in the measurement of the same power device. Therefore, in order to obtain a desired current, it is necessary to adjust the length of the ON time T of the power device.

  Conventionally, various techniques have been disclosed for magnetic cores that can also be used for L loads (see, for example, Patent Document 1).

JP 7-226320 A

  When measuring a small current using the L load, it is preferable to use a large inductance L, and since the fluctuation of the current I with respect to the fluctuation of the time T is small, the measurement can be performed with high accuracy. On the other hand, when the inductance L is large, a large current cannot be measured.

Further, when measuring a large current using an L load, it is preferable to use a small inductance L. Since the fluctuation of the current I with respect to the fluctuation of the time T is large, the set current can be applied with a short pulse, and half It is possible to suppress the charge consumption of the bank capacitor provided in the bridge circuit. On the other hand, when the inductance L is small, a small current cannot be measured with high accuracy.

  From the above, when the inductance L of the L load is fixed, if the range of the current to be measured is widened, the accuracy of the measurement of the large current or the measurement of the small current deteriorates. The target current range needs to be narrowed. That is, when the inductance L of the L load is fixed, the range of current that can be measured with high accuracy is limited.

  In patent document 1, the magnetic core which can change the inductance L is disclosed. However, it does not take into consideration the mounting properties (ease of mounting, etc.), strength, and leakage of magnetic flux to the outside.

  The present invention has been made to solve these problems, and can accurately measure a wide range of currents and prevent leakage of magnetic flux to the outside without changing the mounting property and strength from the conventional one. It aims at providing L load.

In order to solve the above-described problem, the L load according to the present invention is configured to flow a current by being wound around a laminated core formed by laminating a plurality of plate-like cores and a predetermined portion of the laminated core. The laminated core includes at least one notch formed by cutting out the cross-sectional area of the laminated core at a predetermined portion different from a portion around which the wire is wound. Yes, and notches is characterized countersunk portion der Rukoto formed on each of the cores.

According to the present invention, a laminated core formed by laminating a plurality of plate-like cores, and a wiring that is wound around a predetermined portion of the laminated core and can flow current, the laminated core includes: in the predetermined portion different from the wiring is wound portion, the cutout portion formed by cutting to the cross-sectional area changes of the laminated core possess at least one or more notch section of each core counterbore portion der because formed respectively, a wide range of current accurately measured, and, without changing the conventional mounting resistance and strength, it is possible to leakproof flux to the outside.

It is a top view which shows an example of a structure of L load by Embodiment 1 of this invention. It is a top view which shows an example of a structure of L load by Embodiment 2 of this invention. It is a graph which shows an example of the correlation with time and electric current by Embodiment 2 of this invention. It is a top view which shows an example of a structure of L load by Embodiment 3 of this invention. It is a graph which shows an example of correlation with time and current by Embodiment 3 of the present invention. It is a top view which shows an example of a structure of L load by Embodiment 4 of this invention. Is a diagram showing an example of the cross-section of FIG. It is a top view which shows an example of a structure of the core by the modification 1 of this invention. It is a figure which shows an example of the cross section of FIG. It is a top view which shows an example of a structure of the core by the modification 2 of this invention. It is a figure which shows an example of the cross section of FIG. It is a top view which shows another example of a structure of the core by the modification 2 of this invention. It is a top view which shows an example of a structure of the core by the modification 2 of this invention. It is a figure which shows an example of the cross section of FIG. It is a figure which shows an example of the electrical property measurement circuit of the power device by prerequisite technology. It is a graph which shows an example of the correlation of time and an electric current. It is a figure for demonstrating a magnetic circuit. It is a figure which shows an example of a BH curve. It is a top view which shows an example of a structure of the conventional L load. It is a top view which shows another example of the structure of the conventional L load.

  Embodiments of the present invention will be described below with reference to the drawings.

<Prerequisite technology>
First, the prerequisite technology of the present invention will be described.

  FIG. 15 is a diagram illustrating an example of a power device electrical characteristic measurement circuit (half-bridge circuit) according to the base technology. Hereinafter, the switching element 5 will be described as a power device.

  As shown in FIG. 15, the electrical characteristic measuring circuit includes a bank capacitor circuit unit 1, a snubber circuit 2, an L load 3, a flywheel diode 4, a switching element 5, a gate driver 6, and a gate resistor 7. And a gate driver control pulse generator 8. The bank capacitor circuit unit 1 includes a bank capacitor 1a and a power source 1b.

  Next, the operation of the electrical characteristic measurement circuit will be described.

  When the power supply 1b of the bank capacitor circuit unit 1 is boosted to a predetermined voltage, electric charges are accumulated in the bank capacitor 1a of the bank capacitor circuit unit 1 according to the boosting.

  When a gate driver drive signal is output from the gate driver control pulse generator 8 in a state where charges are accumulated in the bank capacitor 1a, a switching element drive voltage is output from the gate driver 6.

  When the switching element driving voltage is output from the gate driver 6, the switching element 5 is turned on, and a current is applied from the bank capacitor 1 a to the switching element 5 via the L load 3. At this time, the current flowing through the switching element 5 is approximated by the following equation (1).

I = 1 / L × Vcc × T (1)
Here, I is a current flowing through the switching element 5 via the L load 3, L is an inductance, Vcc is a voltage of the bank capacitor circuit unit 1, and T is a time for which the switching element is turned on (ON time). .

  From the above formula (1), the current I is inversely proportional to the inductance L and proportional to the ON time T of the switching element 5 and Vcc of the bank capacitor circuit unit 1.

  As described above, the switching element 5 needs to confirm the characteristics over a wide range from a small current to a large current as well as the characteristics of the rated current. At this time, the voltage Vcc of the bank capacitor circuit unit 1 is fixed and cannot be changed. Also, from the viewpoint of work efficiency during measurement, the L load is not normally exchanged in the measurement of the same switching element 5. Therefore, in order to obtain a desired current, it is necessary to adjust the length of the ON time T of the switching element 5.

  FIG. 16 is a graph showing the correlation between the ON time T of the switching element 5 and the current I when the voltage Vcc of the bank capacitor circuit unit 1 is fixed. The horizontal axis represents the ON time of the switching element 5, and the vertical axis represents the current flowing through the switching element 5 via the L load 3.

  In FIG. 16, a graph 9 shows a case where an L load having a large inductance L is used. Graph 10 shows a case where an L load having a small inductance L is used. A graph 11 shows a case where an L load according to the present invention described later is used.

  As shown in FIG. 16, when measuring a small current, it is preferable to use a large inductance L, and since the fluctuation of the current I with respect to the fluctuation of the time T is small, the measurement can be performed with high accuracy (graph 9 in FIG. 16). ).

  At this time, it is unsuitable for measuring a large current using a large inductance L. That is, the amount of charge flowing out from the bank capacitor 1a is an area (time integration of the applied current) composed of the ON time of the switching element 5 and the applied current (current flowing through the switching element 5). If the inductance L is large, it is necessary to lengthen the time T accordingly, so that much charge in the bank capacitor 1a is consumed. However, the size of the bank capacitor 1a is limited due to the installation space of the measurement system including the electrical characteristic measurement circuit, and the capacity is also limited. Therefore, when the inductance L is large, a large current cannot be measured.

  When measuring a large current using an L load, it is preferable to use a small inductance L. Since the fluctuation of the current I with respect to the fluctuation of the time T is large, the set current can be applied to the switching element 5 with a short pulse. Thus, the consumption of electric charges of the bank capacitor 1a can be suppressed (graph 10 in FIG. 16).

  At this time, when measuring a small current using a small inductance L, it is necessary to shorten the time T, but the fluctuation of the current I with respect to the fluctuation of the time T is large, the time T slightly varies, and the fluctuation of the current I. Becomes larger. Further, there are repeated variations in the pulse width of the gate driver control pulse generator 8 that controls the gate driver 6 used for measurement, and repeated variations in the gate driver 6 itself. As described above, since the time T varies, the current I also varies.

  If the current I is considerably small, the time T needs to be shortened accordingly. Since there is a parasitic capacitance at the gate terminal of the switching element 5 and there is a gate resistance between the gate driver 6 and the gate terminal, a certain amount of time is required until the gate voltage reaches the set voltage after the pulse is applied. Time is needed. However, when the inductance L with respect to the current I is small, the current I reaches the set current before the gate voltage reaches the set voltage, and thus the current cannot be applied with high accuracy.

  From the above, in the case where the inductance L of the L load is fixed, if the range of the current to be measured is widened, the accuracy of the measurement of the large current or the measurement of the small current deteriorates, and when trying to improve the measurement accuracy, It is necessary to narrow the range of current to be measured. That is, when the inductance L of the L load is fixed, the range of current that can be measured with high accuracy is limited.

  As described above, a magnetic core capable of changing the inductance L is disclosed in Patent Document 1, but in Patent Document 1, the mounting property (ease of mounting, etc.), strength, and magnetic flux to the outside of the magnetic core. Does not consider leaks.

  The present invention has been made to solve such problems. Specifically, as shown in the graph 11 of FIG. 16, the L load according to the present invention has a characteristic that the inductance L is increased in a region of a small current and the inductance L is decreased when a predetermined current value is exceeded. ing. When the L load according to the present invention is used, the pulse width can be increased because the inductance L is large in the small current region, and the charge L of the bank capacitor 1a can be suppressed because the inductance L is small in the large current region. it can. Hereinafter, the L load according to the present invention will be described in detail.

<Embodiment 1>
How to realize the L load according to the embodiment of the present invention will be described.

  First, a mechanism for determining the inductance L of the L load will be described.

  The inductance L, current I, and magnetic flux φ have the relationship of the following equation (2).

L = φ / I (2)
Here, L is an inductance, I is a current flowing through the coil, and φ is a magnetic flux passing through the coil when a current is passed through the coil.

  From the above equation (2), the ratio between the current I flowing through the coil and the magnetic flux φ passing through the coil at that time is the inductance L. For example, if the value of the current I is constant, the inductance L increases as the magnetic flux φ passing through the coil increases, and the inductance L decreases as the magnetic flux φ passing through the coil decreases. In this way, the inductance L can be controlled by controlling the magnetic flux φ per current I.

  Next, the magnetic circuit will be described. The magnitude of the magnetic flux φ can be controlled using the principle of a magnetic circuit.

  FIG. 17A shows an electric circuit (DC circuit), and FIG. 17B shows a magnetic circuit.

  The magnetic circuit (FIG. 17B) is easy to understand when compared to an electric circuit (FIG. 17A). The magnetic flux φ in the magnetic circuit corresponds to the current I in the electric circuit. The magnetic potential difference nI in the magnetic circuit corresponds to the potential difference V in the electric circuit. Here, n indicates the number of turns of the coil, and I indicates the current flowing through the coil. That is, the magnetic potential difference nI is proportional to the number of turns n of the coil and the applied current I. Further, the magnetic resistance Rm in the magnetic circuit corresponds to the electric resistance R in the electric circuit.

  Just as there is a relationship of I = V / R in the electric circuit, there is a relationship of φ = nI / Rm in the magnetic circuit. That is, the larger the magnetic resistance Rm, the smaller the magnetic flux φ flowing through the coil, and the smaller the magnetic resistance Rm, the larger the magnetic flux φ flowing through the coil.

  From the above, the magnetic flux φ can be controlled by controlling the magnetic resistance Rm. Further, as described above, the inductance L of the coil can be controlled by controlling the magnetic flux φ. That is, the inductance L of the coil can be controlled by controlling the magnetic resistance Rm.

  Next, the magnetic resistance Rm will be described.

  The magnetic resistance Rm, the cross-sectional area s of the L-load core, and the length l of the L-load core have the relationship of the following equation (3).

Rm = 1 / μ × 1 / s × l (3)
Here, μ represents the magnetic permeability of the material used for the L-load core.

  From the above equation (3), the magnetic resistance Rm is inversely proportional to the cross-sectional area s and the permeability μ of the L-load core, and is proportional to the length l of the L-load core.

A soft magnetic material is used for the L-load core. A BH curve of the soft magnetic material is shown in FIG. The vertical axis B of Figure 18 illustrates the magnetic flux per unit area, i.e., the magnetic flux density. The horizontal axis H represents the magnetic field.

  As shown in FIG. 18, the soft magnetic material has a magnetic flux density B that increases in proportion to the magnetic field H. However, when a predetermined magnetic field H is exceeded, the magnetic flux density B is saturated, and the gradient ΔB / ΔH (differential permeability) between the magnetic flux density B and the magnetic field H is reduced to the same level as in vacuum.

  The L load according to the embodiment of the present invention is realized by using the above principle.

  Next, the L load according to the first embodiment of the present invention will be described.

  FIG. 1 is a plan view showing an example of a configuration of an L load according to the first embodiment of the present invention. The L load according to the first embodiment will be described as corresponding to the L load 3 in FIG.

  As shown in FIG. 1, the L load according to the first embodiment is wound around a laminated core 15 formed by laminating a plurality of plate-like cores and a predetermined portion of the laminated core 15, Wiring 14 capable of flowing.

  Further, the laminated core 15 has a notch portion 16 formed by notching so that the cross-sectional area of the laminated core 15 is changed at a predetermined portion different from the portion around which the wiring 14 is wound. Forming.

  As described above, in the first embodiment, a cutout portion 16 that is a portion where the cross-sectional area of the core is reduced is provided only in a part of the laminated core 15, and the laminated core 15 includes a plurality of plate-like cores. It is characterized by being laminated.

  By configuring the L load with the laminated core 15, it becomes easier to produce the notch 16 as compared with the case where the L load is configured with a bulk core.

  In addition, the shape of the cutout portion 16 can be changed by changing the shape of each plate-like core constituting the laminated core 15, which facilitates production.

  Each plate-like core constituting the laminated core 15 is produced by, for example, pressing a material having desired magnetic characteristics (for example, an electromagnetic steel plate). 19 and 20 show an example of the configuration of a conventional L load. In each L load, the core is a bulk body, for example, a sintered body of a magnetic material. Further, since the gap portion 27 is provided in the core shown in FIG. 20, magnetic saturation is suppressed instead of increasing the magnetic resistance.

  As shown in FIG. 1, since the magnetoresistance is inversely proportional to the cross-sectional area of the laminated core 15, only the portion where the notch 16 is formed has a larger magnetoresistance than the other portions.

  In the electric circuit, the flowing current is the same in both the small resistance portion and the large resistance portion. Similarly, in the magnetic circuit, the flowing magnetic flux φ is the same in the notch portion 16 and other portions. Since the portion of the cutout portion 16 is thin (the cross-sectional area of the laminated core 15 is smaller than that of the other portion), the magnetic flux density (magnetic field) is larger than that of the other portion. Accordingly, when the current flowing through the wiring 14 is increased, only the portion of the notch 16 first causes magnetic saturation. When the portion of the notch 16 is magnetically saturated, the differential permeability (ΔB / ΔH) becomes the same as the vacuum, which is equivalent to the core shape shown in FIG. That is, the inductance L increases in the region of small current, and the inductance L decreases in the region of large current, and exhibits characteristics as shown by the graph 11 in FIG. Therefore, a sufficient pulse width can be obtained even in a small current region. Further, it is possible to suppress the charge consumption of the bank capacitor 1a even in a large current region.

  From the above, according to the first embodiment, a wide range of current can be measured with high accuracy. Further, since the outer shape of the laminated core 15 is not different from that of the conventional core (see FIGS. 19 and 20), it is not necessary to change the mounting, and the strength is not different from the conventional one. Further, there is no need to worry about the mounting direction at the time of mounting (the mounting performance is the same as in the conventional case), and the same handling as in the conventional case is possible. Moreover, since the notch 16 is formed inside the laminated core 15, leakage of magnetic flux to the outside can be prevented, and the influence of the magnetic field on external electronic components and the like can be suppressed.

<Embodiment 2>
FIG. 2 is a plan view showing an example of the configuration of the L load according to the second embodiment of the present invention. The L load according to the second embodiment will be described as corresponding to the L load 3 in FIG.

  As shown in FIG. 2, the laminated core 15 according to the second embodiment forms notches 17 and 18. In addition, the cross-sectional area of the laminated core 15 in the cutout portion 18 is smaller than the cross-sectional area of the laminated core 15 in the cutout portion 17. Other configurations are the same as those in the first embodiment, and thus description thereof is omitted here.

  When the current flowing through the wiring 14 is increased, the notch portion 18 first causes magnetic saturation, and when the current is further increased, the notch portion 17 next causes magnetic saturation. At this time, the characteristics shown in FIG. 3 are exhibited.

  From the above, according to the second embodiment, it is possible to perform the measurement more accurately in the medium current region as compared with the first embodiment. Other effects are the same as those of the first embodiment.

<Embodiment 3>
FIG. 4 is a plan view showing an example of the configuration of the L load according to the third embodiment of the present invention.

  In the L load according to the first and second embodiments, the current gradient changes abruptly before and after the inflection point of the inductance L, so that it may be difficult to adjust the current.

  On the other hand, in the third embodiment, as shown in FIG. 4, a notch 19 is formed such that the cross-sectional area of the laminated core 15 changes gradually (continuously). The shape of the notch 19 may be any shape as long as the cross-sectional area of the laminated core 15 gradually changes. Other configurations are the same as those in the first embodiment, and thus description thereof is omitted here.

  Further, the L load shown in FIG. 4 has characteristics as shown in FIG.

  From the above, according to the third embodiment, the current before and after the inflection point of the inductance L becomes gentle, so that the current can be accurately measured near the inflection point. Other effects are the same as those of the first embodiment.

  Here, the structure of the notch parts 16-19 in this Embodiment 1-3 is demonstrated in the modification 1,2.

<Modification 1>
FIG. 8 is a plan view showing an example of the configuration of a plate-like core constituting the laminated core 15 according to the first modification of the present invention. FIG. 9 is a cross-sectional view taken along the line AA in FIG.

  As shown in FIGS. 8 and 9, the plate-like core constituting the laminated core 15 has a counterbore 23 formed in a part thereof.

  The laminated core 15 can change the degree of magnetic saturation stepwise by using the counterbore 23 formed in the core constituting the laminated core 15 as a notch. Other effects are the same as those of the first to third embodiments.

  The number of counterbore portions 23 is not limited to one, and a plurality of counterbore portions 23 may be formed on one core, or the counterbore portion 23 may be formed on each of the plurality of cores.

<Modification 2>
FIG. 10 is a plan view showing an example of the configuration of a plate-like core constituting the laminated core 15 according to the second modification of the present invention. FIG. 11 is a cross-sectional view taken along the line AA in FIG.

  As shown in FIGS. 10 and 11, the plate-like core constituting the laminated core 15 has a through portion 24 formed in a part thereof.

  The laminated core 15 can change the degree of magnetic saturation stepwise by using the penetrating portion 24 formed in the core constituting the laminated core 15 as a notch. Other effects are the same as those of the first to third embodiments.

  Note that the number of through portions 24 is not limited to one, and a plurality of through portions 24 may be formed in one core, or the through portions 24 may be formed in each of the plurality of cores.

  Moreover, you may form a notch part combining the penetration part 24 and the counterbore part 23 of the modification 1. FIG.

  FIG. 12 is a diagram showing another example of the configuration of the plate-like core that constitutes the laminated core 15 according to the second modification of the present invention.

  As shown in FIG. 12, the plate-like core constituting the laminated core 15 has a through portion 25 formed in a part thereof. The penetrating portion 25 is shorter in the longitudinal direction than the penetrating portion 24.

  The laminated core 15 can change the degree of magnetic saturation stepwise by using the through portions 24 and 25 formed in the core constituting the laminated core 15 as a notch. FIGS. 13 and 14 show an example of the configuration of the laminated core 15 in which the cutout portions are formed by combining the through portions 26 having different dimensions.

  Further, by stacking cores having different dimensions, such as the penetrating parts 24 and 25, the dimension in the thickness direction (Z direction) of the notch part can be easily changed.

  In addition, the penetration part 25 is not restricted to one, A plurality may be formed in one core, and the penetration part 25 may be formed in each of the plurality of cores.

  Moreover, you may form a notch part combining the penetration part 25 and the counterbore part 23 of the modification 1. FIG.

<Embodiment 4>
FIG. 6 is a diagram showing an example of the configuration of the L load according to the fourth embodiment of the present invention. FIG. 7 is a cross-sectional view taken along the line AA in FIG. The L load according to the fourth embodiment will be described as corresponding to the L load 3 in FIG.

  As shown in FIGS. 6 and 7, the laminated core 15 according to the fourth embodiment has different saturation magnetic flux densities (that is, different magnetic permeability) in a predetermined portion different from the portion around which the wiring 14 is wound. It has a heterogeneous core stacked portion 20 formed by stacking two types of cores. In the fifth embodiment, the heterogeneous core stacked portion 20 is formed of two types of cores, but may be two or more types. Other configurations are the same as those of the first embodiment, and thus description thereof is omitted here.

  The heterogeneous core laminate 20 is formed by sandwiching a low magnetic permeability core 21 (low magnetic permeability core) between high magnetic permeability cores 22 (high magnetic permeability core). That is, the material properties of the respective plate-like cores to be laminated are made different. In the fourth embodiment, as an example, the outer core constituting the laminated core 15 is formed using a high magnetic permeability material.

  From the above, according to the fourth embodiment, the characteristics of the laminated core 15 can be easily changed by changing the characteristics, thickness, number of laminated layers, etc. of the material forming each core of the laminated core 15. It becomes possible. In addition, by using a material with high magnetic permeability for the outer core constituting the laminated core 15, leakage of magnetic flux to the outside can be more effectively suppressed. Other effects are the same as those of the first embodiment.

  The above-described laminated core 15 is not limited to the configuration described in the first to fourth embodiments, and may further configure the L load having desired characteristics by further combining the configurations described in the respective embodiments.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  DESCRIPTION OF SYMBOLS 1 Bank capacitor circuit part, 2 Snubber circuit, 3 L load, 4 Flywheel diode, 5 Switching element, 6 Gate driver, 7 Gate resistance, 8 Gate driver control pulse generator, 9-11 Graph, 12 Electrical circuit, 13 Magnetic Circuit, 14 wiring, 15 laminated core, 16 to 19 notch, 20 heterogeneous core laminated portion, 21 low magnetic permeability core, 22 high magnetic permeability core, 23 counterbore portion, 24 to 26 penetration portion, 27 gap portion.

Claims (7)

A laminated core formed by laminating a plurality of plate-shaped cores;
A wire that is wound around a predetermined portion of the laminated core and can pass a current;
With
The laminated core is in the predetermined portion different from the wiring is wound portion, a notch cross section is formed by cutting as changes of the laminated core possess at least one or more,
The notch is characterized countersunk portion der Rukoto that is formed on each of the core, L load. The laminated core has two notches,
The L load according to claim 1, wherein one of the cutout portions is the counterbore portion, and the other cutout portion is a through portion formed in at least one of the cores.
  The said notch part is formed by laminating at least one or more cores having a counterbore part and at least one or more cores having a penetrating part. L load.   2. The L load according to claim 1, wherein the laminated core includes the two notched portions having different cross-sectional areas of the laminated core.   The L load according to claim 1, wherein the notch is formed so that a cross-sectional area of the laminated core continuously changes. The laminated core is formed by laminating at least two types of cores having different saturation magnetic flux densities in a predetermined portion different from the portion around which the wiring is wound, instead of the notch portion. characterized in that it has a core lamination portion, L load according to any one of claims 1 to 3. The L load according to claim 6 , wherein the heterogeneous core stacked portion is formed by sandwiching the core having a low magnetic permeability between the cores having a high magnetic permeability.

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