JP2015099818A - High-frequency reactor, and method for designing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency reactor in which an iron core is configured only by an I-type iron core, as a one coil-type high-frequency reactor, and to provide a method for designing the same.SOLUTION: A double square-shaped iron core 20 consists of: three legs in total of a central leg 21 and two side legs 22 and 23 that are bilaterally symmetrical about the central leg 21; and two yokes 24 and 25 magnetically coupling those three legs. In the iron core 20, air gaps 26 are provided between the three legs 21, 22, and 23 and the two yokes 24 and 25, respectively. Thereby, the iron core can be configured by a combination of only I-type iron cores.

Description

  The present invention relates to a high frequency reactor using an iron core having an air gap in a magnetic path as a magnetic core in order to prevent magnetic saturation of the iron core, and a design method thereof.

  In recent years, in the field of power electronics, it has been promoted to increase the driving frequency of switching power supplies and inverter power supplies from the viewpoint of energy saving and space saving.

  For reactors used in such switching power supplies and inverter power supplies, high efficiency and miniaturization are required while supporting high frequency drive frequencies. For example, high frequency range of several kHz to 100 kHz is supported. There is a strong demand for stable mass supply of high-frequency reactors that can be used.

  In recent years, with increasing interest in environmental issues, hybrid vehicles have become widespread. A hybrid vehicle is equipped with a high output motor as a driving force source. An inverter is used as a power source for driving the motor, and a high-frequency reactor is also used in the inverter power supply system. In the automotive field, the miniaturization and weight reduction of parts are particularly strongly aimed at improving fuel efficiency. For this reason, the high frequency reactor mounted on the hybrid vehicle is strongly required to be smaller than before.

  As the core material for these high-frequency reactors, soft magnetic metal materials such as electromagnetic steel sheets are often used.

  In a reactor using an electromagnetic steel plate or the like for an iron core, as seen in Patent Document 1 and Patent Document 2, for example, an air gap is generally provided in a magnetic path in order to prevent magnetic saturation of the iron core.

  In a single-phase AC reactor or DC reactor, as shown in FIGS. 1 and 3 of Patent Document 1 or FIG. 15 of Patent Document 2, two side legs that are symmetrical with respect to the center leg and the center leg are used. A one-coil type (outer iron type) reactor having a Japanese-shaped iron core consisting of a total of three legs and a yoke that magnetically couples the three legs, and winding a coil only on the central leg, As seen in FIG. 10 and FIG. 11 of Patent Document 2, it has a square-shaped iron core composed of two legs and a yoke that magnetically couples the legs, and a coil is attached to each of the two legs. There are two coil type (inner iron type) reactors that wind.

  Among them, in the 1-coil reactor, as in Patent Document 1, it is configured by a yoke assembled in a square shape and a central leg having an air gap, or in Patent Document 3 and Patent Document 4. As described above, there is one constituted by an E-type iron core and an I-type iron core.

JP-A-6-302442 Japanese Patent Laid-Open No. 7-22258 JP2013-4761A Japanese Utility Model Publication No. 6-31122

  The present inventor decided to manufacture the high-frequency reactor with a one-coil reactor, and as a result of earnestly examining the iron core used at that time, it was thought that it would be efficient if the iron core could be composed of only an I-type iron core. It came.

  In other words, an I-type iron core can be manufactured by simply laminating and laminating electromagnetic steel sheets, so that an electromagnetic steel sheet can be punched and laminated into an E shape like an E-type iron core, or The manufacturing cost can be reduced as compared with the case where the lap lamination is performed by cutting at an oblique angle. For this reason, if the iron core of a reactor can be comprised only with an I-type iron core, the manufacturing cost of a reactor can be reduced.

  Further, when the core of the reactor is composed of an E-type core and an I-type core, as shown in FIG. 16 of Patent Document 2, the degree of freedom in designing the core dimensions is greatly limited. However, if the core of the reactor can be composed of only an I-type core, the degree of freedom in designing the core dimensions can be increased.

  The present invention has been made from the above viewpoint, and provides a high-frequency reactor in which an iron core is configured by only an I-type iron core as a one-coil type high-frequency reactor, and a design method thereof.

  In order to solve the above problems, the present invention has the following features.

[1] As an iron core, a total of three legs including a central leg for winding a coil and two side legs symmetrical to the central leg, and a yoke for magnetically coupling the three legs In a one-coil type high frequency reactor that uses an iron core having an air gap in a magnetic path in order to prevent magnetic saturation of the iron core,
A high frequency reactor characterized in that an air gap is provided between each of three legs and a yoke so that the iron core can be constituted only by a combination of I-type iron cores.

  [2] The high frequency reactor according to [1], wherein an air gap is also provided in each of the middle length portion of the central leg and the middle length portion of the yoke leg.

[3] When designing the high-frequency reactor according to [1] or [2],
A first step of performing a reactor design on the premise of an iron core structure having an air gap only at the center leg so as to satisfy the required performance with respect to the inductance value;
A second step of performing a reactor design in which a part of the gap installed in the central leg is also distributed to the side legs without changing the core size of the reactor designed in the first step;
A high frequency reactor design method comprising: a third step of finely adjusting a design of the reactor designed in the second step in consideration of a required specification.

  In the present invention, as a one-coil type high-frequency reactor, a high-frequency reactor in which an iron core is configured by only an I-type iron core can be obtained.

It is a figure which shows the iron core of the conventional high frequency reactor. It is a figure which shows the iron core of the high frequency reactor in one Embodiment of this invention. It is a figure which shows the iron core of the high frequency reactor in other embodiment of this invention.

  An embodiment of the present invention will be described with reference to the drawings.

  When designing a new reactor, if there is a design example that has been made in the past for a requirement specification similar to the requirement specification of the reactor to be newly designed, it is possible to design extremely efficiently by proceeding with the design. It can be carried out.

  Again, in this way, the high frequency reactor in one embodiment of the present invention is designed.

  First, as an iron core, there are a total of three legs, a central leg for winding a coil and two side legs that are symmetrical with respect to the central leg, and a yoke that magnetically couples the three legs. For a 1-coil reactor that uses an iron core that has a shape of a certain day and uses an air gap in the magnetic path to prevent magnetic saturation of the iron core, an E-type iron core 11 ( Since there have been many designs in which the central leg 12 and the side legs 13 and 14) and the I-type iron core 15 constitute the iron core 10 and the air gap 16 is disposed only on the central leg 12, there are many design examples. There are many experiences and knowledge accumulated so far.

  On the other hand, as described above, if the iron core of the one-coil reactor can be composed of only the I-type iron core, the manufacturing cost of the reactor can be reduced and the degree of freedom in designing the core dimensions can be increased.

  For example, as one embodiment of the present invention, as shown in FIG. 2, a total of three legs including a central leg 21 and two side legs 22 and 23 that are symmetric with respect to the central leg 21 and the three legs. In a Japanese-shaped iron core 20 composed of two yokes 24 and 25 that magnetically couple the legs of each other, air is provided between the three legs 21, 22, 23 and the two yokes 24, 25, respectively. By providing the gap 26, the iron core can be constituted by a combination of only the I-type iron core.

  However, conventionally, as a function on the magnetic circuit, since the side leg is positioned as a yoke for returning the magnetic flux generated by the magnetomotive force in the central leg, it is not preferable to arrange an air gap there. It was thought.

  Certainly, the design magnetic flux density (core magnetic flux density at the rated current drive) is relatively high in the reactor (low frequency reactor) used at a relatively low frequency such as a commercial frequency or less than a few kHz, as described above. The provision of the air gap 26 between the side legs 22 and 23 and the yokes 24 and 25 is not preferable because it causes an increase in leakage magnetic flux.

  However, in a reactor (high frequency reactor) used at a high frequency exceeding several kHz, the design magnetic flux density is set to be relatively low in order to suppress high frequency iron loss, and therefore, between the side legs 22 and 23 and the yokes 24 and 25. The adverse effect of providing the air gap 26 on the surface is alleviated. Furthermore, when using a non-oriented high silicon steel plate as an iron core material, it discovered that the bad influence was further relieved.

  The high frequency reactor in one embodiment of the present invention is made based on the above knowledge, and is designed in the following procedure.

  (First Step) As shown in FIG. 1, an E-type iron core 11 and an I-type iron core 15 constitute an iron core so that the required performance with respect to the inductance value is satisfied, and an air gap 16 is provided only at the center leg 11. Reactor design is performed on the assumption of the conventional iron core 10. Here, the width of the center leg 12 is 2a, the length is c, the width of the side legs 13, 14 is a, the length is c, and the gap between the center leg 12 and the side legs 13, 14 is b, The width of the yoke portion of the E-type iron core 11 is a, the length is 4a + 2b, the width of the I-type iron core 15 is a, and the length is 4a + 2b.

  (Second Step) Next, a reactor design in which a part of the air gap 16 installed in the central leg 12 is also distributed to the side legs 13 and 14 without changing the dimensions of the iron core 10 designed in the first step. To do. As a result, as shown in FIG. 2, air gaps 26 are provided between the center legs 21 and the side legs 22 and 23 and the yokes 24 and 25, respectively, and an iron core 20 composed of only an I-type iron core is obtained. It is done.

  (Third step) Then, the design designed in the second step is finely adjusted in consideration of the required specifications (required performance).

  In this way, in this embodiment, first, as the design of the first stage (first process), there are many past design examples, and there is much accumulated experience and knowledge so far. The design is made on the assumption that the core 10 is configured and the air gap is arranged only at the center leg. Next, as the design of the second stage (second process), the core dimensions are the same as the design of the first stage. Designed assuming an iron core 20 in which the air gap of the legs is also distributed and distributed to the side legs, and as a design of the third stage (third process), there is a requirement for the reactor designed in the second stage The procedure for fine-tuning the design in consideration of the specifications is taken, so a design with a distributed air gap in an iron core structure consisting only of an I-type iron core that has little previous experience and knowledge is similar. Compared to the case of starting from the beginning, And knowledge accumulated can take advantage of, can be performed much more easily efficient design.

  Moreover, since the iron core of the one-coil reactor is composed of only the I-type iron core, it is possible to reduce the manufacturing cost of the reactor and increase the degree of freedom in designing the core dimensions.

  Furthermore, since the air gap is provided not only in the central leg 21 but also in the side legs 22 and 23 so that the length of the air gap per location can be reduced, the leakage magnetic flux generated by providing a wide air gap can be reduced. Increase and loss increase in the air gap portion can be suppressed.

  FIG. 3 shows another embodiment of the present invention. As shown in FIG. 3, the iron core 30 in this embodiment is further longer than the iron core 20 in the embodiment shown in FIG. 2, in the middle of the leg length of the central leg 21 and the lengths of the side legs 22 and 23. An air gap 31 is also provided in each intermediate portion.

  In general, the air gap position of the reactor is considered to be provided in the middle part of the length of the leg inside the coil rather than between the leg and the yoke because the magnetic flux confinement effect by the coil is considered. In the embodiment shown in FIG. 3, when the air gap 31 is arranged in the middle part of the length of the side legs 22 and 23, the length of the air gap 26 between the side legs 22 and 23 and the yokes 24 and 25. It is not always necessary to set the length shorter than the length of the air gap 31.

  As Example 1 of the present invention, an AC reactor for an inverter was designed and manufactured based on the above-described embodiment of the present invention.

  The required specifications of the AC reactor for the inverter are an inductance of 350 μH or more at a rated current of 50 Hz to 50 Arms, the reactor superimposed ripple current is 10 kHz-22 Peak to peak, the ambient temperature of the installation site is 40 ° C., the cooling condition is natural cooling, and the insulation standard F It was a seed (heat-resistant temperature 155 degreeC) premise.

  Since the ripple current is a high frequency of 10 kHz and the required performance of the reactor is required to reduce the noise of the reactor, it is necessary to use a 6.5 mass% silicon steel sheet (plate thickness: 0.1 mm) as the iron core material. The design of the high frequency reactor was carried out using commercially available magnetic field analysis software.

  First, as a first step, as in the case of a conventional reactor, an investigation was made on the premise that the core is composed of an E-type iron core and an I-type iron core as shown in FIG. In this case, in order to improve the material yield when punching and extracting the iron core member from the steel plate, as in the conventional case, the study was made in consideration of the dimension restrictions such as a = b and c = 2a + b.

  As before, when an iron core is composed of an E-type iron core and an I-type iron core, there are several design examples for the required specifications similar to the above-mentioned required specifications. It was easy to design.

  The dimensions of the iron core obtained as a result of the study were a = b = 20 mm, c = 60 mm, steel sheet lamination thickness d = 40 mm, and air gap length 3.8 mm. In addition, the coil has 23 turns using a copper thin plate having a thickness of 0.35 mm and a width of 55.7 mm and an insulating paper having a thickness of 0.13 mm. At this time, the assumed temperature rise during rated operation was 64.1 ° C. for the iron core and 93.9 ° C. for the coil.

  Next, as a second step, the iron core dimensions are a = b = 20 mm, c = 60 mm, the steel sheet lamination thickness d = 40 mm, the number of coil turns remains 23 turns, and the iron core is an I-type core as shown in FIG. A design with a structure consisting only of the above was studied.

  At that time, the air gap can be zero, for example, between the side legs and the yoke, and the iron cores can be brought into direct contact with each other. However, since this part causes noise due to electromagnetic attraction, fixing by welding, etc. There was a downside that it was necessary, and an air gap was always provided between the leg and the yoke. That is, air gaps were provided at a total of six locations.

  Moreover, only by changing the feeding length at the time of shearing of the steel plate to 20 mm and 40 mm, the central leg and the side leg can be manufactured using the steel plate hoop having a width of 60 mm in common, and the types of the steel plate hoop width to be prepared Therefore, the air gap length was considered as the same length at all six locations.

  The air gap length is a value that is ¼ of the air gap length of 3.8 mm when an iron core is configured with an E-type iron core and an I-type iron core in consideration of the flow of magnetic flux in the iron core. Investigation started at .95 mm.

  However, it is presumed that the degree of fringing (curving) of the magnetic flux in the air gap portion changes depending on the air gap length and the magnetic resistance of the air gap portion changes, but the air gap length is 0.95 mm × 6 locations. It was found that the inductance specification could not be satisfied.

  For this reason, as a result of further studies to finely adjust the gap length as the third step, it was found that the inductance specification can be satisfied if the gap length is 0.85 mm × 6 locations.

  In this way, first, as the first step, there are many past design examples and much experience and knowledge has been accumulated, and an iron core consisting of an E-type iron core and an I-type iron core with an air gap only on the center leg. Designed on the premise of 10 and then, as the second stage, the design is based on an iron core in which the air gap of the center leg is also distributed and distributed to the side legs, with the core dimensions remaining as designed in the first step. In addition, as the third step, the reactor designed in the second step is designed to fine-tune the design in consideration of the required specifications. Compared to designing from the beginning with a core structure consisting only of type I cores with little experience, and having a distributed air gap, it is possible to make use of accumulated experience and knowledge and make designing much easier and more efficient. Can do.

  As Example 2 of the present invention, the reactor (conventional example) configured in E type and I type, which is designed in Example 1 above, and the reactor of the iron core structure consisting only of I type (example of the present invention) are used. Each was manufactured using a commercially available 6.5 mass% silicon steel plate (plate thickness: 0.1 mm). The coil was completely the same, using a copper thin plate having a thickness of 0.35 mm and a width of 55.7 mm and an insulating paper having a thickness of 0.13 mm, and having 23 turns.

  As a result of measuring the reactor loss characteristics under a rated condition (basic wave current 50 Hz-50 Arms, ripple current 10 kHz-22 App) with a wattmeter using an inverter device, the reactor loss is 41.2 W in the conventional example. Then, the reactor loss was reduced to 38.2W.

  This is because the conventional example has a small air gap length of 3.8 mm at one location, whereas the example of the present invention has a small air gap length of 0.85 mm at one location. Is estimated to be reduced.

  As a result, in the present invention, it was confirmed that the manufacturing cost can be reduced and the loss during rated operation can be reduced.

  As described above, the design study of the reactor in the first embodiment is performed on the assumption that the ambient temperature of the reactor installation place is 40 ° C., and the temperature rise of the coil is 93.9 ° C. (the reached temperature of the coil is 40 + 93.9 = 133). .9 ° C).

  However, after that, although the required specifications of the reactor did not change, there was a possibility that the atmospheric temperature of the reactor installation location would be higher than 40 ° C. Therefore, it was necessary to review the design again.

  When the atmospheric temperature of the reactor installation location is higher than 40 ° C., the problem is the coil reaching temperature, so that the coil temperature rise is about 10 ° C. lower than the design of Example 1 to 83.9 ° C. or less. I made an examination.

  If the cross-sectional area of the iron core, the number of coil turns and the air gap length are not changed as in the design of the first embodiment, the thickness of the copper thin plate used for the coil can be dealt with by making it thicker than the design value of 0.35 mm of the first embodiment. That is the simplest method.

  As a result of the examination, if the thickness of the copper thin plate is changed from 0.35 mm to 0.4 mm and the iron core dimension b is changed from 20 mm to 22 mm, the required specification of the inductance value is satisfied and the coil temperature rise is increased by 80. It was found that it could be 3 ° C.

  As in the conventional example, when an iron core is configured with an E-type iron core and an I-type iron core, there is a limitation in the interrelationship between the iron core dimensions a, b, and c. However, it can be understood that when the iron core is composed of only the I-type iron core as in the example of the present invention, the degree of freedom of design is high and the fine adjustment of the dimensions is easy.

DESCRIPTION OF SYMBOLS 10 Iron core 11 E type iron core 12 Central leg 13 Side leg 14 Side leg 15 I type iron core 16 Air gap 20 Iron core 21 Central leg 22 Side leg 23 Side leg 24 Yoke 25 York 26 Air gap 30 Iron core 31 Air gap

Claims (3)

As an iron core, there are a total of three legs, a central leg for winding a coil, two side legs symmetrical to the central leg, and a yoke that magnetically couples the three legs. In a one-coil type high frequency reactor that uses an iron core having an air gap in the magnetic path to prevent magnetic saturation of the iron core,
A high frequency reactor characterized in that an air gap is provided between each of three legs and a yoke so that the iron core can be constituted only by a combination of I-type iron cores.   The high frequency reactor according to claim 1, wherein an air gap is also provided in each of an intermediate length portion of the central leg and an intermediate length portion of the yoke leg. In designing the high frequency reactor according to claim 1 or 2,
A first step of performing a reactor design on the premise of an iron core structure having an air gap only at the center leg so as to satisfy the required performance with respect to the inductance value;
A second step of performing a reactor design in which a part of the gap installed in the central leg is also distributed to the side legs without changing the core size of the reactor designed in the first step;
A high frequency reactor design method comprising: a third step of finely adjusting a design of the reactor designed in the second step in consideration of a required specification.

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