JP7457779B2 - Trance - Google Patents

Description

The present disclosure relates to a magnetic flux cancellation type transformer.

When a multi-phase LLC converter operates in three phases, the primary winding of the transformer is star-connected via a resonant capacitor, and the switches of each converter are turned on and off so that the current phase of each phase is shifted by 120 degrees from each other ( For example, see Patent Document 1).

US Patent No. 9780678 Patent No. 6696617

Typically, a multiphase LLC converter includes a magnetic flux cancellation type transformer (see, for example, Patent Document 2). Patent Document 2 describes a diagram illustrating a magnetic flux cancellation type transformer (three-phase). As in Patent Document 2, the core of a magnetic flux cancellation type transformer is composed of an outer leg without a winding and a middle leg around which a winding is wound. Each of the middle legs has a gap.

This gap produces the following effects.
Since each middle leg is assigned to each phase, it is desirable to minimize the magnetic flux of other phases to one middle leg. Therefore, a gap is created between the middle legs. The gap has high magnetic resistance. Therefore, the magnetic flux of one middle leg does not pass through the other middle legs, but passes through the outer leg with no gap. In other words, the gap can reduce the magnetic flux of other phases passing through one middle leg. Furthermore, the outer leg is shared by the magnetic flux of each phase, so the magnetic flux of the outer leg can be canceled out in three-phase operation, and iron loss can be reduced.

On the other hand, in order to achieve ZVS (zero volt switching) of the LLC converter switch, the excitation inductance of the transformer needs to be adjusted according to the gap length. Here, if the gap in the center leg is widened, in the case of high frequency operation or when a large current flows, the leakage flux generated near the gap will link with the winding, resulting in increased heat generation due to losses. In other words, a problem with transformers that use the magnetic flux cancellation method is that they are difficult to use in high frequency operation or with large currents.

In order to solve the above problems, an object of the present invention is to provide a magnetic flux cancellation type transformer that can suppress heat generation in the windings even when operating at high frequencies or when a large current flows.

In order to achieve the above object, in the transformer according to the present invention, the position where the winding is wound and the position where the gap is provided are shifted in the middle leg.

Specifically, the transformer according to the present invention has:
An outer leg that is a rectangular frame made of a magnetic material;
A plurality of center legs, which are magnetic bodies and are arranged in a unidirectional grid pattern within the frame of the outer legs;
A primary winding and a secondary winding wound around each of the middle legs;
A transformer comprising:
The middle leg has a gap in the longitudinal direction at a position where the primary winding and the secondary winding are not wound.

By shifting the position where the winding is wound and the position where the gap is provided in the middle leg, it is possible to reduce the influence of leakage magnetic flux generated near the gap on the winding. Therefore, the present invention can provide a magnetic flux cancellation type transformer that can suppress heat generation in the windings even when operating at a high frequency or when a large current flows.

The present invention can provide a magnetic flux cancellation type transformer that can suppress heat generation in the windings even when operating at high frequencies or when a large current flows.

FIG. 3 is a diagram illustrating a transformer according to the present invention. FIG. 3 is a diagram illustrating a transformer according to the present invention. FIG. 2 is a diagram illustrating a transformer according to the present invention. It is a figure explaining the outer leg of the core of the transformer based on this invention. FIG. 3 is a diagram illustrating a transformer according to the present invention. FIG. 2 is a diagram illustrating a transformer according to the present invention.

Embodiments of the invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. Note that components with the same reference numerals in this specification and the drawings indicate the same components. Further, in this embodiment, a three-phase transformer will be described, but the number of phases is not limited to three.

(Embodiment 1)
FIG. 1 is a diagram illustrating a transformer 100 according to the present embodiment. The transformer 100 includes:
An outer leg 10 which is a rectangular frame made of a magnetic material;
A plurality of center legs 20#n, which are made of a magnetic material and are arranged in a lattice pattern in one direction (Y direction in the case of FIG. 1 ) within the frame of the outer leg 10;
A primary winding Pn and a secondary winding Sn are wound around each of the center legs 20#n;
A transformer comprising:
The middle leg 20#n is characterized by having a gap GP in the longitudinal direction (Y direction in the case of FIG. 1) at a position where the primary winding Pn and the secondary winding Sn are not wound.
n is the phase number, and for three phases, n=1, 2, 3.

The magnetic material of the outer frame 10 and the middle leg 20 is, for example, a silicon steel plate or ferrite. Both may be the same type of magnetic material, or may be different magnetic materials.
Note that the gap GP may be a space, but a gap material such as an insulating sheet may be fitted therein. The presence of the gap material improves the strength of the core.
Further, in this embodiment, the middle legs 20 are installed so that the Y direction is the longitudinal direction, but the middle legs 20 may be installed so that the X direction is the longitudinal direction.

Here, the outer leg 10 is composed of a plurality of parts 10-i (i=1 to 8 in the case of FIG. 1) made of the magnetic material. Also, since it is 3-phase, there are three middle legs, 20#1, 20#2, and 20#3, three primary windings, P1, P2, and P3, and three secondary windings, S1, S2, and S3. It is one.

Note that the position of the gap GP may be the position shown in FIG. 2 or 3 (FIG. 2 is an example in which the gap GP is located at the upper end of the middle leg 20 (at the location where it contacts the outer leg)). That is, as shown in FIGS. 1 and 2, both the primary winding Pn and the secondary winding Sn are wound around the middle leg 20 on one side with respect to the gap GP (as shown in FIGS. 1 and 2). In this case, the gap GP is on the primary winding Pn side, but the gap GP may be on the secondary winding Sn side), or as shown in Figure 3, the gap GP is on the side of the secondary winding Sn. 20 (in the case of FIG. 3, the gap GP is between the primary winding Pn and the secondary winding Sn).

That is, the transformer 100 has the following characteristics.
(1) It is composed of a plurality of middle legs 20#n (n=3 in this embodiment) having a gap GP and an outer leg 10 without a gap.
(2) The primary winding Pn and the secondary winding Sn are wound at positions other than the gap GP on the middle leg 20#n. The amount of leakage magnetic flux in the gap GP that interlinks with the primary winding Pn and the secondary winding Sn is reduced, and winding loss can be reduced.
(3) Since the magnetic resistance of the gap GP is large, the magnetic flux generated in each middle leg 20#n does not interfere with each other and passes through the outer leg 10 with low magnetic resistance.
(4) Due to this structure, one transformer 100 can operate in the same manner as n transformers.
(5) By operating the currents flowing through each winding with a phase shift of 360/n degrees, the magnetic flux of the outer leg 10 is canceled out, and iron loss can be reduced.
(6) The core volume of the transformer 100 can be reduced by using the outer leg 10 in common for each phase, and the transformer 100 can be made smaller than when a plurality of (n) transformers are provided.

The core of the transformer 100 is composed of a plurality of parts (outer leg parts 10-1 to 10-8 and middle leg parts 20#1 to 20#3). For this reason, the parts (10-1, 10-2, 10-3, 10-5, 10-6, 10-7) on which the middle leg 20 is installed are moved in the longitudinal direction (Y direction) of the middle leg 20. This allows the distance between the gaps GP to be adjusted.

In other words, since the core of the transformer 100 is composed of a plurality of parts, the gap length of the gap GP can be adjusted for each middle leg. This has the effect of being able to absorb gap length deviations due to manufacturing errors of the core, and the effect of being able to adjust the excitation inductance to a desired value.
Furthermore, by configuring the core with multiple parts (outer leg parts 10-1 to 10-8, middle leg parts 20#1 to 20#3), each part can be made into a simple shape (prismatic or cylindrical). It is possible to reduce manufacturing costs.

<Additional Information>
When a large current flows through the winding, the number of turns is increased to avoid saturation, but the inductance value becomes large. For this reason, a gap is provided in the core to reduce the inductance value. The inductance value can be adjusted by adjusting the gap distance of the core. Specifically, in the transformer 100, widening the gap GP reduces the excitation inductance.
On the other hand, providing a gap in the core generates leakage flux that interlinks with the windings and causes loss. Therefore, in the transformer 100, the position of the gap GP and the position of the windings (Pn, Sn) are shifted as shown in Figures 1 to 3 to reduce the effect of leakage flux.
<End of supplement>

Note that one of the opposing sides on which the middle leg 20#n is installed may be made of one part. Specifically, the outer leg parts (10-5, 10-6, 10-7) may be an integral part without being divided. This is because each gap length can be adjusted using the outer leg parts (10-1, 10-2, 10-3). Additionally, reducing the number of divided parts has the effect of increasing the rigidity of the core.

The transformer 100 is characterized in that the outer leg 10 is configured by interlacing the above-mentioned multiple parts. Interlacing is an assembly method as shown in Fig. 4(A). Specifically, one end of the outer leg parts (10-1, 10-2, 10-3) is installed on the side of the outer leg part 10-4, one end of the outer leg part 10-4 is installed on the side of the outer leg part (10-5, 10-6, 10-7), one end of the outer leg parts (10-5, 10-6, 10-7) is installed on the side of the outer leg part 10-8, and one end of the outer leg part 10-8 is installed on the side of the outer leg parts (10-1, 10-2, 10-3).
4(C) shows an explanation of the "one end" and "side" of part 10-n. "One end" means one bottom surface of prismatic part 10-n, and "side" means one side surface of prismatic part 10-n (the side surface that faces inward when assembled).
Also, if the assembly of parts 10-n as shown in FIG. 4(A) is a "clockwise swastika" assembly, the outer leg 10 may be a "counterclockwise swastika" assembly.

FIG. 4(B) is a diagram when the outer leg 10 composed of a plurality of parts is not assembled. If swastika is not used, for example, the lengths of the outer leg parts (10-1, 10-2, 10-3) and outer leg parts (10-5, 10-6, 10-7) may differ due to manufacturing errors. If they are different, a gap GR will occur at the contact portion 41 between the outer leg part 10-4 and the outer leg parts (10-1, 10-2, 10-3). This gap GR causes the magnetic resistance of each phase to become non-uniform, reducing the magnetic flux canceling effect.

When a kaji is formed as shown in FIG. 4(A), no gap is created at each contact portion 42 even if the lengths of each part are deviated due to manufacturing errors or the like. Since the outer leg 10 is gapless, unnecessary magnetic resistance does not occur. Therefore, the magnetic resistance of each phase in the outer leg 10 becomes uniform, and the magnetic flux canceling effect is enhanced.

(Example)
The transformer 100 of this embodiment can be used as a multi-leg transformer of a multi-phase LLC converter described in Patent Documents 1 and 2.

(Embodiment 2)
FIG. 5 is a diagram illustrating the transformer 101 of this embodiment. The transformer 101 is
an outer leg 10 made of a magnetic material and having a rectangular frame;
A plurality of middle legs 20#n made of a magnetic material and arranged in a grid shape in one direction (in the case of FIG. 5, the Y direction) within the frame of the outer leg 10;
A primary winding Pn and a secondary winding Sn wound around each middle leg 20#n,
A transformer comprising:
Each middle leg 20#n is characterized by having a gap GP on both sides of the section around which the primary winding Pn and the secondary winding Sn are wound in the longitudinal direction (Y direction in the case of FIG. 5). do.

In order to equalize the inductance seen from both sides of the transformer (primary side and secondary side), the gap GP should be placed at the center of the middle leg 20#n (the primary winding Pn and the secondary winding A structure provided between the line Sn and the line Sn is preferable. As explained in the "Supplementary" section above, the excitation inductance can be adjusted by the gap GP. However, in the case of this structure, when the gap GP is widened in order to reduce the excitation inductance, the loss due to leakage magnetic flux generated near the gap GP increases. In other words, with this structure, there is a problem in that it is difficult to adjust the excitation inductance while avoiding loss due to the gap GP.

Therefore, we decided to provide a gap GP at both ends of the middle leg 20#n, as in the transformer 101, in order to create a structure in which the inductance seen from both sides of the transformer can be made equal, and the excitation inductance can be easily adjusted while avoiding loss due to the gap GP. . By widening the outer leg 10, the gap GP can be widened at both ends of the middle leg 20#n, so that leakage magnetic flux generated near the gap GP can be prevented from interfering with the primary winding Pn and the secondary winding Sn. The gap GP can be widened (the excitation inductance can be reduced) (without increasing the loss).

Although the gap GP may be a space, a gap material 15 such as an insulating sheet may be fitted therein as shown in FIG. By fitting the gap material 15 into the gap GP, the middle leg 20#n can be fixed to the outer leg 10.
Also in the transformer 100 described in the first embodiment, the gap material 15 may be fitted into the gap GP.
In FIG. 6, the upper and lower gap members 15 each have an integral structure, but may have a structure in which they are divided into each middle leg 20#n.

The transformer 101 also has the characteristics (1) to (6) of the transformer 100 described in the first embodiment. Moreover, the effects of the transformer 100 described in the first embodiment can also be obtained by having the following structure.

-The core is made up of multiple parts (outer leg parts 10-1 to 10-8, middle legs 20#1 to 20#3).
In the transformer 101, the parts (10-1, 10-2, 10-3, 10-5, 10-6, 10-7) located in the longitudinal direction of the middle leg 20#n can also be moved in the longitudinal direction of the middle leg 20#n to widen the outer legs 10 and adjust the distance between the gaps GP.

- A structure in which one of the opposing sides on which the middle leg 20#n is installed is composed of one part.
・The outer leg 10 has a structure in which the plurality of parts are assembled in a swastika pattern.

10: Outer legs 10-1, 10-2, ..., 10-8, 10-i: Outer leg parts (i is part number)
20, 20#1, 20#2, 20#3,..., 20#n: Middle leg, n is the number of phases 41, 42: Contact part GP: Gap P1, P2, P3,..., Pn : Primary winding, n is the number of phases S1, S2, S3, ..., Sn: Secondary winding, n is the number of phases E ₁ , E ₂ , E ₃ , ..., E _n : DC power supply, n is the number of phases C _R1 , C _R2 : Resonant capacitor Ca: Capacitor SW1: First switch SW2: Second switch CP: Connection point NP: Neutral point To: Output end L _GP1 , L _GP2 , L _GP3 ,...,L _GPn : Resonant reactor, n is the number of phases

Claims (5)

an outer leg that is a magnetic material and has a rectangular frame;
a plurality of middle legs that are magnetic and arranged in a unidirectional grid within the frame of the outer legs;
A primary winding and a secondary winding that are wound adjacent to each other on each of the middle legs;
A magnetic flux cancellation type transformer comprising:
Each of the middle legs has one gap in the longitudinal direction at a position where the primary winding and the secondary winding are not wound,
The outer leg is composed of a plurality of parts made of the magnetic material, and the distance between the gaps can be adjusted by moving the part on which the middle leg is installed in the longitudinal direction of the middle leg .
The primary winding and the secondary winding are respectively wound around the middle leg on one side and the middle leg on the other side with respect to the gap, and the inductances seen from the primary side and the secondary side are symmetrical. There is something
A transformer featuring An outer leg that is a rectangular frame made of a magnetic material;
A plurality of center legs, which are magnetic bodies and are arranged in a unidirectional grid pattern within the frame of the outer legs;
a primary winding and a secondary winding wound adjacent to each other for each of the middle legs;
A magnetic flux cancellation type transformer comprising:
Each of the middle legs has two gaps in a longitudinal direction at positions where the primary winding and the secondary winding are not wound,
The outer leg is composed of a plurality of parts of the magnetic material, and the distance between the gaps can be adjusted by moving the part on which the middle leg is installed in the longitudinal direction of the middle leg ; and
Each of the center legs has a gap on both outer sides of the section in which the primary winding and the secondary winding are wound in the longitudinal direction, and the inductance as viewed from the primary side and the secondary side is symmetrical.
A transformer characterized by: 3. The transformer according to claim 1, wherein one of the opposing sides of the outer leg on which the middle leg is installed is composed of one of the parts. 3. The transformer according to claim 1 , wherein the outer leg is composed of a plurality of parts made of the magnetic material, and the plurality of parts made of the magnetic material are assembled into a kamanshi. The transformer according to claim 1 or 2 , wherein the gap is fitted with a gap material.

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