JP5058120B2 - Trance - Google Patents

Description

  The present invention relates to a switching power supply apparatus using a plurality of transformers and a transformer in which a plurality of transformers are integrally formed, and more particularly to a transformer for the purpose of reducing EMI (Electro Magnetic Interference).

  As shown in FIGS. 10 and 11, a transformer having three cores is known as a transformer core structure in which two transformers are integrated. The transformer 90 includes a first magnetic core 91, a second magnetic core 92, and a third magnetic core 93. A primary coil 94 and a secondary coil 95 are disposed between the magnetic cores 91 to 93. Yes.

  As shown in FIG. 11, a gap 97 is formed between the first magnetic core 91 and the second magnetic core 92. Thus, separate closed magnetic circuits φ1 and φ2 are formed in the left side portion and the right side portion of the transformer 90. That is, the transformer 90 is configured integrally with the left transformer T1 and the right transformer T2. If there is no gap 97 and the first magnetic core 91 and the second magnetic core 92 are connected, as shown in FIG. 12, a closed magnetic circuit φ around the entire coil is formed, and the left transformer T1 and the right transformer It cannot be separated into the transformer T2. As a result, the desired function cannot be exhibited.

USP 4635179 JP 2000-324839 A

  However, when the configuration of FIG. 11 is adopted, there is a problem that a magnetic field 98 is radiated from the gap 97 and propagates to the periphery as electromagnetic noise. The electromagnetic wave noise generated from the gap 97 causes problems such as malfunction of the control circuit board and the filter circuit and other devices in the vicinity of the transformer 90. Therefore, a transformer that hardly emits electromagnetic noise from the gap 97 is desired.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a transformer capable of reducing electromagnetic noise generated from a gap between magnetic cores.

The present invention is a transformer comprising a coil pair consisting of a primary coil and a secondary coil arranged concentrically with the primary coil,
A first magnetic core disposed on one side in the axial direction of the coil pair and covering a partial section in the circumferential direction of the coil pair from the inside to the outside;
The coil pair is provided on the opposite side of the first magnetic core with respect to the central axis of the coil pair, a predetermined gap is formed between the first magnetic core, and a partial section in the circumferential direction of the coil pair extends from the inside to the outside. A second magnetic core covering and covering,
A third magnetic core disposed on the other side in the axial direction of the coil pair and sandwiching the coil pair in the axial direction between the first magnetic core and the second magnetic core;
A base plate formed in a plate shape;
The first magnetic core and the second magnetic core are arranged on the main surface of the base plate, and the base plate is configured to close the opening of the gap in the axial direction of the coil pair. It is in the transformer characterized by the above-mentioned (Claim 1).

Next, the effects of the present invention will be described.
In the present invention, the first magnetic core and the second magnetic core are arranged on a plate-like base plate, and the base plate closes the opening of the gap in the axial direction of the coil pair. Therefore, the electromagnetic wave noise radiated from the gap provided between the first and second magnetic cores can be shielded by the base plate, thereby reducing the electromagnetic wave noise radiation to the control board or the like provided around the transformer. It is possible to prevent malfunctions and the like.

  As described above, according to the present invention, it is possible to provide a transformer capable of reducing electromagnetic noise generated from the gap between the magnetic cores.

A preferred embodiment of the present invention described above will be described.
In the present invention (Claim 1), the base plate is preferably made of a conductive material (Claim 2).
In this case, it becomes easy to block electromagnetic wave noise, and it becomes possible to connect the windings of the transformer with the base plate as GND.

Moreover, it is preferable that the said base plate serves as both the electromagnetic wave shielding part which shields the electromagnetic waves radiated | emitted from the said gap | interval, and the heat sink which radiates the heat which generate | occur | produces from the said magnetic core.
In this case, the cooling effect of the magnetic core can be enhanced. Further, it is not necessary to separately provide a dedicated part for radiating the magnetic core.

Moreover, it is preferable that the base plate is formed with a convex portion that fits into the gap between the first magnetic core and the second magnetic core.
In this case, the first magnetic core, the second magnetic core, and the base plate can be easily fixed. That is, since the variation in the gap is small at the time of mounting, the wobbling when the convex portion is inserted into the gap is small and can be fixed firmly. Moreover, since the contact area between the base plate and the magnetic core is increased, the cooling efficiency is also improved.

Example 1
A transformer according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view of the transformer 1, and FIG. 2 is an exploded perspective view thereof. FIG. 2 is drawn upside down compared to FIG.
As shown in FIGS. 1 and 2, the transformer 1 of this example includes a coil pair 2 including a primary coil 21 and a secondary coil 22 arranged concentrically with the primary coil 21.
A first magnetic core 11 that covers a partial section in the circumferential direction of the coil pair 2 from the inside to the outside is disposed on one side in the axial direction of the coil pair 2.
In addition, a predetermined gap 4 is formed between the first magnetic core 11 and the second magnetic core 12 that covers a partial section in the circumferential direction of the coil pair 2 from the inside to the outside is the central axis of the coil pair 2. A is provided on the opposite side of the first magnetic core 11 with respect to A.
Furthermore, a third magnetic core 13 that sandwiches the coil pair 2 in the axial direction between the first magnetic core 11 and the second magnetic core 12 is disposed on the other side in the axial direction of the coil pair 2.
Moreover, the base plate 3 formed in plate shape is provided. The first magnetic core 11 and the second magnetic core 12 are arranged on the main surface 30 of the base plate 3, and the base plate 3 is configured to close the opening 40 of the gap 4 in the axial direction of the coil pair 2. ing.

More specifically, the base plate 3 is a casing or a member for cooling. The base plate 3 is made of a conductive material such as aluminum or copper. Each magnetic core 11-13 is comprised from magnetic bodies, such as iron and a ferrite. Further, as shown in FIG. 2, the first magnetic core 11 and the second magnetic core 12 are formed with flat surfaces 11 a and 12 a, and these flat surfaces 11 a and 12 a are in close contact with the main surface 30 of the base plate 3. The 1st magnetic core 11 and the 2nd magnetic core 12 are each arrange | positioned.
The third magnetic core 13 includes a first portion 13 a corresponding to the first magnetic core 11, a second portion 13 b corresponding to the second magnetic core 12, and a third portion 13 c corresponding to the gap 4. ing.

As shown in FIG. 2, the first magnetic core 11 includes a plate-like main body portion 11 b, a wall portion 11 c and a column portion 11 d that protrude from the main body portion 11 b toward the third magnetic core 13. The second magnetic core 12 has the same structure, and includes a plate-like main body 12b, a wall 12c and a pillar 12d that protrude from the main body 12b toward the third magnetic core 13.
The third magnetic core 13 includes a plate-like main body portion 13d, wall portions 13f and 13g protruding from both ends of the main body portion 13d toward the first magnetic core 11 and the second magnetic core 12, and the center of the main body portion 13d. The first magnetic core 11 and the column portion 13e protruding toward the second magnetic core 12 are provided at positions.

As shown in FIG. 1, the wall portion 11c of the first magnetic core 11 is in contact with the wall portion 13f of the third magnetic core 13, and the column portion 11d is in contact with the column portion 13e. Further, the wall portion 12c of the second magnetic core 12 is in contact with the wall portion 13g of the third magnetic core 13, and the column portion 12d is in contact with the column portion 13e. And the coil pair 2 is arrange | positioned centering on pillar part 11d, 12d, 13e.
The wall portion 11c and the wall portion 13f can be arranged with a slight gap. In this case, the gap is narrower than the gap 4, for example. Similarly, the column portion 11d and the column portion 13e, the column portion 12d and the column portion 13e, and the wall portion 12c and the wall portion 13g can be arranged with a slight gap therebetween.
As shown in FIG. 2, the third magnetic core 13 includes the first portion 13a from the wall portion 13f to the right end of the column portion 13e. The third magnetic core 13 includes the second portion 13b from the wall portion 13g to the left end of the column portion 13e. Further, the portion facing the gap 4 (the central portion of the column portion 13e) constitutes the third portion 13c.

  On the other hand, the primary coil 21 is formed by winding a copper wire, and the number of turns is appropriately adjusted. The secondary coil 22 is formed by processing a copper plate, and includes output terminals 22a and 22b and an intermediate terminal 22c.

  When an alternating voltage is applied to the primary coil 21 and the secondary coil 22 and an alternating current flows, the coils 21 and 22 generate heat and the core generates heat due to the magnetic flux generated in the magnetic cores 11 to 13. The base plate 3 also functions as a heat sink that absorbs and radiates heat generated from the magnetic cores 11 to 13.

  On the other hand, as shown in FIG. 1, two magnetic fluxes φ1 and φ2 are independently formed in the transformer 1. That is, the first transformer T1 is constituted by the first portion 13a of the third magnetic core 13 and the first magnetic core 11, and the second transformer T2 is constituted by the second portion 13b and the second magnetic core 12. Yes. Since the first magnetic core 11 and the second magnetic core 12 are separated, the two transformers T1 and T2 are independently formed in this way. Here, if the first magnetic core 11 and the second magnetic core 12 are connected to each other, the magnetic flux φ that goes around the whole is formed as described above (see FIG. 12), and there is only one transformer.

  Next, peripheral circuits of the transformer 1 will be described. As shown in FIG. 3, the transformer 1 includes a primary coil 21 and a secondary coil 22, and the primary coil 21 includes a first winding part W1 and a second winding part W2. The secondary coil 22 includes a third winding portion W3 and a fourth winding portion W4. A first transformer T1 is constituted by the first winding part W1 and the third winding part W3, and a second transformer T2 is constituted by the second winding part W2 and the fourth winding part W4.

As illustrated, the primary coil 21 is connected to the inverter 5. When a DC voltage is applied to the input terminals 51 and 52, the inverter 5 converts the voltage into an AC voltage, and an AC current flows through the primary coil 21. The transformer 1 transforms an AC voltage according to the number of turns of the coil. Diodes 63 and 64 (which may be MOS-FETs) are connected to the output terminals 22a and 22b of the secondary coil 22, thereby rectifying the AC voltage and extracting the DC voltage. The cathodes of the diodes 63 and 64 are connected to each other and connected to the positive output terminal 61. Further, the intermediate terminal 22c (see FIG. 2) of the secondary coil 22 is a negative electrode, and a smoothing capacitor C is connected between the positive electrode and the negative electrode.
In this manner, by configuring the two transformers T1 and T2 in the transformer 1, it is possible to reduce the weight, to achieve simplification of the circuit, reduction of loss due to shortening of the coil length, reduction of manufacturing cost, and the like.

  The transformer 1 of this example can be used for a DC-DC converter for a vehicle such as an electric vehicle or a hybrid car. For example, a high voltage of about 300 V is applied to the input terminals 51 and 52. This high voltage is stepped down by the transformer 1, and a DC voltage of about 14V is taken out from the output terminals 61 and 62 to drive vehicle auxiliary equipment parts such as a car air conditioner, a battery, and a light.

On the other hand, as shown in FIG. 4, on the base plate 3, in addition to the transformer 1, a control circuit 7, an inverter for generating an AC voltage by switching a DC input voltage, a diode (63, 64), and a MOSFET 2 A filter circuit including a secondary side rectifier circuit and a smoothing capacitor of a secondary side output unit is attached. The control circuit 7 controls, for example, the inverter 5 described above, and is fixed to the base plate 3 by a fastening member 70 (male screw).
The transformer 1 and the control circuit 7 are housed in a case 71 made of a galvanized steel plate or the like.

The transformer 1 of this example can also be configured as shown in FIGS. In the transformer 1, the primary coil 21 includes a first winding part W1, a second winding part W2, a fourth winding part W4, and a fifth winding part W5, and the secondary coil 22 includes a third winding part W3. And the sixth winding portion W6. The first winding portion W1, the second winding portion W2, and the third winding portion W3 constitute a transformer T1, and a fourth winding portion W4, a fifth winding portion W5, and a sixth winding portion W3. A transformer T2 is constituted by the winding part W6.
The first winding portion W1 and the fourth winding portion W4 are connected in series to form a first coil pair, and the second winding portion W2 and the fifth winding portion W5 are connected in series to form a second coil. A coil pair is configured. Then, a DC voltage is applied between the input terminals 51 and 52, and the main switch Q1 and the second coil pair (second winding part) are passed through the first coil pair (first winding part W1, fourth winding part W4). W2 is a circuit that feeds power to the connection point with the fifth winding W5). The switches Q1 and Q2 are controlled by a pulse control method such as PWM control.
This makes it possible to reduce the size and weight, reduce the number of switching elements, and reduce the ripple components of the input current and output current.

Note that the transformer 1 of this example can be configured as shown in FIG. The transformer 1 differs from the transformer 1 of FIG. 2 in the shapes of the first magnetic core 11 and the second magnetic core 12.
Moreover, you may make it like FIG. The transformer 1 has a plate shape without the column portion 13e and the wall portions 13g and 13f of the third magnetic core 13.

Next, the function and effect of this example will be described.
As shown in FIGS. 1 and 2, in the transformer 1 of this example, the first magnetic core 11 and the second magnetic core 12 are disposed on the base plate 3, and the opening 40 of the gap 4 is closed by the base plate 3. Yes.
Thereby, the electromagnetic wave noise (see FIG. 11) radiated from the gap 4 can be shielded by the base plate 3, and malfunction of the control board 7 (see FIG. 4), the filter circuit, etc. existing around the transformer 1 can be prevented. be able to. In addition, it is possible to prevent noise from entering a radio, such as a car radio, present around the transformer 1.
Further, as shown in FIG. 1, since the column portion 13e of the third magnetic core 13 is present on the opposite side of the opening 40 of the gap 4, electromagnetic noise is shielded by this column portion 13e and radiated upward. It has a difficult structure.

In this example, the base plate 3 is made of a conductive material.
In this case, electromagnetic wave noise can be easily blocked, and the secondary winding of the transformer 1 and a smoothing capacitor can be connected using the base plate 3 as the secondary negative electrode.

The base plate 3 also serves as an electromagnetic wave shielding part that shields electromagnetic waves radiated from the gap 4 and a heat radiating plate that radiates heat generated from the magnetic cores 11 to 13.
In this case, the cooling effect of the magnetic cores 11 to 13 can be enhanced. Further, it is not necessary to separately provide a dedicated part for heat dissipation.

  On the other hand, as shown in FIG. 4, the control board 7 and the like are arranged on the base plate 3 and fixed by a fastening member 70. The thickness of the base plate 3 is preferably 8 mm or more. If the thickness is 8 mm or more, the control board 7 can be firmly fixed by the fastening member 70.

  Further, the transformer 1 is housed in the case 71 together with the control board 7 and the like. Thereby, the electromagnetic wave noise slightly leaking from the transformer 1 can be shielded by the case 71. Therefore, the amount of electromagnetic noise emitted to the outside can be further reduced.

  As described above, according to the present invention, it is possible to provide the transformer 1 in which electromagnetic wave noise is less likely to be radiated from the gap 4 between the magnetic cores 11 and 12.

(Example 2)
In this example, as shown in FIG. 9, the shape of the base plate 3 is changed. As shown in the drawing, in the transformer 1 of this example, a convex portion 31 is formed on the base plate 3 to be inserted into the gap 4 between the first magnetic core 11 and the second magnetic core 12.
In addition, the configuration is the same as that of the first embodiment.

In this case, the first magnetic core 11 and the second magnetic core 12 and the base plate 3 can be easily fixed. That is, since the variation of the gap 4 is small at the time of mounting, the wobbling when the convex portion 31 is inserted into the gap 4 is small and can be firmly fixed. Further, since the contact area between the base plate 3 and the magnetic cores 11 and 12 is increased, the cooling efficiency is also improved.
In addition, the same effects as those of the first embodiment are obtained.

FIG. 3 is a cross-sectional view of a transformer in the first embodiment. FIG. 2 is an exploded perspective view of a transformer in the first embodiment, which is upside down from FIG. 1. FIG. 3 is a circuit diagram of a transformer in the first embodiment. FIG. 3 is an overall cross-sectional view of a transformer and a peripheral substrate in the first embodiment. FIG. 3 is a circuit diagram of a transformer in the first embodiment, in which the circuit configuration is changed. FIG. 6 is a cross-sectional view of the transformer according to the first embodiment, corresponding to FIG. 5. FIG. 3 is an exploded perspective view of a transformer in Example 1, in which the shapes of the first magnetic core and the second magnetic core are changed. FIG. 3 is an exploded perspective view of a transformer in Example 1, in which the shape of a third magnetic core is changed. Sectional drawing of the trans | transformer in Example 2. FIG. The exploded perspective view of the transformer in a conventional example. Sectional drawing of the trans | transformer in a prior art example. Sectional drawing at the time of not providing the clearance gap between magnetic coils in a prior art example.

Explanation of symbols

1 transformer 11 first magnetic core 12 second magnetic core 13 third magnetic core 13a first part 13b second part 13c third part 2 coil pair 21 primary coil 22 secondary coil 3 base plate 4 gap A (coil pair) center Axis

Claims (4)

A transformer comprising a coil pair consisting of a primary coil and a secondary coil arranged concentrically with the primary coil,
A first magnetic core disposed on one side in the axial direction of the coil pair and covering a partial section in the circumferential direction of the coil pair from the inside to the outside;
The coil pair is provided on the opposite side of the first magnetic core with respect to the central axis of the coil pair, a predetermined gap is formed between the first magnetic core, and a partial section in the circumferential direction of the coil pair extends from the inside to the outside. A second magnetic core covering and covering,
A third magnetic core disposed on the other side in the axial direction of the coil pair and sandwiching the coil pair in the axial direction between the first magnetic core and the second magnetic core;
A base plate formed in a plate shape;
The first magnetic core and the second magnetic core are arranged on the main surface of the base plate, and the base plate is configured to close the opening of the gap in the axial direction of the coil pair. Transformer characterized by   2. The transformer according to claim 1, wherein the base plate is made of a conductive material.   3. The transformer according to claim 1, wherein the base plate serves as an electromagnetic wave shielding part that shields electromagnetic waves radiated from the gap and a heat radiating plate that radiates heat generated from the magnetic core.   4. The transformer according to claim 1, wherein a convex portion that is inserted into the gap between the first magnetic core and the second magnetic core is formed on the base plate.

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