JP4936859B2 - Inverter transformer - Google Patents

Description

  The present invention relates to an inverter transformer used in a DC / AC inverter circuit for discharging and lighting a cold cathode discharge lamp (CCFL) for backlights of various display panels used in, for example, notebook personal computers and liquid crystal televisions.

Conventionally, as this type of inverter transformer, one having a configuration in which a primary winding is disposed between two secondary windings is known (see Patent Documents 1 and 2 below).
The inverter transformer having such a configuration is suitable for enhancing the coupling between the primary winding and the secondary winding.

JP-A-2005-167110 JP 2006-165063 A

  In recent years, in order to increase the efficiency of an inverter circuit, there is a demand for an inverter transformer that can increase the value of the leakage inductance while increasing the coupling between the primary winding and the secondary winding. By increasing the value of the leakage inductance, the value of the capacitor can be reduced, whereby the current value supplied to the capacitor in the inverter circuit can be suppressed. On the other hand, increasing the coupling between the primary winding and the secondary winding also improves the conversion efficiency, which is an effective means for increasing the efficiency of the inverter circuit.

  However, it is a general idea that in order to increase the contradictory relationship, that is, to increase the coupling between the primary winding and the secondary winding, it is necessary to reduce the value of the leakage inductance. This type of inverter transformer is difficult to meet such demands.

  For example, those described in Patent Documents 1 and 2 are suitable for increasing the coupling between the primary winding and the secondary winding, but increase the leakage inductance while maintaining high coupling. That is a difficult structure.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an inverter transformer that can increase the value of the leakage inductance while enhancing the coupling between the primary winding and the secondary winding.

The inverter transformer according to the present invention is an inverter transformer in which a primary winding is arranged coaxially between a first secondary winding and a second secondary winding,
A first core portion through which a magnetic flux interlinking with all three windings of the primary winding, the first secondary winding and the second secondary winding passes;
A second core portion that passes through only the magnetic flux interlinked with the first secondary winding and not interlinked with the primary winding and the second secondary winding;
A third core portion that is interlinked with the second secondary winding and through which only the magnetic flux not interlinked with the primary winding and the first secondary winding passes. Features.

In the inverter transformer of the present invention, the first core portion includes a rod-shaped I core communicated with the three windings, and the I core passing from one end of the I core to the outside of the three windings. A U-shaped first U core extending to the other end of the core,
The second core portion passes between the one end of the I core and the outside of the first secondary winding, and between the primary winding and the first secondary winding of the I core. A U-shaped second U-core extending to a portion located at
The third core portion passes through the outside of the second secondary winding from the other end portion of the I core, and the primary winding and the second secondary winding of the I core. A rod-shaped I core communicated with the three windings formed by a U-shaped third U-core extending to a portion located therebetween, and one end of the I core from the three windings. The U-shaped first U core that extends to the other end of the I core through the outside can be used.

  The inverter transformer of the present invention can be configured as a one-input one-output type by electrically connecting the first secondary winding and the second secondary winding to each other.

  According to the inverter transformer of the present invention, the primary winding is arranged coaxially between the first secondary winding and the second secondary winding, and is linked to all three windings. By providing the first core portion through which the magnetic flux to be transmitted passes, it becomes possible to enhance the coupling between the primary winding and the secondary winding.

  A second core portion through which only the magnetic flux interlinking only with the first secondary winding passes; and a third core portion through which only the magnetic flux interlinking with the second secondary winding passes. Accordingly, the leakage inductance value can be increased.

  Therefore, according to the inverter transformer of the present invention, the value of the leakage inductance can be increased while enhancing the coupling between the primary winding and the secondary winding, thereby increasing the efficiency of the inverter circuit. It becomes.

  In general, it is said that as the leakage inductance value increases, the coupling between the primary winding and the secondary winding is greatly reduced. However, in the inverter transformer of the present invention, it is possible to increase the value of the leakage inductance while enhancing the coupling between the primary winding and the secondary winding. This can be explained as follows.

That is, the coupling coefficient k indicating the magnitude of coupling between the primary winding and the secondary winding is expressed by the following equation (1). Here, Ls ′ represents a leakage inductance value, and Ls represents a self-inductance value of the secondary winding.
k = (1-Ls ′ / Ls) ^1/2 (1)

  As shown in the above equation (1), the coupling coefficient is determined by the ratio between the value of the self-inductance Ls of the secondary winding and the value of the leakage inductance Ls ′. Therefore, even when the value of the leakage inductance Ls ′ increases. If the value of the self-inductance Ls of the secondary winding can be significantly increased compared to the value of the leakage inductance Ls ′, the coupling coefficient is brought close to 1, that is, the primary winding and the secondary winding. It becomes possible to enhance the coupling with the line.

  The inverter transformer according to the present invention includes a first core portion through which a magnetic flux interlinked with all three windings passes, and a second core portion through which only a magnetic flux interlinked only with the first secondary winding passes. By providing the third core portion through which only the magnetic flux interlinking only with the second secondary winding passes, the value of the leakage inductance Ls ′ can be increased and the secondary winding self The value of the inductance Ls can be remarkably increased as compared with the value of the leakage inductance Ls ′.

  For this reason, it becomes possible to suppress the influence that the coupling between the primary winding and the secondary winding, which is caused when the value of the leakage inductance Ls ′ becomes large, can be suppressed, and the primary winding and the secondary winding. It is possible to increase the value of the leakage inductance Ls ′ while enhancing the coupling with the.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an inverter transformer according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a plan view of an inverter transformer according to an embodiment of the present invention, FIG. 2 is a bottom view thereof (in a state where a winding is not attached), and FIG. 3 is a perspective view thereof (a state where the winding is not attached). It is.

  The inverter transformer of this embodiment is used in a DC / AC inverter circuit that discharges and lights a cold cathode discharge lamp (CCFL) for backlights of various display panels used in, for example, notebook personal computers and liquid crystal televisions. As shown in FIG. 1, a hollow bobbin in which a primary winding 1 and first and second secondary windings 2 and 3 sandwiching the primary winding 1 are wound coaxially with each other. 4 (partially indicated by a broken line), four terminal blocks 5A to 5D each formed integrally with the bobbin 4, and a rod-shaped I core 6 (partially indicated by a broken line) inserted into the bobbin 4, The first to third U cores 7 to 9 formed in a U-shape are provided.

  The first and second secondary windings 2 and 3 are electrically connected to each other via a circuit formed on a substrate (not shown) so as to function as one coil. . That is, the present embodiment is configured as a 1-input 1-output type inverter transformer.

  As shown in FIG. 3, the bobbin 4 includes a first winding portion 41 disposed in the central portion in the axial direction, and second and third portions respectively disposed on the left and right sides of the first winding portion 41. Winding portions 42 and 43. The first winding portion 41 is separated from other regions by two partitioning rods 44A and 44B facing each other, and the primary winding 1 is wound around the first winding portion 41. It is comprised so that. On the other hand, the second winding portion 42 is separated from other regions by the end rod 45A and the partition rod 44E, and a plurality (two in this embodiment) of the plurality of partition rods 44C and 44D (this embodiment). 3), the first secondary winding 2 is wound around each winding section. The third winding portion 43 is separated from other regions by the end rod 45B and the partition rod 44F, and a plurality (three in this embodiment) of partition rods 44G to 44I (this embodiment). In this case, the second secondary winding 3 is wound around each winding section.

  The partition rods 44C and 44D are formed with notches 46A for passing the first secondary winding 2 to the adjacent winding sections, and the partition rods 44G to 44I include A notch 46C for passing the second secondary winding 3 to the adjacent winding section is formed. The partition rods 44A, 44B, 44E, 44F are formed with notches 46B similar to the notches 46A, respectively. This cut-out portion 46B is used as a mode for electrically connecting the first and second secondary windings 2 and 3 to each other, rather than via the circuit on the substrate as described above. In the case of adopting a mode in which the respective one end portions of the secondary windings 2 and 2 are connected via a predetermined conducting wire (not shown), the conducting wire is passed over. In addition, when using such a conducting wire, in order to ensure the withstand voltage between this conducting wire and the primary winding 1, the insulation process of covering the outer peripheral part of the primary winding 1 with an insulating tape etc. It is preferable to apply.

  The bobbin 4 includes a position between the first winding part 41 and the second winding part 42, and the first winding part 41 and the third winding part 43. Window portions 47A and 47B that expose a part of the I core 6 inserted into the bobbin 4 are respectively formed at positions between them.

  On the other hand, the terminal block 5A holds two secondary terminals 12A and 12B, and one end of the first secondary winding 2 is entangled with the binding portion 12a of the secondary terminal 12A. It is supposed to be lost. The terminal block 5B holds one primary terminal 11A, and one end of the primary winding 1 is entangled with the primary terminal 11A. The terminal block 5C holds one primary terminal 11B, and the other end of the primary winding 1 is entangled with the primary terminal 11B. Further, two secondary terminals 12C and 12D are held on the terminal block 5D, and one end of the second secondary winding 3 is entangled with the binding portion 12a of the secondary terminal 12C. It is supposed to be lost.

  Further, as shown in FIG. 2, a groove 52A for bridging one end of the first secondary winding 2 is formed on the bottom of the terminal block 5A, and the bottom of the terminal block 5D A groove portion 52B for bridging one end portion of the second secondary winding 3 is formed, and a groove portion for bridging one end portion of the primary winding 1 is formed on the bottom surface portion of the terminal block 5B. 51A is formed with a groove 51B for bridging the other end of the primary winding 1 on the bottom surface of the terminal block 5C.

  As shown in FIG. 1, the I core 6 is communicated with three windings of the primary winding 1, the first secondary winding 2, and the second secondary winding 3. Thus, it is inserted and arranged in the bobbin 4. In this arrangement state, the I core 6 has one end 61 and the other end 62 protruding from both ends of the bobbin 4, and the primary winding 1 and the first 2 of the I core 6. A portion (hereinafter referred to as a “first connecting portion”) 63 positioned between the secondary winding 2 and a portion positioned between the primary winding 1 and the second secondary winding 3 ( (Hereinafter referred to as “second connecting portion”) 64 is exposed from the window portions 47A and 47B formed on the bobbin 4, respectively.

On the other hand, the first U core 7 is disposed so as to extend from one end portion 61 of the I core 6 to the other end portion 62 of the I core 6 through the outside of the three windings 2, 1, 3. ing. In the present embodiment, the first U core 7 constitutes a first core portion together with the I core 6, and the first core portion includes all the three windings 1 to 3. A first closed magnetic path C ₁ (virtually indicated by a two-dot chain line in FIG. 1) through which interlinkage magnetic flux (magnetic flux related to mutual inductance) passes is formed.

Further, the second U core 8 is arranged so as to extend from one end portion 61 of the I core 6 to the first connecting portion 63 of the I core 6 through the outside of the first secondary winding 2. Has been. The second U core 8 constitutes a second core portion in the present embodiment, and the second core portion is linked to the first secondary winding 2, and Only the magnetic flux (hereinafter referred to as “first leakage magnetic flux”) that is not linked to the primary winding 1 and the second secondary winding 3 passes therethrough. Further, a second closed magnetism through which the first leakage magnetic flux passes is formed by a part of the I core 6 (a portion from the one end portion 61 to the first connecting portion 63) and the second U core 8. A path C ₂ (shown virtually by a two-dot chain line in FIG. 1) is formed.

The third U core 9 extends from the other end portion 62 of the I core 6 to the second connecting portion 64 of the I core 6 through the outside of the second secondary winding 3. Has been placed. The third U core 9 constitutes a third core portion in the present embodiment, and the third core portion is interlinked with the second secondary winding 3, and Only the magnetic flux (hereinafter referred to as “second leakage magnetic flux”) that does not link with the primary winding 1 and the first secondary winding 2 passes therethrough. In addition, a part of the I core 6 (a part from the other end portion 62 to the second connecting portion 64) and the third U core 9 allow the third leakage magnetic flux to pass through the third core. A closed magnetic path C ₃ (shown virtually by a two-dot chain line in FIG. 1) is formed.

  For the I core 6 and the first to third U cores 7 to 9, for example, a magnetic material such as ferrite, permalloy, sendust, or a dust core obtained by compression molding a fine powder thereof can be used. Further, a gap for adjusting the leakage inductance may be provided between the I core 6 and each of the first to third U cores 7 to 9.

  As described above, in the inverter transformer of this embodiment, the primary winding 1 is arranged coaxially between the first secondary winding 2 and the second secondary winding 3, and three windings are provided. By providing a first core portion (consisting of an I core 6 and a first U core 7) through which a magnetic flux interlinking with all of the lines 1 to 3 is provided, the primary winding 1 and the first winding 1 In addition, the coupling with the second secondary windings 2 and 3 can be enhanced.

  Further, the second core portion (configured by the second U core 8) through which only the magnetic flux interlinking only with the first secondary winding 2 passes, and only the second secondary winding 3 is interlinked. Since the third core portion (consisting of the third U core 9) through which only the magnetic flux to be transmitted passes is provided, the value of the leakage inductance can be increased, and the first and second secondary The value of the self-inductance of the windings 2 and 3 can be significantly increased compared to the value of the leakage inductance.

  Therefore, it is possible to suppress the influence of a decrease in the coupling between the primary winding 1 and the first and second secondary windings 2 and 3 caused by an increase in the leakage inductance value. While increasing the coupling between the primary winding 1 and the first and second secondary windings 2 and 3, the value of the leakage inductance can be increased.

  Hereinafter, the result of comparing and verifying the operation effect of the inverter transformer according to the present embodiment with that of another embodiment will be described. 4 is a schematic diagram schematically showing the inverter transformer shown in FIG. 1, and FIGS. 5 and 6 are schematic diagrams schematically showing the inverter transformers according to Comparative Example 1 and Comparative Example 2, respectively.

  The inverter transformer schematically shown in FIG. 4 is the same as that described with reference to FIGS. 1 to 3, and the primary winding 1 is a first secondary winding 2 and a second secondary winding. 3 is coaxially arranged. The first and second secondary windings 2 and 3 are electrically connected to each other so as to function as one coil. Also, the I core 6 communicated in the three windings 1 to 3, the first U core 7 that constitutes the first core portion together with the I core 6, and the second and third core portions, respectively. Second and third U cores 8 and 9 are provided.

  In the inverter transformer of Comparative Example 1 shown in FIG. 5, the primary winding 101 is adjacent to one secondary winding 102 and arranged coaxially. Further, the I core 106 communicated in the primary winding 101 and the secondary winding 102, and the one end portion 161 of the I core 106 passes through the outside of the primary winding 101 and the secondary winding 102. A U core 107 disposed so as to extend to the other end 162 of the I core 106, and the primary winding 101 of the I core 106 from the other end 162 of the I core 106 through the outside of the secondary winding 102. And a U-core 110 extending to a portion located between the secondary winding 102.

  The I core 106 and the U core 107 pass through the magnetic flux interlinking with both the primary winding 101 and the secondary winding 102, and the U core 110 is interlinked with the secondary winding 102 to be the primary winding. A magnetic flux that does not interlink with the wire 101 passes.

  In the inverter transformer of Comparative Example 2 shown in FIG. 6, a primary winding 101A is coaxially arranged between two secondary windings 102A and 103A that are electrically connected to each other. Further, the I core 106A communicated in the three windings 101A, 102A, and 103A, and the one end portion 161A of the I core 106A through the outside of the three windings 102A, 101A, and 103A. The U core 107A arranged to extend to the other end 162A, and the primary winding of the I core 106A from the one end 161A of the I core 106A through the outside of the secondary winding 102A and the primary winding 101A A U core 110A extending to a portion located between 101A and the secondary winding 103A is provided.

  The I core 106A and the U core 107A carry a magnetic flux interlinking with all three windings 101A, 102A, 103A, and the U core 110A is interlinked with the primary winding 101A and the secondary winding 102A. Magnetic flux not interlinked with the secondary winding 103A passes.

  Each inverter transformer shown in FIGS. 4 to 6 has a different core configuration, and the number of turns of each winding, the gap between the cores, and the like are set to the same value. Also, the same magnetic material is used to form the core.

  Each inverter transformer shown in FIGS. 4 to 6 was driven under the same conditions, and the value of the leakage inductance and the coupling coefficient between the primary winding and the secondary winding were obtained. The results are shown in Table 1 below. Where Ls is the value of the self-inductance of the secondary winding, Lp is the value of the self-inductance of the primary winding, Ls ′ is the value of the leakage inductance, and k is the coupling coefficient between the primary winding and the secondary winding. Each value is shown.

  As shown in Table 1, the comparative example 1 has a large leakage inductance Ls ′ but a small coupling coefficient k, and the comparative example 2 has a large coupling coefficient k but a leakage inductance Ls. Whereas the value of ′ is small, the embodiment according to the present invention has a large leakage inductance Ls ′ and a large coupling coefficient k. Further, the value of the self-inductance Ls of the secondary winding is also increased.

  As mentioned above, although embodiment of the inverter transformer which concerns on this invention was described, the inverter transformer of this invention is not limited to the said embodiment, The thing of a various aspect can be comprised.

  For example, in the above-described embodiment, the first and second secondary windings 2 and 3 are electrically connected to each other to form a one-input one-output type. , 3 may be connected to each other without being connected to each other.

  Further, the first to third core portions are not limited to the combination of the rod-shaped I core and the U-shaped U core as in the above-described embodiment, and the first to third cores are not limited. It is possible to appropriately change the shape and combination of the individual core members constituting the part.

The top view of the inverter transformer concerning one embodiment Bottom view of inverter transformer shown in Fig. 1 (winding not mounted) 1 is a perspective view of the inverter transformer shown in FIG. Schematic diagram schematically showing the inverter transformer (Example) shown in FIG. Schematic diagram schematically showing the inverter transformer of Comparative Example 1 Schematic diagram schematically showing the inverter transformer of Comparative Example 2

Explanation of symbols

1, 101, 101A Primary winding 2 First secondary winding 3 Second secondary winding 4 Bobbin 5A to 5D Terminal block 6, 106, 106A I core 7 First U core 8 Second U Core 9 3rd U core 11A, 11B Primary side terminal 12A-12D Secondary side terminal 12a Tying part 41 1st winding part 42 2nd winding part 43 3rd winding part 44A-44I Partition ４５ 45A, 45B End 鍔 46A-46C Notch 47A, 47B Window 51A, 51B, 52A, 52B Groove 61, 161, 161A (I core) one end 62, 162, 162A (I core) other end 63 First connecting portion 64 Second connecting portion 101, 101A Primary winding 102, 102A, 103A Secondary winding 107, 107A, 110, 110A U-core C ₁ First closed magnetic circuit C ₂ Second closed magnetic circuit C ₃ 3rd closing A road

Claims (3)

The primary winding is an inverter transformer arranged coaxially between the first secondary winding and the second secondary winding,
A first core portion through which a magnetic flux interlinking with all three windings of the primary winding, the first secondary winding and the second secondary winding passes;
A second core portion that passes through only the magnetic flux interlinked with the first secondary winding and not interlinked with the primary winding and the second secondary winding;
A third core portion that is interlinked with the second secondary winding and through which only the magnetic flux not interlinked with the primary winding and the first secondary winding passes. A featured inverter transformer. The first core portion extends from the one end portion of the I core to the other end portion of the I core through the outside of the three windings and communicated with the three windings. A U-shaped first U-core,
The second core portion passes between the one end of the I core and the outside of the first secondary winding, and between the primary winding and the first secondary winding of the I core. A U-shaped second U-core extending to a portion located at
The third core portion passes through the outside of the second secondary winding from the other end portion of the I core, and the primary winding and the second secondary winding of the I core. The inverter transformer according to claim 1, wherein the inverter transformer is configured by a U-shaped third U-core extending to a portion located therebetween. The first secondary winding and the second secondary winding are electrically connected to each other, and are configured as a one-input one-output type. Inverter transformer.

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