Transformer structure and gate drive circuit

Abstract

To improve the mass productivity and assembly of board-mounted transformer structures and to suppress leakage inductance.SOLUTION: A transformer core substrate 1 has holes 10 formed at approximately the radial center of each pulse transformer core 2. Each primary winding of a transformer structure is disposed in the pulse transformer core 2 through each hole 10. The secondary winding wound around each pulse transformer core 2 is composed of a wiring pattern in the substrate 6 and six conductors (electric wires) 3a to 3f soldered to the substrate 6. The transformer core substrate 1 can be connected to a main board by connectors 5a and 5b.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a substrate mounted transformer structure and a gate drive circuit incorporating the structure. [Background technology]

[0002] Known examples of transformers for driving gates of semiconductor elements for pulse power supplies are disclosed in Patent Documents 1 and 2. Patent Document 1 describes a structure in which multiple transformer cores are attached to a printed circuit board so that the hollow portions of the cores are aligned in a row.

[0003] In Patent Document 2, a secondary wire is wound around a core in a state where a wire mounted on a substrate is formed into multiple turns. Also, multiple substrates of gate drive circuits are connected in series, and the primary wire of the pulse transformer is inserted through a hole in the substrate and placed at the center of the core on the substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5221203 [Patent Document 2] Patent No. 6965714 [Patent Document 3] JP 2023-67333 A Summary of the Invention [Problem to be solved by the invention]

[0005] The structures of Patent Documents 1 and 2 have the following problems.

[0006] (1) The structure of Patent Document 1 requires that the secondary winding be wound around each transformer core, and therefore requires a base for mounting on a board. In other words, a base for fixing to the board must be prepared, and the secondary winding must be wound around each individual core, which is not suitable for mass production.

[0007] In addition, the series-connected primary winding is arranged to penetrate the hollow part of all the transformer cores, and only both ends are supported on the printed circuit board, so there are few fixing points and the center may bend. Therefore, if vibrations are applied when the transformer is installed in a device, the primary winding may be shaken and come into contact with the transformer core.

[0008] As a result, depending on the position of the primary winding, the bending may prevent a uniform insulation distance from the transformer core from being secured, which may cause partial discharge. This may deteriorate the insulation and cause a leakage inductance problem.

[0009] (2) The structure of Patent Document 2 requires winding the secondary wire after forming, and is therefore not suitable for mass production. In particular, the substrate of Patent Document 2 requires a separate fixing mechanism when connecting to the gate drive circuit, and since the secondary wire is also a wire, a separate terminal must be provided at the end of the winding for connection, making connectivity with other circuits complicated and making assembly difficult.

[0010] The present invention has been made to solve such conventional problems, and aims to improve the mass productivity and assembly efficiency of a board-mounted transformer structure and to suppress leakage inductance. [Means for solving the problem]

[0011] (1) The transformer structure of the present invention is A conductor for fixing the transformer core on the substrate; a hole formed in the substrate at a position corresponding to an approximate center of the transformer core; a primary winding disposed in a hollow portion of the transformer core through the hole; a secondary winding formed by the conductor and a pattern on the substrate; a connection member for connecting the secondary winding to a circuit; The present invention is characterized by the following:

[0012] (2) One aspect of the transformer structure includes a plurality of the conductors, each of which is provided at equal intervals in the circumferential direction of the transformer core. The transformer core may be bonded to the substrate, and the primary winding may be a Litz wire.

[0013] (3) As another aspect of the transformer structure, a plurality of the substrates may be connected to the substrate of the circuit. In this case, the primary winding may be made of a copper rod. It is also possible to configure the transformer structure with a pair of the transformer cores corresponding to the ON-side circuit and the OFF-side circuit of a push-pull configuration.

[0014] (4) The gate drive circuit of the present invention comprises: a modulation circuit that outputs a first modulation signal and a second modulation signal based on an on command and an off command of a gate command; an on-side rectifier circuit and an off-side rectifier circuit each having the transformer structure; Equipped with The transformer core of the on-side rectifier circuit includes an on-side primary winding to which the first modulation signal is applied, and an on-side secondary winding that transforms and outputs a voltage applied to the primary winding, The transformer core of the off-side rectifier circuit is characterized by having an off-side primary winding to which the second modulation signal is applied, and an off-side secondary winding that transforms and outputs the voltage applied to the primary winding. Effect of the Invention

[0015] According to the present invention, it is possible to improve the mass productivity and assembly properties of a board-mounted transformer structure and to suppress leakage inductance. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1A is a front view of the first embodiment, and FIG. [Diagram 2] FIG. 2 is a perspective view of FIG. [Diagram 3] (a) is a diagram of a configuration with a center tap, and (b) is a diagram of a configuration with multiple different outputs on the secondary side. [Figure 4] (a) is the test result of Model 1, (b) is the test result of Model 2, and (c) is the test result of Model 3. [Diagram 5] FIG. 10A is a perspective view showing an arrangement image of the second embodiment, and FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A transformer structure according to an embodiment of the present invention will be described below. This transformer structure is a printed circuit board mounting type, and is configured as a pulse transformer board using a transformer core.

[0018] The transformer structure employs a pulse transformer substrate that is easy to assemble and has little individual variation, thereby improving productivity and reducing leakage inductance of the transformer core. In this embodiment, the transformer structure is referred to as a transformer core substrate.

[0019] This transformer core substrate is used, for example, in a gate drive circuit with a push-pull configuration as described in Patent Document 3. This gate drive circuit includes a modulation circuit, an ON-side rectification circuit, an OFF-side rectification circuit, a demodulation circuit, and a gate circuit, and controls a semiconductor element to be driven.

[0020] The modulation circuit outputs a first modulation signal and a second modulation signal based on an ON command and an OFF command of the gate command. Here, the transformer core substrate is used for the ON side rectifier circuit and the OFF side rectifier circuit.

[0021] That is, the pulse transformer core of the on-side rectifier circuit has an on-side primary winding to which the first modulation signal is applied, and an on-side secondary winding that transforms the voltage applied to the primary winding and outputs it to the demodulation circuit.

[0022] In addition, the pulse transformer core of the off-side rectifier circuit has an off-side primary winding to which the first modulated signal is applied, and an off-side secondary winding that transforms the voltage applied to the primary winding and outputs it to the demodulation circuit. EXAMPLES

[0023] A first embodiment of the transformer core substrate will be described with reference to Figures 1 to 3. In the figures, reference numeral 1 denotes the transformer core substrate.

[0024] The transformer core substrate 1 includes a pair of pulse transformer cores 2 mounted on a substrate 6 and a plurality of conductors (wires) 3 for fixing both pulse transformer cores 2 to the substrate 6, one pulse transformer core 2 being used in an ON-side rectifier circuit and the other pulse transformer core 2 being used in an OFF-side rectifier circuit.

[0025] The substrate 6 is formed with holes 10 that correspond to approximate radial centers of the pulse transformer cores 2. The primary winding is disposed in the hollow portion 2a of the pulse transformer core 2 through each hole 10.

[0026] On the other hand, the secondary winding wound around each pulse transformer core 2 is composed of a wiring pattern in the substrate 6 and six conductors (electric wires) 3a to 3f soldered to the substrate 6. As shown in Fig. 2, each of these conductors 3a to 3f has an inverted U-shape and is provided at equal intervals at 60-degree positions around each pulse transformer core 2. Each of the conductors 3a to 3f is connected with the pulse transformer core 2 sandwiched therebetween, and simultaneously fixes and conducts electricity to the pulse transformer core 2.

[0027] Moreover, the conductors 3a to 3f and the pins of the female connectors 5a, 5b are connected by wiring patterns provided on the front and back surfaces of the substrate 6. That is, a part of the secondary winding is formed by the wiring pattern of the substrate 6, and the conductors 3a to 3f and the corresponding pins of the female connectors 5a, 5b are wired and connected within the substrate 6. For example, the conductors 3a, 3b and the corresponding pins of the female connector 5a can be connected by the wiring pattern on the front surface of the substrate 6, and the conductors 3c to 3f and the corresponding pins of the female connector 5b can be connected by the wiring pattern on the back side of the substrate. Also, as a secondary winding using a wiring pattern, for example, a configuration having a center tap T as shown in Fig. 3(a) or a configuration in which the secondary side Q has multiple different outputs O1, O2 as shown in Fig. 3(b) is possible (P in Fig. 3 indicates the primary side). In addition, the female connector 5 to be connected and the ratio of the number of turns can be set arbitrarily by the wiring on the board 6. However, no wiring pattern is provided between the pulse transformer core 2 and the hole 10. According to the transformer core substrate 1 configured in this manner, the following effects can be obtained.

[0028] (1) Compared to Patent Documents 1 and 2, the process of winding the secondary winding is eliminated, and mounting by solder flow like TMD components is possible. This makes mass production easier, improves productivity, and enables cost reduction.

[0029] (2) Each pulse transformer core 2 is fixed to the substrate 6 by the conductors 3a to 3f, which improves vibration resistance and improves product quality. In addition, positioning is made easy and the cores are prevented from shifting from their original positions, improving manufacturing efficiency and making the product suitable for mass production.

[0030] In addition, in specifications with severe vibration conditions, the pulse transformer core 2 can be fixed more firmly by using not only the conductors 3a to 3f but also an adhesive. This can also be said to be an effect of mounting the pulse transformer core 2 on the substrate 6, and the quality can be improved by suppressing individual differences.

[0031] (3) Furthermore, the inner diameter of the hole 10 formed in the substrate 6 is formed to be slightly larger than the diameter of the primary winding. This makes it possible to suppress misalignment of the primary winding with respect to the pulse transformer core 2.

[0032] At this time, there is no wiring pattern between the pulse transformer core 2 and the hole 10, and the insulation distance between the primary winding and the secondary winding is uniformly secured around the hole 10. This ensures the insulation distance between the primary winding and the secondary winding, and has the effect of suppressing partial discharge and leakage inductance. This point will be explained based on the comparison test in FIG. 4.

[0033] <Contents of the comparison test> Using frequency response analysis of 2D magnetic field analysis in JMAG (electromagnetic field analysis software), the magnitude of leakage inductance on the primary side was compared for models 1 to 3, in which the shape and arrangement of the windings were changed.

[0034] Here, Fig. 4(a) shows Model 1, Fig. 4(b) shows Model 2, and Fig. 4(c) shows Model 3. In Fig. 4(a) to Fig. 4(c), C indicates the transformer core, P indicates the low voltage side (primary side), and Q indicates the high voltage side (secondary to seventh sides).

[0035] Model 1 In model 1, the low-voltage side P passes through the center of the transformer core C, and the high-voltage side Q is wound around the transformer core C at 60-degree intervals in the circumferential direction. This model 1 imitates the transformer core substrate 1, and the insulation distance between the low-voltage side P and the high-voltage side Q is uniformly secured.

[0036] Model 2 In model 2, the low voltage side P passes through the center part of the transformer core C, but the high voltage side Q is moved to the end of the transformer core C. This model 2 simulates FIG. 10 of Patent Document 1.

[0037] Model 3 In model 3, the low-voltage side P is wound close to one end of the transformer core C, and the high-voltage side Q is wound close to the opposite side. Model 2 mimics Figure 9 of Patent Document 1, and resembles the state in which the primary winding is bent.

[0038] In this test, we used a standard transformer core C. In addition, the current values ​​on both the low-voltage and high-voltage sides were set within the range where there was no magnetic saturation.

[0039] <Test Results> The comparison results (test results) in FIG. 4 show the relative values ​​of leakage inductance (primary side) when Model 1 is taken as "100%." in particular, Model 1 = 100% Model 2 = approx. 150% Model 3 = approx. 250% The comparative results were obtained.

[0040] According to the test results, it was confirmed that the leakage inductance value was the smallest in the model 1 simulating the transformer core substrate 1. In this respect, the leakage inductance suppressing effect of the transformer core substrate 1 was proven.

[0041] As a result, when the transformer core substrate 1 is applied to, for example, the gate circuit of the switching element of Patent Document 3, the effect of speeding up the switching operation of the switching element by suppressing leakage inductance can be expected.

[0042] In addition, in the structure for mounting the model 1, that is, in the structure of the transformer core board 1, the primary winding and the secondary winding are fixed, so that the variation in leakage inductance of each pulse transformer core 2 is reduced. EXAMPLES

[0043] A second embodiment will be described with reference to Fig. 4. Here, an embodiment using a plurality of the transformer core boards 1 is shown, and a main board (circuit board) 30 shown in Fig. 5 is used.

[0044] The main board 30 includes a group of male connectors 31a, 31b that are connected to the female connectors 5a, 5b of the substrate 6, and various electrical components 32 such as gate drive circuits can be mounted according to the number of the transformer core substrates 1. According to this embodiment, the heights of the group of transformer core substrates 1 can be aligned when mounted on the main board 30 by connecting the female connectors 5a, 5b to the male connectors 31a, 31b.

[0045] As a result, the holes 10 of the transformer core substrates 1 can be aligned to approximately the same height, improving assembly. In this case, a copper rod may be used for the primary winding instead of an electric wire, and using a copper rod improves workability when passing the primary winding through the hole 10 of each transformer core substrate 1. In addition, the copper rod suppresses misalignment and tilt of each transformer core substrate 1, improving vibration resistance.

[0046] Furthermore, since it can be connected to the main board 30 via female connectors 5a, 5b, there is no need to prepare a base specifically for fixing the core and connect the secondary winding separately, as in Patent Document 1, which is also expected to improve productivity and assembly.

[0047] The present invention is not limited to the above embodiment, and can be modified within the scope of the claims. For example, the number of pulse transformer cores 2 on the substrate 6 does not have to be two, and the effects of the first and second embodiments can be obtained even if the number of cores is changed.

[0048] In addition, a Litz wire can be used as the primary winding of the transformer core substrate 1, which enables high-speed driving. Furthermore, a gate drive circuit having a push-pull configuration using the transformer core substrate 1 also constitutes the present invention. [Explanation of symbols]

[0049] 1...Transformer core board 2...Pulse transformer core 2...Hollow part 3a~3f...conductor 5a, 5b, 31a, 31b...Connectors 6,30…Substrate 10...hole

Claims

1. A conductor for fixing the transformer core on the substrate; a hole formed in the substrate at a position corresponding to an approximate center of the transformer core; a primary winding disposed in a hollow portion of the transformer core through the hole; a secondary winding formed by the conductor and a pattern on the substrate; a connection member for connecting the secondary winding to a circuit; Equipped A transformer structure characterized in that

2. A plurality of the conductors are provided, The conductors are arranged at equal intervals in the circumferential direction of the transformer core.

2. The transformer structure according to claim 1 .

3. 2. The transformer structure of claim 1, wherein the transformer core is bonded to the substrate.

4. 2. The transformer structure of claim 1, wherein the primary winding is a Litz wire.

5. 2. The transformer structure of claim 1, wherein a plurality of said substrates are connected to a substrate of said circuit.

6. 6. The transformer structure of claim 5, wherein the primary winding is constructed from a copper bar.

7. A pair of the transformer cores is provided corresponding to an ON-side circuit and an OFF-side circuit of a push-pull configuration.

2. The transformer structure according to claim 1 .

8. a modulation circuit that outputs a first modulation signal and a second modulation signal based on an on command and an off command of a gate command; An on-side rectifier circuit and an off-side rectifier circuit each having a transformer structure according to any one of claims 1 to 7; Equipped with The transformer core of the on-side rectifier circuit includes an on-side primary winding to which the first modulation signal is applied, and an on-side secondary winding that transforms and outputs a voltage applied to the primary winding, The transformer core of the off-side rectifier circuit includes an off-side primary winding to which the second modulation signal is applied, and an off-side secondary winding that transforms and outputs the voltage applied to the primary winding. A gate drive circuit comprising:

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