JP2015122912A - Pulse transformer and gate drive circuit using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact pulse transformer with secured insulation between the primary side (high frequency power source side) and the secondary side (gate drive circuit side) thereof.SOLUTION: In a pulse transformer 4 for a gate drive circuit for controlling to drive two switching elements, a transformer body having two primary windings 12, 13 and two secondary windings 14, 15 is accommodated in a resin case 10. Primary winding end parts 12a, 12b, 13a, 13b and secondary winding end parts 14a, 14b, 15a, 15b are exposed from mutually opposite faces of the resin case 10, respectively, and an insulation resin is filled and cured in the resin case 10. Further, between the two primary windings 12, 13, the one end part 12b of the one winding 12 and the one end part 13b of the other winding 13 are short-circuited by means of a connector substrate 11, and the other end part 12a of the one winding 12 and the other end part 13b of the other winding 13 are connected to the high frequency power source by means of a connector 11a.

Description

  The present invention relates to a high-insulation pulse transformer and a gate driving circuit using the high-insulation pulse transformer.

  FIG. 7 is a block diagram showing a circuit configuration for one phase of the inverter. As shown in FIG. 7, switching elements (for example, IGBTs) s1 and s2 are connected in series between the DC voltage Edc. The switching elements s1 and s2 are ON / OFF controlled by the gate drive circuits 1a and 1b, respectively. The gate drive circuits 1a and 1b are provided with pulse transformers 4a and 4b, respectively, and a high-frequency power source 2 is connected to primary windings of the pulse transformers 4a and 4b. The gate drive circuits 1a and 1b are controlled by the control unit 3, respectively.

  The potentials of the gate drive circuits 1a and 1b reciprocate between zero and Edc by turning on / off the switching element s2. For this reason, it is necessary to insulate the gate drive circuits 1a and 1b and the high-frequency power source 2 from each other, and a sufficient insulation capability is required for the voltage applied to the switching elements s1 and s2. As shown in FIG. 7, a high-frequency power source 2 is often used as the power source for the gate drive circuits 1a and 1b, and the pulse transformers 4a and 4b are generally used for the power source unit. Since the gate drive circuits 1a and 1b are generally configured on a connector substrate (printed substrate), the pulse transformers 4a and 4b are also usually disposed on the connector substrate.

  FIG. 8 is a circuit configuration diagram for one phase of the three-level inverter. As shown in FIG. 8, the main circuit of the three-level inverter includes a first capacitor C1 and a second capacitor C2 connected in series, and a switching element between the positive terminal of the first capacitor C1 and the negative terminal of the second capacitor C2. s1 to s4 are sequentially connected in series. Diodes D1 and D2 are connected in series between the common connection point of switching elements s1 and s2 and the common connection point of switching elements s3 and s4. A common connection point of the first and second capacitors C1 and C2 and a common connection point of the diodes D1 and D2 are connected. The common connection point between the switching elements s2 and s3 is an output terminal.

  In the case of such a main circuit, since there are four switching elements s1 to s4, the same number (four) of gate drive circuits 1a to 1d as the switching elements are required.

Japanese Utility Model Publication No. 04-52720 Japanese Utility Model Publication No. 05-36815 JP 2002-343654 A

  However, since the pulse transformers 4a to 4d are arranged on the connector board, it is necessary to ensure insulation between the primary side (high frequency power supply 2 side) and the secondary side (gate drive circuits 1a to 1d side) of the pulse transformer. There is. For this reason, it is necessary to secure a creepage distance between the primary side and the secondary side, and the pulse transformer has been enlarged. In addition, since a circuit having a plurality of switching elements such as a multilevel inverter requires the same number of gate drive circuits as the switching elements, it becomes an obstacle to miniaturization and cost reduction of the gate drive circuit and the entire apparatus.

  As described above, in the pulse transformer, it is possible to secure insulation between the primary side (high-frequency power source side) and the secondary side (gate drive circuit side) of the pulse transformer and to reduce the size of the pulse transformer. It becomes a problem.

  The present invention has been devised in view of the above-described conventional problems, and one aspect thereof is a pulse transformer for a gate drive circuit that drives and controls two switching elements, and includes two primary windings and 2 A transformer body having two secondary windings is housed in a resin case, the ends of the primary winding and the ends of the secondary winding are exposed from the opposing surfaces of the resin case, and the insulating resin is placed in the resin case. The two primary windings are short-circuited with one end of one winding and the other end of the other winding with a connector board, and the other end of one winding and the other are wound. The other end of the winding is connected to a high frequency power source by a connector.

  Further, as one aspect thereof, the resin case is characterized in that irregularities are formed between the end portion of the primary winding and the end portion of the secondary winding exposed from the resin case.

  According to another aspect, there is provided a pulse transformer for a gate drive circuit that drives and controls two switching elements, wherein a transformer body having two primary windings and two secondary windings and a connector substrate are connected to a resin case. And the ends of the two secondary windings are exposed from the resin case, the insulating resin is filled in the resin case and cured, and the two primary windings are one end of one of the windings. And one end of the other winding are short-circuited in the connector substrate, and the other end of one winding and the other end of the other winding are connected to a high-frequency power source by a connector.

  According to the present invention, in the pulse transformer, it is possible to secure insulation between the primary side (high frequency power supply side) and the secondary side (gate drive circuit side) of the pulse transformer and to reduce the size of the pulse transformer. Become.

FIG. 2 is a perspective view showing a pulse transformer in the first embodiment. FIG. 2 is a block diagram showing a gate drive circuit using a pulse transformer in the first embodiment. Schematic which shows the coil | winding structure of a pulse transformer. Schematic which shows the winding structure of the pulse transformer of the state which short-circuited two primary windings. FIG. 6 is a perspective view showing a pulse transformer in the second embodiment. FIG. 9 is a side view showing a pulse transformer in the third embodiment. The block diagram which shows the circuit structure for 1 phase of inverters. The block diagram which shows the circuit structure for 3 levels inverter 1 phase.

  Hereinafter, the first to third embodiments of the pulse transformer according to the present invention will be described in detail with reference to FIGS.

[Embodiment 1]
FIG. 1 is a perspective view showing a pulse transformer 4 according to the first embodiment. FIG. 2 shows a gate drive circuit using the pulse transformer 4. The first embodiment is premised on a gate drive circuit for driving two switching elements s1 and s2 as shown in FIGS. 7 and 8 and a pulse transformer used for the gate drive circuit.

  As shown in FIG. 2, the current output from the high-frequency power source 2 is applied to the primary winding of the pulse transformer 4, and the voltage induced in the secondary winding is output to the power generation units 5a and 5b. The power generators 5a and 5b generate power for each gate drive circuit.

  The signals output from the gate signal generation units 7a and 7b are output to the gate signal command units 8a and 8b via the optical transmission / reception units 6a and 6b, and the switching elements s1 and s2 of the main circuit are output from the gate signal command units 8a and 8b. A gate signal is output to

  Here, the secondary side of the high frequency power source 2 and the pulse transformer 4, the gate signal generation unit 7a and the optical transmission / reception unit 6a, and the gate signal generation unit 7a and the optical transmission / reception unit 6b are insulated. In addition, as shown in FIG. 2, in the connector substrate 11, the optical transceiver 6a, the power generator 5a, the gate signal command unit 8a side (that is, the gate drive circuit side of the switching element s1), the optical transceiver 6b, Insulation is also taken between the power generation unit 5b and the gate signal command unit 8b side (that is, the gate drive circuit side of the switching element s2).

  The pulse transformer 4 includes a primary body 12 and 13 and secondary windings 14 and 15 wound around a core and a bobbin to constitute a transformer body. The transformer main body is accommodated in the resin case 10, and an insulating resin is filled in the resin case 10 and cured and fixed.

  As described above, the transformer main body is accommodated in the resin case 10, the insulating resin is filled in the resin case 10, and cured and fixed, so that a creepage distance does not occur in the resin filling. Therefore, it is possible to improve insulation against partial discharge that occurs when a high voltage is applied.

  Here, as shown in FIG. 3, in the first embodiment, two windings 14 and 15 are provided as secondary windings so that the two switching elements s1 and s2 can be driven. The primary winding is also provided with two windings 12 and 13. The primary winding ends 12 a, 12 b, 13 a, 13 b and the secondary winding ends 14 a, 14 b, 15 a, 15 b are respectively connected to external output pins and exposed from the resin case 10. Here, the end portions 12a, 12b, 13a and 13b of the primary windings 12 and 13 are on the connector substrate 11 side of the resin case 10, and the end portions 14a, 14b, 15a and 15b of the secondary winding are connectors on the resin case 10. It is exposed from the surface facing the substrate 11.

  Thus, by exposing the end portions 12a, 12b, 13a, 13b of the primary winding and the end portions 14a, 14b, 15a, 15b of the secondary winding from the opposing surfaces of the resin case 10, Between the primary windings 12 and 13 and the secondary windings 14 and 15 and between the secondary winding 14 and the secondary winding 15 (in the case of the first embodiment, between the secondary winding 14 and the secondary winding 15 (Edc voltage is also applied), and the insulation against partial discharge generated when a high voltage is applied is enhanced.

  The connector board 11 provided with the connector 11a short-circuits the end portions 12b and 13a of the primary winding as shown in FIG. The connector 11a connected to the high frequency power source 2 is connected to the ends 12a and 13b of the primary winding. At the time of assembly, it can be connected to the high-frequency power source 2 simply by inserting the connector 11a.

  As described above, the end portions 12a, 12b, 13a, 13b of the primary winding and the end portions 14a, 14b, 15a, 15b of the secondary winding are connected to the resin case as in the pulse transformer 4 in the first embodiment. By extending the creeping distance by exposing from 10 opposing surfaces and filling the resin case 10 with an insulating resin, it becomes possible to improve the insulation against partial discharge generated when a high voltage is applied.

  In addition, a connector 11a is used to connect the primary windings 12 and 13 and the high-frequency power source 2, and the primary windings 12 and 13 are short-circuited by the connector substrate 11 so that a highly insulated power source is mounted on the connector substrate 11. Simplify the gate drive circuit and downsize the unit. Moreover, it becomes possible to connect the primary windings 12 and 13 and the high frequency power supply 2 only by inserting the connector 11a.

  In addition, by applying the pulse transformer of the first embodiment to a gate drive circuit, it is possible to provide a highly reliable, compact, highly insulated high voltage, large capacity power converter.

  Further, according to the first embodiment, a circuit configuration for two gates can be provided by a small pulse transformer even when the potential fluctuates due to switching as in the multilevel power conversion device as shown in FIG. It becomes possible.

[Embodiment 2]
FIG. 5 is a perspective view showing the pulse transformer 4 according to the second embodiment. In the second embodiment, the end portions 12a, 12b, 13a, 13b of the primary windings 12, 13 and the connector board 11 are accommodated in the resin case 10, and the end portions 12a, 12b, 13 a and 13 b are not exposed from the resin case 10. Others are the same as in the first embodiment.

  Since the ends 12b and 13a of the primary winding are connected in the connector board 11, the primary windings 12 and 13 are connected in series even if the ends 12b and 13a are housed in the resin case 10. It is possible. Even if the ends 12a and 13b of the primary winding are housed in the resin case 10, the connector 11a can be connected to the high-frequency power source 2.

  According to the pulse transformer 4 in the second embodiment, the end portions 12 a, 12 b, 13 a, 13 b of the primary windings 12, 13 are accommodated in the resin case 10, so that a short circuit current is generated along the creeping surface of the resin case 10. Is suppressed from flowing. Therefore, it is not necessary to increase the size of the resin case 10 in order to increase the creepage distance, and the pulse transformer 4 can be reduced in size. In addition, the same effects as those of the first embodiment are obtained.

[Embodiment 3]
FIG. 6 is a side view showing the pulse transformer 4 according to the third embodiment. In the third embodiment, similarly to the first embodiment, the end portions 12a, 12b, 13a, 13b, 14a, 14b, 15a, and 15b of the primary winding and the secondary winding are exposed to the outside of the resin case 10. Therefore, the resin case 10 needs to satisfy the insulation standard for creepage distance.

  In the third embodiment, as shown in FIG. 6, the unevenness 16 is formed on the side surface (the surface where the end portions 12a, 12b, 13a, 13b, 14a, 14b, 15a, 15b are not exposed) of the resin case 10. Yes. As a result, the resin case further than the first embodiment while ensuring the creepage distances between the end portions 12a, 12b, 13a, 13b of the primary windings and the end portions 14a, 14b, 15a, 15b of the secondary windings. 10 can be reduced in size.

  Although the present invention has been described in detail only for the specific examples described above, it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the technical idea of the present invention. Such variations and modifications are naturally within the scope of the claims.

  For example, in Embodiment 3, the unevenness 16 is formed on the side surface of the resin case 10, but between the end portions 12a, 12b, 13a, 13b of the primary winding and the end portions 14a, 14b, 15a, 15b of the secondary winding. As long as the creepage distance can be increased, the portion where the unevenness is formed need not be the side surface.

  Further, although FIGS. 7 and 8 are shown as examples of the main circuit for outputting the gate signal from the gate drive circuit, the main circuit is not limited to this and may have two or more switching elements.

  Furthermore, although FIG. 2 is shown as an example of the gate drive circuit, other than this may be used as long as the gate drive circuit has a pulse transformer.

4 ... Pulse transformer 10 ... Resin case 11 ... Connector substrate 11a ... Connector 12, 13 ... Primary winding 12a, 12b, 13a, 13b ... End of primary winding 14, 15 ... Secondary winding 14a, 14b, 15a, 15b ... the end of the secondary winding 16 ... irregularities

Claims (4)

A pulse transformer for a gate drive circuit that drives and controls two switching elements,
A transformer body having two primary windings and two secondary windings is housed in a resin case, and the end of the primary winding and the end of the secondary winding are respectively arranged from the opposing surfaces of the resin case. Expose, fill the resin case in the resin case and cure,
In the two primary windings, one end of one winding and one end of the other winding are short-circuited by a connector board, and the other end of one winding and the other end of the other winding A pulse transformer, characterized in that is connected to a high-frequency power source through a connector. The resin case is
2. The pulse transformer according to claim 1, wherein irregularities are formed between an end portion of the primary winding exposed from the resin case and an end portion of the secondary winding. A pulse transformer for a gate drive circuit that drives and controls two switching elements,
A transformer body having two primary windings and two secondary windings and a connector board are housed in a resin case, the ends of the two secondary windings are exposed from the resin case, and the insulating resin is resin case Filled inside and cured,
In the two primary windings, one end of one winding and one end of the other winding are short-circuited in the connector board, and the other end of one winding and the other end of the other winding And a high frequency power supply connected by a connector. A pulse transformer according to claims 1 to 3,
A gate drive circuit characterized by controlling driving of two switching elements.

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