JP6362959B2 - Power conversion circuit, manufacturing method thereof, and power conditioner - Google Patents

Description

  The present invention relates to a power conversion circuit including a snubber circuit, a manufacturing method thereof, and a power conditioner including the power conversion circuit.

  2. Description of the Related Art Conventionally, a power conditioner that converts DC power generated by a solar cell or the like into AC power and supplies it to an electric power system has been developed. The inverter circuit provided in the power conditioner converts DC power into AC power by switching the switching element. In order to suppress a surge voltage generated during switching of the switching element, the inverter circuit is provided with a snubber circuit.

  When the capacity of the power conditioner is increased, it is necessary to increase the capacitance of the capacitor of the snubber circuit so that a larger surge voltage can be suppressed. However, there is also a demand for downsizing of the inverter. It is necessary to devise a way to arrange a larger snubber circuit in the limited space of the inverter.

  In order to reduce the surge voltage, it is necessary to reduce the parasitic inductance. Patent Document 1 describes that a positive conductor and a negative conductor of a power module are arranged opposite to each other and magnetic fields are canceled by generating magnetic fields in opposite directions to reduce parasitic inductance. However, in the case of a multilevel inverter circuit, the number of switching elements to be used is large, and the connection between the elements becomes complicated, so that it is difficult to arrange the connection conductors facing each other.

  As a more general method for reducing the parasitic inductance, there is a method for shortening the connection conductor connecting the snubber circuit and the switching element. Arranging the snubber circuit and the switching element close to each other is also effective in the sense that they are disposed in a limited space of the power conditioner. However, when the snubber circuit and the switching element are arranged close to each other, there is a problem that the life of the capacitor of the snubber circuit is reduced by heat generated from the switching element. Patent Document 2 describes that the temperature rise of the capacitor is suppressed by radiating heat with a heat radiating plate joined to the capacitor of the snubber circuit. However, if there is no room in the device, the heat dissipation becomes worse. Moreover, since it is necessary to newly provide a heat sink for the capacitor, the space in the apparatus is further reduced.

JP 2005-191233 A JP 2010-28560 A

  The present invention has been conceived under the circumstances described above, and an object of the present invention is to provide a power conversion circuit that can reduce parasitic inductance and suppress a temperature rise of a snubber circuit. .

  In order to solve the above problems, the present invention takes the following technical means.

  The power conversion circuit provided by the first aspect of the present invention has a switching element, and connects a switching module in which a positive electrode and a negative electrode are provided on the same surface, a plurality of capacitors, and a connection conductor. The capacitor group is substantially U-shaped in plan view, and the snubber circuit is disposed on the surface side of the switching module where the electrodes are provided, One terminal of the circuit is directly connected to the positive electrode, the other terminal is directly connected to the negative electrode, and further includes a heat insulating plate disposed between the switching module and the snubber circuit. It is characterized by.

  In a preferred embodiment of the present invention, the heat insulating plate is fixed to the snubber circuit.

  In preferable embodiment of this invention, the said heat insulation board is a magnitude | size comparable as the magnitude | size when the said capacitor group is planarly viewed.

In a preferred embodiment of the present invention, the heat insulating plate is a phenol resin plate.

  In a preferred embodiment of the present invention, the capacitor group is formed by connecting two capacitors connected in series to each other in parallel.

  The power conditioner provided by the second aspect of the present invention includes the power conversion circuit provided by the first aspect of the present invention.

  The manufacturing method provided by the third aspect of the present invention is a method for manufacturing a power conversion circuit, in which a plurality of capacitors are connected by connecting conductors, and the connected capacitor group is substantially U-shaped in plan view. A first step to do so, a second step of fixing a heat insulating plate to the back surface of the snubber circuit including the capacitor group, a switching element, and the positive electrode side electrode and the negative electrode side electrode are provided on the same surface. The snubber circuit is configured such that the surface on which the respective electrodes are provided faces the snubber circuit side, and a predetermined interval is provided between the back surface side of the snubber circuit and the heat insulating plate. And a third step of directly connecting the other terminal to the negative electrode and fixing the other terminal directly to the negative electrode.

  According to the present invention, the two terminals of the snubber circuit are directly connected to the positive electrode and the negative electrode of the switching module, respectively, so that the parasitic inductance can be reduced. Moreover, since the heat insulation board is arrange | positioned between the switching module and the snubber circuit, it can suppress that the temperature of a snubber circuit rises with the heat discharge | released from a switching module.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

It is a figure which shows the circuit structure of the inverter circuit which concerns on 1st Embodiment. It is a figure for demonstrating the structure of the inverter circuit which concerns on 1st Embodiment. It is a figure for demonstrating the structure of the inverter circuit which concerns on 1st Embodiment. It is a figure for demonstrating the structure of the capacitor | condenser of a snubber circuit. It is a figure for demonstrating the manufacturing method of the inverter circuit which concerns on 1st Embodiment. It is a figure for demonstrating the manufacturing method of the inverter circuit which concerns on 1st Embodiment. It is a figure for demonstrating the other Example of the snubber circuit which concerns on 1st Embodiment.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings, taking as an example a case where the power conversion circuit according to the present invention is used as an inverter circuit of a power conditioner.

  FIG. 1 is a diagram illustrating a circuit configuration of an inverter circuit according to the first embodiment.

  The inverter circuit shown in FIG. 1 is provided in a power conditioner and converts a DC voltage input from a DC power source such as a solar battery into an AC voltage and outputs the AC voltage. The inverter circuit is a three-phase PWM control type inverter, and is a three-level inverter circuit in which the output phase voltage of each phase becomes a three-level potential. The inverter circuit converts a DC voltage input from a DC power source into an AC voltage by switching on and off each switching element based on a PWM signal input from a control circuit (not shown).

  As shown in FIG. 1A, the inverter circuit includes 12 switching elements S1 to S12, 12 freewheeling diodes, 3 snubber circuits C1 to C3, and 2 voltage dividing capacitors Cp and Cn. I have. In the present embodiment, IGBTs (Insulated Gate Bipolar Transistors) are used as the switching elements S1 to S12. The switching elements S1 to S12 are not limited to IGBTs, and may be bipolar transistors, MOSFETs, reverse blocking thyristors, or the like. Further, the types of the reflux diode and the voltage dividing capacitor are not limited.

  The voltage dividing capacitors Cp and Cn are capacitors having the same capacitance, and divide a DC voltage input from a DC power source (not shown). The voltage dividing capacitor Cp and the voltage dividing capacitor Cn are connected in series at a point O, and are connected in parallel between a point P connected to the positive electrode of the DC power supply and a point N connected to the negative electrode. The potential at the point O is an intermediate potential between the potential at the point N and the potential at the point P.

  The switching elements S1 and S4 are connected in series by connecting the emitter terminal of the switching element S1 and the collector terminal of the switching element S4. The collector terminal of the switching element S1 is connected to the point P, and the emitter terminal of the switching element S4 is connected to the point N to form a bridge structure. Similarly, switching elements S2 and S5 are connected in series to form a bridge structure, and switching elements S3 and S6 are connected in series to form a bridge structure. PWM signals output from the control circuit are input to the gate terminals of the switching elements S1 to S6, respectively.

  The bridge structure formed of switching elements S1 and S4 is a U-phase arm, the bridge structure formed of switching elements S2 and S5 is a V-phase arm, and the bridge structure formed of switching elements S3 and S6 is W Phase arm. The U-phase output line is connected to the connection point U between the switching elements S1 and S4 of the U-phase arm, and the V-phase output line is connected to the connection point V between the switching elements S2 and S5 of the V-phase arm. A W-phase output line is connected to a connection point W between the switching elements S3 and S6 of the W-phase arm.

  The connection point U is connected to the point O via an intermediate switch composed of switching elements S7 and S8. The switching elements S7 and S8 are connected in series with their collector terminals connected. The emitter terminal of the switching element S7 is connected to the point O, and the emitter terminal of the switching element S8 is connected to the point U. Similarly, the connection point V is connected to the point O via an intermediate switch composed of switching elements S9 and S10. Switching elements S9 and S10 have their collector terminals connected, the emitter terminal of switching element S9 is connected to point O, and the emitter terminal of switching element S10 is connected to point V. Further, the connection point W is connected to the point O via an intermediate switch composed of the switching elements S11 and S12. Switching elements S11 and S12 have their collector terminals connected, the emitter terminal of switching element S11 is connected to point O, and the emitter terminal of switching element S12 is connected to point W. The switching elements S7 and S8 perform an on / off operation at the same timing, and conduct the connection between the point O and the point U when in the on state and do not conduct the connection when in the off state. Similarly, the switching elements S9 and S10 also perform the on / off operation at the same timing so that the connection between the point O and the point V is made conductive when in the on state and the connection is not made conductive when in the off state. The switching elements S11 and S12 also perform on / off operations at the same timing so that the connection between the point O and the point W is made conductive when in the on state and the connection is not made conductive when in the off state. PWM signals output from the control circuit are input to the gate terminals of the switching elements S7 and S8, the gate terminals of the switching elements S9 and S10, and the gate terminals of the switching elements S11 and S12, respectively.

  Each of the switching elements S1 to S12 can be switched between an on state and an off state based on the PWM signal. For example, when the switching element S1 is in the on state and the switching element S4 and the switching elements S7, 8 are in the off state, the potential of the U-phase output line is the potential at the point P (that is, the potential on the positive side of the DC power supply). When switching element S4 is on and switching element S1 and switching elements S7, 8 are off, the potential of the U-phase output line is the potential at point N (that is, the potential on the negative side of the DC power supply). Further, when the switching elements S7, 8 are on and the switching elements S1 and S4 are off, the potential of the U-phase output line is the potential at the point O (that is, between the positive side and the negative side of the DC power supply). Potential). As a result, the output phase voltage output from each output line becomes a three-level potential, that is, a positive potential, a negative potential, and an intermediate potential of the DC power supply.

  The free-wheeling diodes are connected in antiparallel between the collector terminals and the emitter terminals of the switching elements S1 to S12. That is, the anode terminal of the freewheeling diode is connected to the emitter terminals of the switching elements S1 to S12, respectively, and the cathode terminal of the freewheeling diode is connected to the collector terminals of the switching elements S1 to S12, respectively. The free-wheeling diode is for preventing a high reverse voltage due to the counter electromotive force generated by switching the switching elements S1 to S12 from being applied to the switching elements S1 to S12.

  Snubber circuit C1 is connected in parallel to both ends of the U-phase arm. Similarly, the snubber circuit C2 is connected in parallel to both ends of the V-phase arm, and the snubber circuit C3 is connected in parallel to both ends of the W-phase arm. The snubber circuits C1 to C3 are each configured by connecting six capacitors in three series and two in parallel. FIG. 1B shows a snubber circuit C1 and shows that three capacitors C11 to C13 connected in series and three capacitors C14 to C16 connected in series are connected in parallel. . The same applies to the snubber circuits C2 and C3. The snubber circuits C1 to C3 are for absorbing a surge voltage generated during switching.

  In the power conditioner according to the present embodiment, an inverter circuit is configured by three circuits of a U-phase circuit, a V-phase circuit, and a W-phase circuit. The U-phase circuit A includes a U-phase arm composed of switching elements S1 and S4, an intermediate switch composed of switching elements S7 and S8, a free wheel diode connected to each switching element S1, S4, S7, and S8, and a snubber circuit C1. It has. The V-phase circuit includes a V-phase arm composed of switching elements S2 and S5, an intermediate switch composed of switching elements S9 and S10, a free wheel diode connected to each switching element S2, S5, S9, and S10, and a snubber circuit C2. I have. The W-phase circuit includes a W-phase arm composed of switching elements S3 and S6, an intermediate switch composed of switching elements S11 and S12, a free wheel diode connected to each switching element S3, S6, S11, and S12, and a snubber circuit C3. I have.

  2 and 3 are diagrams for explaining the structure of the inverter circuit according to the first embodiment, and show the structure of the U-phase circuit A of the inverter circuit. FIG. 2 is a plan view of the U-phase circuit A. FIG. The coordinate axes that define the direction are shown in the lower left of the figure. The Z-axis has a positive direction above the U-phase circuit A (the front direction in FIG. 2). FIG. 3 is a side view of the U-phase circuit A shown in FIG. 2 as viewed from the positive direction of the X axis.

  As shown in FIGS. 2 and 3, the U-phase circuit A includes capacitors C <b> 11 to C <b> 16, connection conductors 11 to 13, a heat insulating plate 2, IGBT modules 31 to 33, a heat sink 5, and a fixing member 6. In FIG. 2, the fixing member 6 is shown by a broken line so that the member located below can be seen. Similarly, in FIG. 3, the fixing member 6 is transmitted and is shown by a broken line.

  Capacitors C11 to C16 are capacitors constituting the snubber circuit C1 (see FIG. 1B). FIG. 4 shows the external appearance of the capacitors C11 to C16. The figure (a) is a top view, the figure (b) is a front view, and the figure (c) is a side view. The capacitors C11 to C16 include a main body 71, terminals 72a and 72b, and a fixing portion 73. The terminals 72a and 72b and the fixing portion 73 are provided with holes and can be fixed with screws or the like. The shapes of the capacitors C11 to C16 are not limited to this.

  The connection conductors 11 to 13 are for connecting the terminals 72a and 72b of the capacitors C11 to C16, and a copper plate is used in the present embodiment. The connection conductors 11 to 13 are not limited to copper plates, but may be any conductor that has some strength.

  The connection conductor 12 has a substantially L shape in plan view, and is provided with screw holes for connection to the terminals 72a and 72b of the capacitors C11 to C16 in the vicinity of both ends. One connection conductor 12 connects the terminal 72b of the capacitor C11 and the terminal 72a of the capacitor C12. The other connecting conductor 12 connects the terminal 72b of the capacitor C12 and the terminal 72a of the capacitor C13. That is, the capacitors C11, C12, and C13 are connected in series by the two connection conductors 12. The first capacitor group in which the capacitors C11, C12, and C13 are connected by the two connecting conductors 12 has a substantially U shape in plan view as shown in FIG.

  The connection conductor 13 has a substantially rectangular shape in plan view, and is provided with screw holes near both ends. One connection conductor 13 connects the terminal 72a of the capacitor C14 and the terminal 72b of the capacitor C15. The other connecting conductor 13 connects the terminal 72a of the capacitor C15 and the terminal 72b of the capacitor C16. That is, the capacitors C14, C15, and C16 are connected in series by the two connection conductors 13. The second capacitor group in which the capacitors C14, C15, and C16 are connected by the two connecting conductors 13 is also substantially U-shaped in plan view as shown in FIG.

  The connection conductor 11 is fixed to a first portion (see FIG. 2) having a substantially rectangular shape that is long in the X-axis direction and provided with screw holes near both ends, and electrodes 31a and 31b of an IGBT module 31 to be described later. The second part of the substantially rectangular shape (see FIG. 2) provided with a screw hole substantially in the center, and the long side of the first part so that the first part and the second part are substantially parallel to each other. It has a third portion (see FIG. 3) that connects the center and the second portion, and has a substantially T shape in plan view (see FIG. 2) and a substantially S shape in side view (see FIG. 3). . A first portion of one connection conductor 11 connects the terminal 72a of the capacitor C11 and the terminal 72b of the capacitor C14. The second portion of the connection conductor 11 is fixed to the electrode 31 b of the IGBT module 31. The first portion of the other connecting conductor 11 connects the terminal 72a of the capacitor C16 and the terminal 72b of the capacitor C13. The second portion of the connection conductor 11 is fixed to the electrode 31 a of the IGBT module 31. The first capacitor group and the second capacitor group are connected in parallel by two connection conductors 11. A snubber circuit C1 (see FIG. 1) is obtained by connecting the first capacitor group and the second capacitor group with two connection conductors 11. As shown in FIG. 2, the snubber circuit C1 is also substantially U-shaped in plan view. In addition, the shape of the connection conductors 11-13 is not limited to what was mentioned above.

  The IGBT modules 31 to 33 are modules each including an IGBT and a free-wheeling diode connected in reverse parallel to the IGBT. The IGBT module 31 includes two IGBTs and corresponds to the switching elements S1 and S4 and the free wheel diode shown in FIG. The IGBT module 32 includes one IGBT and corresponds to the switching element S8 and the free wheel diode shown in FIG. The IGBT module 33 includes one IGBT and corresponds to the switching element S7 and the free wheel diode shown in FIG.

  Each electrode of the IGBT modules 31 to 33 is provided on one surface (the surface on the positive side of the Z axis in FIGS. 2 and 3). Below, the said surface is described as an "electrode formation surface." In FIG. 2, only the electrodes necessary for explaining the present invention are shown, and the other electrodes are not shown. The IGBT module 31 is provided with an electrode 31a and an electrode 31b. The electrode 31a is a positive electrode connected to the collector terminal of the IGBT corresponding to the switching element S1 in FIG. The electrode 31b is a negative electrode connected to the emitter terminal of the IGBT corresponding to the switching element S4 of FIG. A second portion of the connection conductor 11 is fixed to the electrodes 31a and 31b with screws.

  The heat sink 5 is fixed to the back surface of the electrode forming surface of the IGBT modules 31 to 33 (the surface on the negative side of the Z axis in FIG. 3 and hereinafter referred to as “heat dissipating surface”) (see FIG. 3). . The heat sink 5 releases heat generated by the IGBT modules 31 to 33.

  The heat insulating plate 2 is for cutting off the heat released from the IGBT modules 31 to 33, and in this embodiment, a phenol resin plate is used. In addition, the material of the heat insulation board 2 is not restricted to this. For example, any other synthetic resin, glass, glass epoxy, paper phenol, or the like having low thermal conductivity may be used. The heat insulating plate 2 is a substantially rectangular plate having the same size as the plan view of the snubber circuit C1 including the capacitors C11 to C16 and the connecting conductors 11 to 13. The heat insulating plate 2 is fixed to the back surfaces of the connection conductors 11 to 13 (the surface on the negative direction side of the Z axis in FIG. 3), that is, the back surface of the snubber circuit C1. In addition, the heat insulation board 2 will not be limited to the shape mentioned above, if the heat discharge | released from IGBT module 31-33 can be interrupted | blocked. Moreover, if the heat insulation board 2 is directly fixed to the back surface of each connection conductor 11-13, it is necessary to use an insulator.

  The fixing member 6 is for fixing the snubber circuit C1 to the heat sink 5. In this embodiment, the fixing member 6 is made of iron. The material of the fixing member 6 is not limited to this, and only needs to have a certain level of strength. The fixing member 6 has a substantially rectangular first portion (see FIG. 2) that is long in the Y-axis direction and has screw holes in the vicinity of both ends, and a long side of the first portion in the positive direction of the X-axis. A substantially rectangular second portion that extends in the negative direction of the Z-axis from the end of the second portion, and a substantially rectangular third portion that is provided with a screw hole for fixing to the heat sink 5 near the tip. (See FIG. 3), and has a substantially T shape in plan view (see FIG. 2) and a substantially T shape in side view (see FIG. 3). The shape of the fixing member 6 is not limited to this. The first portion of the fixing member 6 is fixed to the fixing portions 73 of the capacitors C12 and C15 with screws. The third portion of the fixing member 6 is fixed to the heat sink 5 with screws. In addition, the fixing place of the fixing member 6 is not limited to this. Since the snubber circuit C1 is fixed to the heat sink 5 by the fixing member 6, the burden on the connection conductor 11, the electrode 31a, and the electrode 31b connecting the snubber circuit C1 and the IGBT module 31 can be reduced. Moreover, by fixing with the connection conductor 11 and the fixing member 6, the heat insulation board 2 and the IGBT modules 31-33 can be kept substantially parallel with a predetermined space | interval. In addition, when the strength of the connection conductor 11 is strong, the fixing member 6 may not be provided.

  Next, a method for manufacturing the inverter circuit will be described. 5 and 6 are diagrams for explaining a method of manufacturing the inverter circuit, and show a process of assembling the U-phase circuit A. FIG.

  First, as shown in FIG. 5A, the snubber circuit C1 is assembled by fixing the capacitors C11 to C16 and the connection conductors 11 to 13 with screws. The left figure is a plan view similar to FIG. 2, and the right figure is a side view similar to FIG. The same applies to FIGS. 5B and 5C below.

  Next, as shown in FIG.5 (b), the heat insulation board 2 is fixed to the back surface of the snubber circuit C1. The heat insulating plate 2 may be fixed to the back surfaces of the connection conductors 11 to 13 with an adhesive, or may be fixed with screws for fixing the capacitors C11 to C16 and the connection conductors 11 to 13.

  Next, as shown in FIG.5 (c), the 1st part of the fixing member 6 is fixed to the fixing | fixed part 73 of the capacitors C12 and C15 with a screw.

  Next, as shown in FIG. 6A, the screw is fixed to the electrode 31 a (and 31 b) of the IGBT module 31 through the hole of the second portion of each connection conductor 11, whereby the snubber circuit C <b> 1 is connected to the IGBT module. Fix to 31. The IGBT modules 31 to 33 are fixed to the heat sink 5 in advance. And as shown in FIG.6 (b), the U-phase circuit A of an inverter circuit is completed by fixing the 3rd part of the fixing member 6 to the heat sink 5. FIG. Each drawing of FIG. 6 is a side view similar to FIG.

  The V-phase circuit and the W-phase circuit are also assembled in the same manner as the U-phase circuit A. The U-phase circuit A, V-phase circuit, and W-phase circuit are fixed to the casing of the power conditioner so that the positive direction of the Y-axis is on the top. A discharge fan is provided above the casing of the power conditioner. Thereby, the flow of the air to the positive direction of a Y-axis can be produced (refer the broken-line arrow of FIG. 3).

  Next, the effect of this embodiment is demonstrated.

  According to the present embodiment, in the snubber circuit C1, the capacitors C11 to C16 and the connection conductors 11 to 13 are connected so as to have a substantially U shape in plan view, and the two connection conductors 11 serving as connection terminals of the snubber circuit C1. These second portions are both located on the positive side of the Y axis (see FIG. 2). Therefore, the connection terminal of the snubber circuit C1 can be directly connected to the electrode 31a and the electrode 31b provided on the electrode forming surface of the IGBT module 31. Thereby, the connection conductor which connects snubber circuit C1 and IGBT module 31 can be shortened, and a parasitic inductance can be reduced.

Moreover, according to this embodiment, the heat insulation board 2 is arrange | positioned between the snubber circuit C1 and IGBT modules 31-33. Therefore, the heat radiated from the IGBT modules 31 to 33 can be blocked by the heat insulating plate 2 (see the thick arrow in FIG. 3), and the radiant heat transmitted to the snubber circuit C1 can be reduced. Further, the heat insulating plate 2 can divide the air flow into a flow passing between the heat insulating plate 2 and the IGBT modules 31 to 33 and a flow passing through the snubber circuit C1 (see the broken line arrow in FIG. 3). Therefore, it is possible to suppress the air warmed by the heat released from the IGBT modules 31 to 33 from flowing toward the snubber circuit C1, and to reduce the convective heat transmitted to the snubber circuit C1. As a result, the temperature rise of the snubber circuit C1 can be suppressed.

  Furthermore, according to the present embodiment, even if the number of capacitors included in the snubber circuit C1 is large in order to increase the capacitance, the snubber circuit C1 is arranged so as to have a substantially U shape in plan view. Can be reduced. Further, since the snubber circuit C1 can be arranged close to the IGBT modules 31 to 33, the arrangement space can be reduced. As a result, the power conditioner can be reduced in size.

  In addition, according to the present embodiment, the connecting conductor 11 also has a fixing member that fixes the snubber circuit C1 and the IGBT module 31 in a predetermined positional relationship at the same time that the snubber circuit C1 and the IGBT module 31 are electrically connected. Also serves as. Moreover, it also serves as a fixing member for fixing the heat insulating plate 2. Therefore, it is possible to reduce the number of components and facilitate the assembly work (see FIGS. 5 and 6).

  In addition, although the said 1st Embodiment demonstrated the case where the snubber circuit C1 connected six capacitors C11-C16 by 3 series 2 parallel, it is not restricted to this. For example, as shown in FIG. 7A, in the snubber circuit C1, capacitors C11 and C13 are connected by a connection conductor 12 ′ without providing capacitors C12 and C15, and capacitors C14 and C16 are connected by a connection conductor 13 ′. It is good also as a 2 series 2 parallel circuit connected by. Further, as shown in FIG. 7B, a capacitor C11 ′ is provided between the capacitors C11 and C12, a capacitor C13 ′ is provided between the capacitors C12 and C13, and a capacitor C14 is provided between the capacitors C14 and C15. 'And a capacitor C16' may be provided between the capacitors C15 and C16 to form a 5 series 2 parallel circuit. Further, the number of series may be further increased, or the number of parallel may be increased.

  Although the case where the inverter circuit is a three-phase three-level inverter circuit has been described in the first embodiment, the present invention is not limited to this. The inverter circuit may be a multi-level inverter circuit having four or more levels, or a two-level inverter circuit. Moreover, a single phase inverter circuit may be sufficient. In the case of a single-phase inverter circuit, two circuits similar to the U-phase circuit A shown in FIGS. 2 and 3 may be provided.

  In the said 1st Embodiment, although the case where an inverter circuit was used for the power conditioner was demonstrated, it is not restricted to this. The inverter circuit according to the first embodiment can be used for, for example, a power supply device such as a welding power supply device, an electromagnetic induction heater, or the like.

  Although the inverter circuit has been described in the first embodiment, the present invention is not limited to this. The present invention can also be applied to a power conversion circuit including a switching element and a snubber circuit, such as a converter circuit and a DC / DC converter circuit.

  The power conversion circuit, the manufacturing method thereof, and the power conditioner according to the present invention are not limited to the above-described embodiments. The specific configuration of each part of the power conversion circuit, the manufacturing method thereof, and the power conditioner according to the present invention can be changed in various ways.

A U phase circuit S1 to S12 Switching element Cp, Cn Voltage dividing capacitor C1 to C3 Snubber circuit C11 to C16, C11 ′, C13 ′, C14 ′, C16 ′ Capacitor 71 Main body 72a, 72b Terminal 73 Fixed portion 11-13, 12 ', 13' Connection conductor 2 Heat insulation plate 31-33 IGBT module (switching module)
31a, 31b Electrode 5 Heat sink 6 Fixing member

Claims (7)

A switching module having a switching element, wherein the positive electrode and the negative electrode are provided on the same surface;
A snubber circuit including a capacitor group in which a plurality of capacitors are connected in series by a plurality of conductor plates and formed in a substantially U shape in plan view ;
Equipped with a,
Before SL snubber circuit is arranged the on the side where the electrodes are provided in the switching module,
One terminal of the snubber circuit is directly connected to the positive electrode, and the other terminal is directly connected to the negative electrode.
It further comprises a heat insulating plate disposed between the switching module and the snubber circuit,
A power conversion circuit characterized by that. The heat insulating plate is fixed to the snubber circuit;
The power conversion circuit according to claim 1.   3. The power conversion circuit according to claim 1, wherein the heat insulating plate has a size approximately equal to a size of the capacitor group in plan view. The heat insulating plate is a phenol resin plate,
The power conversion circuit according to claim 1. The capacitor group is a parallel connection of two capacitors connected in series.
The power conversion circuit according to claim 1.   A power conditioner comprising the power conversion circuit according to claim 1. A method for manufacturing a power conversion circuit, comprising:
A first step of connecting a plurality of capacitors in series by a plurality of conductor plates so that the connected capacitor group is substantially U-shaped in plan view;
A second step of fixing a heat insulating plate to the back surface of the snubber circuit including the capacitor group;
A switching module having a switching element, in which the positive electrode and the negative electrode are provided on the same surface, the surface on which each electrode is provided facing the snubber circuit side, and the back surface side of the snubber circuit The snubber circuit is fixed by directly connecting one terminal of the snubber circuit to the positive electrode and connecting the other terminal directly to the negative electrode so as to leave a predetermined space between the heat insulating plate and the heat insulating plate. A third step;
A manufacturing method comprising:

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