JP5328706B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device using a semiconductor switching element.

  Generally, in a power converter using a semiconductor switching element, the wiring inductance between the capacitor and each semiconductor switching element is reduced from the viewpoint of increasing the power factor of the load and suppressing the occurrence of circuit surge voltage. Is required.

  For example, in the power conversion device disclosed in Patent Document 1 below, in order to reduce the wiring inductance, the sum of the distances of the plurality of forward paths to the capacitor as the current path and the sum of the distances of the plurality of return paths are substantially equal. The forward path and the return path are each composed of one conductive plate so that the directions are reversed.

JP 2007-228639 A

  However, in the conventional power conversion device, although the wiring inductance can be reduced, when the number of parallel semiconductor switching elements increases, the area of each of the conductor plates on the forward path and the return path increases, and the device becomes larger and the thin plate is thin. It is also difficult to manufacture the conductor plate.

  Then, an object of this invention is to provide the power converter device which can implement | achieve size reduction, aiming at reduction of wiring inductance in view of the said situation.

In order to solve the above-described problem, a power converter according to a first aspect of the present invention includes a plurality of first leg circuits in which two arms each having one or more semiconductor switching elements connected in series are connected in series, and two arms. The same number of second leg circuits connected in series as the first leg circuit, the plurality of first leg circuits as a first phase, and the plurality of second leg circuits as a second phase, a single-phase full bridge In the connected power converter,
Each number said that the ring has been a two-parallel configuration plurality of first leg circuit (first, second) and each numbering has been two parallel corresponding to said plurality of first leg circuit The plurality of second leg circuits (first and second ) having a configuration is an arbitrary natural number n (where n is n ≦ 2 ),
The upper arm of the (2n-1) -th first leg circuit and the lower arm of the (2n-1) -th second leg circuit have a current path that is plane-symmetric and the direction of the current is reversed. The lower arm of the (2n-1) th first leg circuit and the upper arm of the (2n-1) th second leg circuit have a current path that is plane-symmetric and the direction of the current is reversed. Thus, the (2n-1) th first leg circuit is arranged on the surface of the symmetry plane, and the (2n-1) th second leg circuit is arranged on the back surface of the symmetry plane,
The upper arm of the 2n-th first leg circuit and the lower arm of the 2n-th second leg circuit have a current path that is plane-symmetric and the direction of the current is reversed, and the 2n-th first leg circuit The 2n-th first leg circuit is connected to the plane of symmetry so that the current path is plane-symmetric and the direction of the current is reverse to the lower arm and the upper arm of the 2n-th second leg circuit. The 2n-th second leg circuit is arranged on the surface of the symmetry plane on the back surface.

  According to the power conversion device of the first aspect of the present invention, even in the case of an even array configuration (2-parallel, 4-parallel,... 2m parallel configuration), one or more first leg circuits and second leg circuits satisfy the following conditions: Each element is arrange | positioned so that it may satisfy | fill.

  In other words, the current path of the upper arm of the first leg circuit and the lower arm of the second leg circuit associated by numbering are symmetrical with respect to the current path, and the direction of the current is reversed. The arm and the upper arm of the second leg circuit associated with each other by the number ring are arranged on the front side and the back side of the symmetry plane so that the current path is plane-symmetric and the direction of the current is opposite.

  Further, in the first leg circuit and the second leg circuit that are numbered in the first leg circuit and the second leg circuit corresponding to the first leg circuit, the current path is reversed with the front and back reversed. The upper arm and the lower arm are arranged on the back surface and the front surface of the symmetrical surface so as to be symmetric and the direction of the current is reversed.

  Thus, by arranging the upper arm and the lower arm so that the current path is plane-symmetric and the direction of the current is opposite, the mutual inductance between the semiconductor switching element and the wiring conductor connecting them is negative. As a result, the wiring inductance can be reduced.

  Further, the semiconductor switching elements and the wiring conductors connecting them can be distributed and arranged on the front and back surfaces of the symmetry plane, and the device can be miniaturized. In addition, the area of the wiring conductor plate (bus bar) that is the wiring conductor can be reduced, and the workability of the wiring conductor plate can also be improved.

In the case of an odd array configuration (3 parallels, 5 parallels,... (2m + 1) parallel configuration), the current path is plane-symmetric and the direction of the current is reverse as in the power converter of the first invention. By arranging the upper arm and the lower arm in such a manner, it is possible to reduce the wiring inductance by making the mutual inductance between the semiconductor switching element and the wiring conductor connecting them negative.

  Further, the semiconductor switching elements and the wiring conductors connecting them can be distributed and arranged on the front and back surfaces of the symmetry plane, and the device can be miniaturized. In addition, the area of the wiring conductor plate (bus bar) that is the wiring conductor can be reduced, and the workability of the wiring conductor plate can also be improved.

Power converter of the second aspect, in the first shot Akira,
In the first leg circuit and the second leg circuit associated by numbering, an upper arm of the first leg circuit and a lower arm of the second leg circuit are arranged with a cooler interposed therebetween. The lower arm of the first leg circuit and the upper arm of the second leg circuit are arranged with the cooler interposed therebetween.

According to the power conversion device of the second invention, by arranging the upper and lower arms of the first leg circuit and the second leg circuit associated by numbering with the cooler interposed therebetween, the elements constituting the leg circuit It is possible to reduce the size of the apparatus by spatially consolidating the coolers, and to solve the heat dissipation that becomes a problem when the size of the apparatus is further reduced.

The power converter of the third invention is either the first or second invention,
The upper arms of the plurality of first leg circuits have the same length of each current path from the DC conductor to the load via the upper arm, and the lower arms of the plurality of first leg circuits are The length of each current path from the load to the DC conductor via the lower arm is the same,
The upper arms of the plurality of second leg circuits have the same length of each current path from the DC conductor to the load via the upper arm, and the lower arms of the plurality of second leg circuits are The length of each current path from the load to the DC conductor via the lower arm is the same.

According to the power conversion device of the third invention, the first leg circuit has the same plurality of current paths that reach the load via the upper arm, and does not cause current imbalance among the plurality of paths. . Similarly, in the first leg circuit, the plurality of current paths from the load to the DC conductor via the lower arm are all the same, and current imbalance does not occur between the plurality of paths.

  The same applies to the second leg circuit. That is, a plurality of current paths that reach the load via the upper arm of the second leg circuit are all the same, and current imbalance does not occur. Further, the plurality of current paths from the load to the DC conductor via the lower arm are all the same, and current imbalance does not occur. Therefore, it is possible to prevent an excessive current from flowing through a specific element while reducing the wiring inductance as described above.

In addition, as a supplement, the power converters according to the first to third inventions have excellent operational effects in the following respects as compared with the conventional power converters.

  First, in the conventional power conversion device, as the number of parallel semiconductor switching elements such as IGBTs increases, the area of the forward and return conductor plates increases, and insulation from the terminals of the semiconductor switching elements that are vacant in the conductor plates occurs. Although the number of opening holes for securing the distance increases, the power converter according to the present invention does not need an opening hole because the conductor plate connected to the terminal of the element is configured independently and in the same shape. There is no difference in the current density of each arm, and local heating does not occur.

  Further, in the conventional power converter, each of the parallel plate conductors of the forward path and the return path is composed of one sheet and is connected to the terminals of all the semiconductor switching elements. In the present invention, it is necessary to disconnect all elements connected to the parallel plate conductors. The situation can be avoided and good maintainability can be realized.

The circuit diagram of the power converter of this embodiment. Explanatory drawing which shows arrangement | positioning of the element of the power converter device of FIG. Sectional drawing cut | disconnected by the III-III line | wire of FIG. Explanatory drawing which shows the electric current path in a steady state. An explanatory view showing a current course at the time of commutation.

  With reference to FIG. 1, the power converter device of this embodiment is demonstrated. A power converter is used for an induction heating device, an induction melting furnace, etc., for example.

  Specifically, the power converter includes a power source 1, a three-phase forward converter 2, a DC reactor 3, an inverse converter 4, a power factor improving capacitor 11 (corresponding to the capacitor of the present invention), heating, and the like. A coil 12.

  The power source 1 is a commercial frequency AC power source and is connected to the three-phase forward converter 2.

  The three-phase forward converter 2 is a circuit that converts AC power of the power source 1 into DC power, and specifically includes a thyristor or the like.

  The DC reactor 3 removes a ripple component of the DC voltage generated by the three-phase forward converter 2 and causes a sudden overcurrent that may occur when the inverse converter 4, the power factor improving capacitor 11, and the heating coil 12 are damaged. Increase.

  The inverse converter 4 is configured by a plurality of inverse conversion stacks 41 to 44 (leg circuit of the present invention), converts the DC power converted by the three-phase forward converter 2 into AC power, and moves to the heating coil 12 side. Output. Details of the inverse converter 4 will be described later.

  The wiring inductance 9 is an inductance generated between the inverse converter 4 and the power factor improving capacitor 11.

  The power factor improving capacitor 11 is a capacitor for improving the delay power factor of the heating coil 12 to a leading power factor.

  The heating coil 12, for example, puts a metal material such as iron into a furnace around which the coil 12 is wound and supplies high frequency power from the inverse converter 4, thereby generating an eddy current in the metal material in the furnace. Thus, the metal material is heated and dissolved by Joule heat.

  Next, the configuration of the inverse converter 4 that will be described later will be described.

  The reverse conversion stack 41 constituting the reverse converter 4 includes an upper arm composed of an IGBT 45a (insulated gate bipolar transistor) as a semiconductor switching element and a reverse blocking diode 51 connected in series by a wiring conductor 61, and an IGBT 45b. And a lower arm constituted by connecting the reverse blocking diode 55 in series with a wiring conductor 65 and connected in series with a wiring conductor 71. The first leg circuit of the present invention (more precisely, the first Corresponds to the first first leg circuit).

  Similarly, the reverse conversion stack 42 includes an upper arm composed of an IGBT 46a and a reverse blocking diode 52 connected in series by a wiring conductor 62, and an IGBT 46b and a reverse blocking diode 56 connected in series by a wiring conductor 66. The lower arm to be configured is connected in series by a wiring conductor 72, and corresponds to a first leg circuit (second first leg circuit).

  The reverse conversion stack 43 is composed of an upper arm composed of an IGBT 47a and a reverse blocking diode 53 connected in series by a wiring conductor 63, and an IGBT 47b and a reverse blocking diode 57 connected in series by a wiring conductor 67. The lower arm is connected in series with the wiring conductor 73, and corresponds to a second leg circuit (more precisely, the first second leg circuit) paired with the inverse conversion stack 41. The pair of inverse transform stacks will be described later.

  The reverse conversion stack 44 is composed of an upper arm composed of an IGBT 48a and a reverse blocking diode 54 connected in series by a wiring conductor 64, and an IGBT 48b and a reverse blocking diode 58 connected in series by a wiring conductor 68. The lower arm is connected in series by the wiring conductor 74, and corresponds to a second leg circuit (second second leg circuit) paired with the inverse conversion stack.

  These reverse conversion stacks 41 to 44 are connected to one end of the heating coil 12 and the capacitor 11 as a U-phase (first phase) of single-phase alternating current between the upper arm and the lower arm of the reverse conversion stacks 41 and 42. A single-phase full connected to one end of the heating coil 12 and the capacitor 11 as a V-phase (second phase) of a single-phase alternating current between the upper arm and the lower arm of the reverse transformation stacks 43 and 44. It has a bridge configuration.

  With reference to FIG. 2, the arrangement | positioning of the element of these inverse transformation stacks 41-44 is demonstrated. FIG. 2 is an external view of the inverse converter 4 viewed from the front (corresponding to the surface of the symmetric surface of the present invention) on the left side, and viewed from the back (corresponding to the back surface of the symmetric surface of the present invention). It is an outline drawing.

  The inverse transformation stack 41 (first first leg circuit) is arranged on the front side (left side in the figure), and the inverse transformation stack 43 (first second leg circuit) is arranged on the back side (right side in the figure). In addition, the current paths are arranged in plane symmetry and the direction of the current is reversed, and the inverse transformation stack 41 and the inverse transformation stack 43 are paired.

  The inverse transformation stack 42 (second first leg circuit) is arranged on the back side (right side in the figure), and the inverse transformation stack 44 (second second leg circuit) is arranged on the front side (in the figure). On the left side, the current path is symmetrical and the direction of the current is reversed, and the inverse transformation stack 42 and the inverse transformation stack 44 are paired.

  Supplementally, the inverse transformation stacks 41 and 42 corresponding to a plurality of first leg circuits are distinguished by numbering such as first and second, and are paired in a form corresponding to this numbering. Numbering is given to the inverse transformation stacks 43 and 44 corresponding to a plurality of second leg circuits.

  Next, a specific configuration of each of the inverse transform stacks 41 to 44 will be described.

  First, the first inverse transformation stack 41 and the inverse transformation stack 43 of the numbering ring are the IGBTs 45a and 45b that constitute the inverse transformation stack 41, and the IGBTs 47b and 47a that constitute the inverse transformation stack 43. Placed in. Further, reverse blocking diodes 51 and 55 constituting the reverse conversion stack 41 and reverse blocking diodes 57 and 53 constituting the reverse conversion stack 43 are arranged on the front side and the back side. Further, the connection conductors 61 and 65 for connecting elements in the inverse conversion stack 41, the P-side DC conductor 5 on the DC side (input side), the U-phase AC conductor 7 on the AC side (output side), and the inverse conversion stack 43 The connection conductors 67 and 63 for connecting the elements, the N-side DC conductor 6 on the DC side, and the V-phase AC conductor 8 on the AC side are arranged on the front side and the back side.

  In addition, the second inverse transformation stack 42 and the inverse transformation stack 44 of the numbering ring are the IGBTs 48a and 48b constituting the inverse transformation stack 44 and the IGBTs 46b and 46a constituting the inverse transformation stack 42 on the front side and the rear side. Placed in. Further, reverse blocking diodes 54 and 58 constituting the reverse conversion stack 44 and reverse blocking diodes 56 and 52 constituting the reverse conversion stack 42 are arranged on the front side and the back side. Further, the connection conductors 64 and 68 for connecting the elements in the inverse conversion stack 44, the P-side DC conductor 5 on the DC side, and the V-phase AC conductor 8 on the AC side, and the connections for connecting the elements in the inverse conversion stack 42 The conductors 66 and 62, the N-side DC conductor 6 on the DC side, and the U-phase AC conductor 7 on the AC side are arranged on the front side and the back side.

  With reference to FIG. 3, the arrangement of the elements of the inverse transformation stacks 41 to 44 on the front side and the back side will be described supplementarily.

  On both sides of the inverse converter 4, a P-side DC conductor 5 on the DC side (input side) and an N-side DC conductor 6 are arranged above and below with different polarities. In addition, an AC side (output side) U-phase AC conductor branching upward and downward from one end (left side in the figure) to the center of the inverse converter 4 and extending to the center of the inverse converter 4. 7 and the V-phase AC conductor 8 are arranged, and the elements constituting the inverse conversion stacks 41 to 44 are sandwiched between the conductors 5, 7 and 6, 8 with the flat plate cooler 13 interposed therebetween. Arranged back to back.

  Supplementally, as described in FIG. 2, the combination of the elements arranged back to back is the elements of the inverse transformation stacks 41 and 43, and 42 and 44 that form a pair. Corresponds to the plane of symmetry.

  Further, an insulating plate (not shown) is inserted between the P-side DC conductor 5 on the DC side (input side) and the N-side DC conductor 6, and similarly, the U-phase AC conductor on the AC side (output side). An insulating plate (not shown) is inserted between 7 and the V-phase AC conductor 8.

  In this way, the elements of the inverse conversion stacks 41 and 43 and 42 and 44 that make a pair can be distributed and arranged on the front side and the back side, and the elements and coolers can be spatially concentrated to reduce the size of the device. Can be achieved. Further, by using a common cooler for the reverse conversion stacks 41 and 43 and 42 and 44 that make a pair, it is possible to improve the cooling efficiency and reduce the number of parts.

  Next, an example of a current path in a steady state will be described with reference to FIG.

  FIG. 4 is a path in a period in which the IGBT 45a of the inverse transformation stack 41 and the IGBT 46a of the inverse transformation stack 42, the IGBT 47b of the inverse transformation stack 43, and the IGBT 48b of the inverse transformation stack 44 are ON, and the DC side (input side) ) Through the U-phase AC conductor 7, the output-side power factor improving capacitor 11, and the heating coil 12 to return from the V-phase AC conductor 8 to the N-side DC conductor 6. The current path in the steady state changes every half cycle according to ON / OFF of the IGBTs 45a, 45b to 48a, 48b of the inverse conversion stacks 41 to 44.

  More specifically, as shown in FIG. 4A, the steady-state current path is a current path that reaches the U-phase AC conductor 7 via the upper arms of the inverse conversion stacks 41 and 42 that are the first leg circuits. A and B, and current paths C and D that return from the V-phase AC conductor 8 to the N-side DC conductor 6 via the lower arms of the inverse conversion stacks 43 and 44 that are the second leg circuits.

  Here, the current paths A and B have the same path length as shown in FIG. Further, the elements existing on the current paths A and B are the same. The same applies to the current paths C and D, the path lengths of the current paths C and D are the same, and the elements existing on the paths are also the same.

  In this way, by making the path lengths of the current paths A and B the same and the path lengths of the current paths C and D the same, it is possible to avoid the occurrence of current imbalance between them. It is possible to prevent an excessive current from flowing through.

  Further, in this case, in the inverse transformation stacks 41 and 43, 42, and 44 that make a pair, the current paths are plane-symmetrical on the front side and the back side.

  More specifically, in the inverse transformation stacks 41 and 43 that make a pair, the current path A and the current path C are plane-symmetrical on the front side and the back side, and the direction of the current is reversed.

  This is the same for the pair of inverse transformation stacks 42 and 44. The current path B and the current path D are symmetrical with respect to the back side and the front side, and the direction of the current is reversed.

  In this way, the IGBTs 45a, 45b to 48a, 48b and these are connected by arranging the current paths of the paired inverse transformation stacks 41 and 43, 42 and 44 so that the current paths are symmetrical and the directions of the currents are reversed. The wiring inductance can be reduced by setting the mutual inductance between the wiring conductors 61 to 68 to be negative.

  Next, an example of a current path at the time of commutation will be described with reference to FIG.

  FIG. 5 shows a transient state due to the load voltage when the IGBT 45b of the reverse conversion stack 41 and the IGBT 46b of the reverse conversion stack 42, and the IGBT 47a of the reverse conversion stack 43 and the IGBT 48a of the reverse conversion stack 44 are turned on from the state of FIG. Shows the path of commutation.

  More specifically, as shown in FIG. 5A, first, the commutation path here is a commutation path X from the upper arm of the inverse conversion stack 41 to the upper arm of the inverse conversion stack 44. And the commutation path Y from the upper arm of the reverse conversion stack 42 to the upper arm of the reverse conversion stack 43. Second, the commutation path Z from the lower arm of the reverse conversion stack 44 to the lower arm of the reverse conversion stack 41, and the commutation path from the lower arm of the reverse conversion stack 43 to the lower arm of the reverse conversion stack 42 There is W.

  Here, as shown in FIG. 5B, the commutation paths X and W are structurally opposite in both sections, and the direction of the commutation path is reversed in all sections. The same applies to the commutation paths Y and Z. In all the sections, both paths are structurally opposite and the directions of the commutation paths are reversed. Therefore, as in the case of the steady state described above, it is possible to reduce the wiring inductance by setting the mutual inductance between the IGBTs 45a, 45b to 48a, 48b and the wiring conductors 61 to 68 connecting them as negative.

  Further, the commutation paths X and Y have the same path length as shown in FIG. Therefore, it is possible to avoid the occurrence of current imbalance between them, and it is possible to prevent an excessive current from flowing through a specific element. This is also true for the commutation paths Z and W. These path lengths are the same, and it is possible to avoid the occurrence of current imbalance and to prevent an excessive current from flowing through a specific element. can do.

  As described above in detail, according to the configuration of the inverter 4 of the power conversion device of the present embodiment, it is possible to reduce the size of the device while reducing the wiring inductance and the current imbalance.

  Moreover, according to the power converter device of this embodiment, the area of a wiring conductor board (bus bar) can be made small and the workability of a wiring conductor board can also be improved.

  Note that the inverse converter 4 of the present embodiment has a two parallel configuration including two inverse conversion stacks 41 and 42 corresponding to the first leg circuit and two inverse conversion stacks 43 and 44 corresponding to the second leg circuit. However, the present invention is not limited to this, and may be a 4-parallel, 2m even-numbered parallel configuration, or a 3-parallel, 5-parallel, ... (2m + 1) odd-numbered array configuration.

1 ... Power (commercial AC power supply), 2 ... three-phase forward converter, 3 ... DC reactor, 4 ... inverse transformer, 9 ... wiring inductance, 11 ... Power factor improving capacitor, 12 ... heating coil, 13 ... cooler , 41 ... inverse transform stack (the first first-leg circuit), 42 ... inverse transform stack (the second first-leg circuit) 43 ... inverse transform stack (the first second-leg circuit), 44 ... Inverse conversion stack (second second leg circuit), 45a to 48a, 45b to 48b... IGBT (semiconductor switching element), 51 to 58... Reverse blocking diode (diode).

Claims (3)

A plurality of first leg circuits in which two arms each having one or more semiconductor switching elements connected in series are connected in series, and the same number of second legs as the first leg circuits in which two arms are connected in series. In a power conversion device in which a plurality of first leg circuits are used as a first phase and a plurality of second leg circuits are used as a second phase in a single-phase full-bridge connection,
Each number said that the ring has been a two-parallel configuration plurality of first leg circuit (first, second) and each numbering has been two parallel corresponding to said plurality of first leg circuit The plurality of second leg circuits (first and second ) having a configuration is an arbitrary natural number n (where n is n ≦ 2 ),
The upper arm of the (2n-1) -th first leg circuit and the lower arm of the (2n-1) -th second leg circuit have a current path that is plane-symmetric and the direction of the current is reversed. The lower arm of the (2n-1) th first leg circuit and the upper arm of the (2n-1) th second leg circuit have a current path that is plane-symmetric and the direction of the current is reversed. Thus, the (2n-1) th first leg circuit is arranged on the surface of the symmetry plane, and the (2n-1) th second leg circuit is arranged on the back surface of the symmetry plane,
The upper arm of the 2n-th first leg circuit and the lower arm of the 2n-th second leg circuit have a current path that is plane-symmetric and the direction of the current is reversed, and the 2n-th first leg circuit The 2n-th first leg circuit is connected to the plane of symmetry so that the current path is plane-symmetric and the direction of the current is reverse to the lower arm and the upper arm of the 2n-th second leg circuit. A power conversion device, wherein the 2n-th second leg circuit is disposed on the surface of a symmetry plane on the back surface. The power converter of claim 1 Symbol placement,
In the first leg circuit and the second leg circuit associated by numbering, an upper arm of the first leg circuit and a lower arm of the second leg circuit are arranged with a cooler interposed therebetween. The power conversion device, wherein a lower arm of the first leg circuit and an upper arm of the second leg circuit are arranged with the cooler interposed therebetween. The power conversion device according to claim 1 or 2 ,
The upper arms of the plurality of first leg circuits have the same length of each current path from the DC conductor to the load via the upper arm, and the lower arms of the plurality of first leg circuits are The length of each current path from the load to the DC conductor via the lower arm is the same,
The upper arms of the plurality of second leg circuits have the same length of each current path from the DC conductor to the load via the upper arm, and the lower arms of the plurality of second leg circuits are A power conversion device characterized in that the length of each current path from the load to the DC conductor via the lower arm is the same.