JP2007006571A - Power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To equalize the duty of smoothing capacitors connected in parallel in a three level power converting circuit employing a series connection of two smoothing capacitor groups each consisting of a parallel connection of a plurality of smoothing capacitors. <P>SOLUTION: Smoothing capacitors 13a-13d are arranged substantially linearly in the X direction, and three terminals P, C and N of a three level power converting circuit are arranged at positions in the center. The power converter comprises a plurality of bus bars extending in the X direction, i.e. a P potential bus bar 21 connecting each positive electrode and P terminal of a first smoothing capacitor group 13x, and an N potential bus bar 22 connecting each negative electrode and N terminal of a second smoothing capacitor group 13y. Each negative electrode of the first smoothing capacitor group 13x and each positive electrode of the second smoothing capacitor group 13y are further provided with three C potential bus bars 23-25 connected, respectively, with two other bus bars and the C terminal wherein the impedances of a plurality of current passages passing respective smoothing capacitors 13a-13d connected in parallel are substantially equalized. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power conversion device including a three-level inverter or converter using a smoothing capacitor connected in parallel.

  In the conventional power conversion device, the electrode terminal of the smoothing capacitor applied to the three-level inverter device and the arrangement of the conductors connecting the same are provided with a plurality of positive electrode terminals, neutral electrode terminals, and negative electrode terminals. The positive electrode terminal and the neutral electrode terminal are alternately provided to form the first group, and one negative electrode terminal and the neutral electrode terminal are alternately provided to form the second group. Each positive electrode terminal is connected by a wide positive bus bar, each neutral electrode terminal is connected by a wide neutral electrode bus bar, and each negative electrode terminal is connected by a wide negative bus bar. In this way, the positive electrode terminal, the neutral electrode terminal, and the negative electrode terminal are arranged close to each other, and the overlapping area of the conductors whose current directions are opposite to each other is increased to reduce the floating inductance by the magnetic flux canceling effect (for example, Patent Document 1). reference).

JP 2001-238458 A

In the conventional power converter, the overlapping area of the conductors whose current directions are opposite to each other is increased, and the stray inductance is reduced by the magnetic flux canceling effect. Here, in order to prevent the current from being biased, one smoothing capacitor is used for each of the positive electrode side and the negative electrode side, and these are connected in series. However, the smoothing capacitor capacity required for a large-capacity power conversion device Therefore, two smoothing capacitor groups in which a plurality of smoothing capacitors are connected in parallel are used.
Moreover, in order to reduce the size of the power conversion device, the degree of freedom of arrangement of the smoothing capacitors connected in parallel is often limited, and it is difficult to make the parallel part a wiring with uniform impedance. As described above, there is a problem that when the impedance of the wirings in the parallel portion varies, the currents of the respective smoothing capacitors are not uniform, and the deterioration of the specific smoothing capacitor proceeds quickly.

  The present invention has been made to solve the above-described problems, and is a smoothing system in which a three-level power conversion circuit and two smoothing capacitor groups in which a plurality of smoothing capacitors are connected in parallel are connected in series. The capacitor circuit is connected in a layout suitable for miniaturization, the impedance of the wiring in the parallel part is made uniform, the duty of the smoothing capacitor connected in parallel is made equal, and the deterioration state of multiple smoothing capacitors is averaged, and the large An object of the present invention is to obtain a highly reliable power conversion device suitable for capacity and size reduction.

  According to a first aspect of the present invention, there is provided a power conversion device including a three-level power conversion circuit including four switching elements and two clamp diodes each having a freewheeling diode connected in antiparallel, and a plurality of smoothing circuits. A device configuration in which a first smoothing capacitor group configured by connecting capacitors in parallel and a smoothing capacitor circuit in which a second smoothing capacitor group is connected in series is connected by a wiring conductor, the first smoothing capacitor Each of the smoothing capacitors of the group and each of the smoothing capacitors of the second smoothing capacitor group are arranged substantially linearly in the X direction, and the first smoothing capacitor group and the second smoothing capacitor group at the position in the X direction. 3 terminals of the P potential, C potential, and N potential of the power conversion circuit are arranged at a central position between the two. A P-potential conductor connecting the positive electrode of each smoothing capacitor of the first smoothing capacitor group and the P-potential terminal, wherein the wiring conductor is a plurality of conductors extending in the X direction; An N potential conductor connecting the negative electrode of each smoothing capacitor of the second smoothing capacitor group and the N potential terminal; a first C potential conductor connected to the negative electrode of each smoothing capacitor of the first smoothing capacitor group; The second C potential conductor connected to the positive electrode of each smoothing capacitor of the second smoothing capacitor group, and the far end and one end of the first C potential conductor from the center position are connected, and A second C-potential conductor having a third C-potential conductor connected to the C-potential terminal connected to the C-potential terminal at the center-position, the far end and the other end being connected from the center position; The above connected in parallel through a conductor It is intended to substantially equal the impedance of the plurality of current paths through the smoothing capacitor.

  According to a second aspect of the present invention, there is provided a power conversion device including a three-level power conversion circuit including four switching elements and two clamp diodes each having a freewheeling diode connected in antiparallel, and a plurality of smoothing circuits. A device configuration in which a first smoothing capacitor group configured by connecting capacitors in parallel and a smoothing capacitor circuit in which a second smoothing capacitor group is connected in series is connected by a wiring conductor, the first smoothing capacitor Each of the smoothing capacitors of the group and each of the smoothing capacitors of the second smoothing capacitor group are arranged substantially linearly in the X direction, and the first smoothing capacitor group and the second smoothing capacitor group at the position in the X direction. 3 terminals of the P potential, C potential, and N potential of the power conversion circuit are arranged at a central position between the two. The wiring conductor is a plurality of conductors each extending in the X direction, the first P potential conductor connected to the positive electrode of each smoothing capacitor of the first smoothing capacitor group, and the first A second P potential conductor connecting the end portion far from the central position of the P potential conductor and the P potential terminal, and a first connected to the negative electrode of each smoothing capacitor of the second smoothing capacitor group. N potential conductors, a second N potential conductor connecting the end of the first N potential conductor far from the center position and the N potential terminal, and each smoothing capacitor group. Each smoothing capacitor including a negative electrode of a capacitor, a positive electrode of each smoothing capacitor of the second smoothing capacitor group, and a C potential conductor connected to the C potential terminal, and connected in parallel via the wiring conductor Multiple current paths through It is an almost equal to the impedance.

  According to a third aspect of the present invention, there is provided a power conversion device including a three-level power conversion circuit including four switching elements and two clamp diodes each having a freewheeling diode connected in antiparallel, and a plurality of smoothing circuits. A device configuration in which a first smoothing capacitor group configured by connecting capacitors in parallel and a smoothing capacitor circuit in which a second smoothing capacitor group is connected in series is connected by a wiring conductor, the first smoothing capacitor Each smoothing capacitor of the group and each smoothing capacitor of the second smoothing capacitor group are arranged substantially linearly in the X direction, and the power conversion is performed at one end position of the smoothing capacitor circuit in the X direction position. Three terminals of P potential, C potential, and N potential of the circuit are provided. A P-potential conductor connecting the positive electrode of each smoothing capacitor of the first smoothing capacitor group and the P-potential terminal, wherein the wiring conductor is a plurality of conductors extending in the X direction; An N potential conductor connecting the negative electrode of each smoothing capacitor of the second smoothing capacitor group and the N potential terminal; a first C potential conductor connected to the negative electrode of each smoothing capacitor of the first smoothing capacitor group; , A second C potential conductor connected to the positive electrode of each smoothing capacitor of the second smoothing capacitor group, and each end and one end of the first and second C potential conductors on the far side from the end position. And a third C potential conductor connected to the C potential terminal at the other end, and impedances of a plurality of current paths passing through the respective smoothing capacitors connected in parallel via the wiring conductor. Almost equal Is shall.

In the power conversion device according to the first aspect of the present invention, the impedances of the plurality of current paths passing through the smoothing capacitors connected in parallel can be reliably equalized, the duties of the plurality of smoothing capacitors are equalized, and the specific smoothing capacitor It is possible to prevent the current from concentrating on the terminal and deteriorating the deterioration. For this reason, a highly reliable power converter suitable for large capacity and miniaturization can be obtained.
In the power conversion device according to claim 2 of the present invention, the impedances of the plurality of current paths passing through the smoothing capacitors connected in parallel can be reliably equalized, the duties of the plurality of smoothing capacitors are equalized, and the specific smoothing capacitor It is possible to prevent the current from concentrating on the terminal and deteriorating the deterioration. For this reason, a highly reliable power converter suitable for large capacity and miniaturization can be obtained.
In the power conversion device according to claim 3 of the present invention, the impedances of the plurality of current paths passing through the smoothing capacitors connected in parallel can be reliably equalized, the duties of the plurality of smoothing capacitors are equalized, and the specific smoothing capacitor It is possible to prevent the current from concentrating on the terminal and deteriorating the deterioration. For this reason, a highly reliable power converter suitable for large capacity and miniaturization can be obtained.

Embodiment 1 FIG.
Hereinafter, a power converter according to Embodiment 1 of the present invention will be described with reference to the drawings.
1 is an external perspective view of a power conversion apparatus according to Embodiment 1 of the present invention.
As shown in the figure, a semiconductor stack unit 11 and a cooling device 12 for cooling the power module of the semiconductor stack unit 11 are provided. The semiconductor stack unit 11 includes a converter unit and an inverter unit (not shown), and the cooling device 12 includes, for example, a pump for sending cooling water to the semiconductor stack unit 11 for a water cooling system, a radiator for cooling the cooling water, and the like. I have. Further, the smoothing capacitors 13a to 13d are arranged substantially in a straight line. The terminals of the smoothing capacitors 13 a to 13 d are installed downward, wired by a bus bar 14 as a wiring conductor, and connected to the semiconductor stack portion 11.

  FIG. 2 is an external view of the bus bar 14 for connecting the smoothing capacitors 13a to 13d and an exploded view thereof. FIG. 3 is a diagram showing a circuit configuration of a power conversion device to which the bus bar 14 is applied. The converter unit 7 and the inverter unit 8 in the semiconductor stack unit 11 and the smoothing capacitor 3a (first smoothing capacitor 3a) shown in FIG. Capacitor group 13x) and smoothing capacitor 3b (second smoothing capacitor group 13y). By connecting the smoothing capacitor groups 3a and 3b in series, three potentials of P potential, C potential, and N potential are provided. The first smoothing capacitor group 13x is configured by connecting two smoothing capacitors 13a and 13b in parallel, and the second smoothing capacitor group 13y is configured by connecting two smoothing capacitors 13c and 13d in parallel.

  As shown in FIG. 2, the bus bar 14 is a stack of a P potential bus bar 21, an N potential bus bar 22, and first to third C potential bus bars 23 to 25 as a plurality of conductors. The conductor is laminated with an insulating film except for the connection portions with the other bus bars 21 to 25, and the other portions are insulated from each other. The protrusions of the bus bars 21 to 24 are portions that are bolted to the terminal portions of the smoothing capacitors 13a to 13d, and the protrusions are passed through the overlapping portions of the other bus bars 21 to 25 or bolted. Make a hole. The bus bars 21 to 25 extend in the linear arrangement direction of the smoothing capacitors 13 a to 13 d and overlap each other, and the P potential bus bar 21, the N potential bus bar 22, and the third C potential bus bar 25 are arranged at the center of the bus bar 14. In order to connect to the semiconductor stack portion 11 at a position, a P potential terminal connection portion 21a, an N potential terminal connection portion 22a, and a C potential terminal connection portion 25a extending in the direction of the semiconductor stack portion 11 are provided. Moreover, in order to supply electricity, the part which is not laminated with an insulating film is provided in the edge part of the 1st-3rd C electric potential bus bars 23-25, and it connects and fixes by means, such as bolting. As a result, the third C potential bus bar 25 is connected to the far end and one end of the first C potential bus bar 23 from the center position (connection position to the semiconductor stack portion 11) of the first C potential bus bar 23. The far side end and the other end are connected from the above-mentioned center position of 24.

  Details of the circuit configuration of the power conversion apparatus are shown below. As shown in FIG. 3, the smoothing capacitor groups 3a and 3b are connected in series to have three potentials of P potential, C potential, and N potential. That is, the potential on the positive electrode side (upper side in the figure) of the smoothing capacitor 3a is the P potential, the potential on the negative electrode side (lower side in the figure) of the smoothing capacitor 3a and the positive electrode side (upper side in the figure) of the smoothing capacitor 3b is the C potential. The potential on the negative electrode side (lower side in the figure) of the capacitor 3b is N potential. The converter unit 7 is a single-phase three-level converter as a three-level power converter, and first to fourth IGBTs each having a freewheeling diode connected in reverse parallel between the P potential unit and the N potential unit. Switching elements 1a to 1d, 1g to 1j are connected in series, the anode side is connected to the C potential section, and the cathode side is connected to the connection point of the first and second switching elements 1a, 1b, 1g, and 1h. A second clamp having the anode side connected to the connection point of the first clamp diodes 6a, 6c and the third and fourth switching elements 1c, 1d, 1i, 1j and the cathode side connected to the C potential portion. Diodes 6b and 6d are provided. The inverter unit 8 is a three-phase two-level inverter, and includes switching elements 2a to 2f such as six IGBTs each having a freewheeling diode connected in antiparallel. 4a and 4b are converter input terminals, 5a to 5c are inverter input terminals, and 6a to 6d are diodes. Moreover, each switching element 1a-1d, 1g-1j, 2a-2f comprises a power module with a freewheeling diode.

  The single-phase three-level converter 7 switches the P potential, C potential, and N potential to output a voltage, and the three-phase two-level inverter 8 switches the P potential and N potential to output a voltage. Here, the single-phase three-level converter 7 includes two sets of the first to fourth switching elements 1a to 1d, 1g to 1j and the first and second clamp diodes 6a, 6c, 6b, and 6d. One set may be used.

FIG. 4 is a diagram showing wiring and current paths between the smoothing capacitors 13a to 13d and the bus bars 21 to 25. As shown in FIG. For convenience, the connection portion to the semiconductor stack portion 11 is shown in the lower part of the figure. In addition, since it connects with the semiconductor stack part 11 in the center part position of the bus bar 14, in the power conversion circuits 7 and 8 by the side of the semiconductor stack part 11, it is between 1st smoothing capacitor group 13x and 2nd smoothing capacitor group 13y. The three terminals of P potential, C potential, and N potential are disposed at the center position of the.
The smoothing capacitors 13a and 13b correspond to the smoothing capacitor 3a on the circuit diagram of FIG. 3, and the smoothing capacitors 13a and 13b are connected in parallel to increase the smoothing capacitor capacity. Similarly, the smoothing capacitors 13c and 13d correspond to the smoothing capacitor 3b on the circuit diagram of FIG. The P potential bus bar 21 is connected to the positive electrodes of the smoothing capacitors 13a and 13b and the P potential terminal. The N potential bus bar 22 is connected to the negative electrodes of the smoothing capacitors 13c and 13d and the N potential terminal. The first C potential bus bar 23 is connected to the negative electrodes of the smoothing capacitors 13a and 13b, and the second C potential bus bar 24 is connected to the positive electrodes of the smoothing capacitors 13c and 13d. The third C potential bus bar 25 has one end connected to the first C potential bus bar 23, the other end connected to the second C potential bus bar 24, and further connected to the C potential terminal at the center.

FIG. 4A shows a current path when a current flows from the P potential terminal to the N potential terminal in such a wiring structure. In the figure, current paths are indicated by thick lines, broken lines, and dotted lines. The broken line part and the dotted line part are parallel parts, and the current in the thick line part is shunted.
The current flowing into the P potential bus bar 21 passes through the smoothing capacitor 13a or 13b connected in parallel, passes through the C potential bus bar 23, 25, 24, flows through the smoothing capacitor 13c or 13d, and flows through the N potential bus bar 22; It flows out from the N potential terminal to the semiconductor stack portion 11. When the impedances in the current paths of the broken line portion and the dotted line portion are different, the current is concentrated on the smaller impedance path. Since the impedance of each of the smoothing capacitors 13a to 13d is substantially equal, if there is a difference in impedance, it is caused by the bus bar 14 (21 to 25). The lengths of the bus bars 21 to 25 passing through are equal. That is, the broken line portion and the dotted line portion have substantially the same conditions such as the length of the portion where the current of the opposite direction overlaps the thick line portion and the length of the other portion, and the broken line current path However, the impedance can be made almost equal even in the dotted current path. For this reason, the electric current which flows into each smoothing capacitor 13a, 13b (13c, 13d) connected in parallel becomes equal.

Next, FIG. 4B shows a current path when a current flows from the P potential terminal to the C potential terminal. In the figure, current paths are indicated by thick lines, broken lines, and dotted lines. The broken line part and the dotted line part are parallel parts, and the current in the thick line part is shunted.
The current flowing into the P potential bus bar 21 passes through the smoothing capacitors 13a or 13b connected in parallel, flows from the first C potential bus bar 23 to the third C potential bus bar 25, and from the C potential terminal to the semiconductor stack portion 11. Will flow out. Also in this case, the impedance of the current path can be made substantially equal between the broken line portion and the dotted line portion, which are parallel portions. Therefore, the currents flowing through the smoothing capacitors 13a and 13b connected in parallel are equal.

Next, FIG. 4C shows a current path when a current flows from the C potential terminal to the N potential terminal. In the figure, current paths are indicated by thick lines, broken lines, and dotted lines. The broken line part and the dotted line part are parallel parts, and the current in the thick line part is shunted.
The current flowing into the third C potential bus bar 25 flows through the N potential bus bar 22 through the smoothing capacitor 13c or 13d connected in parallel via the second C potential bus bar 24, and from the N potential terminal to the semiconductor stack portion. 11 will flow out. Also in this case, the impedance of the current path can be made substantially equal between the broken line portion and the dotted line portion, which are parallel portions. For this reason, the electric current which flows into each smoothing capacitor 13c and 13d connected in parallel becomes equal.

  Next, as a comparative example, an example in which the currents of the smoothing capacitors 13a to 13d connected in parallel are biased is shown in FIG. In FIG. 5, wiring to the smoothing capacitors 13 a to 13 d is performed by bus bars 26 to 28. The P potential bus bar 26 and the N potential bus bar 27 are the same as the P potential bus bar 21 and the N potential bus bar 22 shown in FIG. 4, and the wirings to the smoothing capacitors 13a to 13d are also the same. In this case, the C potential bus bar 28 is composed of one conductor, connected to the negative electrodes of the smoothing capacitors 13a and 13b and the positive electrodes of the smoothing capacitors 13c and 13d, and further connected to the C potential terminal at the center.

  FIG. 5A shows a current path when current flows from the P potential terminal to the N potential terminal with this configuration. In the figure, current paths are indicated by thick lines, broken lines, and dotted lines. The broken line part and the dotted line part are parallel parts, and the current in the thick line part is shunted. As shown in the figure, when comparing the current path of the broken line part and the current path of the dotted line part, the current path of the dotted line part is clearly longer than the current path of the broken line part, and due to the impedance of the bus bar part of the difference, The current flowing through the smoothing capacitor 13a and the smoothing capacitor 13d is smaller than the current flowing through the smoothing capacitor 13b and the smoothing capacitor 13c. In this case, the two smoothing capacitors 13a and 13b (13c and 13d) are arranged in parallel. However, as the number of parallel increases, the difference in current flowing through each smoothing capacitor becomes more prominent.

Next, FIG. 5B shows a current path when a current flows from the P potential terminal to the C potential terminal. Also in this case, the current path in the dotted line portion is clearly longer than the current path in the broken line portion, and the current flowing through the smoothing capacitor 13a is smaller than the current flowing through the smoothing capacitor 13b due to the impedance of the differential busbar portion. Become.
Next, FIG. 5C shows a current path when a current flows from the C potential terminal to the N potential terminal. Also in this case, the current path in the dotted line portion is clearly longer than the current path in the broken line portion, and the current flowing through the smoothing capacitor 13d is smaller than the current flowing through the smoothing capacitor 13c due to the impedance of the differential busbar portion. Become.
Thus, in the bus bar in the comparative example shown in FIG. 5, the currents flowing through the smoothing capacitors 13a and 13b (13c and 13d) connected in parallel cannot be equalized.

As described above, in this embodiment, as shown in FIG. 4, the impedance of the current path in the parallel portion of the wiring can be made substantially equal by the bus bar 14 as shown in FIG. As described above, the impedances of the plurality of current paths passing through the bus bars 14 and passing through the smoothing capacitors 13a, 13b (13c, 13d) connected in parallel can be made substantially equal. Therefore, the smoothing capacitors 13a connected in parallel, The currents flowing through 13b (13c, 13d) can be made equal.
Note that the case where the current flows from the P potential terminal to the N potential terminal, from the P potential terminal to the C potential terminal, and from the C potential terminal to the N potential terminal has been described. The same applies when flowing from the C potential terminal to the P potential terminal and from the N potential terminal to the C potential terminal. In FIG. 4, the current flowing through the single-phase three-level converter 7 has been described, but the current flowing through the three-phase two-level inverter 8 also flows from the P potential terminal to the N potential terminal and from the N potential terminal to the P potential terminal 2. In this case, the current flowing through the smoothing capacitors 13a and 13b (13c and 13d) connected in parallel can be equalized.
In addition, the currents flowing through the overlapping bus bars 21 to 25 are opposite in direction except for the portion between the capacitor terminals through which the current flows through the smoothing capacitors 13a to 13d. It is flowing. Thereby, the inductance can be lowered because the magnetic fluxes cancel each other.

As described above, the bus bar 14 has a wiring structure in which impedances of a plurality of current paths passing through the smoothing capacitors 13a and 13b (13c and 13d) connected in parallel can be easily and reliably substantially equalized. Thereby, the duties of the plurality of smoothing capacitors 13a to 13d are equalized, and it is possible to prevent the current from concentrating on the specific smoothing capacitors 13a to 13d and deteriorating the deterioration.
Therefore, a highly reliable power conversion device can be obtained even with a structure in which a plurality of smoothing capacitors are connected in parallel due to an increase in capacity and a plurality of smoothing capacitors are arranged in a straight line due to further miniaturization.

Embodiment 2. FIG.
FIG. 6 is a diagram showing bus bars 41 to 45 as wiring conductors according to the second embodiment, and wiring and current paths between the bus bars 41 to 45 and the smoothing capacitors 13a to 13d. The external structure and circuit configuration of the power converter are the same as those shown in FIGS. 1 and 3 of the first embodiment.
For convenience, the connection portion to the semiconductor stack portion 11 is shown in the lower part of the figure. In addition, since it connects to the semiconductor stack part 11 in the center part position of a bus bar, in the power converter circuits 7 and 8 by the side of the semiconductor stack part 11, the 1st smoothing capacitor group 13x (13a, 13b) and the 2nd smoothing capacitor group Three terminals of P potential, C potential, and N potential are arranged at a central position between 13y (13c, 13d).
The bus bars 41 to 45 are the first and second P potential bus bars 41 and 43, the first and second N potential bus bars 42 and 44, and the C potential bus bar 45 serving as a plurality of conductors. The second P potential bus bar 43, the second N potential bus bar 44, and the third C potential bus bar 25 are connected to the semiconductor stack portion 11 at the center position of the bus bar 14. In order to do so, each has a connection portion extending in the direction of the semiconductor stack portion 11.

  The first P potential bus bar 41 is connected to the positive electrodes of the smoothing capacitors 13a and 13b, and the first N potential bus bar 42 is connected to the negative electrodes of the smoothing capacitors 13c and 13d. The second P potential bus bar 43 has one end connected to the P potential terminal, and the far end and the other end of the first P potential bus bar 41 from the center position (connection position to the semiconductor stack portion 11). The The second N potential bus bar 44 has one end connected to the N potential terminal, and the far end and the other end of the first N potential bus bar 42 from the center position. The C potential bus bar 45 is connected to the negative electrodes of the smoothing capacitors 13a and 13b and the positive electrodes of the smoothing capacitors 13c and 13d, and is further connected to the C potential terminal at the center.

FIG. 6A shows a current path when a current flows from the P potential terminal to the N potential terminal in such a wiring structure. In the figure, current paths are indicated by thick lines, broken lines, and dotted lines. The broken line part and the dotted line part are parallel parts, and the current in the thick line part is shunted.
The current flowing into the second P potential bus bar 43 passes through the first P potential bus bar 41, passes through the smoothing capacitor 13a or 13b connected in parallel, flows through the C potential bus bar 45, and then flows into the smoothing capacitor 13c or 13d. , Flows through the first N potential bus bar 42, and flows out from the N potential terminal to the semiconductor stack portion 11 via the second N potential bus bar 44. As shown in the drawing, since the lengths of the current paths of the broken line portion and the dotted line portion, which are parallel portions, are substantially equal, the impedance can be made substantially equal. For this reason, the electric current which flows into each smoothing capacitor 13a, 13b (13c, 13d) connected in parallel becomes equal.

Next, FIG. 6B shows a current path when a current flows from the P potential terminal to the C potential terminal.
The current flowing into the second P potential bus bar 43 passes through the first P potential bus bar 41, flows through the smoothing capacitor 13a or 13b connected in parallel, and flows through the C potential bus bar 45, and from the C potential terminal to the semiconductor. It flows out to the stack part 11. Also in this case, the impedance of the current path can be made substantially equal between the broken line portion and the dotted line portion, which are parallel portions. Therefore, the currents flowing through the smoothing capacitors 13a and 13b connected in parallel are equal.
Next, FIG. 6C shows a current path when a current flows from the C potential terminal to the N potential terminal.
The current flowing into the C potential bus bar 45 flows through the first N potential bus bar 42 and the second N potential bus bar 44 through the smoothing capacitors 13c or 13d connected in parallel, and from the N potential terminal to the semiconductor stack portion 11. Will flow out. Also in this case, the impedance of the current path can be made substantially equal between the broken line portion and the dotted line portion, which are parallel portions. For this reason, the electric current which flows into each smoothing capacitor 13c and 13d connected in parallel becomes equal.

As described above, in this embodiment, the impedance of the current path in the parallel portion of the wiring can be made substantially equal. Thus, the impedances of the plurality of current paths passing through the smoothing capacitors 13a and 13b (13c and 13d) connected in parallel through the bus bars 41 to 45 can be made substantially equal. The currents flowing through 13a and 13b (13c and 13d) can be made equal.
Note that the case where the current flows from the P potential terminal to the N potential terminal, from the P potential terminal to the C potential terminal, and from the C potential terminal to the N potential terminal has been described. The same applies when flowing from the C potential terminal to the P potential terminal and from the N potential terminal to the C potential terminal. 6 describes the current flowing through the single-phase three-level converter 7, the current flowing through the three-phase two-level inverter 8 also flows from the P potential terminal to the N potential terminal and from the N potential terminal to the P potential terminal. In this case, the current flowing through the smoothing capacitors 13a and 13b (13c and 13d) connected in parallel can be equalized.
In addition, the currents flowing through the overlapping bus bars 41 to 45 are opposite in direction except for the portion between the capacitor terminals through which the current flows in the smoothing capacitors 13a to 13d. It is flowing. Thereby, the inductance can be lowered because the magnetic fluxes cancel each other.

In this way, the wiring structure of the bus bars 41 to 45 makes it possible to easily and reliably substantially equalize the impedances of a plurality of current paths passing through the smoothing capacitors 13a and 13b (13c and 13d) connected in parallel. Thereby, the duties of the plurality of smoothing capacitors 13a to 13d are equalized, and it is possible to prevent the current from concentrating on the specific smoothing capacitors 13a to 13d and deteriorating the deterioration.
Therefore, a highly reliable power conversion device can be obtained even with a structure in which a plurality of smoothing capacitors are connected in parallel due to an increase in capacity and a plurality of smoothing capacitors are arranged in a straight line due to further miniaturization.

Embodiment 3 FIG.
FIG. 7 is an external view of the bus bar 14a as a wiring conductor for connecting the smoothing capacitors 13a to 13d and an exploded view thereof according to the third embodiment. The external structure and circuit configuration of the power converter are the same as those shown in FIGS. 1 and 3 of the first embodiment.
As shown in FIG. 7, the bus bar 14 a is a stack of a P potential bus bar 31, first to third C potential bus bars 33, 32, 34 and an N potential bus bar 35 as a plurality of conductors. A conductor 35 is laminated with an insulating film except for a connection portion with other bus bars 31 to 35, and is insulated from each other except the connection portion. The protrusions of the bus bars 31 to 33 and 35 are parts to be bolted to the terminal parts of the smoothing capacitors 13a to 13d, and the protrusions are passed through the overlapping parts of the other bus bars 31 to 35 or bolted. Make a hole for.
Each bus bar 31-35 extends and overlaps in the linear arrangement direction of the smoothing capacitors 13a-13d, and the P potential bus bar 31, the third C potential bus bar 34, and the N potential bus bar 35 are connected to one end of the bus bar 14a. In order to connect to the semiconductor stack part 11 at the part position, the P potential terminal connection part 31a, the C potential terminal connection part 34a and N extending in the direction of the semiconductor stack part 11
It has a potential terminal connection portion 35a. Further, at the other end position of the bus bar 14a, the end portions of the C potential bus bars 32 to 34 are provided with a portion that is not laminated with an insulating film so as to be energized, and are connected and fixed by means such as bolting. The N potential bus bar 35 at this end position is shortened so that this bolting can be performed.

FIG. 8 is a diagram showing wiring and current paths of the smoothing capacitors 13a to 13d and the bus bars 31 to 35. As shown in FIG. In addition, in order to connect to the semiconductor stack part 11 in one end part position of the bus bar 14a, in the power conversion circuits 7 and 8 on the semiconductor stack part 11 side, the first smoothing capacitor group 13x and the second smoothing capacitor group 13y The three terminals of P potential, C potential, and N potential are disposed at one end position (in this case, the first smoothing capacitor group 13x side) of the smoothing capacitor circuit constituted by
The P potential bus bar 31 is connected to the positive electrodes of the smoothing capacitors 13a and 13b and the P potential terminal. The first C potential bus bar 33 is connected to the negative electrodes of the smoothing capacitors 13a and 13b, and the second C potential bus bar 32 is connected to the positive electrodes of the smoothing capacitors 13c and 13d. The third C potential bus bar 34 has one end connected to the first and second C potential bus bars 32 and 33 and the other end connected to the C potential terminal. The N potential bus bar 35 is connected to the negative electrodes of the smoothing capacitors 13c and 13d and the N potential terminal.

FIG. 8A shows a current path when current flows from the P potential terminal to the N potential terminal in such a wiring structure. In the figure, current paths are indicated by thick lines, broken lines, and dotted lines. The broken line part and the dotted line part are parallel parts, and the current in the thick line part is shunted.
The current flowing into the P potential bus bar 31 passes through the smoothing capacitor 13a or 13b connected in parallel, passes through the first C potential bus bar 33 and the second C potential bus bar 32, and passes through the smoothing capacitor 13c or 13d. It flows through the N potential bus bar 35 and flows out from the N potential terminal to the semiconductor stack portion 11.
As shown in the drawing, since the lengths of the current paths of the broken line portion and the dotted line portion, which are parallel portions, are substantially equal, the impedance can be made substantially equal. For this reason, the electric current which flows into each smoothing capacitor 13a, 13b (13c, 13d) connected in parallel becomes equal.

Next, FIG. 8B shows a current path when a current flows from the P potential terminal to the C potential terminal.
The current flowing into the P potential bus bar 31 passes through the smoothing capacitors 13a or 13b connected in parallel, flows from the first C potential bus bar 33 to the third C potential bus bar 34, and from the C potential terminal to the semiconductor stack portion 11. Will flow out. Also in this case, the impedance of the current path can be made substantially equal between the broken line portion and the dotted line portion, which are parallel portions. Therefore, the currents flowing through the smoothing capacitors 13a and 13b connected in parallel are equal.
Next, FIG. 8C shows a current path when a current flows from the C potential terminal to the N potential terminal.
The current flowing into the third C potential bus bar 34 passes through the smoothing capacitor 13c or 13d connected in parallel via the second C potential bus bar 32 and flows through the N potential bus bar 35. From the N potential terminal to the semiconductor stack portion 11 will flow out. Also in this case, the impedance of the current path can be made substantially equal between the broken line portion and the dotted line portion, which are parallel portions. For this reason, the electric current which flows into each smoothing capacitor 13c and 13d connected in parallel becomes equal.

  Next, as a comparative example, an example in which the currents of the smoothing capacitors 13a to 13d connected in parallel are biased is shown in FIG. In FIG. 9, the wiring to the smoothing capacitors 13a to 13d is performed by the bus bars 36 to 38. The P potential bus bar 36 and the N potential bus bar 38 are the same as the P potential bus bar 31 and the N potential bus bar 35 shown in FIG. 8, and the wiring with the smoothing capacitors 13a to 13d is also the same. In this case, the C potential bus bar 37 is composed of one conductor, connected to the negative electrodes of the smoothing capacitors 13a and 13b and the positive electrodes of the smoothing capacitors 13c and 13d, and further connected to the C potential terminal at the end.

  FIG. 9A shows a current path when current flows from the P potential terminal to the N potential terminal with this configuration. In the figure, current paths are indicated by thick lines, broken lines, and dotted lines. The broken line part and the dotted line part are parallel parts, and the current in the thick line part is shunted. As shown in the figure, when comparing the current path of the broken line part and the current path of the dotted line part, the current path of the dotted line part is clearly longer than the current path of the broken line part, and due to the impedance of the bus bar part of the difference, The current flowing through the smoothing capacitor 13d is smaller than the current flowing through the smoothing capacitor 13c. In this case, the two smoothing capacitors 13a and 13b (13c and 13d) are arranged in parallel. However, as the number of parallel increases, the difference in current flowing through each smoothing capacitor becomes more prominent.

Next, FIG. 9B shows a current path when a current flows from the P potential terminal to the C potential terminal. Also in this case, the current path in the dotted line portion is clearly longer than the current path in the broken line portion, and the current flowing through the smoothing capacitor 13b is smaller than the current flowing through the smoothing capacitor 13a due to the impedance of the differential busbar portion. Become.
Next, FIG. 9C shows a current path when a current flows from the C potential terminal to the N potential terminal. Also in this case, the current path in the dotted line portion is clearly longer than the current path in the broken line portion, and the current flowing through the smoothing capacitor 13d is smaller than the current flowing through the smoothing capacitor 13c due to the impedance of the differential busbar portion. Become.
As described above, in the bus bar in the comparative example shown in FIG. 9, the currents flowing through the smoothing capacitors 13a and 13b (13c and 13d) connected in parallel cannot be equalized.

As described above, in this embodiment, as shown in FIG. 8, the impedance of the current path in the parallel portion of the wiring can be made substantially equal by the bus bar 14 a as shown in FIG. 7. In this way, the impedances of a plurality of current paths passing through the smoothing capacitors 13a, 13b (13c, 13d) connected in parallel through the bus bar 14a can be made substantially equal, and thus each of the smoothing capacitors 13a connected in parallel, The currents flowing through 13b (13c, 13d) can be made equal.
Note that the case where the current flows from the P potential terminal to the N potential terminal, from the P potential terminal to the C potential terminal, and from the C potential terminal to the N potential terminal has been described. The same applies when flowing from the C potential terminal to the P potential terminal and from the N potential terminal to the C potential terminal. Although the current flowing through the single-phase three-level converter 7 has been described with reference to FIG. 8, the current flowing through the three-phase two-level inverter 8 also flows from the P potential terminal to the N potential terminal and from the N potential terminal to the P potential terminal. In this case, the current flowing through the smoothing capacitors 13a and 13b (13c and 13d) connected in parallel can be equalized.
In addition, the current flowing through the overlapping bus bars 31 to 35 flows in opposite directions except for the portion between the capacitor terminals through which the current flows through the smoothing capacitors 13a to 13d. It is flowing. Thereby, the inductance can be lowered because the magnetic fluxes cancel each other.

As described above, the wiring structure of the bus bar 14a allows the impedances of a plurality of current paths passing through the smoothing capacitors 13a and 13b (13c and 13d) connected in parallel to be easily and reliably substantially equalized. Thereby, the duties of the plurality of smoothing capacitors 13a to 13d are equalized, and it is possible to prevent the current from concentrating on the specific smoothing capacitors 13a to 13d and deteriorating the deterioration.
Therefore, a highly reliable power conversion device can be obtained even with a structure in which a plurality of smoothing capacitors are connected in parallel due to an increase in capacity and a plurality of smoothing capacitors are arranged in a straight line due to further miniaturization.

In the first to third embodiments, the single-phase three-level converter 8 is shown as a three-level power conversion circuit, but a three-level inverter may be used. The three-level converter and inverter can achieve the same effect regardless of whether they are single-phase or multi-phase.
In each of the smoothing capacitor groups 13x and 13y, two smoothing capacitors are connected in parallel, but the same effect can be obtained even when three or more smoothing capacitors are connected in parallel.

It is an external appearance perspective view of the power converter device by Embodiment 1 of this invention. It is the external appearance and exploded view of the bus bar by Embodiment 1 of this invention. It is a figure which shows the circuit structure of the power converter device by Embodiment 1 of this invention. It is a figure which shows the wiring and electric current path | route of the smoothing capacitor and bus bar by Embodiment 1 of this invention. It is a figure which shows the wiring and electric current path | route of the smoothing capacitor and bus bar by the comparative example of Embodiment 1 of this invention. It is a figure which shows the wiring and electric current path | route of the smoothing capacitor and bus bar by Embodiment 2 of this invention. It is the external appearance and exploded view of the bus bar by Embodiment 3 of this invention. It is a figure which shows the wiring and current path of the smoothing capacitor and bus bar by Embodiment 3 of this invention. It is a figure which shows the wiring and electric current path | route of the smoothing capacitor and bus bar by the comparative example of Embodiment 3 of this invention.

Explanation of symbols

1a to 1d, 1g to 1j IGBT, 3a (13x) first smoothing capacitor group,
3b (13y) second smoothing capacitor group,
6a, 6b, 6c, 6d Clamp diode, 7 Single-phase 3-level converter,
11 Semiconductor stack part, 13a-13d Smoothing capacitor,
14, 14a Bus bar as wiring conductor, 21 P potential bus bar,
22 N potential bus bar, 23 1st C potential bus bar, 24 2nd C potential bus bar,
25 third C potential bus bar, 21a P potential terminal connection portion, 22a N potential terminal connection portion, 25a C potential terminal connection portion, 31 P potential bus bar, 32 second C potential bus bar,
33 first C potential bus bar, 34 third C potential bus bar, 35 N potential bus bar,
31a P potential terminal connection, 34a C potential terminal connection, 35a N potential terminal connection,
41 first P-potential bus bar, 42 first N-potential bus bar,
43 second P potential bus bar, 44 second N potential bus bar, 45 C potential bus bar.

Claims (3)

A first smoothing circuit configured by connecting a plurality of smoothing capacitors in parallel, and a three-level power conversion circuit including four switching elements and two clamp diodes each having a freewheeling diode connected in antiparallel. In a power converter in which a smoothing capacitor circuit in which a capacitor group and a second smoothing capacitor group are connected in series is connected by a conductor for wiring,
The smoothing capacitors of the first smoothing capacitor group and the smoothing capacitors of the second smoothing capacitor group are arranged substantially linearly in the X direction, and the first smoothing capacitor group at the X direction position At the central position between the second smoothing capacitor group, three terminals of P potential, C potential, and N potential of the power conversion circuit are arranged,
A P potential conductor connecting the positive electrode of each smoothing capacitor of the first smoothing capacitor group and the P potential terminal, wherein the wiring conductor is a plurality of conductors extending in the X direction; An N potential conductor connecting the negative electrode of each smoothing capacitor of the smoothing capacitor group and the N potential terminal; a first C potential conductor connected to the negative electrode of each smoothing capacitor of the first smoothing capacitor group; The second C potential conductor connected to the positive electrode of each smoothing capacitor of the second smoothing capacitor group, the far end and one end of the first C potential conductor from the center position are connected, and the second And a third C potential conductor connected to the C potential terminal at the center position, the far end and the other end of the C potential conductor being connected from the center position.
A power conversion device characterized in that impedances of a plurality of current paths passing through the respective smoothing capacitors connected in parallel through the wiring conductor are made substantially equal. A first smoothing circuit configured by connecting a plurality of smoothing capacitors in parallel, and a three-level power conversion circuit including four switching elements and two clamp diodes each having a freewheeling diode connected in antiparallel. In a power converter in which a smoothing capacitor circuit in which a capacitor group and a second smoothing capacitor group are connected in series is connected by a conductor for wiring,
The smoothing capacitors of the first smoothing capacitor group and the smoothing capacitors of the second smoothing capacitor group are arranged substantially linearly in the X direction, and the first smoothing capacitor group at the X direction position At the central position between the second smoothing capacitor group, three terminals of P potential, C potential, and N potential of the power conversion circuit are arranged,
A first P potential conductor connected to a positive electrode of each smoothing capacitor of the first smoothing capacitor group, wherein the wiring conductor is a plurality of conductors extending in the X direction; and the first P A second P potential conductor that connects the far end of the potential conductor from the center position to the P potential terminal, and a first N connected to the negative electrode of each smoothing capacitor of the second smoothing capacitor group. A potential conductor, a second N potential conductor connecting the end of the first N potential conductor far from the center position and the N potential terminal, and each smoothing capacitor of the first smoothing capacitor group A negative electrode, a positive electrode of each smoothing capacitor of the second smoothing capacitor group, and a C potential conductor connected to the C potential terminal;
A power conversion device characterized in that impedances of a plurality of current paths passing through the respective smoothing capacitors connected in parallel through the wiring conductor are made substantially equal. A first smoothing circuit configured by connecting a plurality of smoothing capacitors in parallel, and a three-level power conversion circuit including four switching elements and two clamp diodes each having a freewheeling diode connected in antiparallel. In a power converter in which a smoothing capacitor circuit in which a capacitor group and a second smoothing capacitor group are connected in series is connected by a conductor for wiring,
The smoothing capacitors of the first smoothing capacitor group and the smoothing capacitors of the second smoothing capacitor group are arranged substantially linearly in the X direction, and one end of the smoothing capacitor circuit at the X direction position. Three terminals of P potential, C potential, and N potential of the power conversion circuit are arranged at the position,
A P potential conductor connecting the positive electrode of each smoothing capacitor of the first smoothing capacitor group and the P potential terminal, wherein the wiring conductor is a plurality of conductors extending in the X direction; An N potential conductor connecting the negative electrode of each smoothing capacitor of the smoothing capacitor group and the N potential terminal; a first C potential conductor connected to the negative electrode of each smoothing capacitor of the first smoothing capacitor group; A second C potential conductor connected to the positive electrode of each smoothing capacitor of the second smoothing capacitor group, and each end and one end of the first and second C potential conductors on the side far from the end position are connected. A third C potential conductor, the other end of which is connected to the C potential terminal,
A power conversion device characterized in that impedances of a plurality of current paths passing through the respective smoothing capacitors connected in parallel through the wiring conductor are made substantially equal.

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