JP4484335B2 - Power converter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power conversion device in which switching element arms constituting a converter unit and an inverter unit are connected to a P-side bus bar and an N-side bus bar via bus members.
[0002]
[Prior art]
In general, when the power conversion device supplies AC power having a variable frequency to an AC load such as an AC motor, the DC power input by the inverter unit is converted into AC power having a desired frequency, and this is applied to the AC motor or the like. Make output. At this time, when direct current power cannot be obtained directly from the direct current power source, a converter unit is provided on the input side of the inverter unit, and the alternating current power from the alternating current power source is converted into direct current power by the converter unit, and the converted direct current Electric power is input to the inverter unit.
[0003]
FIG. 14 is a main circuit configuration diagram of a power conversion device including such a converter unit and an inverter unit. The converter unit 1 is formed by an R-phase switching element arm formed by switching elements (IGBTs) RP and RN, an S-phase switching element arm formed by switching elements SP and SN, and the switching elements TP and TN. It has a T-phase switching element arm. The inverter unit 2 includes a U-phase switching element arm formed by the switching elements UP and UN, a V-phase switching element arm formed by the switching elements VP and VN, and a W-phase switching element formed by the switching elements WP and WN. It has a switching element arm. A smoothing capacitor 3 is connected between the converter unit 1 and the inverter unit 2. A diode D for preventing reverse voltage is connected to each switching element. A three-phase AC power supply 4 is connected to the switching element arm of each phase of the converter unit 1, while an induction motor 5 as a load is connected to the switching element arm of each phase of the inverter unit 2. .
[0004]
15 is a plan view showing a connection structure for the U-phase switching element arm in FIG. 14, and FIG. 16 is a view taken along the line AA in FIG. The switching element UP in FIG. 14 is composed of switching elements UP1, UP2, UP3, and the switching element UN is composed of switching elements UN1, UN2, UN3. Note that “C”, “E”, and “G” attached to the terminals of the respective switching elements are symbols indicating “collector”, “emitter”, and “gate”, respectively.
[0005]
As shown in FIG. 15, the smoothing capacitor 3 is composed of four smoothing capacitors 3A, 3B, 3C, and 3D. The positive terminals of the capacitors 3A and 3C are connected by a P-side load connection bus 6P, and the negative terminals of the capacitors 3B and 3D are connected by an N-side load connection bus 6N (avoid drawing complexity). Therefore, the bus 6N side is shown by a two-dot chain line.) The minus terminal of the capacitor 3A and the plus terminal of the capacitor 3B and the minus terminal of the capacitor 3C and the plus terminal of the capacitor 3D are connected by a capacitor connection bus 7, respectively.
[0006]
The P-side load connection bus 6P includes a capacitor connection portion 6Pa connected to the positive terminals of the capacitors 3A and 3C, an element connection portion 6Pb1 connected to each collector of the switching elements UP1 and UP2, and the element connection portion 6Pb1. A connecting part 6Pc1 connecting between the capacitor connecting part 6Pa, an element connecting part 6Pb2 connected to the collector of the switching element UP3, and a connecting part 6Pc2 connecting between the element connecting part 6Pb2 and the capacitor connecting part 6Pa. Have. Similarly, the N-side load connection bus 6N includes a capacitor connection portion 6Na connected to the negative terminals of the capacitors 3B and 3D, an element connection portion 6Nb1 connected to the emitters of the switching elements UN1 and UN2, and this element connection. A connecting portion 6Nc1 connecting between the portion 6Nb1 and the capacitor connecting portion 6Na, an element connecting portion 6Nb2 connected to the emitter of the switching element UN3, and a connecting portion 6Nc2 connecting between the element connecting portion 6Nb2 and the capacitor connecting portion 6Na. ,have. The one end portions of the P-side load connection bus 6P and the N-side load connection bus 6N are fixed to the P-side bus bus 9P and the N-side bus bus 9N, respectively.
[0007]
The configuration of FIG. 15 described above is a configuration in which the number of switching element arms, that is, the number of element parameters is three. The switching element arms UP1, UN1 and the switching element arms UP2, UN2 are adjacent to each other and are connected by the element connecting portions 6Pb1, 6Nb1, which are the same members. This is called a first group having 2 element parameters. Further, since the switching element arms UP3 and UN3 are connected to the element connecting portions 6Pb2 and 6Nb2 different from 6Pb1 and 6Nb1, they are referred to as a second group having an element parameter of 1. In this specification, a combination of a plurality of switching element arms or a single switching element arm is referred to as a “group”, and by introducing such a concept of “group”, switching element arms in various forms, The connection relationship and operation between the bus members and conductors will be described as clearly as possible. In addition, a smoothing capacitor is also included in the group defined as described above. Therefore, as is apparent from the connection state, the capacitors 3A and 3B belong to the first group, and the capacitors 3C and 3D belong to the second group.
[0008]
FIG. 17 is an explanatory diagram showing a schematic structure of the U / R phase unit 10 that houses the U-phase switching element arm of the inverter unit 2 and the R-phase switching element arm of the converter unit 1 in FIG. In this figure, the U / R phase unit 10 has a casing 11 in which frames 11 a are formed on both sides, and a cooler 12 having cooling fins 12 a is disposed inside the casing 11. ing. Then, the switching elements UP1, UN1, UP2, UN2, UP3, UN3 forming the U-phase switching element arms on the cooling fin 12a, and the R-phase switching element arms are switched to the switching elements RP1, RN1, RP2, RN2. Is attached. In addition, U-phase smoothing capacitors 3A to 3D are disposed on the front side of these switching elements in the drawing direction, and an R-phase smoothing capacitor (not shown) is provided on the opposite side of these switching elements in the drawing direction. It is arranged.
[0009]
18 is a circuit diagram showing a connection state of each switching element in FIG. The protection operation for the switching element will be described with reference to FIG. When the P-side element and the N-side element constituting the switching element arm are turned on at the same time, a DC short-circuited state occurs. Therefore, for control purposes, the other element is always turned off while one element is turned on. It is like that. However, sometimes a state in which both the P-side element and the N-side element are simultaneously turned on may occur due to erroneous control or other abnormal causes. For example, when both of the switching elements UP1 and UN1 are turned on simultaneously, the switching element arm is short-circuited, and currents from the capacitors 3A and 3B and further from the capacitors 3C and 3D flow into the short-circuited switching element arm. Therefore, the switching elements UP1 and UN1 are destroyed as they are. Therefore, conventionally, a current detection means such as a Hall element is provided, and when a current of a certain level or more flows, all switching elements are turned on for a predetermined time to distribute each short circuit current. A protective operation is performed in which the amount of current flowing through the current is narrowed and then the operation is stopped. In FIG. 18, XP1 and XN1 indicate impedance components when a short-circuit current flows through each switching element of the first group when all switching elements are turned on. Similarly, XP2 and XN2 are short-circuited. The impedance component when the current flows through each switching element of the second group is shown.
[0010]
[Problems to be solved by the invention]
However, in the conventional device, a surge voltage is generated after detecting a current of a certain level or more and turning on all the switching elements until the operation is stopped, and the switching elements are destroyed due to the surge voltage. There were occasional accidents that would have been done. Therefore, when the inventors of the present application conducted an investigation to investigate the cause, the following was found.
[0011]
That is, when all the switching elements are turned on, it is preferable that an equal current flows through each switching element. However, the impedances XP1, XN1 on the first group side and the impedances XP2, XN2 on the second group side are the same. In addition, the capacities of the capacitors 3A and 3B are different from the capacities of the capacitors 3C and 3D. Therefore, the current from the first group of capacitors 3A and 3B flows into each switching element of the second group, or the current from the second group of capacitors 3C and 3D flows into each switching element of the first group. Therefore, the difference between the amount of current flowing through the switching element on the first group side and the amount of current flowing through the switching element on the second group side becomes large.
[0012]
Thus, when a large difference occurs in the amount of current flowing through the switching elements between the groups, a large difference also occurs in the gate-emitter voltage between the switching elements. Since the gate-emitter between the switching elements is connected to the gate-emitter between the switching elements of other groups in the control circuit, even if the elements belong to different groups, mutual interference occurs. As a result, the voltage between the gate and the emitter greatly fluctuates. Due to such voltage fluctuation between the gate and the emitter, the gate signal oscillates, and as a result, the above surge voltage is generated.
[0013]
This invention is made | formed in view of the said situation, and it aims at providing the power converter device which suppresses generation | occurrence | production of a surge voltage and can perform a reliable and stable short circuit protection operation | movement.
[0014]
[Means for Solving the Problems]
As means for solving the above-mentioned problems, the invention according to claim 1 is provided with a converter part and an inverter part, and one phase of the converter part and the inverter part is constituted by a plurality of sets of switching element arms. The switching element arms are grouped into a plurality of groups with a group having a predetermined element number as a unit, and each group has a smoothing capacitor connected to the plurality of sets of switching element arms via a load connection bus. The one phase is connected to the other phase in the other unit via the P-side bus bus and the N-side bus bus, and when a short circuit accident occurs in any switching element arm , A short-circuit protection operation is performed by stopping operation after all switching element arms are turned on for a predetermined time. In the converter, an individual load connection bus is formed for each group, and the load connection bus and the P side bus are connected between the load connection bus, the P side bus bus and the N side bus bus. A connection conductor for suppressing outflow current having a higher impedance than that of the bus and the N-side busbar is connected, and the amount of current flowing out from the smoothing capacitor belonging to each group toward the other group during the short-circuit protection operation is suppressed. It is characterized by that.
[0015]
According to the above configuration, during the short-circuit protection operation, most of the current flowing through the switching element arm of each group comes from the smoothing capacitors belonging to its own group, and the current from the smoothing capacitors belonging to other groups is suppressed as much as possible. It becomes. Therefore, mutual interference is effectively prevented from occurring with respect to voltage fluctuations applied to the switching elements between the groups.
[0016]
According to a second aspect of the present invention, in the first aspect of the present invention, the groups having the predetermined element para number are a first group having an element para number of 2 and a second group having an element para number of one. It is characterized by being.
[0017]
The invention according to claim 3 is the invention according to claim 1, characterized in that each group having the predetermined element para number is a first group and a second group having both element para numbers. To do.
[0018]
According to a fourth aspect of the present invention, in the first aspect of the present invention, each of the groups having the predetermined element para number includes the first to M-1th groups having the element para number of 2, and the element para number of one. (M is an integer of 3 or more).
[0019]
The invention according to claim 5 is characterized in that each of the groups having the predetermined element parameter number is a first to Mth group in which the element parameter number is 2, where M is an integer of 3 or more. To do.
[0020]
According to a sixth aspect of the invention, there is provided the auxiliary capacitor according to any one of the first to fifth aspects, comprising an auxiliary capacitor that supplements the capacity of the smoothing capacitor, and the auxiliary capacitor, the P-side bus bus and the N-side bus bar. The bus is connected by the outflow current suppressing connection conductor.
[0021]
The invention according to claim 7 is the invention according to any one of claims 2 to 5, wherein the switching element arm of one group and the switching element arm of the other group of the two adjacent groups have the same load. Connected to the connecting bus, the load connecting bus is formed so that the impedance corresponding to one group side and the impedance corresponding to the other group side have a predetermined ratio, The position defined at the predetermined ratio and the P-side bus bar and the N-side bus bar are connected by the outflow current suppressing connection conductor.
[0022]
The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the load connecting bus of the group closest to the P-side bus bus and the N-side bus bus among the plurality of groups is the P-side bus. It is directly connected to the bus and the N-side bus bar.
[0023]
The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein a snubber capacitor is connected between the P side and the N side of the load connection buses of each group. Features.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the same components as those described in FIGS. 14 to 18 are denoted by the same reference numerals, and redundant description will be omitted. FIG. 1 is a plan view showing the main structure of the first embodiment of the present invention, and FIG. 2 is a view taken along the line BB in FIG. FIG. 1 corresponds to FIG. 15 showing the conventional structure, and shows a connection structure for only the U-phase switching element arm, but the V-phase and W-phase connection structures are also the same as FIG. It is.
[0025]
FIG. 1 differs from FIG. 15 in that the load connecting buses 6P and 6N are formed by separating the load connecting buses 6P1 and 6P2 and 6N1 and 6N2, respectively, and the bus busses 9P and 9N are separated from each other. This is the point of being connected by connection conductors 13P1, 13P2, 13N1, and 13N2 for controlling outflow current.
[0026]
That is, the capacitor connection 6Pa1 of the P-side load connection bus 6P1 is connected to the positive terminal of the capacitor 3A, and this capacitor connection 6Pa1 is connected to the P-side bus 9P by the outflow current suppressing connection conductor 13P1. . The outflow current suppressing connection conductor 13P1 has a higher impedance than the P-side load connection bus 6P1 and the P-side bus bus 9P. In this embodiment, for example, a hyperon wire is used. The capacitor connection 6Na1 of the N-side load connection bus 6N1 is connected to the negative terminal of the capacitor 3B. The capacitor connection 6Na1 is also connected to the N-side bus bus by the outflow current suppressing connection conductor 13N1 using a hyperon wire. Connected to 9N.
[0027]
Similarly, the capacitor connection 6Pa2 of the P-side load connection bus 6P2 is connected to the positive terminal of the capacitor 3C, and this capacitor connection 6Pa2 is connected to the P-side bus 9P by the outflow current suppressing connection conductor 13P2. Yes. The capacitor connection 6Na2 of the N-side load connection bus 6N2 is connected to the negative terminal of the capacitor 3D, and the capacitor connection 6Na2 is connected to the N-side bus 9S by the outflow current suppressing connection conductor 13N2. .
[0028]
FIG. 3 is a circuit diagram showing a connection state of each switching element in FIG. FIG. 3 differs from FIG. 18 in that impedance XP3 and XN3 are added between the capacitors 3A and 3B and the bus buses 9P and 9N by connecting the outflow current suppressing connection conductors 13P1 and 13N1. In addition, since the outflow current suppressing connection conductors 13P2 and 13N2 are connected, impedances XP4 and XN4 are added between the capacitors 3C and 3D and the bus buses 9P and 9N.
[0029]
Next, the operation and action of the first embodiment configured as described above will be described. Now, for example, it is assumed that both the switching elements UP1 and UN1 are turned on at the same time, and the switching element arm is short-circuited. Then, the current detection means (not shown) such as a Hall element detects that a current of a certain level or more has flowed, turns on all the switching elements for a predetermined time, and distributes the short-circuit current. Reduce the amount of current flowing through the. As a result, currents from the capacitors 3A and 3B belonging to the first group flow through the switching element arms UP1 and UN1 and UP2 and UN2 belonging to the same first group via the impedances XP1 and XN1, respectively, The currents from the capacitors 3C and 3D belonging to this group flow through the switching element arms UP3 and UN3 belonging to the same second group via the impedances XP1 and XN1.
[0030]
At this time, the current from the capacitors 3A and 3B of the first group is likely to slightly flow out to the switching element arms UP3 and UN3 side of the second group through the outflow current suppressing connection conductors 13P1, 13P2, 13N1, and 13N2. However, since the high impedances XP3, XN3, XP4, and XN4 exist, this outflow is greatly suppressed. Or, conversely, the current from the capacitors 3C, 3D of the second group passes to the switching element arms UP1, UN1, UP2, UN2 side of the first group via the outflow current suppressing connection conductors 13P1, 13P2, 13N1, 13N2. Even if it is likely to flow out, since the high impedances XP3, XN3, XP4, and XN4 exist, this outflow is also greatly suppressed.
[0031]
Therefore, there is a large difference between the gate-emitter voltage of each switching element UP1, UN1 and UP2, UN2 of the first group and the voltage of each switching element UP3, UN3 of the second group. It does not occur, and oscillation does not occur in the gate signal of each switching element during a predetermined time when all the switching elements are turned on. Therefore, generation of surge voltage can be prevented.
[0032]
FIG. 4 is a plan view showing the main structure of the second embodiment of the present invention. In the first embodiment, the U phase is configured by the first group having the element parameter of 2 and the second group having the element parameter of 1. However, in the second embodiment, the U phase has the U phase. These are both constituted by the first and second groups having the element parameter of 2. 4 differs from FIG. 1 in that a switching element arm formed by switching elements UP4 and UN4 is added, and the element connection portions 6Pb2 and 6Nb2 are switched not only by the collector of the switching element UP3 but also by the emitter of the switching element UN3. The only difference is that it is also connected to the collector of element UP4 and the emitter of switching element UN4. Therefore, also in the configuration of the second embodiment, similarly to the configuration of the first embodiment, it is possible to avoid the oscillation of the gate signal during the short circuit protection operation period and to prevent the generation of the surge voltage.
[0033]
FIG. 5 is a plan view showing the main structure of the third embodiment of the present invention. This embodiment has a configuration including an auxiliary smoothing capacitor that does not belong to any group. That is, each group has a smoothing capacitor belonging to itself, but the capacity of the smoothing capacitor may become insufficient due to changes in various conditions. Therefore, in order to compensate for the shortage of the capacity of the entire smoothing capacitor, an independent auxiliary capacitor that does not belong to any group is provided, so that the situation where the smoothing capacitor of each group runs short due to changes in various conditions can be dealt with. I have to. Capacitors 3E and 3F in the figure are such auxiliary capacitors.
[0034]
In FIG. 5, the auxiliary capacitors 3E and 3F are arranged between the second group of smoothing capacitors 3D and the bus buses 9P and 9N, and have substantially the same shape as the capacitor connecting portions 6Pa1 and 6Na1. Connection buses 6P3 and 6N3 are connected to the positive terminal of the capacitor 3E and the negative terminal of the capacitor 3F, respectively. The negative terminal of the capacitor 3E and the positive terminal of the capacitor 3F are connected by a capacitor connection bus 7. The connection bus 6P3 and the P-side bus 9P are connected by the outflow current suppressing connection conductor 13P3, and the connection bus 6N3 is connected by the outflow current suppressing connection conductor 13N3.
[0035]
FIG. 6 is a circuit diagram showing a connection state of each switching element in FIG. The auxiliary capacitors 3E and 3F are connected to the bus buses 9P and 9N. Since this connection is made by the outflow current suppressing connection conductors 13P3 and 13N3, the result is that high impedances XP5 and XN5 are added. It has become. Therefore, it is possible to effectively block the current from the auxiliary capacitors 3E and 3F that try to flow out to each switching element that is turned on during the short-circuit protection operation period, avoid the oscillation of the gate signal, and suppress the surge voltage. Occurrence can be prevented.
[0036]
FIG. 7 is a plan view showing the main structure of the fourth embodiment of the present invention. In the configuration of FIG. 7, the capacitor connection portions 6Pa1 and 6Pa2 and 6Na1 and 6Na2 in FIG. 1 are integrally formed to form capacitor connection portions 6Pa and 6Na. The shape of the capacitor connection portions 6Pa and 6Na in FIG. 7 is substantially the same on the upper half side and the lower half side, as is apparent from comparison with the capacitor connection portions 6Pa and 6Na in FIG. The impedance corresponding to the first group side and the impedance corresponding to the second group side are formed to have a one-to-one ratio.
[0037]
Therefore, the current from the capacitors 3A to 3D flows to the first and second groups at a substantially equal rate, and as a result, the current from the capacitors 3A and 3B flows to the first group. It can be considered that the current from the capacitors 3C and 3D flows to the second group. Such an effect is difficult to expect in the case of a normal amount of current, but when a large amount of current flows as in short circuit protection, the impedance value of the bus member is thus reduced. By adjusting, a remarkable effect that cannot be ignored can be obtained. The configuration of FIG. 7 shows the case where the element parameter number of the second group is 2, but when the element parameter number of the second group is 1, the ratio of the impedance is 1: 2. What is necessary is just to form the capacitor | condenser connection part 6Pa so that it may become.
[0038]
In the case of this embodiment, each of the capacitor connecting portions 6Pa and 6Na is integrally formed by the same member and is shared by both the first and second groups. As described above, it is difficult to say that “an individual load connection bus is formed for each group”. However, as described above, even though they are formed of the same member in appearance, as a result, it is possible to obtain the effect that the current from the own capacitor flows in each group. It can be considered that an individual load connection bus is formed every time.
[0039]
The capacitor connecting portions 6Pa and 6Na and the bus bars 9P and 9N are connected by one outflow current suppressing connection conductors 13P and 13N, respectively. The attachment position Q1 on one end side of the outflow current suppressing connection conductor 13P on the capacitor connection portion 6Pa defines an impedance component corresponding to the first group side and an impedance component corresponding to the second group side. The position, that is, the substantially central position in the vertical direction of the capacitor connecting portion 6Pa. Similarly, the attachment position Q2 on one end side of the outflow current suppressing connection conductor 13N on the capacitor connecting portion 6Na defines an impedance component corresponding to the first group side and an impedance component corresponding to the second group side. This is the position at which the capacitor is connected, that is, the substantially central position in the vertical direction of the capacitor connecting portion 6Na.
[0040]
Since the load connection buses 6P, 6N and the bus bus buses 9P, 9N are thus connected by the outflow current suppressing connection conductors 13P, 13N, the current from the V phase or the W phase flows into the U phase. Can be effectively suppressed. Even if it flows in, the one end side of the outflow current suppressing connection conductors 13P and 13N is attached to the positions Q1 and Q2 on the load connection buses 6P and 6N. 2 can flow evenly. Furthermore, in this embodiment, the number of connecting conductors for suppressing outflow current to be connected is only one of 13P and 13N, so that the wiring work of the worker at the time of assembly can be facilitated.
[0041]
FIG. 8 is a plan view showing the main structure of the fifth embodiment of the present invention. In the fifth embodiment, each end of the capacitor connecting portions 6Pa2 and 6Nb2 of the load connecting buses 6P2 and 6N2 of the second group which is the group closest to the bus busses 9P and 9N is directly connected to the bus bus buses 9P and 9N. It is intended to be connected. The first group load connection buses 6P1 and 6N1 are connected by the outflow current suppressing connection conductors 13P and 13N.
[0042]
Therefore, the four outflow current suppressing connection conductors used in FIG. 1 can be reduced to two in this embodiment, and the wiring work for the worker can be facilitated accordingly. In general, since various wire rods are connected to the bus bar, it is required to reduce the number of wires connected to the bus bar as much as possible, but the configuration of FIG. 8 meets this requirement. It has become a thing.
[0043]
FIG. 9 is a plan view showing the main structure of the sixth embodiment of the present invention, and FIG. 10 is a circuit diagram showing the connection state of each switching element in FIG. 9 has substantially the same configuration as that of FIG. 1, but a snubber capacitor 14A is arranged between the connection points of the outflow current suppressing connection conductors 13P1 and 13N1 in the load connection buses 6P1 and 6N1, and similarly for load connection. The difference is that a snubber capacitor 14B is disposed between the connection points of the outflow current suppressing connection conductors 13P2 and 13N2 in the buses 6P2 and 6N2.
[0044]
Between the load connection buses 6P1 and 6N1 and between the load connection busses 6P2 and 6N2, the outflow current suppression connection conductors 13P1 and 13N1 and the outflow current suppression connection conductors 13P2 and 13N2 having large impedance are connected, respectively. Voltage is likely to be generated. However, in the configuration of FIG. 9, since a large voltage change between the P-side bus member and the N-side bus member can be absorbed by the snubber capacitors 14A and 14B, the generation of a surge voltage can be effectively prevented. As described above, according to the sixth embodiment, it is possible to prevent the outflow current suppression connecting conductor originally added for the purpose of preventing the generation of the surge voltage from causing the generation of the surge voltage from another viewpoint. it can.
[0045]
FIG. 11 and FIG. 12 are explanatory views showing a schematic configuration of a main part of the seventh and eighth embodiments of the present invention, respectively. In each of the embodiments described so far, one phase (for example, U phase) is divided into two groups and the total number of element parameters is 3 or 4. However, these embodiments have one The phases are divided into groups of 3 or more, and the total number of elements is 5 or more or 6 or more.
[0046]
That is, FIG. 11 shows a configuration in the case where the U phase is composed of first to Mth (M is an integer of 3 or more) group units, and the total number of element parameters is an odd number of 2M-1. Show. In this case, as shown in the figure, each of the first to M−1 groups has an element parameter of 2, and only the last M-th group has an element parameter of 1. Each group and the bus buses 9P, 9N are connected to each other by connecting conductors 13P1, 13N1,..., 13P (M-1), 13N (M-1),.
[0047]
FIG. 13 is a detailed configuration diagram of the units of each group in FIG. 11, and FIG. 13A is a configuration diagram of the units of the first group (units of the second to M-1th groups are the same configuration as this). (B) is a block diagram of units of the Mth group. As is apparent from the drawing, FIG. 13A has the same configuration as the first group in FIG. 1, and FIG. 13B has the same configuration as the second group in FIG. It is what has.
[0048]
FIG. 12 shows a configuration in which the U phase is configured by units of first to Mth groups (M is an integer of 3 or more), and the total number of element parameters is an even number of 2M. In this case, as shown in the figure, each of the first to Mth groups has two element parameters. Each group and the bus bars 9P, 9N are connected by the outflow current suppressing connection conductors 13P1, 13N1,..., 13PM, 13NM.
[0049]
Thus, according to the seventh and eighth embodiments, a combination of a plurality of groups having two element parameters and one group having one element parameter, or a plurality of groups having two element parameters. One phase can be composed of a large number of element parameters by combination. Therefore, even if the number of element parameters increases, design work and assembly work on site can be simplified, and the components can be shared.
[0050]
【The invention's effect】
As described above, according to the present invention, an individual load connection bus is formed for each group, and the load connection bus is connected between the load connection bus and the P-side bus bus and the N-side bus bus. In addition, an outflow current suppression connecting conductor having a higher impedance than the P-side bus bus and the N-side bus bus is connected, and the amount of current flowing out from the smoothing capacitor belonging to each group to the other group during the short-circuit protection operation is suppressed. Since the configuration is adopted, it is possible to suppress the generation of a surge voltage and perform a reliable and stable short-circuit protection operation.
[Brief description of the drawings]
FIG. 1 is a plan view showing a main part structure of a first embodiment of the present invention.
FIG. 2 is a view taken along arrow BB in FIG.
3 is a circuit diagram showing a connection state of each switching element in FIG. 1;
FIG. 4 is a plan view showing a main part structure of a second embodiment of the present invention.
FIG. 5 is a plan view showing a main part structure of a third embodiment of the present invention.
6 is a circuit diagram showing a connection state of each switching element in FIG. 5;
FIG. 7 is a plan view showing a main part structure of a fourth embodiment of the present invention.
FIG. 8 is a plan view showing a main part structure of a fifth embodiment of the present invention.
FIG. 9 is a plan view showing the main structure of a sixth embodiment of the present invention.
10 is a circuit diagram showing a connection state of each switching element in FIG. 9;
FIG. 11 is an explanatory diagram showing a schematic configuration of a main part of a seventh embodiment of the present invention.
FIG. 12 is an explanatory diagram showing a schematic configuration of a main part of an eighth embodiment of the present invention.
13 is a detailed configuration diagram of units in each group in FIG. 11, wherein (a) is a configuration diagram of units in a first group, and (b) is a configuration diagram of units in an Mth group.
FIG. 14 is a main circuit configuration diagram of a power conversion device including a converter unit and an inverter unit.
15 is a plan view showing a connection structure for a U-phase switching element arm in FIG. 14;
16 is an AA arrow view of FIG.
FIG. 17 is an explanatory diagram showing a schematic structure of a U / R phase unit 10 that houses the U-phase switching element arm of the inverter unit 2 and the R-phase switching element arm of the converter unit 1 in FIG. 14;
18 is a circuit diagram showing a connection state of each switching element in FIG.
[Explanation of symbols]
1 Converter section
2 Inverter section
3,3A-3E Smoothing capacitor
4 3-phase AC power supply
5 Induction motor
RP, RN Converter side R phase switching element
SP, SN Converter side S phase switching element
TP, TN Converter side T phase switching element
UP, UN Inverter side U-phase switching element
VP, VN Inverter side V-phase switching element
WP, WN Inverter side W-phase switching element
UP1-UP4 U-phase P-side switching element
UN1-UN4 U-phase N-side switching element
C Switching element collector
E Emitter of switching element
G Gate of switching element
D Reverse voltage prevention diode
6P P side load connection bus
6Pa, 6Pa1, 6Pa2 capacitor connection
6Pb1, 6Pb2 element connection
6Pc1, 6Pc2 joint
6N N side load connection bus
6Na, 6Na1, 6Na2 capacitor connection
6Nb1, 6Nb2 element connection
6Nc1, 6Nc2 joint
7 Capacitor connection bus
8 element connection bus
9P P side bus bar
9N N side bus bar
10 U / R phase unit
11 Case
11a frame
12 Cooler
12a Cooling fin 1
13P, 13P1-13P3 P side outflow current suppression connection conductor
13N, 13N1 to 13N3 N side outflow current suppression connection conductor
14A, 14B Snubber capacitor
XP1, XN1 Impedance of the first group
XP2, XN2 Impedance of the second group
XP3 to XP5, XN3 to XN5 Impedance of outflow current suppression connection conductor

Claims (9)

A converter unit and an inverter unit are provided, and one phase of the converter unit and the inverter unit is constituted by a plurality of sets of switching element arms, and the plurality of sets of switching element arms are divided into a plurality of groups in units of groups having a predetermined element number. And each group has a smoothing capacitor connected to the plurality of sets of switching element arms via a load connection bus, and the one phase includes a P-side bus bus and an N-side bus bus. If a short circuit accident occurs in any of the switching element arms, the operation is stopped after all the switching element arms are turned on for a predetermined time. In the power converter that performs short-circuit protection operation by
An individual load connection bus is formed for each group, and the load connection bus, the P side bus bus and the N side are connected between the load connection bus and the P side bus bus and the N side bus bus. A connection conductor for suppressing outflow current having an impedance higher than that of the bus bar is connected, and the amount of current flowing out from the smoothing capacitor belonging to each group to the other group during the short-circuit protection operation is suppressed. Power converter. Each group having the predetermined element number is a first group having an element number of 2 and a second group having an element number of 1.
The power conversion device according to claim 1. Each group having the predetermined element parameter is a first group and a second group each having an element parameter of 2.
The power conversion device according to claim 1. Each group having the predetermined element parameter number is a first to M−1th group having an element parameter number of 2 and an Mth group having an element parameter number of 1 (M is an integer of 3 or more).
The power conversion device according to claim 1. Each group having the predetermined element parameter number is a first to Mth group in which the element parameter number is 2 (M is an integer of 3 or more).
The power conversion device according to claim 1. An auxiliary capacitor for compensating the capacity of the smoothing capacitor is provided, and the auxiliary capacitor and the P-side bus bus and the N-side bus bus are connected by the connecting conductor for suppressing outflow current,
The power converter according to any one of claims 1 to 5 characterized by things. The switching element arm of one group of the two adjacent groups and the switching element arm of the other group are connected to the same load connection bus, and this load connection bus corresponds to one group side. The impedance component corresponding to the other group side and the impedance component corresponding to the other group side are formed at a predetermined ratio, and the positions defined by the predetermined ratio, the P-side bus bus and the N-side bus bus Are connected by the outflow current suppressing connection conductor,
The power conversion device according to claim 2, wherein the power conversion device is a power conversion device. The load connection buses of the group closest to the P-side bus bus and the N-side bus bus among the plurality of groups are directly connected to the P-side bus bus and the N-side bus bus,
The power converter according to any one of claims 1 to 7 characterized by things. A snubber capacitor is connected between the P side and the N side of the load connecting buses of each group,
The power converter according to any one of claims 1 to 8, wherein

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