JP2003189633A - Power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power converter for reducing inductance of a circuit made up of a smoothing capacitor and a switching element. <P>SOLUTION: Each phase fuse 11, 21, and 31 is inserted between a positive-side DC main line and each phase unit block 41, 42, and 43. When a V-phase switching element 22 or 23 is short-circuited, short-circuited currents B and C of other phase smooth capacitors 16 and 36 are caused to flow into the V- phase fuse 21, and the current is twice the current carried at the other phase fuses 11 and 31. When a fuse that is brown out by melting at about the two- times current is selected, only the V-phase fuse is blown out by melting. In this constitution, a circuit made up of the smooth capacitor and the switching element has no unnecessary part, and circuital inductance can be reduced to a maximum. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage-type power conversion device such as a two-level inverter device or a three-level inverter device, and more particularly to a protective fuse for a short circuit failure.

[0002]

2. Description of the Related Art In a conventional voltage type power conversion device, FIG. 7 is a block diagram of a two-level inverter device. In the case of a two-level inverter device, as shown in FIG.
Regarding the phase, the protective fuse 11 is the smoothing capacitor 1
It was installed in the form inserted between 6 and the positive side switching element 12. The same applies to the V phase and the W phase.

FIG. 8 is a schematic configuration diagram of a three-level inverter device, FIG. 9 is an internal configuration diagram of a U-phase unit block 44 of the three-level inverter device, and in the case of the three-level inverter device, FIG. As shown in FIG. 9, for the U-phase unit block 44, for example, the protective fuse 1
1. The protective fuse 19 was installed in such a manner that it was inserted between the smoothing capacitor and the switching element.
The same applies to the V-phase unit block 45 and the W-phase unit block 46.

[0004]

In the prior art, when a short-circuit fault occurs, the fuse can be blown by the short-circuit current flowing from the smoothing capacitor in the fault occurrence phase, but on the other hand, the smoothing capacitor and the switching element are Due to the presence of the fuse, the circuit inductance increases correspondingly, and the surge voltage generated when the switching element cuts off the current increases.

According to the present invention, when a short circuit fault occurs,
The fuse cannot be blown by the short-circuit current flowing from the smoothing capacitor of the failure phase, but the fuse can be blown by the short-circuit current of the smoothing capacitor of the other phase, and the inductance of the circuit composed of the smoothing capacitor and the switching element is reduced. Therefore, it is an object of the present invention to provide a power conversion device having a feature that the surge voltage can be reduced.

[0006]

In order to solve the above problems, the present invention relates to a voltage type power converter for converting DC power into three-phase AC power, in which a smoothing capacitor is installed for each phase and smoothing is performed. Connect the positive electrode of the capacitor to the positive side DC bus side electrode of the positive side switching element and the positive side DC bus side electrode of the positive side reverse conducting diode, and connect the negative electrode of the smoothing capacitor and the negative side DC bus line of the negative side switching element. Side unit and the negative side DC bus side electrode of the negative side reverse conducting diode are provided for each phase, and each phase unit block is provided with a positive side or a negative side and a DC bus line between the positive side and the negative side. It is characterized in that a fuse is provided in either one or both.

According to the present invention, there is provided a power conversion device capable of fusing a fuse by a short-circuit current flowing from a smoothing capacitor of another phase when a short-circuit fault occurs and minimizing the circuit inductance composed of a smoothing capacitor and a switching element. it can.

Further, according to the present invention, in a voltage type three-level power converter for converting DC power into three-phase AC power, a positive-side smoothing capacitor and a negative-side smoothing capacitor are installed for each phase, and a switching element is 4 Connect in series with each other, connect a diode in anti-parallel to each switching element, connect one pole of the positive side clamp diode to the midpoint of the positive side smoothing capacitor and the negative side smoothing capacitor, and switch the other pole. Connect between the 1st element and the 2nd element counting from the positive side DC bus of the element, and connect one pole of the negative side clamping diode to the middle point of the positive side smoothing capacitor and the negative side smoothing capacitor. , The other pole is the first element counting from the negative side DC bus of the switching element and 2
Connected between the positive side of the positive side smoothing capacitor and the positive side DC bus of the switching element connected to the positive side of the positive side DC bus of the switching element, and the negative side of the negative side smoothing capacitor. And a phase unit block having a configuration in which the electrode on the negative side DC bus side of the first element counting from the negative side DC bus line of the switching element is connected for each phase, and the positive side or the negative side of each phase unit block It is characterized in that a fuse is provided on both sides of the DC bus.

According to the present invention, when a short-circuit fault occurs, the fuse can be blown by the short-circuit current flowing from the other-phase smoothing capacitor, and the circuit inductance composed of the smoothing capacitor and the switching element can be minimized. Can be provided.

[0010]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. In the following drawings, the same reference numerals indicate the same or corresponding parts including the drawings of the conventional example.

(First Embodiment) A first embodiment of the power converter according to the present invention will be described with reference to FIG.

In the first embodiment constituting the voltage type two-level power converter, as shown in FIG. 1, the DC power supplied from the DC power source 1 is supplied to the U side through the positive side DC bus and the negative side DC bus. It is supplied to the phase unit block 41, the V phase unit block 42, and the W phase unit block 43 via the U phase fuse 11, the V phase fuse 21, and the W phase fuse 31, respectively. Here, the fuse is inserted between the positive side DC bus and each phase unit block, but it may be inserted between the negative side DC bus and each phase unit block. Also, it may be included in both of the above.

The internal structure of each phase unit block 41, 42, 43 is, for example, as shown in FIG.
1 includes a smoothing capacitor 16, a positive side switching element 12, a negative side switching element 13, a positive side reverse conducting diode 14 and a negative side reverse conducting diode 15. Then, the positive electrode of the smoothing capacitor 16 and the collector which is the positive side DC bus side electrode of the positive side switching element 12 and the cathode which is the positive side DC bus side electrode of the positive side reverse conducting diode 14 are connected, and the smoothing capacitor 16 is connected. Of the negative side switching element 13 is connected to the negative side DC bus side electrode of the negative side switching element 13 and the negative side reverse conducting diode 15 is connected to the negative side DC bus side electrode of the anode. V-phase unit block 42, W-phase unit block 43
Is also the same.

FIG. 2 shows the operation when a short-circuit fault occurs in the V-phase switching elements 22 and 23. First, the short-circuit current A is V from the V-phase smoothing capacitor 26.
It flows through the phase switching elements 22 and 23. Since this current does not pass through the V-phase fuse 21, the fuse 21
Is not blown.

Next, the short-circuit current B flows from the U-phase smoothing capacitor 16 through the U-phase fuse 11, the V-phase fuse 21, and the V-phase switching elements 22 and 23. At the same time, the short-circuit current C from the W-phase smoothing capacitor 36 causes the W-phase fuse 3
1, V-phase fuse 21, V-phase switching element 22, 2
Flow through 3.

From the above, the U-phase fuse 11 and the W-phase fuse 3 are included in the V-phase fuse 21 which is the failure occurrence phase.
A current that is twice as large as the current flowing in 1 flows, and by selecting a fuse having a characteristic of being blown by about twice the current, it becomes possible to blow only the V-phase fuse 21.

Further, in this circuit configuration, there is no extra component in the circuit composed of the smoothing capacitor and the switching element (for example, for the U phase, the U-phase fuse 11 includes the U-phase smoothing capacitor 16 and the switching element 14).
The circuit inductance can be minimized because it does not have the configuration of the conventional example that exists between and. As a result, the surge voltage generated at the time of current interruption can be reduced, so that the maximum interruption current can be increased or the DC voltage can be increased, and a power conversion device capable of expanding the device capacity can be provided.

(Second Embodiment) Next, referring to FIG.
A second embodiment of the power conversion device according to the present invention will be described.

In this embodiment, as shown in FIG. 3, in addition to the structure of the first embodiment, a collective smoothing capacitor 3 is provided between the positive side DC bus and the negative side DC bus. . With such a configuration, for example, when a short-circuit failure occurs in the V-phase switching elements 22 and 23, the short-circuit current D from the collective smoothing capacitor 3 is added as the short-circuit current flowing in the V-phase fuse 21. Therefore, the V-phase fuse 21 can be blown at a higher speed and more easily.

(Third Embodiment) Next, a third embodiment of the power converter according to the present invention will be described with reference to FIGS. 4 and 5. Note that FIG. 4 also shows the collective positive-side smoothing capacitor 4 and the collective negative-side smoothing capacitor 5 for use in the description of the following fourth embodiment, but this third embodiment is shown.
In these embodiments, these parts are absent.

In the third embodiment constituting the voltage type three-level power converter, as shown in FIG. 4, the DC power supplied from the DC power supply 1 is a positive DC bus, a neutral point,
The U-phase unit block 44, the V-phase unit block 45, and the W-phase unit block 46 are respectively connected to the U-phase through the negative side DC bus.
Phase fuses 11, 19 and V phase fuses 21, 2
9 and W-phase fuses 31 and 39.

The internal structure of each phase unit block is, as shown in FIG. 5, a positive side smoothing capacitor, a negative side smoothing capacitor,
It consists of four switching elements connected in series and a diode connected in anti-parallel to each switching element, a positive side clamping diode and a negative side clamping diode. Then, connect the anode, which is one pole of the positive side clamp diode, to the midpoint of the positive side smoothing capacitor and the negative side smoothing capacitor, and the cathode that is the other pole is the first counting from the positive side DC bus of the switching element. Connected between the element of No. 2 and the second element, and connect the cathode, which is one pole of the negative side clamp diode, to the midpoint of the positive side smoothing capacitor and the negative side smoothing capacitor, and the other pole anode. It is connected between the first element and the second element counting from the negative side DC bus of the switching element.
Also, the positive electrode of the positive side smoothing capacitor and the collector, which is the electrode on the positive side DC bus side of the first element counting from the positive side DC bus of the switching element, are connected, and the negative electrode of the negative side smoothing capacitor and the negative side of the switching element are connected. 1 counting from the side DC bus
The third element is connected to the emitter, which is the electrode on the negative DC bus side.

Next, the operation of the third embodiment will be described with reference to FIG.
Will be described with reference to. Since FIG. 6 is also used for the description of the operation of the next fourth embodiment, the collective positive-side smoothing capacitor 4,
And the collective negative side smoothing capacitor 5 exists, and the short circuit current D
Are displayed, it is assumed that these parts do not exist in the operation of the third embodiment.

As shown in FIG. 6, when a short circuit failure occurs in the first, second and third elements from the positive side DC bus of the V phase switching element, first, the short circuit current A is output from the V phase positive side smoothing capacitor. It flows through three V-phase switching elements and the V-phase negative side clamp diode. Since this current does not pass through the V-phase positive side fuse 21, the fuse 21
Is not blown.

Next, the short-circuit current B from the U-phase positive-side smoothing capacitor causes the U-phase positive-side fuse 11, the V-phase positive-side fuse 21, and the
It flows through three V-phase switching elements and the V-phase negative side clamp diode. At the same time, a short-circuit current C similarly flows from the W-phase positive side smoothing capacitor.

From the above, a current twice as much as the current flowing through the U-phase positive fuse 11 and the W-phase positive fuse 31 flows through the V-phase positive fuse 21 which is the failure occurrence phase, By selecting a fuse having the characteristic of being blown by a current of about twice, it becomes possible to blow only the V-phase positive side fuse 21.

Further, in this circuit configuration, since there is no extra component in the circuit composed of the smoothing capacitor and the switching element, the circuit inductance can be minimized.
As a result, the surge voltage generated at the time of current interruption can be reduced, so that the maximum interruption current can be increased or the DC voltage can be increased, and a power conversion device capable of expanding the device capacity can be provided.

(Fourth Embodiment) Next, referring to FIG.
A fourth embodiment of the power conversion device according to the present invention will be described.

In this embodiment, as shown in FIG. 6, in addition to the structure of the third embodiment, a collective positive side smoothing capacitor 4 is provided between the positive side DC bus and the neutral point, and a negative side. The collective negative side smoothing capacitor 5 is provided between the DC bus and the neutral point. With such a configuration, when a short-circuit fault occurs in the first, second, and third elements from the positive-side DC bus of the V-phase switching element, a short-circuit current flowing through the V-phase positive-side fuse 21 is collectively positive. The short circuit current D from the side smoothing capacitor 4 will be added. Therefore, it becomes possible to blow the V-phase positive side fuse 21 at a higher speed and more easily.

[0030]

As described above, according to the present invention, it is possible to provide a power converter which can minimize the circuit inductance and can be protected by a fuse even when a short circuit failure occurs.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining a first embodiment of a power conversion device according to the present invention.

FIG. 2 is a diagram for explaining the operation of the first embodiment of the power conversion device according to the present invention.

FIG. 3 is a configuration diagram for explaining a second embodiment of a power conversion device according to the present invention.

FIG. 4 is a third and a fourth power conversion device according to the present invention.
FIG. 3 is a configuration diagram for explaining an embodiment of FIG.

5 is an internal configuration diagram of each unit block in FIG.

FIG. 6 is a third and a fourth power conversion device according to the present invention.
For explaining the operation of the embodiment of FIG.

FIG. 7 is a configuration diagram of a conventional power conversion device.

FIG. 8 is a configuration diagram of a conventional three-level power conversion device.

9 is an internal configuration diagram of a U-phase unit block in FIG.

[Explanation of symbols] 1 ... DC power supply 2 ... Motor 3 ... Collective smoothing capacitor 4 ... Collective positive side smoothing capacitor (for 3 levels) 5 ... Collective negative side smoothing capacitor (for 3 levels) 11 ... U phase fuse or U phase Positive side fuse (for 3 levels) 12 ... U phase positive side switching element 13 ... U phase negative side switching element 14 ... U phase positive side diode 15 ... U phase negative side diode 16 ... U phase smoothing capacitor 19 ... U phase negative side Fuse (for 3 levels) 21 ... V phase fuse or V phase positive side fuse (for 3 levels) 22 ... V phase positive side switching element 23 ... V phase negative side switching element 24 ... V phase positive side diode 25 ... V phase Negative side diode 26 ... V phase smoothing capacitor 29 ... V phase negative side fuse (for 3 levels) 31 ... W phase fuse or W phase positive side fuse (for 3 levels) 32 ... W phase positive side switch Pitching element 33 ... W phase negative side switching element 34 ... W phase positive side diode 35 ... W phase negative side diode 36 ... W phase smoothing capacitor 39 ... W phase negative side fuse (for 3 levels) 41 ... U phase unit block 42 ... V-phase unit block 43 ... W-phase unit block 44 ... 3-level U-phase unit block 45 ... 3-level V-phase unit block 46 ... 3-level W-phase unit block

Claims (4)

[Claims] 1. A voltage type power converter for converting DC power into three-phase AC power, wherein a smoothing capacitor is provided for each phase, and the positive electrode of the smoothing capacitor and the positive side DC bus side of the positive side switching element are connected. An electrode and a positive side DC bus side electrode of the positive side reverse conducting diode, and a negative electrode of the smoothing capacitor and a negative side DC bus side electrode of the negative side switching element and a negative side DC bus side of the negative side reverse conducting diode. Each phase is provided with a phase unit block configured to connect to a side electrode, and a fuse is provided on either or both of the positive or negative side of each phase unit block and the DC busbar. Power converter. 2. The power conversion device according to claim 1, wherein:
A power conversion device comprising a collective smoothing capacitor different from the smoothing capacitor installed for each phase. 3. A voltage type 3-level power converter for converting DC power into 3-phase AC power, wherein a positive-side smoothing capacitor and a negative-side smoothing capacitor are provided for each phase, and four switching elements are connected in series. Then, a diode is connected in antiparallel to each of the switching elements, one pole of the positive side clamp diode is connected to the midpoint of the positive side smoothing capacitor and the negative side smoothing capacitor, and the other pole is connected to the switching element. 1 from the positive side DC bus of
Is connected between the second element and the second element, one pole of the negative side clamp diode is connected to the midpoint of the positive side smoothing capacitor and the negative side smoothing capacitor, and the other pole is connected to the switching element. Connected between the first element and the second element counting from the negative side DC bus, the positive side DC of the first element counting from the positive side of the positive side smoothing capacitor and the positive side DC bus of the switching element. A phase unit block having a configuration in which an electrode on the busbar side is connected and the negative electrode of the negative side smoothing capacitor and the electrode on the negative side DC busbar side of the first element counting from the negative side DC busbar of the switching element are connected. A power conversion device, characterized in that a fuse is provided for each phase and provided both between the positive or negative side of each phase unit block and the DC bus. 4. The power conversion device according to claim 3,
A power converter comprising a collective positive side smoothing capacitor and a collective negative side smoothing capacitor, which are different from the positive side smoothing capacitor and the negative side smoothing capacitor installed for each phase.