JP3660480B2 - Power converter wiring structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wiring structure of a power conversion device, and more particularly to a wiring structure of a power conversion device that prevents partial discharge between wirings to which a high voltage is applied.
[0002]
[Prior art]
Conventionally, a GTO (gate turn-off thyristor) inverter is used for driving an induction motor of a rolling mill. As this inverter, a three-level inverter is used. FIG. 6 shows a circuit example of an inverter for one phase.
[0003]
In the figure, 1 to 4 are GTOs, 5 to 8 are free wheel diodes, 9 and 10 are anode reactors, 11 to 14 are snubber diodes, 15 to 18 are snubber capacitors, 19 to 22 are diodes of a voltage clamp circuit, 24 is a clamp diode for three levels, 25 to 28 are voltage clamp circuit capacitors, 29 and 30 are power supply capacitors, 31 and 32 are DC power supplies, 33 and 34 are energy regeneration circuits, 35 is a resistor, and 36 is an output terminal. .
[0004]
This circuit is connected to a snubber circuit composed of diodes 11 to 14 and capacitors 15 to 18 for suppressing a surge voltage at the time of turn-off of each GTO 1 to 4 and preventing destruction of the GTO.
[0005]
The operation of this snubber circuit will be described when the GTO 1 is turned off.
[0006]
When the GTO 1 is turned on, a current path flowing through the GTO 1 is a DC power source 31-an ano-reactor 9-GTO 1 -GTO 2-an output terminal 36-a load-DC power source 32. When the GTO 1 is turned off in this state, the current of the GTO 1 decreases and the reduced current flows through the path of the snubber diode 11 and the snubber diode 15. Since the snubber capacitor 15 is charged by the energy accumulated in the anode reactor 9 even after the current of the GTO 1 becomes zero, the voltage of the snubber capacitor 15 becomes higher than that of the DC power supply 31, and the voltage is applied to the GTO 1. become. When other GTOs 2 to 4 are turned off, they operate in the same manner as GTO1.
[0007]
FIG. 7 shows current waveforms and voltage waveforms of GTO1 to GTO4 when turning off.
[0008]
When the currents of GTO1 to GTO4 decrease, spike-like voltages are applied to both ends of GTO1 to GTO4 as shown in the figure. When the peak value of this voltage is Vdsp, the current change rate di / dt of GTO 1 to 4, the wiring inductance ls of the snubber circuit, the voltage Vds of the snubber diodes 11 to 14, and the voltage Vcs of the snubber capacitors 15 to 18, The formula is obtained.
[0009]
Vdsp = ls × di / dt + Vds + Vcs
It is known that if the voltage Vdsp of the GTO 1 to 4 becomes too large, the GTO 1 to 4 are destroyed by the switching power and the GTO performance cannot be obtained. For this reason, as understood from the above equation, it is important to make the wiring inductance ls of the snubber circuit as small as possible.
[0010]
FIG. 8 is a diagram for explaining the principle for reducing the wiring inductance ls of the snubber circuits of GTO1 to GTO4.
[0011]
As shown in the drawing, a conductor A as a wiring from the snubber diode 11 to the snubber capacitor 15 and a conductor B as a wiring from the snubber capacitor 15 to GTO 1 are arranged close to each other in parallel, and between the conductor A and the conductor B, A solid insulator C is disposed. As a result, the current flowing through the snubber circuit, i.e., the current i flowing through the conductor A and the conductor B, has the same magnitude and flows in opposite directions, thereby canceling out the magnetic fluxes generated by both the currents i. The wiring inductance of the conductor A and the conductor B can be reduced.
[0012]
Next, an example of a conventional snubber circuit wiring structure will be described.
[0013]
FIG. 9A is a partial plan view showing a wiring structure composed of conductor A, conductor B, and insulator C, and FIG. 9B is a cross-sectional view of the wiring structure shown in FIG. 9A.
[0014]
As shown in these drawings, the width of the insulator C is larger than the width of the conductors A and B. With this configuration, it is possible to prevent creeping discharge that is discharged through the surface of the insulator C when a high voltage is applied between the conductors A and B.
[0015]
[Problems to be solved by the invention]
However, in the above conventional wiring structure, in order to reduce the wiring inductance, the conductors are arranged close to each other with an insulator interposed therebetween. Therefore, the GTO is turned off and a large voltage, for example, a high voltage of several thousand volts is applied between the conductors. When applied, a partial discharge is generated in the insulator, and local insulation deterioration progresses in the insulator, eventually leading to dielectric breakdown. Moreover, in order to prevent creeping discharge, there is a problem that the width of the insulator C must be larger than the width of the conductors A and B.
[0016]
In view of the above-mentioned various conventional problems, the present invention can prevent partial discharge in an insulator to prevent deterioration of the insulator, and can increase the creeping distance between conductors with a simple structure. Another object of the present invention is to provide a wiring structure for a power converter.
[0017]
[Means for Solving the Problems]
In connection with the on / off control of the semiconductor switching element that controls the load current, in the wiring structure of the power conversion device in which two wiring conductors that have the same current magnitude and flow in opposite directions are disposed in close proximity via an insulator,
The insulator is composed of a narrow part in contact with each wiring conductor and a wide part in contact with the wiring conductor via the narrow part, and the narrow part in contact with each wiring conductor is configured to be narrower than the wiring conductor, The portion of the wide portion that does not contact the narrow portion is configured wider than the wiring conductor, and the portion that contacts the wiring conductor via the narrow portion of the wide portion is disposed in the middle of each narrow portion that contacts the wiring conductor. It is characterized by that.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
[0023]
1A is a partial plan view showing an example of a wiring structure used in the snubber circuit of the power converter shown in FIG. 8, and FIG. 1B is a cross-sectional view of the wiring structure shown in FIG. is there.
[0024]
A is a conductor as a wiring from the snubber diode 11 to the snubber capacitor 15 shown in FIG. 8, B is a conductor as a wiring from the snubber capacitor 15 to GTO1, and C is a conductor A and a conductor arranged in parallel in close proximity. B is a solid insulator disposed between B.
[0025]
As shown in the figure, the solid insulator C includes a wide portion c2 that is wider than the conductors A and B, and a narrow portion that is formed integrally with the wide portion c2 and is narrower than the conductor A and is in contact with the conductor A. A portion c1 and a narrow portion c3 that is formed narrower than the conductor B and is in contact with the conductor B are configured. In addition, although the thickness of narrow part c1, c3 and the expansion part c2 can be set arbitrarily, in this embodiment, it forms in the substantially same thickness.
[0026]
As described above, according to the present embodiment, by configuring the solid insulator C in this way, the creepage distance on the solid insulator C from the conductor A to the conductor B can be set to the same wide insulation shown in the conventional example. Even if the GTO is turned off and a high voltage is applied between the conductors A and B, creeping discharge can be sufficiently prevented. In addition, since the solid insulator C is configured so that the conductor A and the conductor B are in contact with each other through the narrow portions c1 and c3, the partial discharge in the narrow portion can be made smaller than that of the conventional one. it can. Furthermore, the electric field strength at the ends of the conductors A and B can be weakened, and partial discharge from the ends can be prevented.
[0027]
Next, a second embodiment of the present invention will be described with reference to FIG.
[0028]
2A is a partial plan view showing an example of a wiring structure used in the snubber circuit of the power converter shown in FIG. 8, and FIG. 2B is a cross-sectional view of the wiring structure shown in FIG. is there.
[0029]
Compared with the first embodiment, the present embodiment is configured such that the narrow portions c1 and c3 of the solid insulator C shown in the first embodiment are integrally formed with the wide portion c2. The difference is that the narrow portions c1 and c3 and the wide portion c2 are configured separately, and the other configurations are not different.
[0030]
In the present embodiment, the same effects as in the first embodiment can be obtained, and the number of solid insulators to be superimposed can be arbitrarily set. As a result, the thicknesses of the narrow portions c1 and c2 and the wide portions c2 Each width can be set independently.
[0031]
Next, a third embodiment of the present invention will be described with reference to FIG.
[0032]
3A is a partial plan view showing an example of a wiring structure used in the snubber circuit of the power converter shown in FIG. 8, and FIG. 3B is a partial side view of the wiring structure shown in FIG. FIG.
[0033]
In this embodiment, the narrow portions c1 and c3 of the solid insulator C shown in the first and second embodiments are continuous in the length direction as in the wide portion c2 as compared with the first and second embodiments. In contrast, in the present embodiment, the narrow portion c1 and the narrow portion c3 have a predetermined distance in the length direction between the conductor A and the wide portion c2 and between the conductor B and the wide portion c2, respectively. It is different in that it is arranged so as to be scattered and other configurations are not different.
[0034]
In the present embodiment, the same effects as those of the first and second embodiments can be obtained, and the narrow portions c1 and c3 are considered in consideration of the strength of the wiring structure and the magnitude of the high voltage applied at turn-off. Arrangement, number, etc. can be set arbitrarily.
[0035]
Next, a fourth embodiment of the present invention will be described with reference to FIG.
[0036]
4A is a partial plan view showing an example of a wiring structure used in the snubber circuit of the power converter shown in FIG. 8, and FIG. 4B is a cross-sectional view of the wiring structure shown in FIG. is there.
[0037]
In the present embodiment, the cathode electrode of the snubber diode 11 (12 to 14) shown in FIG. 8 is provided on the surface of the conductor A opposite to the side where the solid insulator C is disposed, as compared with the third embodiment. It is different in that it is connected in a stacked manner, and other configurations are not different. In addition, H is a heat sink provided for heat dissipation of the snubber diode 11 (12 to 14).
[0038]
According to the present embodiment, the same effects as those of the third embodiment can be obtained, and the snubber diode 11 (12 to 14) and the conductor A are directly connected. In addition, the wiring inductance can be reduced.
[0039]
Furthermore, according to the present embodiment, the wiring structure unit configured as described above is integrated by tightening together four screws corresponding to the four snubber diodes 11 to 14 with screws. By comprising in this way, a some snubber circuit can be comprised compactly.
[0040]
Next, a fifth embodiment of the present invention will be described with reference to FIG.
[0041]
FIG. 5 is a partial cross-sectional view showing an example of a wiring structure used in the snubber circuit of the power conversion device shown in FIG.
[0042]
Compared with the third embodiment, this embodiment has a length direction of the wide portion c2 of the solid insulator C when connecting the snubber capacitor 15 connected to the end portions of the conductors A and B in the length direction. The length is different from that of the end portions of the conductors A and B, and other configurations are not different.
[0043]
This embodiment can achieve the same effects as those of the third embodiment, can increase the creeping distance between the terminals of the snubber capacitor 15, and can prevent creeping discharge.
[0044]
In each of the above-described embodiments, the arrangement structure of the conductor and the insulator for reducing the inductance of the snubber circuit of the GTO inverter has been described. However, in the inverter circuit of FIG. The above embodiments can also be applied to a wiring structure in which the magnitude of current is the same and the flow direction is opposite, such as between the wiring between the power supply and the anode reactor 9 and between the power supply 32 and the wiring between the anode reactor 10. Needless to say. Moreover, although GTO was demonstrated as a switching element, even if it uses MOSFET, IGBT, etc., the effect similar to said each embodiment is acquired.
[0045]
As described above, according to the present invention, in accordance with the on / off control of the semiconductor switching element that controls the load current, the two wiring conductors having the same current magnitude and flowing in the opposite directions are disposed close to each other via the insulator. In the wiring structure of the power converter, the portion that contacts the wiring conductor is configured to be narrower than the wiring conductor, and the portion that does not contact the wiring conductor is configured to be wider than the wiring conductor, so the creepage distance between the wiring conductors can be increased. Further, the electric field strength at the conductor end can be weakened, and even when a large voltage is applied between the conductors, partial discharge of the insulator can be prevented, and insulation deterioration of the insulator can be suppressed.
[Brief description of the drawings]
FIGS. 1A and 1B are a partial plan view and a cross-sectional view showing an example of a wiring structure used in the snubber circuit of the power conversion device shown in FIG. 8 according to the first embodiment of the present invention. FIG.
FIGS. 2A and 2B are a partial plan view and a cross-sectional view showing an example of a wiring structure used in the snubber circuit of the power conversion device shown in FIG. 8 according to the second embodiment of the present invention.
FIGS. 3A and 3B are a partial plan view and a partial side view showing an example of a wiring structure used in the snubber circuit of the power conversion device shown in FIG. 8 according to the third embodiment of the present invention.
4 is a partial plan view and a cross-sectional view illustrating an example of a wiring structure in which snubber diodes of the snubber circuit of the power conversion device illustrated in FIG. 8 are coupled according to the fourth embodiment of the present invention.
5 is a partial side view showing an example of a wiring structure to which a snubber capacitor of the snubber circuit of the power converter shown in FIG. 8 is connected according to the fifth embodiment of the present invention.
FIG. 6 is a circuit example of one phase of an inverter.
FIG. 7 is a voltage / current waveform when a GTO used in an inverter is turned off.
FIG. 8 is a diagram for explaining the principle of reducing the wiring inductance of the snubber circuit of the inverter.
9 is a partial plan view and a partial cross-sectional view showing an example of a wiring structure used in the snubber circuit of the power conversion device shown in FIG. 8 according to a conventional example.
[Explanation of symbols]
1-4 GTO
11-14 Snubber diodes 15-18 Snubber capacitor A Wiring conductor B Wiring conductor C Solid insulators c1, c3 Narrow portion c2 of solid insulator Wide portion of solid insulator

Claims (3)

In connection with the on / off control of the semiconductor switching element that controls the load current, in the wiring structure of the power conversion device in which two wiring conductors that have the same current magnitude and flow in opposite directions are disposed in close proximity via an insulator,
The insulator is composed of a narrow part in contact with each wiring conductor and a wide part in contact with the wiring conductor via the narrow part, and the narrow part in contact with each wiring conductor is configured to be narrower than the wiring conductor, The portion of the wide portion that does not contact the narrow portion is configured wider than the wiring conductor, and the portion that contacts the wiring conductor via the narrow portion of the wide portion is disposed in the middle of each narrow portion that contacts the wiring conductor. The wiring structure of the power converter characterized by the above-mentioned. In the wiring structure of the power converter according to claim 1,
A narrowing portion of the insulator that is in contact with the wiring conductor is disposed at a predetermined interval in a longitudinal direction of the wiring conductor. In the wiring structure of the power conversion device according to claim 1 or 2,
The two wiring conductors are conductors of a snubber circuit of the semiconductor switching element, and are connected to a snubber capacitor at an end of the two wiring conductors, and a wide portion of the insulator that does not contact the wiring conductor is A wiring structure of a power converter, wherein the wiring structure protrudes from the end toward the snubber capacitor.

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