JP4765017B2 - AC-AC power converter - Google Patents

Description

  The present invention relates to an AC-AC power converter known as a matrix converter, and more particularly to an assembly structure of the unit.

In recent years, matrix converters have attracted attention as a next-generation power supply device that replaces a conventional power supply device that combines a PWM converter and an inverter, and product development has been promoted.
As is well known, a matrix converter has a plurality of bidirectional AC switching element elements arranged in a matrix, and the AC switching elements are turned on and off to cut / combine the input AC voltage so that an arbitrary AC voltage can be obtained. It can be converted and output.
Since this matrix converter performs AC-AC conversion directly without using direct current, the operating loss is lower and the energy saving effect is higher than that of a conventional power supply device combining a converter and an inverter. Since a large capacity smoothing capacitor and direct current reactor arranged in the DC link circuit between the two are not required, the device can be miniaturized. Therefore, the power supply device can be applied to various industrial equipment such as vertical transport equipment (elevators). Application to is expected.

Next, the system outline of the matrix converter is shown in FIG. In the figure, 1 is a three-phase AC power source, 2 is a load such as an electric motor, 3 is a matrix converter, and 4 is a filter circuit (AC filter) that is connected to a power line as a countermeasure for normal mode noise and attenuates harmonics.
Here, the matrix converter 3 includes a total of nine bidirectional AC switching elements 5 arranged in a matrix corresponding to the U, V, and W phases and connected to the three-phase power supply 1, and this bidirectional alternating current is provided. As shown in FIG. 5 (a), the switching element 5 is formed by combining the IGBT 5a, which is a semiconductor switching element, with the diode 5b and connecting them in reverse parallel, or by using two elements of the reverse blocking IGBT 5c as shown in FIG. 5 (b). It consists of IGBT modules connected in reverse parallel. Although not shown, a snubber circuit in which capacitors and diodes are combined on the input side and output side of the AC switching element 5 in order to protect the IGBT from the surge voltage generated when the AC switching element 5 is turned on and off. It has.

The filter circuit 4 is composed of a combination of a filter capacitor 6, a filter reactor 7 (series reactor), and a filter resistor 8. As the filter capacitor 6, a filter capacitor 4 conventionally used in an inverter-type power supply device 3 It is assumed that a three-phase capacitor (commercially available product) in which a set of capacitor elements (for example, an oil capacitor and an electrolytic capacitor) is star-connected in a package is used.
In order to construct a matrix converter to be applied to various industrial equipment, the AC switching element and the snubber circuit component are arranged in a case to form a unit, and this unit is a filter circuit component (filter capacitor 6, filter reactor 7). The product is configured by mounting it on the device panel together with the control circuit.
On the other hand, with regard to the assembly structure of the matrix converter, the wiring inductance of the unit is defined by defining the AC switching element connected between the input terminal and the output terminal, the arrangement of the input filter capacitor, and the bus path of the bus bar connecting between them. Has been proposed prior to the same applicant as the present invention (see Patent Document 1).
JP 2004-236374 A

  By the way, the assembly structure of the matrix converter disclosed in the above-mentioned Patent Document 1 has AC switching elements corresponding to each phase distributed and arranged in a grid pattern, and the filter capacitor is arranged in the vicinity of the terminal block on the input side. Since the star connection is made between the input terminal of each phase and the neutral point terminal, the bus bar of each phase is wired between the input terminal of the terminal block and each AC switching element. There is a limit to shortening the wiring length of the bus bar from the filter capacitor to the AC switching element of each phase. Therefore, when this wiring structure is applied as it is to a matrix converter in which a snubber circuit is combined with an AC switching element (semiconductor switching element) to suppress surge voltage as described above, the wiring inductance of the bus bar laid in the wiring path is reduced to a snubber. As a duty of the circuit, the diode and capacitor parts of the snubber circuit become large (for this reason, the size of the snubber circuit part is almost proportional to the duty). Therefore, in order to promote the miniaturization of the device, a countermeasure for reducing the duty to the snubber circuit is also an important issue.

In addition, when the filter capacitor described above is installed in a matrix converter unit using an oil capacitor for three phases as described above, the occupied space of the filter capacitor increases. There is also a problem that the apparatus panel to be accommodated becomes larger.
The present invention has been made in view of the above points, and its purpose is to improve the assembly and wiring structure of the unit so that the duty of the snubber circuit attached to the AC switching element can be reduced and the unit and the device panel can be miniaturized. An AC-AC power converter is provided.

In order to achieve the above object, according to the present invention, a bidirectional AC switching element, a snubber circuit of an AC switching element, and a filter capacitor of a power supply line combined in a matrix are connected between an input terminal and an output terminal. In an AC-AC power converter that converts a three-phase AC input into a desired AC output by on / off control of the AC switching element,
Inside the unit case, the AC switching elements are aligned in a vertical line with the terminals facing left and right, and the filter capacitors divided into each phase are placed side by side close to the side of the AC switching element line Then, the filter capacitor of each phase is connected to the input terminal of the AC switching element corresponding to this via the connection bar and is Δ-connected (Claim 1).
(1) A film capacitor is employed as a filter capacitor for each phase to be Δ-connected.
(2) The bidirectional AC switching element is composed of an IGBT module having a package structure in which an IGBT connected in antiparallel is mounted and the input and output side terminals are arranged at both ends.

As described above, IGBT modules with input and output terminals arranged at both ends of the package as AC switching elements are arranged in a row in the top and bottom, and filter capacitors divided into each phase are arranged close to each other, and then the connection bar is By connecting the filter capacitor of each phase to the input side terminal of the AC switching element via Δ, the wiring length of the connection bar is shortened to reduce the wiring inductance, thereby reducing the duty of the snubber circuit Therefore, the circuit component can be miniaturized.
In addition, by using a Δ connection for the filter capacitors for three phases, it is possible to reduce the capacitor capacity of each phase to 1/3 (substitution of Y connection and Δ connection) compared to the Y connection. The size of the unit can be reduced by adopting a film capacitor that is smaller in size than other devices, and has excellent high frequency characteristics, allowable current, and pressure resistance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on the examples shown in FIGS.
First, FIG. 3 shows a connection diagram of the main circuit according to the embodiment of the present invention. In the figure, 1 is a three-phase AC power source, 2 is a load, 3 is a matrix converter unit, 4 is a filter circuit (filter capacitor 6, filter reactor 7, filter resistor 8) connected to the power source side of unit 3, and 5 is an AC Switching element (the IGBT module shown in FIG. 5A), 9 is a snubber circuit on the input side with respect to the AC switching element 5, 10 is a snubber circuit on the output side, and 11 is an input terminal (R, S, T) of the unit 3 , 12 are output terminals (U, V, W).
Here, as for the filter capacitor 6 of the filter circuit 4, after adopting a film capacitor (commercially available exterior square) for each phase, a unit case together with the AC switching element 5, the snubber circuits 9 and 10 as described later. The matrix converter unit 3 is constructed by incorporating the capacitors and Δ-connecting them.

Next, a specific assembly structure constituting the matrix converter unit 3 and its wiring structure are shown in FIGS. First, FIG. 1 is a front view showing the component arrangement of the unit 3, and a total of nine AC switching elements 5 corresponding to the U, V, and W phases are arranged side by side in the center of the unit case 13. Yes. Here, the AC switching element 5 is an IGBT module having a package structure in which the antiparallel-connected IGBT shown in FIG. 5 is mounted and the input and output side terminals are arranged at both ends. Are arranged in a line in the vertical direction, input and output snubber circuits 9 and 10 are arranged on both sides thereof and connected to terminals, and then a unit case 13 through a bus bar (not shown). Are connected to an input terminal 11 and an output terminal 12 arranged at the lower left and right.
On the other hand, the filter capacitor (film capacitor) 6 divided into each of the three phases as described in FIG. 3 is arranged close to the side of the AC switching elements 5 aligned vertically and opposed to the input side terminal. Yes. In the illustrated example, two film capacitors are connected in parallel for each phase, and a total of six film capacitors are divided into three sets and juxtaposed to the side of the AC switching element 5 corresponding to the U, V, and W phases. However, the number of capacitors used is not limited to two, and one or a plurality of capacitors are connected in parallel depending on the capacity of the matrix converter. A connecting bar 14 shown in FIG. 2 is wired between the terminals of each filter capacitor 6 and the corresponding input side terminal of the AC switching element 5 so as to be Δ-connected (see FIG. 3). Reference numeral 15 denotes a protective fuse connected to the input line of the semiconductor switching element 5.

Further, the connecting bar 14 is made of a copper rectangular conductor having a cross-sectional area determined so as to make the wiring inductance as small as possible, and is laid so as to overlap the back side of the snubber circuit 9 along the arrangement of the AC switching elements 5. The connection end branching laterally from the connection point is overlapped with the terminal of the snubber circuit 9 and fastened together with the terminal of the switching element.
According to the assembly and wiring structure of the above embodiment, the wiring length between the filter capacitor 6 and the AC switching element 5 can be minimized to reduce the duty of the snubber circuit, and the snubber circuit can be miniaturized. In addition, the AC switching elements 5 are arranged in a vertical line, and the filter capacitors 6 are arranged on the sides of the AC switching elements 5 so that the configuration of the unit 3 is compact. The width of the device panel on which the unit 3 is mounted is reduced. Can be greatly reduced. Although not shown, the unit case 13 is equipped with a heat radiation fin of the AC switching element 5 on the back surface, and is housed in an apparatus panel for cooling by blowing.

The front view of the unit assembly structure of the matrix converter by the Example of this invention Partial enlarged view showing the wiring structure between the filter capacitor and the AC switching element in FIG. Connection diagram of matrix converter corresponding to FIG. System schematic of matrix converter FIG. 5 is a configuration diagram of a semiconductor switching element applied to the bidirectional alternating current switching element in FIG. Circuit diagram of IGBT module connected to

Explanation of symbols

1 Three-phase AC power supply 2 Load 3 Matrix converter unit 4 Filter circuit 5 AC switching element 6 Filter capacitor 9, 10 Snubber circuit 11 Input terminal 12 Output terminal 13 Unit case 14 Connection bar

Claims (3)

It is a unit constructed by connecting a bidirectional AC switch combined in a matrix, an AC switch snubber circuit, and a power line filter capacitor between the input terminal and the output terminal. Oite the AC-AC power conversion equipment for converting phase AC input to a desired AC output,
Inside the unit case, the AC switching elements are aligned in a vertical line with the terminals facing left and right, and the filter capacitors divided into each phase are input close to the side of the AC switching element line. An AC-AC power converter characterized in that a filter capacitor of each phase is connected to an input terminal of an AC switching element corresponding to this via a connection bar after being arranged opposite to the terminal and Δ connected. 2. The AC-AC power converter according to claim 1, wherein the filter capacitor of each phase is a film capacitor. 2. The power converter according to claim 1, wherein the bidirectional AC switching element is an IGBT module having a package structure in which an antiparallel-connected IGBT is mounted and input and output side terminals are arranged at both ends. -AC power converter.

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