JP2000175462A - Three-phase inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress leakage current and power source noise, and realize miniaturization and reduction in the number of constituent part items and cost. SOLUTION: One phase of a three-phase AC power source 21, of which the phase in not connected with a single-phase forward converting circuit 31, is connected with an intermediate connection part of capacitors C1 and C2 of a smoothing circuit 33, and with one phase of a three-phase load 26 which phase is not connected with a single-phase backward converting circuit 32. Thereby DC voltages applied to the capacitors C1 and C2 are fixed to about double the potentials of a line voltage of the three-phase AC power source 21, at a maximum, when a ground potential is set as a reference. The DC voltages are applied to a load 26 via the backward converting circuit 32. The potential of one phase of the load 26 is set at a ground potential, and the instantaneous value of a voltage of the other phase is restrained at about double the potential of the line voltage of the power source 21 at a maximum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase inverter for converting the voltage and frequency of a three-phase AC power supply and outputting the converted voltage.

[0002]

2. Description of the Related Art FIG. 11 is a block diagram showing a configuration of a general three-phase inverter device. In this inverter device, a three-phase forward conversion circuit 11 having a configuration in which three diode rows in which a pair of diodes are connected in series is connected in parallel, three diode rows in which a pair of diodes are connected in series are connected in parallel, and The three-phase inversion circuit 12 has a configuration in which a switch element is connected in anti-parallel to each diode, and a smoothing capacitor 13 is connected in parallel.
The anti-parallel connection means that two elements are connected in parallel with opposite polarities.

In the three diode rows of the three-phase forward conversion circuit 11, three phases of a three-phase AC power supply 21 are supplied one by one to an intermediate connection between a pair of diodes in each row.

The outputs of the three phases of the three-phase inversion circuit 12 are supplied to the three diode rows of the three-phase inversion circuit 12 from the intermediate connection of a pair of diodes in each row. Are supplied one by one.

In the three-phase inverter device shown in FIG. 11, when one phase of the three-phase AC power supply 21 is grounded, an unspecified potential with respect to the ground potential is applied to the three-phase load device 26. It has been known. The applied unspecified potential is changed at high speed by the switch element in the three-phase inversion circuit 12, and the leakage current is increased by the stray capacitance between the three-phase load device 26 and the ground potential. And an increase in leakage current. Therefore, it is preferable to suppress the influence of the unspecified potential as much as possible. In addition, it is required to reduce the size of the inverter device, reduce the number of components, and reduce the cost.

As a single-phase inverter circuit, a circuit has been proposed in which measures have been taken to reduce leakage current and power supply noise (Fuji Times, Vol. 71, No. 1).
7, p. 407-410, 1998). As shown in FIG. 12, this single-phase inverter circuit has a single-phase high power factor converter circuit 14 having a configuration in which a pair of diodes are connected in series, and one switching element is connected in anti-parallel to each diode.
And a single-phase inversion circuit 15 having a configuration in which a pair of diodes are connected in series and a switching element is connected in each diode in an anti-parallel manner, and a smoothing circuit 16 in which a pair of capacitors are connected in series is connected in parallel. Configuration.

One output phase of the two phases of the single-phase AC power supply 22 is supplied to an intermediate connection between a pair of diodes of the single-phase high power factor converter circuit 14 via the AC reactor 17. The other output phase of the single-phase AC power supply 22 is supplied to an intermediate connection portion of a pair of capacitors of the smoothing circuit 16 and one output phase of a single-phase reverse conversion circuit output portion 27. The other output phase of the single-phase inversion circuit output section 27 is supplied with an output from an intermediate connection of a pair of diodes of the single-phase inversion circuit 15.

According to the single-phase inverter circuit shown in FIG. 12, it is possible to suppress both the leakage current and the power supply noise, and to further reduce the size, the number of components and the cost. It is said that it can be obtained.

[0009]

However, in the three-phase inverter device, it is still difficult to realize the suppression of the leakage current and the power supply noise as in the above-described single-phase inverter circuit. It is also difficult to satisfy the demands for reduction in the number of components, reduction in the number of components, and cost reduction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in a three-phase inverter device, it is possible to suppress leakage current and power supply noise, and to further reduce the size, the number of components, and the cost. It is an object of the present invention to obtain a three-phase inverter device that can be used.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to an inverter device for converting one or both of a voltage and a frequency of a three-phase AC power supply and outputting the converted voltage to a three-phase load device. A single-phase forward conversion circuit connected to two of the three-phase outputs of the three-phase AC power supply, and a DC connected to the single-phase forward conversion circuit, and at least a pair of capacitors connected in series; A smoothing circuit connected to one of the three-phase input terminals of the three-phase AC power supply, and one of the intermediate connection parts connected to the other one-phase output of the three-phase AC power supply; And a single-phase inversion circuit connected to the remaining two-phase inputs of the three-phase load device, and controlling the single-phase inversion circuit to supply a three-phase AC voltage to the three-phase load device And three-phase control means.

According to the present invention, the single-phase forward conversion circuit is connected to two phases of the three-phase output of the three-phase AC power supply, and one of the intermediate connections between the capacitors of the smoothing circuit is connected to the three-phase AC power supply. Connected to the remaining one-phase output, connected to one phase of the three-phase input of the three-phase load device, a single-phase inversion circuit is connected to the remaining two-phase input of the three-phase load device, and connected to the three-phase load device. The control means controls the single-phase reverse conversion circuit so that the three-phase AC voltage is supplied to the three-phase load device.

The present invention is also an inverter device for converting one or both of a voltage and a frequency of a three-phase AC power supply and outputting the converted voltage to a three-phase load device, wherein the single-phase full-bridge rectifier and the single-phase full-bridge rectifier are provided. A single-phase high power factor forward conversion circuit composed of switch elements connected in anti-parallel, connected to the DC side of the single-phase high power factor forward conversion circuit, and at least a pair of capacitors are connected in series. One of the intermediate connection portions is connected to the remaining one-phase output of the three-phase AC power supply, and is connected to one of the three-phase inputs of the three-phase load device. A single-phase inversion circuit connected to and connected to the remaining two-phase inputs of the three-phase load device, and controlling the single-phase inversion circuit to supply a three-phase AC voltage to the three-phase load device. Three-phase control Comprising the stage, and a high power factor forward transform control means for controlling the single-phase high power factor sequence conversion circuit to improve power factor and schematic sinusoidal current flowing from the 3-phase AC power source.

According to the present invention, the single-phase high power factor forward conversion circuit includes a single-phase full-bridge rectifier and a switch element connected in anti-parallel to the single-phase full-bridge rectifier, and includes an intermediate connection between capacitors of the smoothing circuit. One of the parts is connected to the remaining one-phase output of the three-phase AC power supply and to one of the three-phase inputs of the three-phase load device, and the single-phase inverting circuit is connected to the other of the three-phase load device. , And the three-phase control means controls the single-phase reverse conversion circuit so that the three-phase AC voltage is supplied to the three-phase load device. The single-phase high power factor forward conversion circuit is controlled so that the current flowing from the AC power supply is substantially sinusoidal and the power factor is improved.

The present invention is also an inverter device for converting one or both of the voltage and frequency of a three-phase AC power supply and outputting the converted voltage to a three-phase load device. And a single-phase forward conversion circuit connected to the DC-side of the single-phase forward conversion circuit, and at least a pair of capacitors are connected in series. One of the intermediate connection portions of the capacitors is connected to the three-phase A smoothing circuit that is connected to the remaining one-phase output of the AC power supply and that can be connected to one phase of the three-phase input of the three-phase load device via an opening / closing means for switching the opening and closing of the circuit; A three-phase inverting circuit connected to a circuit and connected to a three-phase input of the three-phase load device, and an output of the three-phase inverting circuit being a three-phase voltage substantially equal to a power supply voltage. Closed, and the three phases Almost 2 power supply voltage output of the converter circuit
Switching circuit control means for controlling the switching means so as to open the circuit when the three-phase voltage is up to twice, and supplying a three-phase AC voltage to the three-phase load device in accordance with the open / closed state of the switching means And three-phase control means for controlling the three-phase inversion circuit.

According to the present invention, the single-phase forward conversion circuit is connected to two phases of the three-phase output of the three-phase AC power supply, and one of the intermediate connections between the capacitors of the smoothing circuit is connected to the three-phase AC power supply. Connected to the remaining one-phase output, and connected to one of the three-phase inputs of the three-phase load device via a switching means,
A three-phase inversion circuit is connected to the three-phase input of the three-phase load device;
The switching circuit control means causes the switching means to be in a closed state when the output of the three-phase inversion circuit is a three-phase voltage up to substantially the same voltage as the power supply voltage, and the output of the three-phase inversion circuit is approximately two times the power supply voltage. The three-phase voltage is controlled so as to be in the open state when the three-phase voltage is up to twice, and the three-phase control means supplies the three-phase AC voltage to the three-phase load device in accordance with the open / close state of the open / close means. The three-phase inversion circuit is controlled.

The present invention is also an inverter device for converting one or both of the voltage and frequency of a three-phase AC power supply and outputting the converted voltage to a three-phase load device. A phase-sequencing circuit, connected to the DC side of the three-phase forward-conversion circuit, and at least a pair of capacitors are connected in series, and one of the intermediate connections between the capacitors is connected to one phase of the three-phase AC power supply. An output circuit connected to one of three-phase inputs of a three-phase load device, and a smoothing circuit connected to one of three-phase inputs of the three-phase load device; 3
A single-phase inversion circuit connected to the remaining two-phase input of the phase load device, and a closed state when the output of the single-phase inversion circuit is a three-phase voltage up to substantially the same voltage as the power supply voltage; Open / close circuit control means for controlling the open / close means so as to be in an open circuit state when the output of the single-phase inversion circuit is a three-phase voltage up to approximately half the power supply voltage; And three-phase control means for controlling the single-phase inverting circuit so as to supply a three-phase AC voltage to the three-phase load device.

According to the present invention, the three-phase forward conversion circuit is connected to the three-phase output of the three-phase AC power supply, and one of the intermediate connections between the capacitors of the smoothing circuit is opened and closed to the one-phase output of the three-phase AC power supply. Means connected to one phase of the three-phase input of the three-phase load device,
A closed state when the switching means is connected to the remaining two-phase input of the phase load device and the switching means controls the output of the single-phase inversion circuit to a three-phase voltage substantially equal to the power supply voltage, and When the output of the single-phase inverting circuit is a three-phase voltage up to approximately one half of the power supply voltage, the circuit is controlled to be in an open circuit state. The single-phase reverse conversion circuit is controlled so that the three-phase AC voltage is supplied to the three-phase load device.

The present invention also relates to an inverter device for converting one or both of the voltage and frequency of a three-phase AC power supply and outputting the converted voltage to a three-phase load device, wherein the inverter device is connected to a three-phase output of the three-phase AC power supply. A phase-sequential conversion circuit, connected to the DC side of the three-phase sequential conversion circuit, and at least a pair of capacitors are connected in series, and one of the intermediate connections between the capacitors is connected to a three-phase input of a three-phase load device. And a second opening / closing means for switching the opening / closing of the circuit to the one-phase output of the three-phase AC power supply. A three-phase inverting circuit connected to the smoothing circuit and connected to a three-phase input of the three-phase load device, and corresponding to an output voltage range of the three-phase inverting circuit. And the first opening and closing Open / close circuit control means for controlling the open / close state of each stage and the second open / close means; and three-phase load devices corresponding to the open / close states of the first open / close means and the second open / close means. Three-phase control means for controlling the three-phase inversion circuit so as to supply an AC voltage;
Is provided.

According to the present invention, the three-phase forward conversion circuit is connected to the three-phase output of the three-phase AC power supply, and one of the intermediate connections between the capacitors of the smoothing circuit is connected to the three-phase input of the three-phase load device. And a three-phase inverter is connected to the one-phase output of the three-phase AC power supply via the second switching means. The first switching means and the second switching means are respectively connected to the input and controlled by the switching circuit control means to control the open / close state of the first switching means and the second switching means in accordance with the output voltage range of the three-phase inversion circuit. The three-phase reverse conversion circuit is controlled so that the three-phase AC voltage is supplied to the three-phase load device according to the open / close state of the first switch and the second switch.

The present invention is also an inverter device for converting one or both of a voltage and a frequency of a three-phase AC power supply and outputting the converted voltage to a three-phase load device. The inverter device is connected to a three-phase output of the three-phase AC power supply. A phase-sequencing circuit, connected to the DC side of the three-phase forward-conversion circuit, and at least a pair of capacitors connected in series, one of the intermediate connections between the capacitors being connected to the neutral point of the three-phase AC power supply And a three-phase inversion circuit connected to the smoothing circuit and connected to a three-phase input of the three-phase load device.

According to the present invention, the three-phase forward conversion circuit is connected to the three-phase output of the three-phase AC power supply, and one of the intermediate connections between the capacitors of the smoothing circuit is connected to the neutral point of the three-phase AC power supply. , A three-phase inversion circuit is connected to the three-phase input of the three-phase load device.

In the present invention, the intermediate connection between the capacitors of the smoothing circuit may be connected to a neutral point of the three-phase load device.

According to the present invention, the intermediate connection between the capacitors of the smoothing circuit is also connected to the neutral point of the three-phase load device.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a three-phase inverter device according to the present invention will be described in detail with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a block diagram illustrating a configuration of the three-phase inverter device according to the first embodiment of the present invention. This inverter device includes a pair of diodes D
A single-phase forward conversion circuit 31 having a configuration in which a diode array in which the diodes D11 and D12 are connected in series and a diode array in which a pair of diodes D21 and D22 are connected in parallel, and a diode in which a pair of diodes D61 and D62 are connected in series A column and a diode column in which a pair of diodes D71 and D72 are connected in series are connected in parallel, and each diode D6
1, D62, D71, D72, one by one switch element S
61, S62, S71, and S72 are connected in anti-parallel to a single-phase inversion circuit 32, and a pair of capacitors C1 and C2.
Are connected in parallel with a smoothing circuit 33 that is connected in series.

In the two diode rows of the single-phase forward conversion circuit 31, the intermediate connection between the diodes D11 and D12, and the diodes D21 and D22
And two of the three phases of the three-phase AC power supply 21 are supplied one by one to the intermediate connection part. The remaining one phase of the three-phase AC power supply 21 is grounded, and is supplied to an intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33 and one of the three-phase inputs of the three-phase load device 26. ing.
The remaining two phases of the input of the three-phase load device 26 include an output from an intermediate connection between the diodes D61 and D62 of the single-phase inversion circuit 32 and an output from an intermediate connection between the diodes D71 and D72. Are supplied respectively.

The single-phase reverse conversion circuit 32 is controlled by three-phase control means 34. The three-phase control means 34 is means for controlling the three-phase load device 26 to supply a three-phase AC voltage.

Next, the operation of the first embodiment will be described. Since one phase of the three-phase AC power supply 21 that is not connected to the single-phase forward conversion circuit 31 is connected to an intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33, the line of the three-phase AC power supply 21 is connected. A potential of about √2 times the inter-voltage is applied between the two poles of both capacitors C1 and C2 of the smoothing circuit 33. The smoothing circuit 3 is controlled by the three-phase control means 34.
3 for the output from the intermediate connection unit 3
Of the three-phase load device 26
Voltage V having a desired voltage value and frequency
Apply RS.

The smoothing circuit 33 is controlled by the three-phase control means 34.
Controls the output of the remaining one phase of the single-phase inverting circuit 32 with respect to the output from the intermediate connection of the three-phase load device 26 so that the phase between the other lines of the three-phase load device 26 is 120 ° relative to the voltage VRS. Apply different voltage VST. Since the remaining voltage VTR is naturally determined by the voltage VRS and the voltage VST, a three-phase AC output can be obtained with the configuration of the single-phase inversion circuit 32.

According to the first embodiment, three-phase AC power supply 21
One phase not connected to the single-phase forward conversion circuit 31
3 is connected to the intermediate connection between the capacitors C1 and C2, and is connected to the single-phase inversion circuit 3 of the three-phase load device 26.
2 is connected to one phase that is not connected to
DC voltage applied to each of the three-phase AC power supply 21 at the maximum with respect to the ground potential.
The DC voltage is fixed to about twice as much and the DC voltage is applied to the three-phase load device 26 via the three-phase inversion circuit 32. Therefore, the potential of one phase of the three-phase load device 26 is set to the ground potential, The instantaneous value of the voltage can be suppressed to a potential of about √2 times the line voltage of the three-phase AC power supply 21 at the maximum. as a result,
Leakage current and power supply noise can be suppressed.

According to the first embodiment, the forward conversion circuit 3
1 is similar to a general single-phase forward conversion circuit, and the configuration of the inverse conversion circuit 32 is also similar to a general single-phase reverse conversion circuit, so that the inverter device can be downsized and the number of components can be reduced. And cost reduction becomes possible. Furthermore, the loss can be reduced with the reduction in the number of components.

The inverter having the above configuration may be arbitrarily combined with an AC reactor and a DC reactor, so that the power factor of the power supply can be improved and harmonic components of the current can be suppressed. .

Embodiment 2 FIG. 2 is a block diagram illustrating a configuration of the three-phase inverter device according to the second embodiment of the present invention. This inverter device is different from the first embodiment in that a single-phase high power factor forward conversion circuit 41 is provided instead of the single-phase forward conversion circuit 31, and that the single-phase high power factor forward conversion circuit 4
The AC reactor 4 is connected to the three-phase AC power supply 21
2 and 43 and the single-phase high power factor forward conversion circuit 41
Is provided with a high power factor forward conversion control means 44 for controlling the power factor. Other configurations are the same as those in the first embodiment (see FIG. 1), and thus the same configurations will be denoted by the same reference numerals and description thereof will be omitted.

The single-phase high power factor forward conversion circuit 41 includes a rectifier train in which a pair of single-phase full-bridge rectifiers D111 and D112 are connected in series and a pair of single-phase full-bridge rectifiers D121 and D121.
122 are connected in parallel with a rectifier train in which the single-phase full-bridge rectifiers D111, D112, D1 are connected.
21 and D122, one for each of the switching elements S111 and S1.
12, S121 and S122 are connected in anti-parallel.

The high power factor forward conversion control means 44 controls the single-phase high power factor forward conversion circuit 41 so as to make the current flowing from the three-phase AC power supply 21 into a substantially sinusoidal wave and to improve the power factor.

Next, the operation of the second embodiment will be described. One-phase output inside the single-phase high power factor forward conversion circuit 41, 3
Between the phase of the phase AC power supply 21 and the phase connected to the intermediate connection point between the capacitors C1 and C2 of the smoothing circuit 33,
A voltage VRS_conv having a desired voltage value and frequency is generated. This voltage VRS_conv is applied between the AC reactors with respect to the power supply phase voltage VRS, and the power supply current flowing thereby is determined. Accordingly, the single-phase high-power-factor forward-conversion circuit 41 is controlled by the high-power-factor forward-conversion control means 44, and the power supply current is converted into a substantially sinusoidal wave, so that the voltage VRS_conv can improve the power factor.
Generate.

Another one inside the single-phase high power factor forward conversion circuit 41
The same control is performed by the high power factor forward conversion control unit 44 between the phase output and the phase of the three-phase AC power supply 21 connected to the intermediate connection point between the capacitors C1 and C2, and the power supply current is reduced. A voltage VST_conv that can be converted into a substantially sine wave and that can improve the power factor is generated.

Since the control of the inverse conversion circuit 32 is the same as that of the first embodiment, the description is omitted.

According to the second embodiment, the same effects as those of the first embodiment, that is, suppression of leakage current, suppression of power supply noise, downsizing of the inverter device, reduction in the number of components, reduction in cost, and reduction in loss are achieved. In addition to the effect that reduction can be achieved, the single-phase high power factor forward conversion circuit 41 is used as the forward conversion circuit of the three-phase AC power supply 21. The effect is obtained that the wave is waved and the power factor can be improved.

Embodiment 3 FIG. 3 is a block diagram illustrating a configuration of the three-phase inverter device according to the third embodiment of the present invention. This inverter device is different from the first embodiment in that a three-phase inversion circuit 52 is provided instead of the single-phase inversion circuit 32 and the three-phase outputs of the three-phase inversion circuit 52 are supplied to the three-phase load device 26. Each phase is supplied one by one, and an intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33 is connected to an output point of one phase of the three-phase inversion circuit 52 by an opening / closing means 54 such as a switch. , An opening / closing circuit control means 55 for controlling the opening / closing of the opening / closing means 54, and a three-phase control means 56 for controlling the three-phase inversion circuit 52. . Other configurations are the same as those in the first embodiment (see FIG. 1), and thus the same configurations will be denoted by the same reference numerals and description thereof will be omitted.

The three-phase inversion circuit 52 includes a diode array in which a pair of diodes D261 and D262 are connected in series, a diode array in which a pair of diodes D271 and D272 are connected in series, and a diode array in which a pair of diodes D281 and D282 are connected in series. Are connected in parallel, and the respective diodes D261, D262, D271, D272, D28
1, D282, one by one switch element S261, S26
2, S271, S272, S281, and S282 are connected in anti-parallel. The three-phase inversion circuit 52-3
The output of each phase is supplied to each phase of the three-phase load device 26 one by one from an intermediate connection between a pair of diodes in each diode row.

When the three-phase inversion circuit 52 causes the three-phase inversion circuit 52 to output a three-phase voltage up to substantially the same voltage as the power supply voltage, the switching circuit control means 55 closes the circuit. When the possible output voltage of the circuit 10 is up to approximately twice the power supply voltage, the circuit 10 is controlled to be in an open circuit state.

The three-phase control means 56 includes a three-phase inverse conversion circuit 52
In response to this, control is performed so that a three-phase AC voltage is supplied to the three-phase load device 26 in accordance with the open / close state of the open / close means 54.

FIG. 4 is a flowchart for explaining the operation of the inverter device according to the third embodiment. First, it is determined whether or not the range of the output voltage Vout of the three-phase inversion circuit 52 is larger than the line voltage Vin of the three-phase AC power supply 21 (step S1). When Vout is equal to or higher than Vin, that is, when an output voltage equal to or higher than the line voltage Vin of the three-phase AC power supply 21 is required, the opening / closing means 54 is opened and the one-phase arm in the three-phase inversion circuit 52 is And the connection between the smoothing circuit 33 and the intermediate connection between the capacitors C1 and C2 is interrupted (step S2).

In this state, the three-phase arms of the three-phase inversion circuit 52 are controlled by the three-phase control means 56, and the phase voltage of each output phase of the three-phase inversion circuit 52 is set to a high level with respect to the low voltage side of the smoothing circuit 33. About 2√ of the three-phase line voltage, which is the voltage side potential
Switching control is performed at twice the voltage (step S3).
As a result, a three-phase AC voltage is applied to the three-phase load device 26, and a series of controls ends.

On the other hand, when Vout is smaller than Vin in step S1, that is, when an output voltage smaller than the line voltage Vin of the three-phase AC power supply 21 is required, the opening / closing means 54 is closed and the three-phase inverse conversion is performed. The one-phase arm in the circuit 52 is connected to the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33 (Step S4). Then, three-phase control means for controlling two phases in the three-phase inverse conversion circuit 52 which are not connected to the intermediate connection part of the capacitors C1 and C2 of the smoothing circuit 33 so as to realize the same control as in the first embodiment. 56 is controlled (step S5), and a series of controls ends.

According to the third embodiment, three-phase inversion circuit 5
The switching means 54 for switching the output voltage from the switching circuit 2 is provided, and the switching state of the switching means 54 is controlled to be switched. Phase voltage and power supply voltage
It can be switched to a three-phase voltage up to twice. Then, from the three-phase inversion circuit 52, the voltage from the three-phase inversion
When a phase voltage is output, the same effects as in the first embodiment, namely, suppression of leakage current, suppression of power supply noise,
The effects are obtained that the inverter device can be reduced in size, the number of components can be reduced, the cost can be reduced, and the loss can be reduced.

Embodiment 4 FIG. 5 is a block diagram showing a configuration of the three-phase inverter device according to Embodiment 4 of the present invention. This inverter device is different from the first embodiment in that a three-phase forward conversion circuit 61 is provided instead of the single-phase forward conversion circuit 31, and three phases of the three-phase AC power supply 21 are added to three phases of the three-phase forward conversion circuit 61. The output is supplied one phase at a time, and one of the three phases of the three-phase AC power supply 21 is connected to the ground connection between the capacitors C1 and C2 of the smoothing circuit 33 by opening and closing a switch. That is, they are connected via the means 64 and the switching circuit control means 65 for controlling the opening and closing of the switching means 64 is provided. Other configurations are the same as those in the first embodiment (see FIG. 1), and thus the same configurations will be denoted by the same reference numerals and description thereof will be omitted.

The three-phase forward conversion circuit 61 includes a diode row in which a pair of diodes D311 and D312 are connected in series, a diode row in which a pair of diodes D321 and D322 are connected in series, and a diode row in which a pair of diodes D331 and D332 are connected in series. Are connected in parallel. The output of the three-phase AC power supply 21 is supplied one phase at a time to an intermediate connection between a pair of diodes in each diode row.

The switching circuit control means 65 supplies the three-phase load device 26 with the switching means 64 approximately one half of the power supply voltage.
When the three-phase voltage up to (1/2) is output, control is performed such that the circuit is open, and when the voltage that can be output to the three-phase load device 26 is substantially equal to the power supply voltage, the circuit is closed. I do.

FIG. 6 is a flowchart for explaining the operation of the inverter device according to the fourth embodiment. First, it is determined whether or not the range of the output voltage Vout of the single-phase inversion circuit 32 is larger than the line voltage Vin of the three-phase AC power supply 21 (step S11). Then, when Vout is almost equal to the voltage of Vin, that is, the line voltage Vin of the three-phase AC power supply 21
When an output voltage up to substantially the same voltage is required, the opening / closing means 64 is closed and the one-phase arm in the three-phase forward conversion circuit 61 and the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33 are connected. Connection is made (step S12). In this state, the same control as in the first embodiment is performed on the single-phase inversion circuit 32 by the three-phase control means 34 (step S14).
A three-phase AC voltage is applied to the phase load device 26, and a series of controls ends.

On the other hand, when Vout is up to approximately half (1/2) times the voltage of Vin in step S11, that is, approximately 1/2 (1/2) of the line voltage Vin of the three-phase AC power supply 21. When an output voltage up to twice is required, the opening / closing means 64 is opened and the connection between the one-phase arm in the three-phase forward conversion circuit 61 and the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33 is cut off. (Step S13), and proceed to Step S14.
A three-phase AC voltage is applied to the three-phase load device 26 to end a series of controls.

According to the fourth embodiment, single-phase inversion circuit 3
An open / close means 64 for switching the output voltage from the power supply 2 is provided, and the open / close state of the open / close means 64 is controlled to be switched. Phase voltage and power supply voltage
It is possible to switch to a three-phase voltage up to one-half (1/2) times. When the three-phase voltage is output from the single-phase inverting conversion circuit 32 up to substantially the same voltage as the power supply voltage, the same effects as those of the first embodiment, that is, suppression of leakage current, suppression of power supply noise, The following effects can be obtained: downsizing, reduction in the number of components, reduction in cost, and reduction in loss.

When the three-phase voltage up to approximately one half (1/2) times the power supply voltage is output from the single-phase inversion circuit 32, the voltage change due to switching is approximately one half.
(1/2) times, a greater effect is obtained in suppressing leakage current and power supply noise, and in addition, the ratio of the carrier frequency component to the output voltage is suppressed, and the ripple component of the current and the load A stable state can be suppressed.

Embodiment 5 FIG. 7 is a block diagram showing a configuration of the three-phase inverter device according to the fifth embodiment of the present invention. This inverter device is different from the first embodiment in that a three-phase forward conversion circuit 61 is provided instead of the single-phase forward conversion circuit 31, and three phases of the three-phase AC power supply 21 are added to three phases of the three-phase forward conversion circuit 61. The output is supplied one by one, and the three-phase inversion circuit 52 is used instead of the single-phase inversion circuit 32.
And the three-phase output of the three-phase inversion circuit 52 is supplied to each phase of the three-phase load device 26 one by one, and the intermediate connection between the capacitor C1 and the capacitor C2 of the smoothing circuit 33 is connected. The fact that it is connected to the output point of the one-phase part of the three-phase inversion circuit 52 via the first opening / closing means 54 such as a switch, and that one of the three phases of the three-phase AC power supply 21 is grounded; The connection between the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33 via the second opening / closing means 64 such as a switch, and the opening / closing of the first opening / closing means 54 and the second opening / closing means 64 are respectively controlled. That is, the first switching circuit control means 55 and the second switching circuit control means 65 are provided, and the three-phase control means 56 for controlling the three-phase inverse conversion circuit 52 is provided. Other configurations are the same as those in the first embodiment (see FIG. 1), and thus the same configurations will be denoted by the same reference numerals and description thereof will be omitted.

Three-phase inversion circuit 52, first opening / closing means 5
4. First switching circuit control means 55 and three-phase control means 5
Reference numeral 6 denotes a three-phase inversion circuit 52, an opening / closing means 54, and opening / closing circuit control means 55 and 3 of the third embodiment shown in FIG.
It has the same configuration as the phase control means 56. Therefore, the description of those circuits and each means will be omitted because they are duplicated.

Three-phase forward conversion circuit 61, second opening / closing means 64
The second switching circuit control means 65 includes a three-phase forward conversion circuit 61 and a switching means 64 of the fourth embodiment shown in FIG.
And a configuration similar to that of the switching circuit control means 65. Therefore, the description of those circuits and each means will be omitted because they are duplicated.

FIG. 8 is a flowchart for explaining the operation of the inverter device according to the fifth embodiment. First, it is determined whether or not the range of the output voltage Vout of the three-phase inversion circuit 52 is larger than the line voltage Vin of the three-phase AC power supply 21 (step S21). When Vout is higher than Vin, that is, when an output voltage up to approximately twice the line voltage Vin of the three-phase AC power supply 21 is required, the second switching circuit control means 65 controls the second switching circuit 64. Is closed, and the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33 is connected to the three-phase AC power supply 21 (step S22).

The first opening / closing means 54 is opened by the first opening / closing circuit control means 55, and the three-phase inversion circuit 5
2 and the capacitors C1 and C of the smoothing circuit 33
2 is disconnected from the intermediate connection unit (step S2).
3). In this state, the three-phase control means 56 controls the three-phase arms of the three-phase inversion circuit 52 to change the phase voltage of each output phase of the three-phase inversion circuit 52 on the high voltage side with respect to the low voltage side of the smoothing circuit 33. Switching control is performed at a voltage of about 2√2 times the voltage between the three-phase lines (potential) (step S24), a three-phase AC voltage is applied to the three-phase load device 26, and a series of controls is completed.

On the other hand, when Vout is smaller than Vin in step S21, that is, when an output voltage smaller than the line voltage Vin of the three-phase AC power supply 21 is required, Vout is set to Vin.
It is determined whether or not it is almost half (１ ／) times (step S25). Vout is almost half (1) of Vin
In the case of (/ 2) times, it is further determined whether or not the three-phase equilibrium of the current of the three-phase AC power supply 21 is emphasized (step S26).

When importance is placed on three-phase balance in step S26, the second switching circuit 64 is opened by the second switching circuit control means 65, and the capacitor C of the smoothing circuit 33 is opened.
The connection between the intermediate connection section of the power supply C1 and the three-phase AC power supply 21 is cut off (step S27). Then, the first opening / closing means 54 is opened by the first opening / closing circuit control means 55, and
The connection between the one-phase arm in the phase inversion circuit 52 and the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33 is cut off (step S28).

In this state, the three-phase control means 56 controls the three-phase arms of the three-phase inversion circuit 52, respectively, and changes the phase voltage of each output phase of the three-phase inversion circuit 52 to a high voltage with respect to the low voltage side of the smoothing circuit 33. Approximately $ 2 of the three-phase line voltage that is the voltage side potential
Switching control is performed at twice the voltage (step S29).
A three-phase AC voltage is applied to the phase load device 26, and a series of controls ends.

In step S26, without emphasizing the three-phase balance,
When emphasis is placed on suppressing leakage current and power supply noise,
The second switching circuit control means 65 controls the second switching means 64
Are closed, and the capacitors C1 and C2 of the smoothing circuit 33 are closed.
Is connected to the three-phase AC power supply 21 (step S30). Then, the first opening / closing means 54 is closed by the first opening / closing circuit control means 55, and the three-phase inversion circuit 52
Are connected to the capacitors C1 and C2 of the smoothing circuit 33.
(Step S31). In this state, the three-phase control means 56
The same control as in the first embodiment is performed for the two phases not connected to the intermediate connection part of the capacitors C1 and C2 of the smoothing circuit 33 (step S32), and the three-phase AC voltage is applied to the three-phase load device 26. To end a series of controls.

If Vout is not approximately one-half (1/2) times Vin in step S25, the second opening / closing means 64 is opened by the second opening / closing circuit control means 65, and
The intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33 and 3
The connection with the phase AC power supply 21 is interrupted (step S3).
3). Then, the first switching means 54 is closed by the first switching circuit control means 55, and the one-phase arm in the three-phase inversion circuit 52 is connected to the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33 (step). S34). 3 in that state
The same control as that of the first embodiment is performed by the phase control means 56 for the two phases in the three-phase inversion circuit 52 that are not connected to the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33 (step S35). ) A three-phase AC voltage is applied to the three-phase load device 26 to end a series of controls.

According to the fifth embodiment, three-phase inversion circuit 5
First switching means 5 for switching the output voltage from 2
Fourth and second opening / closing means 64 are provided, and the open / close states of the first and second opening / closing means 54 and 64 are switched and controlled.
Switching to a three-phase voltage up to approximately one half (1/2) times the power supply voltage, a three-phase voltage up to approximately the same voltage as the power supply voltage, and a three-phase voltage up to approximately twice the power supply voltage it can. When the three-phase inversion circuit 52 outputs a three-phase voltage up to substantially the same voltage as the power supply voltage, the same effects as in the first embodiment, namely, suppression of leakage current, suppression of power supply noise, The following effects can be obtained: downsizing, reduction in the number of components, reduction in cost, and reduction in loss.

When the three-phase inversion circuit 52 outputs a three-phase voltage up to approximately one half (1/2) times the power supply voltage, the voltage change due to switching is almost one half.
(1/2) times, a greater effect is obtained in suppressing leakage current and power supply noise, and in addition, the ratio of the carrier frequency component to the output voltage is suppressed, and the ripple component of the current and the load A stable state can be suppressed.

Embodiment 6 FIG. FIG. 9 is a block diagram showing a configuration of a three-phase inverter device according to Embodiment 6 of the present invention. This inverter device is different from the first embodiment in that a three-phase Y connection power supply 2
3 and that a three-phase forward conversion circuit 61 is provided instead of the single-phase forward conversion circuit 31,
The three-phase output of the phase Y connection power supply is supplied one phase at a time, and the three-phase reverse conversion circuit 52 is provided instead of the single-phase reverse conversion circuit 32, and the three-phase output of the three-phase reverse conversion circuit 52 is output. One phase is supplied to each phase of the three-phase load device 26, and the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33 is connected to the neutral point of the three-phase Y connection power supply. . For other configurations, the first embodiment (see FIG. 1)
Therefore, the same components are denoted by the same reference numerals and description thereof will be omitted.

The three-phase inverse conversion circuit 52 and the three-phase forward conversion circuit 61 are respectively a three-phase inverse conversion circuit 52 of the third embodiment shown in FIG. 3 and a three-phase forward conversion circuit of the fourth embodiment shown in FIG. It has the same configuration as 61. Therefore, the description of those circuits is omitted because they are duplicated.

Next, the operation of the sixth embodiment will be described. The voltage between the connection point of the smoothing circuit 33 and the three-phase Y connection power supply 23 and the higher potential side of the smoothing circuit 33 is three-phase Y
It is about √2 times the effective value of the phase voltage of the connection power supply 23. Similarly, the voltage between the connection point of the smoothing circuit 33 and the three-phase Y connection power supply 23 and the lower potential side of the smoothing circuit 33 is also about √2 times the effective phase voltage of the three-phase Y connection power supply 23. . Therefore, the DC voltage applied to the three-phase inversion circuit 52 is
Thus, the effective value of the output voltage between the sine-wave output lines of the three-phase inversion circuit 52 is approximately √3 times the effective value of the phase voltage of the three-phase Y connection power supply 23. .

On the other hand, when the neutral point of the three-phase Y connection power supply 23 is not connected to the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33, the DC voltage applied to the three-phase inversion circuit 52 is About の of the effective value of the phase voltage of the three-phase Y connection power supply 23
That is, the effective value of the output voltage between the sine wave output lines of the three-phase inversion circuit 52 is up to about three-half (3/2) times the effective value of the phase voltage. Accordingly, by connecting the neutral point of the three-phase Y connection power supply 23 to the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33, the output voltage increases by about 15%.

According to the sixth embodiment, three-phase Y connection power supply 2
3 is connected to the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33, so that the output of the three-phase inversion circuit 52 can be increased, and furthermore, the ground potential applied to the three-phase load device 26 , The leakage current and the power supply noise can be suppressed.

As in the modification shown in FIG. 10, a three-phase Y connection load device 28 is used instead of the three-phase load device 26.
3 is connected to the intermediate connection between the capacitors C1 and C2 of the smoothing circuit 33.
Both the neutral point of the phase Y connection load device 28 and the neutral point of the three-phase Y connection power supply 23 may be connected. In this way, 3
In addition to the effect of increasing the output of the phase inversion conversion circuit 52 and the effect of suppressing the instantaneous voltage with respect to the ground potential applied to the three-phase Y-connection load device 28, the neutral point potential of the three-phase Y-connection load device 28 is stabilized. , Leakage current and power supply noise can be further suppressed.

[0074]

As described above, according to the present invention, according to the present invention, the single-phase forward conversion circuit is connected to two phases of the three-phase output of the three-phase AC power supply, and the intermediate connection between the capacitors of the smoothing circuit is provided. One is connected to the remaining one-phase output of the three-phase AC power supply and to one of the three-phase inputs of the three-phase load device, and the single-phase inverting circuit is connected to the remaining two of the three-phase load device. Connected to the three-phase load device by the three-phase control means.
Since the single-phase inversion circuit is controlled so that the phase AC voltage is supplied, the potential of one phase of the three-phase load device is set to the ground potential,
The instantaneous value of the voltage of the other phase can be suppressed to a potential that is at most about √2 times the line voltage of the three-phase AC power supply. As a result, leakage current and power supply noise can be suppressed. Further, since a general single-phase forward conversion circuit and a general single-phase reverse conversion circuit can be used, the inverter device can be reduced in size, the number of components can be reduced, and the cost can be reduced. Furthermore, the loss can be reduced with the reduction in the number of components.

According to the next invention, the single-phase high power factor forward conversion circuit comprises a single-phase full-bridge rectifier and a switch element connected in anti-parallel to the single-phase full-bridge rectifier,
One of the intermediate connections between the capacitors of the smoothing circuit is 3
Is connected to the remaining one-phase output of the three-phase AC power supply, is connected to one of the three-phase inputs of the three-phase load device, and is connected to the remaining two-phase input of the three-phase load device by the single-phase inversion circuit. And 3
The single-phase inversion circuit is controlled by the phase control means so that the three-phase AC voltage is supplied to the three-phase load device, and the current flowing from the three-phase AC power supply is substantially sinusoidal by the high power factor forward conversion control means. Since the single-phase high power factor forward conversion circuit is controlled so that the power factor is improved by being converted into a wave, the current flowing from the three-phase AC power supply is converted into a substantially sine wave, and the power factor can be improved.

According to the next invention, the single-phase forward conversion circuit has three
One of the intermediate connections between the capacitors of the smoothing circuit is connected to the remaining one-phase output of the three-phase AC power supply and connected to two of the three-phase outputs of the three-phase AC power supply. One of the three-phase inputs is connected to one of the three-phase inputs via a switching means, the three-phase inversion circuit is connected to the three-phase input of the three-phase load device, and the switching means is controlled by the switching circuit control means. The circuit is closed when the output is a three-phase voltage up to substantially the same voltage as the power supply voltage, and is open when the output of the three-phase inversion circuit is a three-phase voltage up to almost twice the power supply voltage. And the three-phase control means controls the three-phase inverse conversion circuit so that the three-phase AC voltage is supplied to the three-phase load device in accordance with the open / close state of the open / close means. The output from the circuit is a three-phase voltage up to the same voltage as the power supply voltage, It can be switched between three-phase voltage to approximately twice the source voltage.

According to the next invention, the three-phase forward conversion circuit has three
One of the intermediate connections between the capacitors of the smoothing circuit is connected to the one-phase output of the three-phase AC power supply via switching means, and the three-phase load of the three-phase load device is connected to the three-phase output of the three-phase AC power supply. One of the inputs is connected to one phase, a single-phase inversion circuit is connected to the remaining two-phase input of the three-phase load device, and the switching means is controlled by the switching circuit control means. When the three-phase voltage is set to substantially the same voltage, the circuit is closed, and the output of the single-phase inversion circuit is set to approximately two times the power supply voltage.
In the case where the three-phase voltage is reduced to 1 / times, the circuit is controlled to be in an open circuit state, and the three-phase control means supplies a three-phase AC voltage to the three-phase load device in accordance with the open / close state of the open / close means. The single-phase inversion circuit is controlled in such a manner that the output from the single-phase inversion circuit is reduced to a voltage approximately equal to the power supply voltage.
It is possible to switch between a phase voltage and a three-phase voltage up to approximately half the power supply voltage. When the output of the single-phase inversion circuit is up to approximately one half of the power supply voltage, the voltage change due to switching becomes approximately one half, so that
In addition to obtaining a greater effect on suppressing the leakage current and the power supply noise, the ratio of the carrier frequency component to the output voltage is suppressed, and the ripple component of the current and the unstable state of the load can be suppressed.

According to the next invention, the three-phase forward conversion circuit includes three
One of the intermediate connections between the capacitors of the smoothing circuit is connected to one of the three-phase inputs of the three-phase load device via the first opening / closing means. A three-phase inverter is connected to the one-phase output of the three-phase AC power supply via the second switching means, a three-phase inversion circuit is connected to the three-phase input of the three-phase load device, and the three-phase inversion circuit is controlled by the switching circuit control means. The open / close states of the first open / close means and the second open / close means are controlled in accordance with the output voltage ranges of the first and second open / close means, and the three-phase control means sets the open / close states of the first open / close means and the second open / close means. Correspondingly, the three-phase inversion circuit is controlled so that the three-phase AC voltage is supplied to the three-phase load device, so that the output from the three-phase inversion circuit is reduced to approximately one half of the power supply voltage. The three-phase voltage, the three-phase voltage up to substantially the same voltage as the power supply voltage, and the power supply voltage It can be switched between three-phase voltage of up to twice.

According to the next invention, the three-phase forward conversion circuit is
Connected to the three-phase output of the three-phase AC power supply, one of the intermediate connections between the capacitors of the smoothing circuit is connected to the neutral point of the three-phase AC power supply, and the three-phase inverting circuit is connected to the three-phase input of the three-phase load device. Since the connection is made, the output of the three-phase inversion circuit can be increased, and the instantaneous voltage with respect to the ground potential applied to the three-phase load device can be suppressed, so that the leakage current and the power supply noise can be suppressed. .

According to the next invention, the intermediate connection between the capacitors of the smoothing circuit is also connected to the neutral point of the three-phase load device, so that the neutral point potential of the three-phase load device is stabilized and the leakage current is reduced. In addition, power supply noise can be further suppressed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a three-phase inverter device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a three-phase inverter device according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a three-phase inverter device according to a third embodiment of the present invention.

FIG. 4 is a flowchart illustrating an operation of the inverter device according to the third embodiment;

FIG. 5 is a block diagram showing a configuration of a three-phase inverter device according to a fourth embodiment of the present invention.

FIG. 6 is a flowchart illustrating an operation of the inverter device according to the fourth embodiment.

FIG. 7 is a block diagram showing a configuration of a three-phase inverter device according to a fifth embodiment of the present invention.

FIG. 8 is a flowchart illustrating an operation of the inverter device according to the fifth embodiment.

FIG. 9 is a block diagram showing a configuration of a three-phase inverter device according to a sixth embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of a three-phase inverter device according to a seventh embodiment of the present invention.

FIG. 11 is a block diagram illustrating a configuration of a general three-phase inverter device.

FIG. 12 is a block diagram showing a configuration of a conventional single-phase inverter circuit in which measures are taken to reduce leakage current and power supply noise.

[Explanation of symbols]

C1, C2 capacitors, D111, D112, D12
1, D122 Single phase full bridge rectifier, S111, S
112, S121, S122 Switch elements, 21, 22
3 three-phase AC power supply, 26, 28 three-phase load device, 31
Single-phase forward conversion circuit, 32 single-phase reverse conversion circuit, 33 smoothing circuit, 34, 56 three-phase control means, 41 single-phase high power factor forward conversion circuit, 42, 43 reactor, 44 high power factor forward conversion control means, 52 Three-phase reverse conversion circuit, 54, 64 switching means, 55, 65 switching circuit control means, 61 three-phase forward conversion circuit.

Claims (7)

[Claims] 1. An inverter device for converting one or both of a voltage and a frequency of a three-phase AC power supply and outputting the converted voltage to a three-phase load device, the inverter device being connected to two phases of the three-phase output of the three-phase AC power supply. A single-phase forward conversion circuit, which is connected to the DC side of the single-phase forward conversion circuit, and at least a pair of capacitors are connected in series, and one of intermediate connections between the capacitors is connected to the three-phase AC power supply. A smoothing circuit connected to the remaining one-phase output and connected to one of the three-phase inputs of the three-phase load device; and a remaining two-phase connected to the smoothing circuit and the three-phase load device. A single-phase reverse conversion circuit connected to an input; and three-phase control means for controlling the single-phase reverse conversion circuit so as to supply a three-phase AC voltage to the three-phase load device. Three-phase inverter device. 2. An inverter device for converting one or both of a voltage and a frequency of a three-phase AC power supply and outputting the converted voltage to a three-phase load device, comprising: a single-phase full-bridge rectifier; and an anti-parallel connection to the single-phase full-bridge rectifier. A single-phase high power factor forward conversion circuit comprising a switched element, connected to the DC side of the single-phase high power factor forward conversion circuit, and at least a pair of capacitors are connected in series, and an intermediate connection between the capacitors One of the sections is connected to the remaining one-phase output of the three-phase AC power source, and is connected to one of the three-phase inputs of the three-phase load device; And a single-phase inversion circuit connected to the remaining two-phase input of the three-phase load device, and three-phase control for controlling the single-phase inversion circuit to supply a three-phase AC voltage to the three-phase load device Means and before High power factor forward conversion control means for controlling the single phase high power factor forward conversion circuit so as to improve the power factor by converting the current flowing from the three-phase AC power supply into a substantially sinusoidal wave. Three-phase inverter device. 3. An inverter device for converting one or both of a voltage and a frequency of a three-phase AC power supply and outputting the converted voltage to a three-phase load device, wherein the inverter device is connected to two of the three-phase outputs of the three-phase AC power supply. A single-phase forward conversion circuit, which is connected to the DC side of the single-phase forward conversion circuit, and at least a pair of capacitors are connected in series, and one of intermediate connections between the capacitors is connected to the three-phase AC power supply. A smoothing circuit that is connected to the remaining one-phase output and that can be connected to one phase of the three-phase input of the three-phase load device via an opening / closing means for switching the opening and closing of the circuit; and a connection to the smoothing circuit. And a three-phase inverting circuit connected to a three-phase input of the three-phase load device, and a closed state when the output of the three-phase inverting circuit is a three-phase voltage substantially equal to a power supply voltage. And the three-phase inversion circuit Switching circuit control means for controlling the switching means so as to open the circuit when the output is a three-phase voltage up to approximately twice the power supply voltage; and the three-phase load device corresponding to the switching state of the switching means And a three-phase control means for controlling the three-phase inversion circuit so as to supply a three-phase AC voltage to the three-phase inverter. 4. An inverter device for converting one or both of a voltage and a frequency of a three-phase AC power supply to output to a three-phase load device, wherein the three-phase forward conversion connected to the three-phase output of the three-phase AC power supply A circuit, connected to the DC side of the three-phase forward conversion circuit, and at least a pair of capacitors are connected in series, and one of the intermediate connection portions of the capacitors is connected to a one-phase output of the three-phase AC power supply, A smoothing circuit that can be connected via switching means for switching the opening and closing of the circuit and is connected to one of three-phase inputs of a three-phase load device; and the three-phase load connected to the smoothing circuit. A single-phase inversion circuit connected to the remaining two-phase input of the device; a closed state when the output of the single-phase inversion circuit is a three-phase voltage up to substantially the same voltage as a power supply voltage; Power supply for the output of the inverse conversion circuit Switching circuit control means for controlling the opening / closing means so as to open the circuit when the three-phase voltage is approximately half the pressure, and the three-phase load device corresponding to the open / closed state of the switching means And a three-phase control unit for controlling the single-phase inversion circuit so as to supply a three-phase AC voltage to the three-phase inverter. 5. An inverter device for converting one or both of a voltage and a frequency of a three-phase AC power supply to output to a three-phase load device, wherein the three-phase forward conversion connected to the three-phase output of the three-phase AC power supply And a circuit connected to the DC side of the three-phase forward conversion circuit, and at least a pair of capacitors are connected in series, and one of the intermediate connection portions between the capacitors is connected to a three-phase load device.
One of the phase inputs may be connected via a first opening / closing means for switching the opening and closing of the circuit, and a second for switching the opening and closing of the circuit to the one-phase output of the three-phase AC power supply. A smoothing circuit that can be connected via switching means; a three-phase inversion circuit connected to the smoothing circuit and connected to a three-phase input of the three-phase load device; and an output voltage range of the three-phase inversion circuit Corresponding to the first
Switching circuit control means for controlling the respective open / close states of the open / close means and the second open / close means; and the three-phase load device corresponding to the open / close states of the first open / close means and the second open / close means. And a three-phase control means for controlling the three-phase inversion circuit so as to supply a three-phase AC voltage. 6. An inverter device for converting one or both of a voltage and a frequency of a three-phase AC power supply and outputting the converted voltage and frequency to a three-phase load device, wherein the three-phase forward conversion is connected to the three-phase output of the three-phase AC power supply. And a circuit connected to the DC side of the three-phase forward conversion circuit, and at least a pair of capacitors are connected in series, and one of intermediate connections between the capacitors is connected to a neutral point of the three-phase AC power supply. A three-phase inverter connected to the smoothing circuit and connected to a three-phase input of the three-phase load device. 7. The three-phase inverter device according to claim 6, wherein the intermediate connection between the capacitors of the smoothing circuit is also connected to a neutral point of the three-phase load device.