JP3171551B2 - High voltage output power converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an output voltage of 3 kV.
More particularly, the present invention relates to a high-voltage output power converter using a switching element including a self-extinguishing device.

[0002]

2. Description of the Related Art Various power converters capable of outputting a high voltage have been proposed. In particular, a multi-level inverter, particularly a three-level inverter, is well known as a power converter for outputting a high voltage whose output voltage exceeds 3 kV (see Japanese Patent Application Laid-Open No. 55-43996). FIG. 5 shows a main circuit of the three-level inverter described in this publication.

[0003] The power converter shown in FIG. 5 relates to a three-level inverter device, which converts AC power input from an AC input terminal 11 into DC power by a converter 12 and outputs the DC power to DC buses P and N. I do. Two series voltage dividing capacitors 13 and 14 having a common connection point as a neutral point C are connected between the DC buses P and N. These voltage dividing capacitors 13 and 14 constitute a voltage dividing circuit. DC buses P and N are further provided with three sets of three-level power conversion circuits 1.
5R, 15S and 15T are connected in parallel on the DC side. The internal configuration of these three sets of three-level power conversion circuits is the same, and if the first power conversion circuit 15R is described, four series-connected _four diodes D _{1 to} D ₄ are connected in anti-parallel. Semiconductor switching elements S _{1 to} S
₄ and two diodes D ₅ and D _{6 in the} same direction as the anti-parallel diode. The switching elements S ₁ ,
S2 and the diodes D ₁ and D ₂ in antiparallel to S ₂ constitute a positive side arm, and the switching elements S ₃ and S ₄
A negative arm is formed by the diodes D ₃ and D ₄ in antiparallel to them. The cathode of the diode D ₅ is connected to the cathode of the diode D _2, a diode D _5,
Common connection point of the D ₆ is connected to the dividing capacitors neutral C, the anode of the diode D ₆ is connected to the anode of the diode D _3. The power conversion circuits 15R, 15S,
15T has the same internal connection as described above, and the common connection point of the diodes D ₅ and D ₆ is commonly connected to the neutral point C of the voltage dividing capacitor. First, second, third power conversion circuit 15R, 15S, of 15T, the switching element S _2, AC output terminals from a connection point S ₃ R, S, T is derived, the AC output terminals R, S, The load motor 16 is connected to T. Generally, GTO (Gate Turn-Off Thyristor) is used as the semiconductor switching elements S _{1 to} S _4.
And IGBT (gate-insulated bipolar transistor)
A self-extinguishing device such as is used.

According to the three-level inverter main circuit shown in FIG. 5, three-level voltages can be obtained at the AC output terminals R, S and T by the selective on / off operation of the switching elements S _{1 to} S ₄ , and the output can be obtained. Thus, the load motor 16 can be stably operated with less harmonic components contained in the AC power.

The DC voltage output from the converter 12 is divided into two by the voltage dividing capacitors 13 and 14, and the switching elements S _{1 to} S ₂ and S _{3 to} S ₄ of each arm are divided by the voltage dividing capacitors 13 and 14 respectively. Only a voltage is applied, and the elements S _{1 to} S ₄ are characterized in that the voltage utilization is improved as compared with using two switching elements of the same rating connected in series.

In addition to the three-level inverter main circuit shown in FIG. 5, a capacitor-divided type N-level inverter main circuit including a multi-level, for example, five-level type main circuit has also been proposed (for example, FIG. 5). , The Institute of Electrical Engineers of Japan, SPC-93-71, Semiconductor Power Conversion Study Group, Ikuo Ikuo et al.
G "December 1993).

In the three-level inverter main circuit shown in FIG. 5, a self-extinguishing type device is generally used as the switching elements S _{1 to} S ₄ . As the self-extinguishing device, in addition to the above-mentioned GTO and IGBT, there are MOS devices such as relatively new devices such as IEGT (injection promoting transistor) and SI thyristor (static induction thyristor). At present, the voltage rating of the arc-extinguishing type device is the highest in GTO, and GTO with a rated voltage of 4.5 kV or 6 kV is commercialized. Other self-extinguishing devices are still rated at a lower voltage, but at 4.5
Research to improve it to the kV class is continuing in various fields. When commercializing a high-voltage output power converter from these points, a GTO is used as a self-extinguishing device, and the three-level inverter main circuit configuration of FIG. 5 actually uses a 4.5 kV or 6 kV rated voltage GTO. A high-voltage output power converter that supplies power to the load motor 16 at an AC output voltage of 3 kV class has been put to practical use.

However, when including overseas, the load motor 16
Has various voltage ratings, for example, 4.2 kV class,
It is often used in a region exceeding 3 kV, such as a 6 kV class and a 10 kV class. In general, as the capacity of the load motor 16 increases, the rated voltage thereof is often set to a higher value. For example, when a power converter for supplying AC power to the load motor 16 having a rated voltage of 6 kV class is configured, the switching element S in the related art shown in FIG.
Since ₁ to S ₄ and diodes D ₁ to D ₆ is insufficient its rated voltage, it becomes necessary to use two or more self-arc-extinguishing devices and diodes respectively connected in series. In order to use a self-extinguishing device or diode connected in series in this way, a combination of a resistor or a series circuit of a capacitor and such is used so that the shared voltage of the self-extinguishing device connected in series is equal. Voltage balancing circuits need to be connected in parallel with each self-extinguishing device or diode. Voltage balancing circuits for these self-extinguishing devices and diodes not only increase the number of parts connected to the main circuit, but also increase power loss, as is well known in various documents.

Further, it is very difficult for a self-extinguishing device or diode connected in series to completely share the applied voltage evenly under transient operating conditions in the main circuit. Although it differs depending on the number and operating conditions, it is common to use at least about 10% of the voltage sharing imbalance. Therefore, the constant voltage utilization rate of the self-extinguishing device and the diode is reduced by that much, and the power conversion device is uneconomical.

On the other hand, the self-extinguishing type device constituting the switching elements S _{1 to} S ₄ is a switching element capable of turning on or off a main circuit current by a control signal. For example, the DC power can be subjected to PWM control in the main circuit configuration of the three-level inverter in FIG. 5 to supply variable load AC power to the load motor 16. When the PWM control is performed in this manner, an AC output voltage of an arbitrary voltage can be obtained, and thus various power converters use the PWM control method. By the way, P
When performing WM control, an allowable switching frequency differs depending on the type of the self-extinguishing type device. For example, G
The allowable switching frequency for TO is generally 500H
z, and generally 2 to 10 kHz for IGBT
It is about. In general, the switching frequency of a self-extinguishing device decreases as the rated values of voltage and current increase.
This is PW less than the ohmic loss caused by flowing current in the power loss generated by the self-extinguishing device.
This is because the switching loss when the self-extinguishing device is turned on and off by the M control increases. On the other hand, in the power converter, in order to obtain an AC output close to a sine waveform with less harmonic components, it is desirable to increase the switching frequency, but a self-extinguishing device is generated by suppressing an increase in switching loss. In order to rationally dissipate the heat loss and cool the device, the switching frequency as described above is selectively used according to each self-extinguishing device.

Therefore, in the high-voltage output power converter, the switching loss increases as the voltage becomes higher. Therefore, a power converter capable of suppressing the switching frequency as low as possible and supplying AC power with less harmonics is desired.

It is desirable that an AC power supply for supplying AC power through the AC input terminal 11 can also supply AC power with a small amount of harmonics. However, it is also known that the magnitude of the harmonics is generally determined by the condition of the converter 12. ing.

[0013]

Outlined INVENTION Problems to be Solved] above, when trying to obtain a high-voltage AC output by using a self-arc-extinguishing devices as semiconductor switching elements S ₁ to S _4, functional self arc-extinguishing device In a three-level inverter configured using the minimum required number of elements, the output voltage of the 3 kV class is limited, and the 4.2 kV class or 6 kV
In order to provide a high-voltage output power converter that outputs a voltage of a class, the self-extinguishing device is formed by connecting each of the switching elements S _{1 to} S ₄ in FIG. 5 to a series connection of two or more self-extinguishing devices. Had to be composed of As described above, in the high-voltage output power converter configured by connecting the self-arc-extinguishing devices in series, the following various technical problems cannot be sufficiently solved.

That is, when the self-extinguishing devices constituting the semiconductor switching elements S _{1 to} S ₄ are connected in series and used in a high-voltage output power converter exceeding 3 kV, the following problems occur. (1) Since the self-extinguishing device used in series is turned off at a relatively high speed of several microseconds, the serial connection technology itself is very useful, for example, by selectively combining the turn-off characteristics of the self-extinguishing device. was difficult. (2) The self-extinguishing type devices connected in series need to have a margin of 10% or more in the voltage rating in order to cope with the transient imbalance of voltage sharing. (3) To connect self-extinguishing devices in series,
It was necessary to provide a voltage balance circuit so that the voltage sharing was as even as possible. When the voltage balance circuit is provided, the number of main circuit connection components increases, and the reliability of the power conversion device also decreases. (4) When the self-arc-extinguishing devices are configured in series, the number of main circuit connecting parts increases, which not only increases the size of the power converter, but also becomes economically disadvantageous.

On the other hand, when PWM control is performed on a power converter configured using a self-extinguishing type device, practically 5
It is desirable to perform the switching operation at a switching frequency of 00 Hz or more, but this causes the following problem. (5) In the self-extinguishing type device, the switching frequency increases due to an increase in the switching frequency compared to the ohmic loss at the time of the ON operation. (6) If the power loss generated by the self-extinguishing type device is large, the cooling device for dissipating the heat loss must be increased in size.

Further, from the side of the AC power supply that supplies the AC power to the power converter, it is desired that the harmonic components generated on the power converter be small.

Therefore, the present invention provides a method for connecting a switching element consisting of a self-extinguishing type device without connecting in series.
It can output a high voltage exceeding kV, has a simple main circuit configuration and high reliability, and is economical and highly efficient.
It is an object of the present invention to provide a high-voltage output power converter capable of realizing miniaturization.

[0018]

In order to achieve the above object, the present invention is directed to a DC power supply provided independently for each of three phases, and an output terminal of a DC power supply corresponding to each phase. A voltage-dividing circuit comprising at least two voltage-dividing capacitors connected in series with each other, and at least four voltage-dividing circuits connected in series between output terminals of the corresponding DC power supply for each phase.
First and second multi-level single-phase power conversion circuits each having a switching element composed of a plurality of self-arc-extinguishing devices. A divided potential is applied from a voltage dividing circuit to a series connection point of the switching elements of the negative arm through a unique diode, and an AC terminal of the first multilevel single-phase power conversion circuit is connected to a common bus common to each phase. Connected, second
And a three-phase single-phase inverter circuit from which an AC output terminal of a corresponding phase is derived from an AC terminal of the multi-level single-phase power conversion circuit.

According to a second aspect of the present invention, in the device according to the first aspect, the voltage dividing circuit includes two voltage dividing capacitors, and the first and second multi-level single-phase power conversion circuits each include four capacitors.
It is a three-level single-phase power conversion circuit including a plurality of switching elements.

According to a third aspect of the present invention, in the device according to the first or second aspect, the switching element is a modular self-extinguishing device, and the common bus is grounded via an impedance element. And

According to a fourth aspect of the present invention, in the device according to the first or second aspect, the switching element is formed of a modular self-extinguishing device, and the common bus is connected through a fuse or a parallel circuit of a fuse and an impedance element. It is characterized by being grounded.

According to a fifth aspect of the present invention, in the high-voltage output power converter according to the first aspect, a common voltage control circuit for generating a voltage command signal for three sets of single-phase inverter circuits;
A carrier generation circuit for generating a carrier for PWM control; a first modulation circuit for performing PWM control on a first multi-level single-phase power conversion circuit based on the voltage command signal and the carrier; A second modulation circuit that performs PWM control on the second multi-level single-phase power conversion circuit.

According to a sixth aspect of the present invention, in the high-voltage output power converter according to the fifth aspect, the phase of the carrier inputted from the carrier generation circuit to the first modulation circuit and the carrier inputted to the second modulation circuit are provided. Are different from each other.

According to a seventh aspect of the present invention, in the high voltage output power converter according to the second aspect, the DC power supply is insulated for each single-phase power conversion circuit.

According to an eighth aspect of the present invention, in the high voltage output power converter according to the seventh aspect, the DC power supply has three sets of secondary windings for outputting insulated AC voltages having different voltage phases. It is characterized by comprising a multi-winding insulating transformer and a converter for rectifying the AC output of the secondary winding corresponding to each phase.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a high-voltage output power converter according to the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. FIG.
The power converter shown in (1) includes three sets of DC power supplies E _d1 , E _d2 , and E _d3 insulated from each other in accordance with the number of output phases (three phases). Each DC power supply has a voltage dividing capacitor 13, 1
Four and two sets of three-level power conversion circuits are provided.
That is, the three-level power conversion circuits 15R1, 1
5R2, and a three-level power conversion circuit 15 for the S phase.
S1 and 15S2 are provided, and the T phase is provided with three-level power conversion circuits 15T1 and 15T2, and each phase constitutes a single-phase inverter circuit with two sets of three-level power conversion circuits. The internal configuration of each three-level power conversion circuit is the same as that of the three-level power conversion circuits 15R, 15S, and 15T already described with reference to FIG. 5, and elements corresponding to each other are denoted by the same reference numerals. The difference between input and output will be explained. Here, as the switching elements S _{1 to} S ₄ , a GTO, which is a kind of a self-extinguishing type device, is used here. It has already been mentioned that the DC side of the power conversion circuit of each phase is connected to DC power supplies insulated from each other. The connection mode between the two sets of power conversion circuits of each phase and the diodes D ₅ , D ₆ and the neutral point C of the voltage dividing capacitor is not different from that of FIG. Here, the difference from the case of FIG.
This is the connection of the AC output terminals of the set of power conversion circuits. That is, the first power conversion circuits 15R1, 15S1, 1 of each phase
The AC output terminal U of 5T1 is connected to the common bus O to form a neutral point of the three-phase circuit, and the second power conversion circuit 15 of each phase is connected.
The AC output terminals of R2, 15S2, and 15T2 constitute the AC output terminals R, S, and T of the three-phase inverter circuit. A desired three-phase AC voltage is output to the AC output terminals R, S, and T, and supplied to the load motor 16.

In the circuit device shown in FIG. 1, three sets of single-phase inverter circuits constituted by using two sets of three-level power conversion circuits are provided with DC power supplied from respective DC power supplies E _d1 , E _d2 , and E _d3. Is converted to three-phase AC power, and AC output terminals R,
The electric power is supplied to the load motor 16 via S and T. At this time, each single-phase inverter circuit outputs the phase voltages of R, S, and T phases of the three-phase AC power. However, since the AC output terminal U is connected to the common bus O, the entire three-phase AC power is output. The output voltage of each single-phase inverter circuit is 3 ^-1/2 (= 0.58) times the input voltage of the load motor 16. Thus, the fact that the AC output voltage of each single-phase inverter circuit is 3 ^-1/2 times the input voltage of the load motor 16 means that the three-level power conversion circuit 15
This means that the DC input voltages of R, 15S and 15T can be increased by 3 ^-1/2 times. That is, ^31/2 times the rated voltage than the conventional method by the configuration of FIG. 1 without the series connected to the switching element S ₁ to S ₄ consisting of self-turn-off device constituting a three-level power converter circuit Means that a high-voltage output power conversion device capable of operating the load motor 16 can be realized.

3 using two sets of three-level power conversion circuits
By configuring the set of single-phase inverter circuits as shown in FIG. 1, the AC output voltage supplied to the load motor 16 can also be a multi-stage waveform with a maximum of five levels, and a clean (ie, close to a sine wave) waveform Of the switching elements S _{1 to} S ₁ which can output only up to about 3 kV class as described above.
_By directly converting ₄ to the configuration of FIG.
An AC output voltage up to the V class can be obtained. Therefore, without connecting the switching elements in series,
Using a level power conversion circuit, a power conversion device that outputs a higher voltage can be configured, so that it is possible to prevent a reduction in the voltage utilization rate due to a conventional series connection of switching elements, and it is technically difficult. There is no need to provide a voltage balance circuit associated with the series connection, so that the reliability and economy of the power converter can be improved, and the size of the device can be further reduced.

In the embodiment shown in FIG.
As disclosed in Japanese Patent Application Publication No. 96-96, a main circuit configuration including three sets of single-phase inverter circuits configured using two sets of three-level power conversion circuits for each phase has been exemplified. The above-described operation and effect can be obtained even when a multi-level power conversion circuit as disclosed in Japanese Patent No. 36711 is used in place of the three-level power conversion circuit in FIG.

In the embodiment of FIG. 1, three sets of DC power supplies E _d1 , E _d2 and E _d3 are provided which are insulated from each other. Independently separated DC power supplies E _d1 , E _d2 , E
By providing _d3 , it is possible to eliminate a cross current flowing between the three phases of the single-phase inverter circuit, prevent mutual interference due to the cross current, and obtain stable operation characteristics.

FIG. 2 shows a second embodiment of the present invention. A feature of the device of FIG. 2 is that in the circuit device of FIG. 1, a common bus O forming a neutral point is grounded via a parallel connection of a fuse 17 and an impedance element 18. In some cases, the fuse 17 or the impedance element 18 may be omitted and the impedance element 1 may be omitted.
It is also possible to ground only through 8 or only through fuse 17.

As shown in FIG. 2, the common bus O is connected to the fuse 1
By grounding through 7 and the impedance element 18, will be common bus O is fixed to the ground potential, constituting a self-extinguishing type device the switching element S ₁ to S ₄ for use in the three-level power converter circuit In this case, the ground insulation voltage of these self-arc-extinguishing devices and main circuit components is the output voltage (phase voltage) of a single-phase inverter circuit, which is equivalent to 3 ^-1/2 times the AC output voltage (line voltage). It can be selected as a standard. Fuse 17 due to ground fault current
Is blown, the common bus O is connected to the impedance element 18.
, The fault current is interrupted, or the ground fault current is suppressed by the impedance element 18 for a short time until the device stops, and the rise of the device with respect to the ground is suppressed. be able to.

The self-extinguishing device includes a flat device and a modular device. Flat devices dissipate heat by attaching cooling fins to both sides of the device. In contrast,
In the module type device, a device chip is attached by electrically insulating one of the heat sinks, and the heat sink is electrically insulated. Therefore, a method of cooling devices having different potentials by a common cooling fin is adopted. As described above, the modular type self-extinguishing device has an advantage that a common cooling fin can be used to dissipate heat loss inside the device. Therefore, a modular type self-extinguishing device is used in IGBTs and recent new MOS devices. A structure that is an arc-extinguishing device is desired. However, in the case of a modular device, it is difficult to electrically insulate the heatsink from the device chip, and it has been difficult to significantly improve the withstand voltage of the modular self-extinguishing device.

As shown in FIG. 2, the common bus O is grounded via the impedance element 18 and the like, and the potential of the common bus O is fixed to the ground potential, so that the switching elements S _{1 to} S _{4 used} are also resistant. It can be constituted by a modular self-extinguishing device having a low ground insulation voltage. By using a modular self-extinguishing device, it is possible to reduce the size of the power converter and improve the economic efficiency.

When a flat device and a module device are compared, it is known that the module device is weaker in terms of mechanical structural resistance in addition to the ground insulation voltage resistance. When a power converter is configured by using a switching element composed of a module type self-extinguishing device, the electrical insulation between the heat sink and the device chip is deteriorated due to a fault current caused by a DC short circuit fault and the like, and the power converter is formed via a common bus O. There is a risk that a large ground fault current will flow through the ground loop that is created. In such a case, the ground fault current needs to be suppressed promptly. However, as shown in FIG.
8 or both can ground the common bus O to reduce ground fault currents,
The reliability of protection against grounding accidents can be further improved.

FIG. 3 shows a third embodiment of the present invention. The main circuit in this embodiment is substantially the same as that of FIG. ₁ except that the switching elements S _{1 to} S ₄ are IGBTs, which are one type of self-extinguishing type devices similar to GTO. Is shown in FIG. The feature of the apparatus of FIG. 3 lies in the control unit. Here, as a control device, a voltage control circuit 20, a carrier generation circuit 21, a first modulation circuit 221 and a second modulation circuit 22
2 are provided. The voltage control circuit 20 includes a modulation circuit 22
Output voltage command signals e _c1 and e _c2 to be input to 1, ₂₂₂ . The carrier waves e ₁ and e ₂ are also input to the modulation circuits 221 and 222 from the carrier generation circuit 21. Modulation circuit 22
1 is a PW based on the voltage command signal e _c1 and the carrier wave e _1.
A control signal for M control is generated and supplied to the first three-level power conversion circuits 15R1, 15S1, 15T1 to control each switching element. Similarly, the modulation circuit 2
22 is P based on the voltage command signal e _c2 and the carrier e _2.
A control signal for WM control is generated and supplied to the second three-level power conversion circuits 15R2, 15S2, 15T2 to control each switching element.

When PWM control of each power conversion circuit is performed by the two sets of modulation circuits 221 and 222, the phase difference between the two sets of voltage command signals e _c1 and e _c2 is controlled, and the same carrier waves e ₁ and e as described above. ₂ may be used for PWM control, and the phase difference between the voltage command signals e _c1 and e _c2 is not controlled, and a 180 ° phase difference is provided between the carrier waves e ₁ and e _2. Is also good.

In the circuit configuration of FIG. 3 in which the first and second power conversion circuits are controlled by the two sets of modulation circuits 221 and 222 in the same phase, the five-level output voltage more approximated to a sine wave Can be supplied to the load motor 16 and the switching frequency for PWM control is synthesized. Therefore, even if the switching frequency of the switching element constituting each three-level power conversion circuit is reduced, the harmonic An output voltage with few waves can be obtained.

In a self-extinguishing device with a high rated voltage,
Under a switching frequency of about 500 Hz, the switching loss is usually 70% and the ohmic loss is 30%. However, if the switching frequency can be reduced to about 300 Hz, the switching loss of the self-arc-extinguishing type device can be reduced. Is 28 (= 70−70 × 300/500)
%. In addition, this effect not only reduces the switching loss of the self-extinguishing type device, but also provides an additional power loss reducing effect in the snubber circuit and other main circuit components attached to each switching element. Loss can be greatly reduced.

FIG. 4 shows a fourth embodiment of the present invention. This embodiment has a feature in a DC power supply portion of a main circuit. That is, in this embodiment, a common primary winding 240 and three sets of secondary windings 24 are provided.
A multi-winding insulated transformer 24 having 1,242,243;
Converters 251, 252, 2 connected to each secondary winding
53 constitutes a DC power supply separated for each phase. The output voltage of the three secondary windings of the transformer 24 is 20
For example, when the output voltage phase of the secondary winding 242 is set to 0 ° so as to have a phase difference of 0 °, the output voltage phases of the other two sets of secondary windings 241 and 243 are from + 20 ° to −−. The internal winding configuration and connection of the secondary windings 241 to 243 are performed so as to be 20 °. Such a transformer has 20
° A known phase-shifting 18-phase rectifier transformer can be used. By configuring the 18-phase rectifier circuit in this way, the harmonic current component viewed from the AC power supply to which the primary winding 240 of the transformer 24 is connected is (18n ± 1).
(n is a positive integer) only harmonics, which can be less than the harmonic current component corresponding to harmonic regulation. Also in the case of the circuit of FIG. 4, since there is no interference between the DC power supplies of each phase, a stable operation can be performed, and a high-voltage output power conversion device in which the influence of harmonics is reduced on the input AC power supply side can be realized. it can.

The present invention is not limited to the above-described internal configuration of the multi-level power conversion circuit or the PWM control method.
Various changes can be made without departing from the spirit of the invention.

[0042]

As described above, according to the present invention, a high-voltage output power conversion device having the following effects can be provided. (1) According to the invention described in claim 1, it is possible to supply a self-extinguishing type device without series, 3 ^1/2 times (= 1.73-fold) higher output voltage than the conventional . As a result, a) when connecting self-extinguishing devices in series in order to obtain a high voltage output, a voltage balancing circuit which was conventionally required is not required, and it is necessary to perform series connection of self-extinguishing devices which are technically difficult. There is no. As a result, the number of main circuit connection parts is reduced, and a compact and highly reliable power converter can be provided.

B) By eliminating the need for series connection, the voltage utilization rate of the self-extinguishing device itself is improved by 10% or more, and an economical power converter can be obtained. c) Since a high-voltage output power converter can be configured using a self-extinguishing device that is not connected in series, a transformer for boosting the output voltage is omitted and a power conversion system with a simplified main circuit is provided. Can be. (2) According to the third or fourth aspect of the present invention, in addition to the above-described effects, a high-voltage output power that makes the ground withstand voltage 3 ^-1/2 times (= 0.58 times) the conventional value. A conversion device can be provided. As a result, a) a power converter using a modular self-extinguishing device can be obtained, and the adoption of a modular self-extinguishing device simplifies the cooling and assembly of the power converter and achieves economical power consumption. It can be a conversion device. b) The protection of the modular self-extinguishing device is also improved, and a highly reliable power converter against grounding accidents can be provided. (3) According to the invention described in claim 5 or claim 6, in addition to the above-described effects, even if the switching frequency of the self-extinguishing type device is reduced, it is possible to supply AC power with less harmonic components. it can. As a result, a) the power loss of the self-extinguishing device can be reduced by about 28% compared with the conventional device. b) Since the power loss of the snubber circuit and other main circuit components for the self-extinguishing type device is also reduced, it is possible to provide a power converter that has a high operating efficiency and is sufficient for a small cooling device. (4) According to the invention as set forth in claim 7, in addition to the above-mentioned effects, a high-voltage output power converter capable of preventing mutual interference on the DC power supply side and improving reliability of stable operation is provided. be able to. (5) According to the invention described in claim 8, in addition to the above-described effects, it is possible to provide a high-voltage output power converter capable of greatly reducing harmonic components even on the input AC power supply side.

[Brief description of the drawings]

FIG. 1 is a main circuit connection diagram of a high-voltage output power converter according to a first embodiment of the present invention.

FIG. 2 is a main circuit connection diagram of a high-voltage output power converter according to a second embodiment of the present invention.

FIG. 3 is a main circuit connection diagram of a high-voltage output power converter according to a third embodiment of the present invention.

FIG. 4 is a main circuit connection diagram of a high-voltage output power conversion device according to a fourth embodiment of the present invention.

FIG. 5 is a main circuit connection diagram of a conventional high-voltage output power converter.

[Explanation of symbols]

E _d1, E _d2, E _d3 DC power supply 13 and 14 voltage dividing capacitors 15R1,15S1,15T1 first 3 levels single-phase power conversion circuit 15R2,15S2,15T2 second three-level single-phase power conversion circuit S _1, S ₂ , S ₃ , S ₄ Switching element D _{1 to} D ₆ Diode O Common bus R, S, T AC output terminal 16 Load motor 17 Fuse 18 Impedance element 20 Voltage control circuit 21 Carrier generation circuit 221, 222 Modulation circuit 24 Multi-turn Wire insulated transformer 251,252,253 Converter

Claims (8)

(57) [Claims] A DC power supply provided independently for each of three phases, and at least two voltage dividing capacitors connected in series between output terminals of the corresponding DC power supply for each phase. First and second multilevel single-phase power having a voltage circuit and, for each phase, at least four self-turn-off devices connected in series between output terminals of a corresponding DC power supply. A conversion circuit, and separates the voltage dividing circuit from the voltage dividing circuit via a diode unique to a series connection point between the switching elements of the positive arm and the negative arm in the first and second multi-level single-phase power conversion circuits. A voltage potential is applied, an AC terminal of the first multi-level single-phase power conversion circuit is connected to a common bus common to each phase, and a voltage of a corresponding phase is supplied from the AC terminal of the second multi-level single-phase power conversion circuit. AC output end There high voltage output power converter and a single-phase inverter circuit 3 sets of derived. 2. The apparatus according to claim 1, wherein said voltage dividing circuit comprises two voltage dividing capacitors, and said first and second multi-level single-phase power converting circuits each comprise four switching elements. A high-voltage output power conversion device that is a three-level single-phase power conversion circuit. 3. A high-voltage output power converter according to claim 1, wherein said switching element comprises a modular self-extinguishing device, and said common bus is grounded via an impedance element. . 4. An apparatus according to claim 1, wherein said switching element comprises a modular self-extinguishing device, and said common bus is grounded via a fuse or a parallel circuit of a fuse and an impedance element. High voltage output power converter. 5. A high-voltage output power converter according to claim 1, wherein a common voltage control circuit for generating a voltage command signal for said three sets of single-phase inverter circuits and a carrier wave for PWM control are generated. A carrier generation circuit; a first modulation circuit that performs PWM control on a first multi-level single-phase power conversion circuit based on the voltage command signal and the carrier; and a second modulation circuit based on the voltage command signal and the carrier. A high-voltage output power conversion device comprising: a second modulation circuit that performs PWM control on the level single-phase power conversion circuit. 6. The high-voltage output power converter according to claim 5, wherein a phase of a carrier inputted from said carrier generation circuit to said first modulation circuit and a phase of a carrier inputted to said second modulation circuit are determined. The high-voltage output power converters are different from each other. 7. The high-voltage output power converter according to claim 2, wherein the DC power supply is insulated for each single-phase power conversion circuit. 8. The high voltage output power converter according to claim 7, wherein said DC power supply has three sets of secondary windings outputting insulated AC voltages having mutually different voltage phases. A high-voltage output power converter comprising a transformer and a converter for rectifying an AC output of the secondary winding corresponding to each phase.