JPH09182451A - High-voltage output power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-voltage output power converter by which a high voltage can be output well without connecting switching elements in series. SOLUTION: A high-voltage output power converter is provided with DC power supplies Ed1 to Ed3 which are installed independently at every phase of three phases, with first and second multilevel single-phase power conversion circuits 15R1 to 15T1, 15R2 to 15T2 which comprise at least four switching elements S1 to S4 connected in series across output terminals of corresponding DC power supplies at every phase and with three sets of single-phase inverter circuits in which AC terminals U's of the first multilevel single-phase power conversion circuits are connected to a common bus O which is common to every phase and from which AC output terminals R's, S's, T's, at phases corresponding to the AC terminals of the second multilevel single-phase power conversion circuits are derived.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an output voltage of 3 kV.
The present invention relates to a high voltage output power converter that exceeds the above range, and particularly to a high voltage output power converter that uses a switching element composed of a self-extinguishing type device.

[0002]

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

The power conversion apparatus shown in FIG. 5 relates to a three-level inverter apparatus, in which AC power input from an AC input terminal 11 is converted into DC power by a converter 12 and the DC power is output to DC busbars P and N. To do. Between the DC buses P and N, two series voltage dividing capacitors 13 and 14 having a common connection point as a neutral point C are connected. These voltage dividing capacitors 13 and 14 form a voltage dividing circuit. Three sets of three-level power conversion circuits 1 are provided on the DC buses P and N.
5R, 15S, and 15T are connected in parallel on the DC side. Internal structure of these three sets of three-level power converter circuit are the same and will be described for the first power conversion circuit 15R, respectively diodes D ₁ to D ₄ are four of the connected in series connected in antiparallel Semiconductor switching elements S _{1 to} S
₄ and two diodes D ₅ and D _{6 in the} same direction as the antiparallel diode. Switching element S ₁ ,
S ₂ and diodes D ₁ and D ₂ anti-parallel to them constitute a positive arm, and switching elements S ₃ and S ₄
And the negative side arm is constituted by the diodes D ₃ and D ₄ which are anti-parallel to them. The cathode of the diode D ₅ is connected to the cathode of the diode D ₂ , and the diode D ₅ ,
The common connection point of D ₆ is connected to the voltage dividing capacitor neutral point C, and the anode of the diode D ₆ is connected to the anode of the diode D ₃ . Power conversion circuits 15R, 15S,
15T has the same internal connection as described above, and the common connection points of the diodes D ₅ and D ₆ are commonly connected to the neutral point C of the voltage dividing capacitor. AC output terminals R, S, T are derived from the connection points of the switching elements S ₂ , S ₃ of the first, second, and third power conversion circuits 15R, 15S, 15T, and the AC output terminals R, S, The load motor 16 is connected to T. The semiconductor switching elements S _{1 to} S ₄ are generally GTO (gate turn-off thyristor).
And IGBT (gate insulation type bipolar transistor)
Self-extinguishing devices such as are used.

[0004] According to the three-level inverter main circuit shown in FIG. 5, it is possible to obtain the switching element S ₁ to S ₄ of the AC output terminal R by selective on-off operation, S, a 3-level voltage to T, moreover outputs The harmonic components contained in the AC power generated are small, and the load motor 16 can be operated stably.

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

In addition to the three-level inverter main circuit shown in FIG. 5, a capacitor-dividing type N-level inverter main circuit is proposed, including a multi-level one, for example, a five-level one (for example, a five-level type). , Institute of Electrical Engineers, Semiconductor Power Conversion Workshop Material SPC-93-71, Ikuo Ide et al. “SV using a capacitor voltage dividing multi-level inverter
G "December 1993).

In the three-level inverter main circuit shown in FIG. 5, it is common to use self-turn-off devices as the switching elements S _{1 to} S ₄ . In addition to the GTO and IGBT described above, self-extinguishing devices include MOS devices such as IEGT (injection promoting transistor) and SI thyristor (static induction thyristor), which are relatively new devices. GTO has the highest voltage rating for arc-extinguishing devices so far, and GTO with 4.5 kV or 6 kV rated voltage has been commercialized. The rated voltage of other self-extinguishing devices is still low, but it is 4.5
Research to improve to the kV class continues in various fields. From these points, when commercializing a high-voltage output power converter, a GTO is used as a self-extinguishing device, and the 3-level inverter main circuit configuration of FIG. 5 that actually uses a GTO with a rated voltage of 4.5 kV or 6 kV is used. Therefore, 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 into practical use.

However, including overseas, the load motor 16
Has various voltage ratings, such as 4.2kV class,
It is often used in the area exceeding 3 kV such as 6 kV class and 10 kV class. When the load motor 16 has a large capacity, a high rated voltage is generally selected in many cases. For example, when configuring a power conversion device that supplies AC power to the load motor 16 having a rated voltage of 6 kV class, the switching element S is used in the related art as shown in FIG.
_Since the rated voltage of _{1 to} S ₄ and the diodes D _{1 to} D ₆ are insufficient, it is necessary to use two or more self-extinguishing devices or diodes connected in series. In this way, in order to use self-extinguishing devices and diodes connected in series, it is configured by combining resistors and series circuits of capacitors and capacitors so that the shared voltages of the self-extinguishing devices connected in series are equal. It is necessary to connect a voltage balancing circuit to each self-extinguishing device or diode in parallel. The voltage balancing circuit for these self-extinguishing type devices and diodes has a drawback that not only increases the number of main circuit connecting components, but also increases power loss, as is known in various documents.

Further, it is very difficult for the self-arc-extinguishing type device and the diode connected in series to completely divide the applied voltage evenly under the transient operating condition in the main circuit. It is generally used in consideration of the unbalance of the voltage sharing of at least about 10%, though it varies depending on the number and the operating conditions. Therefore, the constant voltage utilization rate of the self-arc-extinguishing device and the diode is correspondingly reduced, resulting in an uneconomical power conversion device.

On the other hand, the self-extinguishing type devices that constitute the switching elements S _{1 to} S ₄ are switching elements capable of turning on or off the main circuit current according to a control signal. The DC power can be PWM-controlled by the main circuit configuration of the three-level inverter shown in FIG. 5, for example, to supply the variable-voltage AC power to the load motor 16. When the PWM control is performed in this way, an AC output voltage of an arbitrary voltage can be obtained, so that various power conversion devices use the PWM control method. By the way, P
When performing WM control, the allowable switching frequency depends on the type of self-extinguishing device. For example, G
Allowable switching frequency for TO is generally 500H
z, and generally 2 to 10 kHz in the case of IGBT
It is a degree. Generally, the self-extinguishing type device has a lower switching frequency as the rated value of voltage / current increases.
This is PW rather than the ohmic loss generated by passing a current in the power loss generated by the self-extinguishing device.
This is because the switching loss becomes large when the self-extinguishing device is turned on / off by the M control. On the other hand, in the power conversion device, it is desirable to increase the switching frequency in order to obtain an AC output close to a sinusoidal waveform with a small amount of harmonics, but a self-extinguishing device is generated by suppressing an increase in switching loss. To reasonably dissipate the heat loss and cool the device, the switching frequency as described above is selected and used according to each self-turn-off device.

Therefore, in the high-voltage output power converter, since the switching loss increases as the voltage increases, a power converter capable of supplying the alternating-current power with a reduced harmonic content while keeping the switching frequency as low as possible is desired.

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

[0013]

When the self-extinguishing type device outlined above is used as the semiconductor switching elements S _{1 to} S ₄ to obtain a high voltage AC output, the self-extinguishing type device is functionally operated. In a 3-level inverter configured using the minimum number of required elements, the limit is to obtain an output voltage of 3kV class, and 4.2kV class or 6kV class.
And outputs the class of voltage to the high voltage output power converter, the series connection of two or more self-arc-extinguishing devices each switching element S ₁ to S ₄ in FIG. 5 a self-extinguishing type device Had to consist of. As described above, the high-voltage output power converter configured by connecting the self-extinguishing type devices in series could not sufficiently solve various technical problems described below.

That is, when the self-extinguishing type devices constituting the semiconductor switching elements S _{1 to} S ₄ are used in series connection in a high voltage output power converter exceeding 3 kV, the following problems have occurred. (1) Since the self-extinguishing type devices used in series connection turn off at a relatively high speed of a few microseconds, the series connection technology itself is extremely effective, such as selecting and combining the turn-off characteristics of the self-extinguishing type devices. was difficult. (2) The self-extinguishing type devices connected in series had to have a margin of 10% or more in voltage rating in order to cope with 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 would be as even as possible. When the voltage balance circuit is provided, the number of main circuit connecting components increases and the reliability of the power conversion device also decreases. (4) When the self-extinguishing type devices are connected in series, the number of main circuit connecting components increases, which not only increases the size of the power conversion device but also is economically disadvantageous.

On the other hand, in the case of PWM control of the power converter constituted by using the self-extinguishing type device, it is practically 5
It is desirable to perform switching operation at a switching frequency of 00 Hz or higher, but this causes the following problems. (5) In the self-extinguishing type device, since the switching loss increases more than the ohmic loss during the ON operation due to the increase of the switching frequency, it becomes necessary to reduce the energizing current. (6) If the electric power loss generated by the self-extinguishing type device is large, the cooling device for dissipating the lost heat must be upsized.

Furthermore, from the viewpoint of the AC power supply side that supplies AC power to the power conversion device, it is desirable that the harmonic components generated on the power conversion device side be small.

Therefore, according to the present invention, the switching element composed of the self-extinguishing type device is not connected in series.
It is possible to output a high voltage exceeding kV, and the main circuit configuration is simple and highly reliable, economical and highly efficient.
It is an object of the present invention to provide a high voltage output power conversion device that can be downsized.

[0018]

In order to achieve the above object, the invention of claim 1 provides a DC power source independently provided for each of the three phases and an output terminal of the DC power source corresponding to each phase. A voltage dividing circuit consisting of at least two voltage dividing capacitors connected in series between each, and at least four voltage dividing circuits connected in series between the output terminals of the corresponding DC power source for each phase.
A first arm and a second multi-level single-phase power conversion circuit having switching elements composed of self-extinguishing devices, and a positive arm in the first and second multi-level single-phase power conversion circuits; The voltage dividing potential is applied from the voltage dividing circuit to the series connection point of the switching elements of the negative arm through the diode unique to the AC terminal of the first multilevel single-phase power conversion circuit to the common bus common to each phase. Connected, second
The high voltage output power conversion device is provided with three sets of single-phase inverter circuits in which the AC output terminals of the corresponding phases are derived from the AC terminals of the multilevel single-phase power conversion circuit.

According to a second aspect of the present invention, in the apparatus according to the first aspect, the voltage dividing circuit is composed of two voltage dividing capacitors, and the first and second multilevel single-phase power conversion circuits are respectively 4
It is characterized in that it is a three-level single-phase power conversion circuit composed of switching elements.

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

According to a fourth aspect of the present invention, in the apparatus according to the first or second aspect, the switching element is a module type self-extinguishing type device, and the common busbar is provided with 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 that generates a carrier wave for PWM control, a first modulation circuit that PWM-controls a first multilevel single-phase power conversion circuit based on a voltage command signal and a carrier wave, and a first modulation circuit that is based on the voltage command signal and the carrier wave And a second modulation circuit for PWM-controlling the second multilevel 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 wave input from the carrier wave generation circuit to the first modulation circuit and the carrier wave input to the second modulation circuit. Are different from each other in phase.

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

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a high voltage output power converter according to the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. FIG.
The power converter shown in (3) includes three sets of DC power supplies E _d1 , E _d2 , and E _d3 which are insulated from each other according to the number of output phases (three phases). Each DC power supply has a voltage dividing capacitor 13, 1
4 and 2 sets of 3 level power conversion circuits are provided.
That is, the R-phase has three-level power conversion circuits 15R1, 1
5R2 is provided, and a 3-level power conversion circuit 15 is provided for the S phase.
S1 and 15S2 are provided, the T-phase is provided with three-level power conversion circuits 15T1 and 15T2, and two sets of three-level power conversion circuits in each phase constitute a single-phase inverter circuit. 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 the elements corresponding to each other have the same reference numerals. Add explanation about the difference between input and output. As the switching elements S _{1 to} S ₄ , GTO, which is one type of self-extinguishing type device, is used here. It has already been stated that the DC side of the power conversion circuit of each phase is connected to the DC power source insulated from each other. The connection mode between the power conversion circuits of two sets for each phase and the diodes D ₅ , D ₆ and the voltage dividing capacitor neutral point C is no different from the case of FIG. Here, the difference from FIG. 5 is that each phase 2
It is a connection of AC output terminals of a pair of power conversion circuits. That is, the first power conversion circuits 15R1, 15S1, 1 for each phase
The AC output terminal U of 5T1 is connected to the common bus O to form the neutral point of the three-phase circuit, and the second power conversion circuit 15 of each phase is formed.
The AC output terminals of R2, 15S2 and 15T2 form 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, T and is supplied to the load motor 16.

In the circuit device shown in FIG. 1, three sets of single-phase inverter circuits formed by using two sets of three-level power conversion circuits have DC power supplied from DC power supplies E _d1 , E _d2 , and E _d3. Is converted into three-phase AC power, and AC output terminals R,
Supply to the load motor 16 via S and T. At this time, each single-phase inverter circuit outputs the phase voltage of each phase of R, S, and T of the three-phase AC power, but since the AC output terminal U side is connected to the common bus O, the three-phase total The output voltage of each single-phase inverter circuit is 3 ^−1/2 (= 0.58) times the input voltage of the load motor 16 because of the Y-connection configuration. Thus, the fact that the AC output voltage of each single-phase inverter circuit becomes 3 ^-1/2 times the input voltage of the load motor 16 means that the three-level power conversion circuit 15 can be compared with the conventional system of FIG.
It means that the DC input voltage of R, 15S, and 15T can also be multiplied by 3 ^-1/2 . 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 It means that it is possible to realize a high-voltage output power converter capable of operating the load motor 16 of FIG.

3 using two sets of 3-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 have a multi-stage waveform with a maximum of 5 levels, and a clean (that is, close to a sine wave) waveform. Of the switching elements S _{1 to} S, which can output the AC output voltage of
_By converting ₄ into the configuration shown in FIG.
AC output voltage up to V class can be obtained. Therefore, without connecting switching elements in series,
Since the power conversion device that outputs a higher voltage can be configured by using the level power conversion circuit, it is possible to prevent a decrease in the voltage utilization rate due to the conventional series connection of switching elements, which is technically difficult. It is not necessary to provide a voltage balance circuit associated with the series connection, the reliability and economy of the power conversion device can be improved, and the size of the device can be reduced.

In the embodiment shown in FIG. 1, JP-A-55-439 is used.
As shown in Japanese Patent Laid-Open No. 96-96, a main circuit configuration composed of three sets of single-phase inverter circuits configured by using two sets of three-level power conversion circuits for each phase has been illustrated. Even if the multi-level power conversion circuit as disclosed in Japanese Patent No. 36711 is used as a main circuit configuration instead of the three-level power conversion circuit of FIG. 1, the above-described actions and effects can be achieved.

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

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

As shown in FIG. 2, the common bus O is connected to the fuse 1
By grounding via 7 and the impedance element 18, the common bus O is fixed to the ground potential, and the switching elements S _{1 to} S ₄ used in the three-level power conversion circuit are constituted by self-extinguishing type devices. In doing so, the ground insulation voltage of those self-extinguishing devices and main circuit components is equivalent to 3 ^-1/2 times the AC output voltage (line voltage), which is the output voltage (phase voltage) of the single-phase inverter circuit. It becomes possible to select it as a standard. Fuse 17 due to ground fault current
If the fuse is blown, the common bus line O becomes the impedance element 18
The fault current is cut off or the fault current is controlled by the impedance element 18 for a short time until the device is stopped, while suppressing the rise of the ground potential of the device. be able to.

Self-extinguishing devices include flat devices and modular devices. The flat device dissipates heat by attaching cooling fins on both sides of the device. In contrast,
In the module type device, one of the heatsinks is electrically insulated and the device chip is attached, and the heatsink is electrically insulated. Therefore, a common cooling fin is used to cool the devices of different potentials. In this way, the modular self-extinguishing device has the advantage that a common cooling fin can be used to dissipate the heat loss inside the device. Therefore, the modular self-extinguishing device can be used in the IGBT and recent new MOS devices. A structure for an arc extinguishing device is desired. However, in the module type device, it is difficult to electrically insulate the heat sink from the device chip, and it is difficult to significantly improve the withstand voltage of the module type self-extinguishing type 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 configured by a modular self-extinguishing device with a low ground insulation voltage. By using the module type self-extinguishing type device, it is possible to reduce the size of the power conversion device and improve the economical efficiency.

When the flat type device and the module type device are compared with each other, it is known that the module type device is weaker in terms of mechanical withstanding capacity in addition to the dielectric strength withstand voltage performance. When a power conversion device is configured by using a switching element composed of a module type self-extinguishing type device, the electrical insulation between the heat sink and the device chip deteriorates due to a fault current due to a DC short circuit accident, and the power is formed via the common bus O. There is a risk of large ground fault currents flowing through the ground loops. In such a case, it is necessary to promptly suppress the ground fault current. However, as shown in FIG. 2, the fuse 17 or the impedance element 1
Ground fault current can be suppressed by grounding common bus O through 8 or both, and
The reliability of protection against ground accidents can be further improved.

FIG. 3 shows a third embodiment of the present invention. The main circuit in this embodiment is functionally substantially the same as that of FIG. 1, but here, as the switching elements S _{1 to} S ₄ , the IGBT, which is a kind of self-extinguishing type device like the GTO, is used. The one using is shown. The characteristic of the device of FIG. 3 lies in the part of the control device. Here, as a control device, a voltage control circuit 20, a carrier wave generation circuit 21, a first modulation circuit 221, and a second modulation circuit 22 are provided.
2 are provided. The voltage control circuit 20 is a modulation circuit 22.
It outputs the voltage command signals e _c1 and e _c2 for inputting to 1, 222. The carrier waves e ₁ and e ₂ are also input from the carrier wave generation circuit 21 to the modulation circuits 221 and 222. Modulation circuit 22
1 is PW based on the voltage command signal e _c1 and the carrier wave e _1.
A control signal for M control is created and supplied to the first three-level power conversion circuits 15R1, 15S1, 15T1 to control the respective switching elements. Similarly, the modulation circuit 2
22 is P based on the voltage command signal e _c2 and the carrier wave e _2.
A control signal for WM control is created and supplied to the second three-level power conversion circuits 15R2, 15S2, 15T2 to control the respective switching elements.

When the respective power conversion circuits are PWM-controlled by the two sets of modulation circuits 221, 222, the phase difference between the two sets of voltage command signals e _c1 and e _c2 is controlled, and carrier waves e ₁ and e similar to the above are used. ₂ may be used for PWM control, and the phase difference between the voltage command signals e _c1 and e _c2 is not controlled, but the phase difference of 180 ° is provided between the carrier waves e ₁ and e _2. 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 output voltage of five levels closer to a sine wave is obtained. Can be generated and supplied to the load motor 16, and the switching frequencies for PWM control are combined. Therefore, even if the switching frequencies of the switching elements forming the respective three-level power conversion circuits are reduced, An output voltage with few waves can be obtained.

In high rated voltage self-extinguishing devices,
At a switching frequency of about 500 Hz, the switching loss is usually 70% and the ohmic loss is 30%. However, if the switching frequency could be reduced to about 300 Hz, the switching loss of the self-extinguishing type device is shown. Is 28 (= 70-70 × 300/500)
It can be reduced to%. In addition, this effect not only reduces the switching loss of the self-extinguishing type device but also reduces the additional power loss in the snubber circuit and other main circuit parts attached to each switching element, so that the power consumption of the entire device is reduced. The loss can be significantly reduced.

FIG. 4 shows a fourth embodiment of the present invention. This embodiment is characterized by the direct current power source portion of the main circuit. That is, in this embodiment, a common primary winding 240 and three sets of secondary windings 24 are provided.
A multi-winding isolation transformer 24 having 1,242,243,
Converters 251, 252, 2 connected to each secondary winding
The DC power supply is separated from each of the components 53 and 53 for each phase. The output voltage of the three secondary windings of the transformer 24 is 20
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 secondary windings 241 and 243 are + 20 ° to −20 ° or −. The internal winding configuration and connection of the secondary windings 241 to 243 are performed so as to be 20 °. 20 such transformers
A known phase-shifting 18-phase rectifier transformer can be used. By configuring the 18-phase rectifier circuit in this manner, the harmonic current component seen from the AC power source to which the primary winding 240 of the transformer 24 is connected is the (18n ± 1) th.
(n is a positive integer) harmonics only, and can be equal to or less than the harmonic current component corresponding to the harmonic regulation. In the case of the circuit of FIG. 4 as well, there is no interference between the DC power supplies of each phase, so stable operation is possible, and it is possible to realize a high-voltage output power converter that reduces the effects of harmonics on the input AC power supply side. it can.

The present invention is not limited to the internal configuration of the multilevel power conversion circuit and the PWM control method described above.
Various changes can be made and implemented within the scope of not changing the gist.

[0042]

As described above, according to the present invention, it is possible to provide a high voltage output power converter having the following effects. (1) According to the invention described in claim 1, it is possible to supply an output voltage that is 3 ^1/2 times (= 1.73 times) higher than the conventional output voltage without connecting the self-extinguishing type devices in series. . As a result, a) It is not necessary to use the voltage balancing circuit that was required in the past when connecting the self-extinguishing devices in series for high voltage output, and it is necessary to connect the self-extinguishing devices in series, which is technically difficult. There is no. As a result, the number of main circuit connecting parts is reduced, and it is possible to provide a compact and highly reliable power conversion device.

B) By eliminating the need for series connection, the voltage utilization factor of the self-arc-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 can be omitted, and a power conversion system with a simplified main circuit can be provided. You can (2) According to the invention described in claim 3 or claim 4, in addition to the above effects, high voltage output power that makes the ^withstand voltage insulation voltage 3 ^-1/2 times (= 0.58 times) that of the conventional one. A conversion device can be provided. As a result, a) A power converter using a module-type self-arc-extinguishing device can be provided. By adopting the module-type self-arc-extinguishing device, cooling and assembling of the power converter can be simplified and economical power consumption can be reduced. It can be a conversion device. b) The protection of the module type self-extinguishing type device is also improved, and the power conversion device with high reliability against a grounding accident can be provided. (3) According to the invention described in claim 5 or claim 6, in addition to the above effects, it is possible to supply alternating-current power with less harmonic components even if the switching frequency of the self-arc-extinguishing device is reduced. it can. As a result, a) the power loss of the self-extinguishing type device can be reduced by about 28% as compared with the conventional type. b) Since the power loss of the snubber circuit for the self-extinguishing type device and other main circuit components is also reduced, it is possible to obtain a power conversion device that has high operating efficiency and that requires a small cooling device. (4) According to the invention described in claim 7, in addition to the above effects, there is provided a high voltage output power converter capable of preventing mutual interference on the DC power supply side and improving the reliability of stable operation. be able to. (5) According to the invention described in claim 8, in addition to the above effects, it is possible to provide a high-voltage output power converter capable of significantly reducing harmonic components even on the input AC power supply side.

[Brief description of the drawings]

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

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

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

FIG. 4 is a main circuit wiring diagram of a high voltage output power converter according to a fourth embodiment of the present invention.

FIG. 5 is a main circuit connection diagram of a high-voltage output power converter according to the related art.

[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 wave generation circuit 221, 222 Modulation circuit 24 Multiple winding Line insulation transformer 251,252,253 converter

Claims (8)

[Claims] 1. A component comprising a DC power supply provided independently for each of the three phases and at least two voltage dividing capacitors connected in series between the output terminals of the corresponding DC power supply for each phase. First and second multi-level single-phase power having a voltage circuit and a switching element composed of at least four self-extinguishing type devices connected in series between output terminals of corresponding DC power supplies for each phase The voltage dividing circuit has a conversion circuit, and is divided from the voltage dividing circuit via a diode unique to the series connection point of the switching elements of the positive side arm and the negative side arm in the first and second multilevel single-phase power conversion circuits. A piezo-electric potential is applied, the AC terminals of the first multi-level single-phase power conversion circuit are connected to a common bus common to each phase, and the corresponding AC terminals of the second multi-level single-phase power conversion circuit are connected. AC output end There high voltage output power converter and a single-phase inverter circuit 3 sets of derived. 2. The device according to claim 1, wherein the voltage dividing circuit comprises two voltage dividing capacitors, and each of the first and second multilevel single-phase power conversion circuits comprises four switching elements. A high-voltage output power converter that is a three-level single-phase power converter circuit. 3. The high voltage output power converter according to claim 1, wherein the switching element is a module type self-extinguishing type device, and the common bus is grounded via an impedance element. . 4. The apparatus according to claim 1, wherein the switching element is a module type self-extinguishing type device, and the common busbar is grounded via a fuse or a parallel circuit of a fuse and an impedance element. High voltage output power converter. 5. The high-voltage output power converter according to claim 1, wherein a common voltage control circuit that generates a voltage command signal for the 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 PWM-controls a first multilevel single-phase power conversion circuit based on the voltage command signal and the carrier wave, and a second modulation circuit based on the voltage command signal and the carrier wave. A high-voltage output power conversion device comprising a second modulation circuit that PWM-controls a level single-phase power conversion circuit. 6. The high voltage output power converter according to claim 5, wherein the phase of the carrier wave input from the carrier wave generation circuit to the first modulation circuit and the phase of the carrier wave input to the second modulation circuit. High voltage output power converter with different output. 7. The high-voltage output power converter according to claim 2, wherein the DC power source is insulated for each of the single-phase power converter circuits. 8. A high voltage output power converter according to claim 7, wherein said DC power supply has three sets of secondary windings for outputting isolated AC voltages having mutually different voltage phases. A high-voltage output power converter comprising a transformer and a converter for rectifying the AC output of the secondary winding corresponding to each phase.