JP2000050636A - Multiplex inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an economical, practical multiplex inverter device which enables resolution of problems, such as installation of an input transformer in an electric room, reduction in main circuit wiring, and those arising from process of regenerative power and increase in capacitance. SOLUTION: This multiplex inverter device has input transformers 31, 32, 33 divided into a plurality of pieces, and at least one of the divided input transformers is installed separately from unit inverter cells 4U1-4U3, 4V1-4V3, 4W1-4W3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter for obtaining a high voltage output of several kV, and more particularly to a multiplex inverter for obtaining a high voltage output by using a plurality of unit inverters.

[0002]

2. Description of the Related Art Conventionally, an AC motor is operated at a variable speed.
The need for power saving has become widespread, mainly for square torque loads such as pumps and blowers. In particular, a large number of small-capacity low-voltage AC motors perform an energy-saving operation in combination with a general-purpose inverter device. On the other hand, large-capacity AC motors are, for example, 3kV system, 6kV system, and 4kV overseas.
Since the motor is a high-voltage motor such as a V-system, the application of energy-saving operation has been limited due to problems such as the motor voltage and the installation of an inverter transformer.

[0003] As with the low-voltage AC motor, a high-voltage AC motor is also partly commercialized with an inverter device that outputs a high voltage for the purpose of easily changing its speed and enabling energy-saving operation. . Here, as an example of an inverter device which outputs a high voltage, Japanese Patent Application No. 9-2980 filed in the prior application is used.
No. 77725, “Multi-inverter device and control method thereof”
This will be described below.

FIGS. 10 to 12 show examples of the configuration of a multiplex inverter device in Japanese Patent Application No. 9-277725. FIG.
0 is a multiplex inverter device that can obtain a high voltage output, 1 is a commercial AC power supply, 2 is a switch, 3 is an input transformer, 3P is a primary winding, 3S is a secondary winding and a plurality of windings. Consists of lines. 4 is an inverter circuit 4U1-4U3,4V
Each layer of the inverter circuit 4 is configured by connecting unit inverter cells of 1 to 4V3 and 4W1 to 4W3 in series. 5
Is a polyphase load driven by multiple inverter devices,
The above-described high-voltage AC motor or the like is applied.

FIG. 11 shows unit inverter cells 4U1 to 4U-4.
3 shows a configuration of a unit inverter cell circuit of U3, 4V1 to 4V3, 4W1 to 4W3. In this figure, a secondary winding 3P of a transformer 3 is connected to AC input terminals 101R, 101S, 101T of a unit inverter cell circuit, and the input three-phase AC power is converted into DC power by a rectifier 102, and a filter capacitor is provided. The DC power smoothed in 103 is converted into AC power of a variable frequency by an inverter 104, and single-phase AC power is output from inverter output terminals 105P and 105N. Reference numeral 106 denotes an initial charging circuit that prevents the filter capacitor 103 from being rapidly charged at the start of operation because the rectifier 102 is a rectifier circuit using diodes D1 to D6. Inverter 104 uses semiconductor switching elements Q1 to Q4 to perform PWM control from a substantially constant DC voltage and outputs a variable AC voltage to inverter output terminals 105P and 105N.

The operation of the multiplex inverter device shown in FIG. 10 is described in detail in FIG. 1 of Japanese Patent Application No. 9-277725, but the power of the commercial AC power supply 1 is supplied to the input transformer via the switch 2. Supply 3 The secondary winding 3S of the input transformer 3 is composed of a plurality of three-phase windings.
Are the AC input terminals 101R, 101S,
The inverter circuit 4 converts AC power supplied from the commercial AC power supply 1 into AC power of a variable frequency to supply power to the polyphase load 5.

The conventional multiplex inverter device shown in FIG. 10 comprises a secondary winding 3S of the input transformer 3 and an inverter circuit 4
Unit inverter cells 4U1-4U3, 4V1-4V
3, 4W1 to 4W3 are connected as wiring for three-phase AC power. For this purpose, when n unit inverter cells are connected in series to form a three-phase output multiplex inverter device, three-phase wiring × three-phase output × n series = 9n, ie, n = 3 in FIG. In that case, 27 wires are required between the input transformer 3 and the inverter circuit 4.

[0008] Since these 27 wires are high-voltage wires that carry a main circuit current and are connected to a high-voltage circuit, 9n wires (27 wires in Fig. 10) are all connected as external wires during installation work. This required a lot of construction work and required a lot of time. This is because if the output voltage of the multiplex inverter device is further increased, the number of connections is further increased. In the actual device example, n = 6 and 54 electric wires are required.

In order to solve these problems, it is known to implement a device configuration as shown in FIG. FIG. 12 is an installation diagram of a multiplex inverter device. In this method, the input transformer 3 and the inverter circuit 4 are integrally configured as shown in the drawing and installed in the same electric room. Thus, the problem that the number of circuit wirings between the input transformer 3 and the inverter circuit 4 is large is solved by performing these main circuit wirings at the time of connecting the apparatus at a factory.

On the other hand, as shown in FIG. 12, when the input transformer 3 and the inverter 4 are installed integrally, the ratio of the occupied area of the input transformer 3 to the whole is very large. About half of the container 3 was generated, and the size of the electric room to be installed increased, and the number of auxiliary equipment such as coolers also increased.

Since the input transformer 3 is heavy,
It has been a very difficult task to carry in and install the input transformer 3 weighing several tons in an electric room where semiconductor applied equipment is installed.

On the other hand, in the multiplex inverter apparatus as shown in FIG. 10, when the polyphase load 5 is an AC motor, if the AC motor is to be rapidly decelerated, regenerative power flows from the polyphase load 5 into the inverter circuit 4. 11, the regenerative power cannot be processed by the unit inverter cell circuit shown in FIG. 11, and there has been a problem that the output voltage cannot be controlled or an overvoltage occurs.

In the multiplex inverter device as shown in FIG. 10, since the device capacity is determined by the capacity of the unit inverter cell, it is necessary to prepare a large number of rated capacities for the unit inverter cell in order to make the capacity of the multiplex inverter device series. was there.

[0014]

The multiplex inverter device configured as described above has the following problems. (1) If the input transformer 3 and the inverter circuit 4 are integrally installed in an electric room, the installation area becomes large. There has been a problem that the electric room and incidental facilities are large and expensive due to increased heat generation in the electric room. (2) It is difficult to install the input transformer 3 having a very large weight in the electric room, and the floor strength of the electric room needs to be strengthened in order to install a heavy object. (3) There is a problem that the number of main circuit wires between the input transformer 3 and the inverter circuit 4 becomes very large. (4) When power regeneration occurs in the multiplex inverter device from the polyphase load, the regenerative power cannot be processed by the inverter circuit 4, and the unit inverter cell circuit has a problem that voltage control becomes impossible or overvoltage occurs. (5) To increase the number of types of the rated capacity of the multiplex inverter device, it is necessary to provide the corresponding rated capacity of the unit inverter cell, and it is particularly difficult to increase the capacity of the multiplex inverter device.

Accordingly, the present invention has been made in order to solve such problems, and it is necessary to install an input transformer in an electric room, reduce the number of main circuit wirings, process regenerative electric power, and increase capacity. It is an object of the present invention to provide an economical and practical multiplex inverter device that can solve the above problems.

[0016]

Accordingly, the present invention has the following constitution in order to achieve the above object. First, an invention corresponding to claim 1 forms an input transformer having a plurality of secondary windings and a plurality of unit inverter cells connected in series in n stages to form each phase, and is combined with the input transformer. In a multiplex inverter device for supplying power to a polyphase load, the input transformer is divided into a plurality of parts, and at least a part of the disassembled input transformer is separated from an electric room in which the unit inverter cells are installed. It is characterized in that it is installed in a place. Therefore, when the input transformer is divided and partly installed, the installation area of the electric room can be reduced, the heat generation in the electric room can be reduced, and the installation of the input transformer in the electric room can be reduced (labor and floor strength). .

Next, according to a second aspect of the present invention, an input transformer having 3n sets of a plurality of single-phase secondary windings and a plurality of unit inverter cells connected in series in n stages constitute each phase. In the multiplex inverter device described above, the plurality of single-phase secondary windings of the input transformer are connected to the single-phase secondary winding so that the phase relationship corresponds to the three phases of the commercial AC power supplied to the primary winding of the input transformer. It is characterized in that three windings form a three-phase set, and at least two sets are out of phase between the sets of secondary windings forming the three-phase set. Therefore, by configuring the input transformer with a single-phase secondary winding, the main circuit wiring between the input transformer and the inverter circuit can be reduced to 2/3 of the conventional one, and the single-phase secondary of the input transformer can be reduced. By shifting the phases between the three-phase sets of windings, an economical multiplex inverter device capable of reducing the harmonic current of the power supply system can be provided.

According to a third aspect of the present invention, a set of three secondary windings (three-phase set) corresponding to three phases of a commercial AC power supply input to an input transformer is connected in series. Is connected to the unit inverter cell.

Further, according to a fourth aspect of the present invention, a set of three secondary windings (three-phase set) corresponding to three phases of a commercial AC power supply input to the input transformer is connected to an inverter circuit. It is characterized in that it is connected to each of the unit inverter cells in the n-th stage.

Therefore, in the inventions corresponding to claims 3 and 4, even if the secondary winding of the input transformer is a plurality of single-phase windings, the input power of each unit inverter cell is the same. On the primary side of the input transformer, the current of the commercial AC power source is balanced in each phase, so that an economical multiplex inverter device capable of reducing the harmonic current of the power supply system can be provided.

The invention corresponding to claim 5 is characterized in that the input transformer is installed in a place different from the unit inverter cell. Therefore, even if the input transformer is installed in another place, the number of main circuit wires between the input transformer and the unit inverter cell is reduced to 2/3, so that the installation work is easy, and The installation area of the electric room in which the unit inverter cell is installed can be reduced, the generated heat can be reduced, and the weight of the electric room can be reduced by reducing the weight of the electric room. It is possible to provide a multiplex inverter device in which construction costs and operation costs are reduced, for example, by eliminating the need for loading.

Further, the invention corresponding to claim 6 is characterized in that the input transformer is divided into a plurality of parts and one part of the divided input transformer is installed in a place different from the unit inverter cell. However, similarly to the invention corresponding to claim 5, a multiplex inverter device with reduced construction costs and operation costs can be provided.

According to a seventh aspect of the present invention, there is provided a multiplex inverter device in which an input transformer is divided into a plurality of parts and a part of the divided input converter is installed at a place different from the unit inverter cell. The secondary winding of only one input transformer separately provided is a single-phase winding. Therefore, a multiplex inverter device with reduced construction costs and operation costs can be provided.

Further, the invention according to claim 8 provides an input transformer having a plurality of secondary windings and a multiplex inverter device in which a plurality of unit inverter cells are connected in series in n stages to constitute each phase. When the outputs of the multiple inverters are connected in parallel to increase the output capacity and the capacity is increased, the output of at least one of the multiple inverters is balanced to balance the output capacity of the multiple inverters connected in parallel. It is characterized in that the voltage is finely adjusted. Therefore, if two multiplex inverters are connected in parallel, the load balance will greatly differ due to a slight difference in the output voltage. However, if a fine adjustment function of the output voltage is provided, the operation can be stably balanced with the output capacity. Thus, a large capacity multiplex inverter device can be provided.

According to a ninth aspect of the present invention, as means for finely adjusting the output voltage, the output capacity of a multiplex inverter device connected in parallel by variably controlling a DC voltage of a part of a single inverter cell. It is characterized in that the operation is carried out in a balanced manner.

According to a tenth aspect of the present invention, when two multiplex inverters are connected in parallel, they are connected in parallel via an AC reactor having an intermediate terminal, and a polyphase load is connected to an intermediate terminal of the AC reactor. The fine adjustment function of the output voltage is performed by the induced voltage of the AC reactor.

Therefore, in the multiplex inverter device according to the present invention, the capacity can be easily increased, and the unit inverter cell rating conventionally corresponding to the output capacity rating of the multiplex inverter device can be realized. Although a capacity is required, the type of the rated capacity of the unit inverter cell can be reduced, and a multiplex inverter device that can be easily standardized can be provided.

According to an eleventh aspect of the present invention, there is provided an input transformer having a plurality of secondary windings and a plurality of unit inverter cells connected in series in n stages to form each phase. In order to process regenerative power from the multi-phase load in a multiplex inverter device that supplies power to a multi-phase load in combination with the above, a regenerative power processing resistor is provided on the output terminal side of the multiplex inverter device. It is characterized in that connection is made only when regenerative power from a load is processed. Therefore,
When the regenerative power processing resistors are collectively provided on the output terminal side of the multiplex inverter device, it is possible to prevent the output voltage control of the multiplex inverter device from being impossible and an overvoltage with a simple configuration.

Further, according to a twelfth aspect of the present invention, there is provided a multiplex inverter device in which a regenerative power processing resistor is provided on an output terminal side, wherein the regenerative power processing resistor is connected to an n-stage unit inverter cell in series. It is characterized in that it is connected to a stage (here, n> m) to process regenerative power from a multi-phase load. By connecting the regenerative power processing resistor at the m-th stage in this way, the rated voltage of the regenerative power processing resistor and the connection device can be reduced.

The invention according to claim 13 is characterized in that the regenerative power processing resistor can be connected only within a predetermined range of the polyphase load. In general, fluid control devices such as blowers and pumps connected to a multi-phase load, when the multi-phase load is operated at high speed, decelerate quickly because the resistance of the load fluid is large near high speed, and the speed decreases. Because the deceleration time is prolonged, for example, if the regenerative power processing resistor is connected to multiple inverters in a range of medium speed or less where the deceleration time is prolonged, the power capacity of the regenerative power processing resistor is reduced. Thus, a predetermined deceleration effect can be obtained.

According to a fourteenth aspect of the present invention, in the case where the polyphase load is an induction motor, a multiplex inverter is provided so that the power supplied to the regenerative power processing resistor is supplied only from the induction motor. By controlling the output voltage phase of the device,
The multi-phase inverter mainly supplies an exciting current component of the induction motor. Thus, the power capacity of the regenerative power processing resistor can be reduced while active power is supplied to the regenerative power processing resistor from the unit inverter cell side.

Finally, the invention according to claim 15 is the invention according to claim 15, wherein, when the regenerative power processing resistor is connected, the output voltage up to the mth stage of the unit inverter cells connected in series is changed to the total output voltage of the multiplex inverter device. Is controlled to be larger than the m / n ratio (where n> m). Therefore, by controlling the voltage applied to the regenerative power processing resistor to a large value, it is possible to use the fact that the power processed by the regenerative power processing resistor is proportional to the square of the voltage, and is substantially proportional to the speed. Effective regenerative deceleration can be performed even with a polyphase load in which the voltage changes.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a circuit diagram showing a first embodiment according to the present invention. A commercial AC power supply 1;
Switches 21, 22, 23 and three sets of input transformers 31, 3
In each of the input transformers 2 and 33, the primary winding 31P and 3
2P, 33P and n sets of three-phase secondary windings 31S, 32
S, 33S, and 4U, 4V, 4W unit inverter cells 4U1 provided for each phase in n stages.
A multiplex inverter device is configured by an inverter circuit 4 including 〜4U3, 4V1 to 4V3, and 4W1 to 4W3, and supplies power to the multiphase load 5. (In this FIG. 1, n =
In FIG. 1, the input transformer 3 of FIG. 10 is divided into three and illustrated as input transformers 31, 32, and 33. Each of the input transformers 31, 32, 33 has three sets of secondary windings, each having an electrical angle of
゜ The secondary winding has a shifted 18-phase configuration. As shown, each of the secondary windings 31S, 32S, 33S is connected to each unit inverter cell 4U1-4W1, 4U2-4W2, 4U3-4.
It is connected to W3.

The basic operation of the multiple inverter device of FIG. 1 is the same as that of the conventional multiple inverter device of FIG.
The input harmonic components and the like corresponding to the commercial AC power supply 1 are also the same.

The input transformer 3 is divided into three sets to form the input transformers 31, 32, 33. Some of the input transformers thus divided, for example, the input transformer 33 are provided with the inverter circuit 4. If the input transformers 31 and 32 are installed in the same electric room as the inverter circuit 4 separately from the electric room to be operated, the following operation and effect can be obtained. (1) Since the installation area of the input transformer in the electric room may be 2/3, the space of the electric room can be reduced. (2) Heat generation in the electric room is also reduced by about 17%. (Because the loss of the normal input transformer and the inverter circuit is almost equal)
Therefore, it is possible to reduce the size of the auxiliary equipment such as a cooler. (3) Since the number of input transformers is reduced by the weight, it is easy to enhance the floor strength of the electric room and the installation work in the electric room becomes easy.

Although the input transformer is divided into three sets in FIG. 1, this division is not particularly limited in the present invention, and the input transformer is installed separately from the electric room. The number is not particularly limited in the present invention.

(Second Embodiment) FIG. 2 is a circuit diagram showing an embodiment corresponding to the second, third, and fifth aspects.

The same reference numerals as in claim 1 and the conventional FIG. 10 indicate the same elements. The difference from FIG. 10 is that 3n of the input transformer 3
A point that the set of secondary windings 3S1 is composed of a single-phase winding, and unit inverter cells 4U11 to 4U31, 4V1 that are connected in n stages in series to each of the 4V, 4U, and 4W phases of the inverter circuit 4.
1 to 4V31 and 4W11 to 4W31 are constituted by unit inverter cells of single-phase AC input. (Figure 2
And n = 3. As shown in FIG. 3, a single-phase AC input unit inverter cell is a unit inverter cell shown in FIG. 11 in which a rectifier 102 is replaced by a single-phase rectifier circuit, and other operations are the same. is there.

The secondary winding 3S1 of the input transformer 3 shown in FIG.
Are 3n sets (9 pieces) of single-phase windings, and correspond to n sets (here, 3 sets) of commercial AC power supplies 1 whose electric phases are shifted by 60 ° / n (20 ° in this figure). Each of the windings is a single-phase winding. In FIG. 2, unit inverter cells 4U11 to 4U31 and 4V11 to 4V3
1 and 4W114W31 connected to the secondary winding 3S1
Have an electrical phase difference of 20 °, and the secondary winding 3S1 connected to the unit inverter cells 4U11, 4U21 and 4U31 has a three-phase R.P. S. This is a winding corresponding to T.

In the configuration as shown in FIG. 2, even if the secondary winding 3S1 of the input transformer 3 is a 3n set of single-phase windings, it has a 6n-phase configuration (18-phase configuration in this figure). Power supply 1
Becomes the input current of the 18-phase rectification, and the harmonic component of the input current can be reduced. As described above, the secondary winding 3S1 is a single-phase winding input transformer 3 and a single-phase AC input unit inverter cell 4U11-4U31, 4V11-4V3.
The following operational effects can be obtained by combining 1,4W11 to 4W31. (1) Even if the secondary winding 3S1 of the input transformer 3 is a 3n-set single-phase winding, an input current of 6n-phase rectification flows through the commercial AC power supply 1 to reduce harmonic current components. Can be. (2) The main circuit wiring between the input transformer 3 and the inverter circuit 4 is the same as that of the conventional circuit because the secondary winding 3S1 is a single-phase alternating current.
3 and the number of wirings during this period is reduced. As a result, the main circuit wiring work at the factory and the installation wiring work at the site are greatly reduced.

(Third Embodiment) FIG. 4 is a circuit diagram showing an embodiment corresponding to the fourth, fifth, sixth and seventh aspects. In this figure, the same reference numerals as those in claims 1 and 2 indicate the same elements. In FIG. 4, when power is supplied from the commercial AC power supply 1 to the input transformer divided into two via the circuit breakers 21 and 22, the input transformer 31 has a secondary winding 31S having a three-phase winding configuration, and an input transformer. Reference numeral 32 denotes a single-phase winding configuration of the secondary winding 32S1, and the unit inverter cells 4U1 to 4U41, 4V1 to 4V4 of the inverter circuits 41 and 42.
Power is supplied to 1,4W1 to 4W41. Here, the unit inverter cells 4U1, 4U2, 4V1, 4V2, 4W1,
4W2 is a three-phase AC input, a unit inverter cell 4U31,
4U41, 4V31, 4V41, 4W31, 4W41
Is a single-phase AC input. Secondary winding 3 of input transformer 32
2S1 corresponds to the three-phase AC phase of the commercial AC power supply 1,
When the windings connected to the unit inverter cells 4U31, 4V31, 4W31, and 4U41, 4V41, 4W41 are combined, they are connected so as to form a △ connection and a Y connection, respectively. As a result, the input current of the input transformer 32 becomes 12
It becomes the input current of the phase rectification, and the harmonic current component can be reduced by the input current of the multi-phase rectification similarly to the input current on the input transformer 31 side.

In FIG. 4, three secondary windings 32S connected to the n-th stage of the unit inverter cell are provided because there are two stages of unit inverter cells connected to the input transformer 32 and 3 × 2 = 6.
1 have a configuration corresponding to the three phases of the commercial AC power supply 1 mutually. However, in the case where the inverter circuit 42 connects three stages of unit inverter cells, the secondary winding 32S1 may have a three-phase configuration between the unit inverter cells connected in series similarly to FIG. it can.

As shown in FIG. 4, in the input transformer 31, the secondary winding 31S may be a three-phase winding, or may be a single-phase winding similar to the input transformer 32. In the multiple inverter device configured as shown in FIG.
Is provided separately from the inverter circuit 42, it is possible to realize a multiplex inverter device having the same effects as those in FIGS.

(Fourth Embodiment) FIG. 5 is a circuit diagram showing an embodiment corresponding to claims 8 and 9. FIG. 6 is an example of a circuit diagram of a unit inverter cell according to claim 9.

The circuit diagram of FIG. 5 shows an example of a circuit configuration of a multiplex inverter device for driving a multi-phase load 5 by connecting two inverter circuits 4 and their outputs in parallel. In this figure, the output current of one inverter circuit 4 is detected.
A current detector 6, a current detector 7 for detecting the current of the polyphase load 5, and a balance control circuit for controlling the output currents of the two inverter circuits 4 based on the detection signals of the current detectors 6 and 7 8 is provided, and the unit inverter cells 4U3a, 4V3a, 4W3
This is a configuration for controlling a.

Here, the unit inverter cells 4U3a, 4V
As shown in FIG. 6, the rectifiers 3a and 4W3a are composed of thyristors S1 to S6, and the DC voltage of a unit inverter cell can be controlled by controlling the phases of the thyristors S1 to S6. Therefore, the DC voltage of the unit inverter cells 4U3a, 4V3a, 4W3a can be finely adjusted in accordance with the output control signal of the balance control circuit 8, and the output voltage of the unit inverter cells can be finely adjusted.

When two outputs of the inverter circuit 4 are connected in parallel to increase the capacity of the multiplex inverter device and supply AC power to the polyphase load 5, the circuit impedance from the commercial AC power supply 1 to the polyphase load 5 The output current of each inverter circuit 4 is likely to be unbalanced due to the difference between the unit inverter cells 4U3a and 4V3
a, 4W3a DC voltage is finely adjusted, and the cell output voltage is finely adjusted so that the output current is balanced, so that the load balance of the two inverter circuits 4 can be obtained.

5 and 6, one of the inverter circuits 4
Although the method of finely adjusting the output voltage of the unit cell has been described by finely adjusting the DC voltage of the unit inverter cell, the output voltage control method is not limited. As described above, two inverter circuits 4 can be connected in parallel to balance the load and supply power to the polyphase load 5.
The following effects and effects can be obtained. (1) The capacity of a multiplex inverter device can be increased, and a unit inverter cell having a rated capacity corresponding to the capacity of the polyphase load 5 has conventionally been required. However, the capacity can be increased by connecting the inverter circuits 4 in parallel. The type of the rated capacity of the inverter cell can be reduced. (2) Since the load balance of the inverter circuits 4 operated in parallel is easily controlled, the operation reliability of the large-capacity multiplex inverter device can be improved.

(Fifth Embodiment) FIG. 7 is a circuit diagram showing an embodiment according to the tenth aspect. In the configuration of FIG. 7, when two inverter circuits 4 are connected in parallel, they are connected in parallel via a three-phase reactor 9 with an intermediate terminal, and a multi-phase load 5 is connected.
Is connected to the intermediate terminal of the three-phase reactor 9.

In the large-capacity multiplex inverter device configured as shown in FIG. 7, the load balance between the two inverter circuits 4 is corrected by correcting the difference in the influence of the circuit impedance by the induced voltage of the three-phase AC reactor 9. Can be taken. The parallel connection via the three-phase reactor 9 as shown in FIG. 7 may be performed by the multiplex inverter device shown in FIG. The method using the three-phase AC reactor 9 as shown in FIG. 7 also has the effect and action that can realize a large-capacity multiplex inverter device similar to that shown in FIG.

(Sixth Embodiment) FIG. 8 is a circuit showing an embodiment corresponding to claim 11, claim 13, or claim 14. The circuit diagram of FIG. 8 is obtained by adding a regenerative power processing resistor 10 to a circuit breaker 11 to the conventional circuit diagram of FIG. In this figure, since the unit inverter cells are configured as shown in the circuit diagrams of FIGS. 11 and 3, if the polyphase load is to be decelerated rapidly when the polyphase load is an AC motor, the polyphase load 5 The regenerative power flows into the DC circuit of the unit inverter cell from the side, and the DC voltage of the unit inverter cell rises, resulting in an overvoltage or inability to control the output voltage. When the power is processed, the circuit breaker 11 is closed, and the regenerative power processing resistor 10 consumes at least a part of the regenerative power.

The circuit breaker 11 is turned on when the multi-phase load 5 is decelerated. However, if the equipment connected to the multi-phase load 5 is a fluid control device such as a blower or a pump, the resistance of the fluid in the high-speed operation region is reduced. Since it is large, the deceleration in the high-speed area is relatively fast, so that the circuit breaker 11 may be turned on only in the medium-speed area or the low-speed area where the fluid resistance decreases, and the regenerative power processing resistor 10 may consume the regenerative power. .

When the polyphase load 5 is an AC motor, the output voltage of the inverter circuit 4 and the output frequency have a substantially proportional relationship, so that the processing power of the regenerative power processing resistor 10 also corresponds to the square of the output voltage. Change, the multi-phase load 5
If the circuit breaker 11 is closed only in the predetermined deceleration range, the predetermined regenerative power is processed and the deceleration time of the polyphase load 5 is secured while reducing the power capacity of the regenerative power processing resistor 10. be able to.

When the polyphase load 5 is an induction motor, the excitation current of the induction motor is supplied during this deceleration period.
When the inverter circuit 4 is operated, active power is supplied from the inverter circuit 4 to the regenerative power processing resistor 10 and the power capacity of the regenerative power processing resistor 10 is increased. The output voltage phase of the inverter circuit 4 is adjusted so that the output current of the inverter circuit 4 is controlled so that most of the output current is only the exciting current of the induction motor.

When controlling in this manner, the inverter circuit 4
Is approximately 9 times the current of the regenerative power processing resistor 10.
The phase is shifted by 0 °, and the power consumed by the regenerative power processing resistor 10 is mostly the regenerative power of the polyphase load 5,
The power capacity of the regenerative power processing resistor 10 can be reduced.

In the multiplex inverter device and the control method configured as described above, the following effects can be obtained. (1) Even if regenerative power is generated from the multi-phase load 5, the regenerative power is processed by the regenerative power processing resistor 10 to prevent overvoltage of the inverter circuit 4 and control the output voltage. . (2) The regenerative power processing resistor 10 consumes only the regenerative power of the multi-phase load 5, and the circuit breaker 11 only during a predetermined deceleration period.
Therefore, the power capacity can be reduced to achieve an economical system configuration.

(Seventh Embodiment) FIG. 9 is a circuit diagram showing an embodiment corresponding to claim 12, claim 13, claim 14, and claim 15. In this figure, the input transformers 31 and 3
2. In a multiplex inverter device composed of inverter circuits 41 and 42, when the unit inverter cells are connected in series in n stages, the circuit of the circuit breaker 11 and the regenerative power processing resistor 10 is connected to the nth stage of the unit inverter cells. Connected. (In this figure, n = 4, n1 = 2) When a regenerative power processing resistor is connected to the n1th stage as shown in FIG. 9, the rated voltages of the circuit breaker 11 and the regenerative power processing resistor 10 are shown in FIG. And the same effect can be obtained.

Further, as described above, the regenerative power processing resistor 10 can control the output voltage phases of the inverter circuits 41 and 42 so as to process only the regenerative power of the multi-phase load 5. The load 5 can be applied only during a predetermined deceleration period.

Further, as described above, the output voltage of the multiplex inverter device is controlled in a substantially proportional relationship with the output frequency, but the regenerative power that can be consumed by the regenerative power processing resistor 10 is proportional to the square of the voltage. Therefore, if the voltage of the inverter circuit 41 is controlled to be higher than the voltage of the inverter circuit 42 during at least a part of the period of the regenerative power processing, the processing power of the regenerative power processing resistor 10 can be increased, and the multi-phase load 5 Thus, more effective regenerative deceleration can be performed.

FIG. 9 shows a circuit diagram of a multiplex inverter device in which the input transformers 31 and 32 and the inverter circuits 41 and 42 are respectively divided into two, but the presence or absence of division of the input transformer and the inverter circuit is particularly limited. However, it is apparent that the same effect and action can be obtained without division.

[0062]

According to the present invention described above, an input transformer having a secondary multiple winding and a plurality of unit inverter cells n
The following effects can be obtained in a multiplex inverter device in which inverter circuits constituting each phase connected in stages are combined. (1) To provide a multiplex inverter device in which at least one of the input transformers is separately installed to reduce the installation area, floor weight strength, and calorific value of an electric room, thereby making construction and operation costs economical. Can be. (2) When increasing the capacity of a multiplex inverter device, it is possible to provide a highly reliable large-capacity multiplex inverter device capable of performing parallel operation by load balancing two multiplex inverter devices. (3) It is possible to provide a multiplex inverter device capable of economically processing the regenerative power of the load of the multiplex inverter device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a multiplex inverter device of the present invention.

FIG. 2 is a schematic configuration diagram showing a multiplex inverter device according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of a unit inverter cell applied to a second embodiment of the multiplex inverter device of the present invention.

FIG. 4 is a schematic configuration diagram showing a third embodiment of the multiplex inverter device of the present invention.

FIG. 5 is a schematic configuration diagram showing a fourth embodiment of the multiplex inverter device of the present invention.

FIG. 6 is a circuit diagram of a unit inverter cell applied to a multiplex inverter device according to a fourth embodiment of the present invention.

FIG. 7 is a schematic configuration diagram showing a multiplex inverter device according to a fifth embodiment of the present invention.

FIG. 8 is a schematic configuration diagram showing a multiplex inverter device according to a sixth embodiment of the present invention.

FIG. 9 is a schematic configuration diagram showing a multiplex inverter device according to a seventh embodiment of the present invention.

FIG. 10 is a schematic configuration diagram showing a conventional multiplex inverter device.

FIG. 11 is a circuit diagram of a unit inverter cell applied to an embodiment of a conventional multiple inverter device.

FIG. 12 is a diagram showing an example of installation of a conventional multiple inverter device in an electric room.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Commercial AC power supply 2, 21-23 ... Switch 3 ... Input transformer 31, 32, 33 ... Input transformer 3P ... Primary winding 31P, 32P, 33P ... Primary winding 3S ... Secondary winding 31S-33S , 3S1, 32S1 secondary winding 4 inverter circuit 41, 42 inverter circuit 4U1-4U3, 4V1-4V3, 4W1-4W3 unit inverter cells 4U11-4U41, 4V11-4V41, 4W11-
4W41, 4U3a, 4V3a, 4W3a unit inverter cell 5 polyphase load 6, 7 current detector 8 balance control circuit 9 three-phase reactor 11 circuit breaker 10 regenerative power processing resistor Q1 to Q6 semiconductor Switching elements D1 to D6 Diodes S1 to S6 Thyristors 101R, 101S, 101T AC input terminals 102 Rectifiers 103 Filter capacitors 104 Inverters 105P and 105N Inverter output terminals 106 Initial charge circuit

Claims (15)

[Claims] An input transformer having a plurality of secondary windings and a plurality of unit inverter cells connected in n stages (n is a natural number) to form each phase, and combined with the input transformer to form a multi-phase. A multiplex inverter device for supplying power to a load, wherein the input transformer is divided into a plurality of parts, and at least a part of the divided input transformer is placed separately from the unit inverter cells. Inverter device. 2. An input transformer having a plurality of secondary windings and a plurality of unit inverter cells connected in series in n stages to form each phase, and in combination with the input transformer, power is supplied to a polyphase load. In the multiplex inverter device to be supplied, the input transformer has 3n sets of single-phase windings on a secondary side, and connects the secondary-side single-phase windings to a unit inverter cell to operate the multiplex inverter device. In some cases, the combined input current of the input transformer has a current waveform of 12-phase rectification or more. 3. The single-phase secondary winding of the input transformer connected to each of the unit inverter cells connected in series, the single-phase secondary winding corresponding to three-phase alternating current input to the input transformer. Are connected to each other.
A multiplex inverter device as described. 4. A single-phase secondary winding corresponding to a three-phase AC input from an input transformer is connected to each of the unit inverter cells of each output phase of the n-th stage (n is a natural number). The multiplex inverter device according to claim 2, wherein 5. The multiplex inverter device according to claim 2, wherein the input transformer is installed separately from the unit inverter cell. 6. The input transformer according to claim 2, wherein the input transformer is divided into a plurality of parts, and a part of the divided input transformer is installed separately from a unit inverter cell. A multiplex inverter device according to any one of the above. 7. In a multiplex inverter device in which an input transformer is divided into a plurality of parts and the divided input transformers are separately installed, a plurality of secondary windings on the separately arranged input transformer side are: A multiplex inverter device having a single-phase winding. 8. A multiplex inverter device comprising an input transformer having a plurality of secondary windings and a plurality of unit inverter cells connected in series in n stages (n is a natural number). A multiplex inverter device comprising: means for finely adjusting the output voltage of at least one of the multiplex inverter devices connected in parallel when the units are connected in parallel to adjust the load current balance. 9. The multiplex inverter device according to claim 8, wherein a DC voltage of at least a part of the unit inverter cells connected in series is variably controlled. 10. A multiplex inverter apparatus comprising an input transformer having a plurality of secondary windings and a plurality of unit inverter cells connected in series in n stages (n is a natural number). A multi-inverter device comprising: a three-phase reactor connected between two multiplex inverter output terminals when a plurality of multiplex inverters are connected in parallel; and a load connected to an intermediate terminal of the three-phase reactor. 11. An input transformer having a plurality of secondary windings and a plurality of unit inverter cells connected in series in n stages (n is a natural number) to form each layer, and combined with the input transformer to form a polyphase. A multiplex inverter device for supplying power to a load, wherein a regenerative power processing resistor is connected to an output terminal side of the multiplex inverter when processing regenerative power from the polyphase load. apparatus. 12. A regenerative power processing resistor of the multiplex inverter device is connected to an m-th stage (n>m; m and n are natural numbers) of unit inverter cells connected in series in n stages, and A multiplex inverter device for processing regenerative power from a load. 13. The regenerative power processing resistor has a reduced rated power by connecting only within a predetermined range of a deceleration period of the multi-phase load. The multiplex inverter device according to claim 11 or 12. 14. A period in which the regenerative power processing resistor is connected, an output voltage phase of the multiplex inverter device is adjusted, and an exciting current component is mainly supplied from the multiplex inverter device to the multi-phase load. The multiplex inverter device according to any one of claims 11 to 13, wherein the multiplex inverter device is controlled such that: 15. An output voltage up to the m-th unit inverter cell connected in series when the regenerative power processing resistor is connected is controlled to be larger than the m / n ratio of all output voltages of the multiplex inverter device. The multiplex inverter device according to any one of claims 12 to 14, wherein regenerative power of a polyphase load is processed.