JP3431506B2 - Multiple inverter device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device for obtaining a high voltage output of several kV, and more particularly to a multiple inverter device 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 is becoming widespread, centering on square torque loads such as pumps and blowers. In particular, small-capacity low-voltage AC motors are used in a large number of energy-saving operations in combination with general-purpose inverter devices. On the other hand, large-capacity AC motors are, for example, 3kV system, 6kV system, 4k overseas.
Since it is a high-voltage electric motor such as V system, the application of energy-saving operation has been limited due to problems such as electric motor voltage and installation of an inverter transformer.

Similar to the low-voltage AC motor, a high-voltage AC motor is easily put into practical use in part for the purpose of easily changing the speed to enable energy-saving operation. . Here, as an example of an inverter device that outputs a high voltage, Japanese Patent Application No. 9-2
No. 77725 "Multiple inverter device and its control method"
Will be described below.

10 to 12 show examples of the configuration of the multiplex inverter device in Japanese Patent Application No. 9-277725. Figure 1
0 is a multiple inverter device capable of obtaining a high voltage output, 1 is a commercial AC power source, 2 is a switch, 3 is an input transformer, 3P is a primary winding, 3S is a secondary winding, and a plurality of windings are provided. Composed of lines. 4 is an inverter circuit 4U1-4U3, 4V
Unit inverter cells of 1 to 4V3 and 4W1 to 4W3 are connected in series to configure each layer of the inverter circuit 4. 5
Is a multi-phase load driven by a multiple inverter device,
The above-mentioned high-voltage AC motor or the like is applied.

FIG. 11 shows unit inverter cells 4U1-4.
The structure of the unit inverter cell circuit of U3, 4V1-4V3, 4W1-4W3 is shown. In this figure, the secondary winding 3P of the transformer 3 is connected to the AC input terminals 101R, 101S, 101T of the unit inverter cell circuit, and the input three-phase AC power is converted into DC power by the rectifier 102, and the filter capacitor The DC power smoothed by 103 is converted into AC power of variable frequency by the inverter 104, and single-phase AC power is output from the 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 rectifying circuit using the diodes D1 to D6. The inverter 104 uses the semiconductor switching elements Q1 to Q4 to perform PWM control from a substantially constant DC voltage and output a variable AC voltage to the inverter output terminals 105P and 105N.

The operation of the multiple 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 input through the switch 2 to the input transformer. Supply to 3. The secondary winding 3S of the input transformer 3 is composed of a plurality of three-phase windings.
Is the AC input terminals 101R, 101S of the inverter cell,
The AC power supplied from the commercial AC power supply 1 is connected to the 101T and converted into AC power of variable frequency by the inverter circuit 4 to supply power to the multi-phase load 5.

The conventional multiple inverter device shown in FIG. 10 has 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 respectively connected as wiring for three-phase AC power. For this reason, if n unit inverter cells are connected in series to form a three-phase output multiple inverter device, three-phase wiring × three-phase output × n series = 9n, that is, n = 3 in the configuration of FIG. In some cases, 27 wires are required between the input transformer 3 and the inverter circuit 4.

Since these 27 wires are high-voltage electric wires that carry the main circuit current and are connected to the high-voltage circuit, all 9n wires (27 wires in FIG. 10) are connected as external wires during installation work. Then it took a lot of work and required a lot of time. This is because when the output voltage of the multiple inverter device is further increased, the number of connections is also increased, and in the actual device example, 54 wires are required when n = 6.

In order to solve these problems, it is known to configure the device as shown in FIG. FIG. 12 is an installation diagram of the multiple inverter device, which is a method in which the input transformer 3 and the inverter circuit 4 are integrally configured as shown and installed in the same electric room. As a result, the problem that the number of circuit wirings between the input transformer 3 and the inverter circuit 4 is large is solved by making these main circuit wirings at the time of device connection at the factory.

On the other hand, when the input transformer 3 and the inverter 4 are integrally installed as shown in FIG. 12, the ratio of the occupied area of the input transformer 3 to the whole is very large, and the input transformer is included in the loss of the entire multiple inverter device. The amount of equipment 3 generated was about half, and the electric room to be installed became larger and the number of auxiliary equipment such as coolers also increased.

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

On the other hand, in the multiple inverter device as shown in FIG. 10, when the multiphase load 5 is an AC motor and an attempt is made to rapidly reduce the speed of the AC motor, regenerative power flows from the multiphase load 5 into the inverter circuit 4. The unit inverter cell circuit as shown in FIG. 11 cannot process the regenerated power, and there is a problem that the output voltage cannot be controlled or an overvoltage occurs.

Further, in the multiple 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 many rated capacities for the unit inverter cell when trying to make the capacity of the multiple inverter device into a series. was there.

[0014]

The multiple inverter device constructed as described above has the following problems. (1) When the input transformer 3 and the inverter circuit 4 are integrally installed in the electric room, the installation area becomes large. There is a problem in that the heat generation in the electric room increases and the electric room and ancillary equipment become large and expensive. (2) The work of installing the input transformer 3 having a very large weight in the electric room is difficult, and the floor strength of the electric room needs to be strengthened in order to install a heavy object. (3) There has been a problem that the number of main circuit wires between the input transformer 3 and the inverter circuit 4 becomes very large. (4) When electric power is regenerated from the multi-phase load to the multiple inverter device, the inverter circuit 4 cannot process the regenerated electric power, and the unit inverter cell circuit has a problem that voltage control becomes impossible and overvoltage occurs. (5) If many types of rated capacity of the multiple inverter device are to be provided, it is necessary to provide the rated capacity of the unit inverter cell corresponding thereto, and there is a problem that it is particularly difficult to expand the capacity of the multiple inverter device.

Therefore, it is an object of the present invention to provide an economical and practical multiple inverter device which can solve the problems associated with the reduction of main circuit wiring and the expansion of capacity.

[0016]

[0017]

Therefore, the present invention is based on the above
To achieve the purpose, it has the following configuration. First, the contract
The invention corresponding to claim 1 is an input transformer having a plurality of 3n sets of single-phase secondary windings, and a multiple inverter device in which a plurality of unit inverter cells are connected in series in n stages to form each phase, The plurality of single-phase secondary windings of the input transformer have three single-phase secondary windings so that the phase relationship corresponds to the three phases of the commercial AC power input to the input transformer primary winding. It is characterized in that a pair of phases is formed, and at least two pairs are out of phase with each other between the pairs of secondary windings forming the pair of three phases. 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 that of the conventional one, and the single-phase secondary winding of the input transformer can be reduced. By shifting the phases of the three phases of the windings from each other, it is possible to provide an economical multiple inverter device capable of reducing the harmonic current of the power supply system.

In the invention according to claim 2 , three sets of secondary windings (three-phase sets) corresponding to three phases of the commercial AC power source input to the input transformer are connected in series. Is connected to the unit inverter cell of.

[0019]

Therefore, in the invention according to claim 2 , even if the input transformer secondary winding is a plurality of single-phase windings, since the input power of each unit inverter cell is the same, the input transformer is On the primary winding side, the current of the commercial AC power supply is balanced in each phase, and an economical multiple inverter device capable of reducing the harmonic current of the power supply system can be provided.

[0021]

[0022]

[0023]

Further, the invention according to claim 3 is a multiple 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 to form each phase. When the outputs of the multiple inverter devices are connected in parallel to expand the output capacity and the capacity is expanded, the output of at least one of the multiple inverter devices is balanced in order to balance the output capacities of the multiple inverter devices connected in parallel. It is characterized by finely adjusting the voltage. Therefore, if two multi-inverter devices are connected in parallel, the load balance will differ greatly due to a slight difference in output voltage. However, if a fine adjustment function of the output voltage is provided, stable output capacity balance operation can be performed. A large capacity multiple inverter device can be provided.

Further, the invention according to claim 4 is, as means for finely adjusting the output voltage, variably controlling a DC voltage of a part of a single inverter cell to output capacitance of a multiple inverter device connected in parallel. It is characterized by operating in equilibrium.

In the invention according to claim 5 , when two multi-inverters are connected in parallel, they are connected in parallel via an AC reactor having an intermediate terminal, and a multi-phase load is connected to the intermediate terminal of the AC reactor. The fine adjustment function of the output voltage described above is performed by the induced voltage of the AC reactor.

Therefore, in the multiple inverter device according to the inventions corresponding to claims 3 to 5 , the capacity can be easily expanded, and conventionally, the rating of the unit inverter cell corresponding to the output capacity rating of the multiple inverter device. Although the capacity was required, the number of types of rated capacity of the unit inverter cell can be reduced, and the multiple inverter device can be standardized easily.

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

[0034] (First Embodiment) FIG. 1 is a circuit diagram showing an embodiment corresponding to the first embodiment <br/>. Commercial AC power supply 1, switches 21, 22, 23 and three sets of input transformers 3
1, 32, 33, each input transformer has a primary winding 31
P, 32P, 33P and n sets of three-phase secondary windings 31S,
A unit inverter cell 4 having 32S and 33S and provided in n stages for each phase to configure each phase of 4U, 4V, and 4W.
A multiple inverter device is configured with the inverter circuit 4 including U1 to 4U3, 4V1 to 4V3, and 4W1 to 4W3, and power is supplied to the multiphase load 5. In FIG. 1, n = 3 is shown in FIG. 1. In FIG. 1, the input transformer 3 of FIG.
Is shown as. Each of the input transformers 31, 32, 33 has three sets of secondary windings, and the secondary windings are 18-phase secondary windings that are offset from each other by an electrical angle of 20 °. Each of the secondary windings 31S, 32S, 33S has a unit inverter cell 4U1-4W1, 4U2-4W2, 4U3 as shown in the drawing.
~ 4W3 is connected.

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 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 and 33. Some of the divided input transformers, for example, the input transformer 33 is installed in the inverter circuit 4. If the input transformers 31 and 32 are separately installed in the same electric room as the inverter circuit 4, the following operational effects can be obtained. (1) Since the installation area of the input transformer in the electric room is 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 are almost equal)
Therefore, ancillary installation such as a cooler can be reduced. (3) Since the input transformer for the weight is reduced, the floor strength of the electric room can be easily strengthened, and the installation work in the electric room becomes easy.

In FIG. 1, the input transformer is divided into three sets for explanation, but this division is not particularly limited in the present invention, and the input transformer to be installed separately from the electric room is described. The number is not particularly limited in the present invention.

(Second Embodiment) FIG. 2 is a circuit diagram showing a second embodiment.

The same reference numerals as those in the first embodiment and the conventional FIG. 10 indicate the same elements. The part different from FIG. 10 is the input transformer 3.
And the unit inverter cells 4U11 to 4U3 serially connected to each of the 4V, 4U, and 4W phases of the inverter circuit 4 in n stages.
1, 4V11 to 4V31 and 4W11 to 4W31 are configured by unit inverter cells of single-phase AC input. (Indicated as n = 3 in FIG. 2.) As shown in FIG. 3, the unit inverter cell of the single-phase AC input is different from the unit inverter cell shown in FIG. 11 in that the rectifier 102 is a single-phase rectifier circuit. The other operations are the same.

Secondary winding 3S1 of the input transformer 3 shown in FIG.
3n sets (9 pieces) of single-phase windings correspond to n sets (here, 3 sets) of commercial AC power supply 1 whose electrical phase is 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 are included.
Secondary winding 3S1 connected to 1 and 4W114W31
Each have an electrical phase difference of 20 °, and the secondary winding 3S1 connected to the unit inverter cells 4U11, 4U21 and 4U31 is a three-phase R.R. S. It is a winding corresponding to T.

In the case of the configuration 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
Current becomes an input current for 18-phase rectification, and the harmonic component of the input current can be reduced. As described above, the secondary winding 3S1 is the single-phase winding input transformer 3 and the single-phase AC input unit inverter cells 4U11 to 4U31, 4V11 to 4V3.
By combining 1, 4W11 to 4W31, the following operational effects can be obtained. (1) Even if the secondary winding 3S1 of the input transformer 3 is a 3n set of single-phase windings, the input current for 6n-phase rectification is passed through the commercial AC power supply 1, and the harmonic current component is reduced. You can (2) As for the main circuit wiring between the input transformer 3 and the inverter circuit 4, since the secondary winding 3S1 is a single-phase alternating current,
As a result, the number of wirings is reduced to 3, and the main circuit wiring work at the factory and the installation and wiring work at the site are greatly reduced.

(Third Embodiment) FIG. 4 is a circuit diagram showing a third embodiment. In this figure, the same symbols as those in claims 1 and 2 indicate the same elements. In FIG. 4, when power is supplied from the commercial AC power source 1 to the input transformer divided into two via the circuit breakers 21 and 22, the input transformer 31 is connected to the secondary winding 31.
S is a three-phase winding configuration, and the input transformer 32 is a secondary winding 32S1.
Has a single-phase winding configuration, and unit inverter cells 4U1 to 4U41, 4V1 of the inverter circuit 41 and the inverter circuit 42
Power is supplied to 4V41, 4W1 to 4W41. Here, the unit inverter cells 4U1, 4U2, 4V1, 4V2
4W1 and 4W2 are three-phase AC input, unit inverter cell 4
U31, 4U41, 4V31, 4V41, 4W31, 4
W41 is a single-phase AC input. The secondary winding 32S1 of the input transformer 32 corresponds to the three-phase AC phase of the commercial AC power supply 1 and corresponds to the unit inverter cells 4U31, 4V31, 4W3.
When the windings connected to 1 and 4U41, 4V41, and 4W41 are combined, they are connected so as to form a Δ connection and a Y connection, respectively. As a result, the input current of the input transformer 32 becomes a 12-phase rectified input current, and like the input current of the input transformer 31 side, the harmonic current component can be reduced by the multi-phase rectified input current.

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

As shown in FIG. 4, in the input transformer 31, the secondary winding 31S may be a three-phase winding or a single-phase winding similar to the input transformer 32. In the multiple inverter device configured as shown in FIG. 4, the divided input transformer 32
If it is placed separately from the inverter circuit 42, it is possible to realize a multiple inverter device having the same effect as that of FIG. 1 or 2.

(Fourth Embodiment) FIG. 5 is a circuit diagram showing a third embodiment. FIG. 6 is a circuit diagram example of a unit inverter cell.

The circuit diagram of FIG. 5 shows an example of the configuration circuit of a multiple inverter device for driving the multi-phase load 5 by connecting the outputs of two inverter circuits 4 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 currents of the polyphase load 5, and a balance control circuit for controlling the output currents of the two inverter circuits 4 to be balanced by the detection signals of the current detectors 6 and 7. 8 is provided, and unit inverter cells 4U3a, 4V3a, 4W3 are provided by the output control signal of the balance control circuit 8.
This is a configuration for controlling a.

Here, the unit inverter cells 4U3a, 4V
6, the rectifier 102 is composed of thyristors S1 to S6, and the DC voltage of the unit inverter cell can be controlled by the phase control of the thyristors S1 to S6. Therefore, the DC voltage of the unit inverter cells 4U3a, 4V3a, 4W3a can be finely adjusted according to the output control signal of the balance control circuit 8 to finely adjust the output voltage of the unit inverter cell.

When two outputs of the inverter circuit 4 are connected in parallel and the capacity of the multiple inverter device is increased to supply AC power to the polyphase load 5, the circuit impedance from the commercial AC power supply 1 to the polyphase load 5 is increased. The output currents of the respective inverter circuits 4 are likely to be unbalanced due to the difference between the unit inverter cells 4U3a and 4V3 as described above.
The load balance of the two inverter circuits 4 can be obtained by finely adjusting the DC voltage of a, 4W3a and finely adjusting the cell output voltage so that the output currents are balanced.

In FIGS. 5 and 6, one inverter circuit 4 is used.
Although the method of finely adjusting the output voltage of (1) is performed by finely adjusting the DC voltage of the unit inverter cell, this output voltage control method is not limited. As described above, the two inverter circuits 4 are connected in parallel so that the load can be balanced and the power can be supplied to the polyphase load 5.
The following effects / actions can be obtained. (1) The capacity of the multiple inverter device can be increased, and conventionally, a unit inverter cell having a rated capacity corresponding to the capacity of the multi-phase load 5 was required. However, the capacity can be increased by connecting the inverter circuits 4 in parallel. The type of rated capacity of the inverter cell can be reduced. (2) Since the load balance of the inverter circuits 4 that are operated in parallel is easily controlled, the operational reliability of a large capacity multiple inverter device can be improved.

(Fifth Embodiment) FIG. 7 is a circuit diagram showing a fifth embodiment. 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 the multiphase load 5 is connected to the intermediate terminal of the three-phase reactor 9.

In the large-capacity multiple 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 effect of the circuit impedance described above 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 multiple inverter device shown in FIG. The method using the three-phase AC reactor 9 as shown in FIG. 7 also has the effect / action of realizing a large-capacity multiple inverter device similar to that shown in FIG.

(Sixth Embodiment) FIG. 8 is a circuit diagram showing a sixth embodiment. The circuit diagram of FIG. 8 is obtained by adding the regenerative power processing resistor 10 to the circuit breaker 11 in addition to the conventional circuit diagram of FIG. 10. In this figure, since the unit inverter cells are configured as shown in the circuit diagrams of FIG. 11 and FIG. 3, when the polyphase load 5 is an AC motor and the polyphase load 5 is rapidly decelerated, There is a problem that 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 overvoltage or inability to control the output voltage. When processing the electric power, the breaker 11 is closed so that 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, but when the equipment connected to the multi-phase load 5 is a fluid control equipment such as a blower or a pump, the resistance of the fluid is high in the high-speed operation region. Since it is large, the deceleration in the high speed region is relatively fast. Therefore, the breaker 11 may be inserted only in the medium speed region or the low speed region in which the resistance of the fluid decreases to cause the regenerative power processing resistor 10 to consume the regenerative power. .

When the multi-phase load 5 is an AC motor, the output voltage of the inverter circuit 4 and the output frequency have a substantially proportional relationship, and therefore the processing power of the regenerative power processing resistor 10 also corresponds to the square of the output voltage. Since it changes, as described above, 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 multi-phase load 5 is an induction motor, in order to supply the exciting current of the induction motor during this deceleration period,
When the inverter circuit 4 is operated, effective 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 increases, but as a means for solving this, The output voltage phase of the inverter circuit 4 is adjusted so that most of the output current of the inverter circuit 4 is the exciting current of the induction motor.

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

With the multiple inverter device and control method configured as described above, the following advantageous effects can be obtained. (1) Even if regenerative power is generated from the polyphase load 5, the regenerative power is processed by the regenerative power processing resistor 10 to prevent overvoltage of the inverter circuit 4 and output voltage control can be performed. . (2) The regenerative power processing resistor 10 consumes only the regenerative power of the polyphase load 5, and the circuit breaker 11 only during a predetermined deceleration period.
Since it is turned on by the power supply, the power capacity can be reduced and an economical system configuration can be realized.

(Seventh Embodiment) FIG. 9 is a circuit diagram showing a seventh embodiment. In this figure, input transformers 31 and 32,
In the multiple inverter device composed of the inverter circuits 41 and 42, when n unit inverter cells are connected in series,
The circuit of the breaker 11 and the regenerative power processing resistor 10 is connected to the n-th stage of the unit inverter cell. (In this figure, n
(= 4, n1 = 2) When the regenerative power processing resistor is connected to the n1th stage as shown in FIG. 9, the rated voltage of the circuit breaker 11 and the regenerative power processing resistor 10 is reduced from that of FIG.
A similar effect can be obtained.

Further, 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 multiphase load 5 as described above. The load 5 can be applied only during a predetermined deceleration period.

Further, as described above, the output voltage of the multiple inverter device is controlled in a substantially proportional relationship with its 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, when 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 regenerative power processing, the processing power of the regenerative power processing resistor 10 can be increased and the multiphase load 5 Thus, effective regenerative deceleration can be performed.

Further, 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 each divided into two parts. However, whether or not the input transformer or the inverter circuit is divided is particularly limited. Instead, it is clear that the same effect can be obtained without the division.

[0062]

According to the present invention described above, an input transformer having a secondary multi-winding and a plurality of unit inverter cells n are provided.
The following effects are achieved in the multiple inverter device in which the inverter circuits that are connected in series and configure each phase are combined.
The phase between the three-phase pairs of the single-phase secondary winding of the input transformer is
Reduce the harmonic current of the power system by shifting
be able to. When increasing the capacity of the multiple inverter device, it is possible to provide a highly reliable large-capacity multiple inverter device in which two multiple inverter devices can be load-balanced and operated in parallel.

[Brief description of drawings]

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

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

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

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

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

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

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

FIG. 10 is a schematic configuration diagram showing a conventional multiple 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 Codes] 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 Windings 31S to 33S, 3S1, 32S1 ... Secondary winding 4 ... Inverter circuits 41, 42 ... Inverter circuits 4U1-4U3, 4V1-4V3, 4W1-4W3 ... Unit inverter cells 4U11-4U41, 4V11-4V41, 4W11-
4W41, 4U3a, 4V3a, 4W3a ... Unit inverter cell 5 ... Multi-phase load 6, 7 ... Current detector 8 ... Balance control circuit 9 ... 3-phase reactor 11 ... Breaker 10 ... Regenerative power processing resistors Q1-Q6 ... Semiconductor Switching elements D1 to D6 ... Diodes S1 to S6 ... Thyristors 101R, 101S, 101T ... AC input terminal 102 ... Rectifier 103 ... Filter capacitor 104 ... Inverter 105P, 105N ... Inverter output terminal 106 ... Initial charging circuit

Claims (5)

(57) [Claims] 1. 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 phase, and combined with the input transformer. In a multiple inverter device that supplies power to a phase load, the plurality of single-phase secondary windings of the input transformer are
The single-phase secondary windings form a set of three phases so that the phase relationship corresponds to the three phases of the AC power source input to the secondary winding. A multiple inverter device characterized in that at least two pairs of them are out of phase with each other. 2. The single-phase secondary winding of the input transformer connected to each of the unit inverter cells connected in series is a single-phase secondary winding corresponding to the three-phase alternating current input by the input transformer. 2. Each of the above is connected.
The described multiple inverter device. 3. A multiple 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), wherein a plurality of the multiple inverter devices are provided. A multi-inverter device characterized in that, when the units are connected in parallel, at least one of the multi-inverter devices connected in parallel is provided with means for finely adjusting the output voltage to adjust the balance of the load current. 4. The multiple inverter device according to claim 3, wherein the DC voltage of at least a part of the unit inverter cells connected in series is variably controlled. 5. A multi-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 multi-inverter device, characterized in that, when two units are connected in parallel, a three-phase reactor is connected between two multi-inverter output terminals, and a load is connected to an intermediate terminal of the three-phase reactor.