JP2002369541A - Power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems, such as complicated construction and high cost in a power converter structured to output large current by connecting a plurality of inverter circuits in parallel, which requires a total current sensor for detecting total current generated after parallel connection. SOLUTION: This power converter comprises a voltage controller 33 for controlling the detected voltage of a voltage sensor 61 which detects the voltage generated, after the plurality of inverter circuits 60 are connected in parallel, so as to match the command value of a voltage command circuit 31 for giving a command value for the output voltage of the power converter 91; and a current command circuit 34 for giving a command value for the current to be outputted of each of the inverters based on the output of the voltage controller 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter having an inverter circuit for converting a DC voltage to an AC voltage, and is used for a UPS (Uninterruptible Power Supply) and the like.

[0002]

2. Description of the Related Art There are various methods for obtaining an AC voltage from a DC voltage, but recently, an inverter circuit using a semiconductor power element has been generally used. However, there is a limit to the current that can be supplied by one mass-produced semiconductor power element, and a method of connecting inverter circuits in parallel is used to obtain a large current output. When a plurality of inverter circuits are connected in parallel, it is necessary to control the load sharing, and various sharing control methods have been proposed. FIG. 19 is a configuration diagram of a conventional power conversion device described in, for example, “Uninterruptible Power Supply (UPS) Introduction Practice Guide”, 1987, pp. 62 to 64, showing a configuration of a parallel operation circuit of inverters. In the figure, 1 is a DC voltage source such as a battery, 3 is an AC load to which the power conversion circuit supplies power, 51 is a first power conversion circuit that converts the DC power of the DC voltage source 1 into AC power, 5
Reference numeral 5 denotes a second power conversion circuit connected in parallel with the power conversion circuit 51. The configuration of the second power conversion circuit is the same as that of the first power conversion circuit 51, so that the internal illustration is omitted and the detailed description is omitted.

[0005] Reference numeral 52 denotes first and second power conversion circuits 51 and 5.
5 is a total current sensor inserted into the output circuit to the load 3 after being connected in parallel. 53 divides the output signal of the total current sensor 52 by the number N of operating power conversion circuits connected in parallel, and This is a current distribution circuit that calculates a current value per unit and outputs it to each power conversion circuit. Note that FIG.
In the circuit of (2), since the number of parallel operation units is 2, N = 2.

[0004] Reference numeral 60 denotes an inverter circuit composed of a power semiconductor element and a filter circuit, and since its configuration is very general, detailed description thereof will be omitted. 61 is an individual current sensor inserted in the output circuit of the first power conversion circuit 51,
62 is a voltage sensor for detecting the output voltage of each inverter 60; 63 is an input of the output signal of the current distribution circuit 53, the output signal of the individual current sensor 61, and the output signal of the voltage sensor 62; The signal is supplied to the current distribution circuit 53
Of each inverter 60 so as to match the value of the distribution output signal of
Is a voltage command generation circuit that outputs a command signal of the output voltage of the first embodiment.

An inverter control circuit 64 receives the output of the voltage command generation circuit 63 and the output of the voltage sensor 62 and controls the inverter circuit 60 so that the magnitudes of both signals match. In the configuration of FIG. 19, the power conversion device 90 is configured by other parts except the DC voltage source 1 and the AC load 3.

Next, the operation will be described. The power conversion device 90 of FIG. 19 is of a type in which the current capacity of the system is increased by operating a voltage-controlled power conversion circuit that controls an AC output voltage in parallel. The total output current of the inverters 51 and 55 connected in parallel is detected by a total output current sensor 52, and this output is divided by the number of parallel units to obtain a current value to be borne by each unit by a current distribution circuit 52. . Next, the voltage command generation circuit 63 controls the frequency, phase, and voltage amplitude of each power conversion circuit, and outputs a voltage command signal so that each inverter circuit can share the current value to be shared.

[0007] Here, the number of parallel units is not simply the number of connected units, but the number of connected units that are operating normally. For example, in a power converter in which a plurality of inverter circuits are connected in parallel, it often occurs that one of the inverter circuits needs to be stopped for maintenance. In such a case, the distribution ratio (the number N described above) of the current distribution circuit 53 must be changed each time.
There was a problem that it was not easy to add or reduce the number of parallel units.

[0008]

Since the conventional power conversion circuit is configured as described above, a total current sensor and a current distribution circuit for obtaining a current value to be shared by each power conversion circuit from the total current value. In addition, a voltage command generation circuit that controls the frequency, phase, and amplitude of each power conversion circuit is required to individually control the voltage of each inverter. Therefore, there is a problem that the circuit configuration is complicated. Further, there is a problem that it is not easy to add or reduce the number of parallel units.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and comprises a total current sensor for detecting a total current of each power converter, and a current distribution circuit for calculating a current to be shared by each inverter from the total current sensor. It is an object of the present invention to provide a power conversion device that does not require the control of the frequency, phase, and voltage amplitude of each inverter circuit, and that can easily add or reduce the number of parallel circuits.

[0010]

A power converter according to the present invention includes an inverter circuit for converting DC power input to an input terminal into AC power by a semiconductor element, and a filter circuit connected to an output terminal of the inverter circuit. And a current controller that controls an output current of the inverter circuit. A plurality of the power conversion circuits are connected in parallel, and a voltage at an output terminal of the power connection circuit connected in parallel is detected. A voltage sensor, a voltage controller that controls a voltage of an output terminal of the filter circuit by controlling the plurality of power conversion circuits by a given voltage command signal and a signal of the voltage sensor, and an output signal of the voltage controller. A current command generation circuit for commanding an output current value of each of the plurality of power conversion circuits.

Further, the current capacity of at least one of the plurality of power conversion circuits is different from the current capacity of the other power conversion circuits, and the current command generation circuit has a load ratio of each power conversion circuit substantially equal to each other. And a constant-rate distribution circuit for outputting a current command value.

Further, each of the plurality of power conversion circuits has an operation detection circuit for outputting a signal indicating whether or not the operation is being performed. An adjustment circuit is provided for calculating the total current capacity of the power conversion circuit and adjusting the current command value based on the calculated total current capacity.

A current command value corresponding to each power conversion circuit output from the current command generation circuit is compared with a current capacity of the corresponding power conversion circuit, and the power conversion circuit corresponding to the current command value is compared. A current command value monitoring circuit for transmitting a signal for stopping the operation of the power converter when the current capacity exceeds the above.

The current command value of the current command generating circuit is compared with the current capacity of a corresponding power conversion circuit, and a state where the current command value exceeds the current capacity of the corresponding power conversion circuit is determined by a predetermined value. And a current command value overload monitoring circuit for transmitting a signal for stopping the operation of the power conversion device when the time has elapsed.

The predetermined time is set in advance according to the magnitude of the difference between the current command value and the current capacity when the current command value exceeds the current capacity of the corresponding power conversion circuit. It is stipulated.

Further, the plurality of power conversion circuits have a current sensor for detecting an output current of each power conversion circuit,
The current command value output from the current command generation circuit is compared with the output value of the current sensor of the power conversion circuit corresponding thereto, and when the difference exceeds a predetermined level, the operation of the power conversion device is stopped. It is provided with a current control state monitoring circuit for transmitting a signal.

Also, it is determined from the current command value output from the current command generation circuit and the output state of the operation detection circuit whether or not some of the power conversion circuits can be disconnected in the current operation state. It is provided with a disconnection possibility determination circuit and a display for displaying a determination result of the disconnection possibility determination circuit.

The current capacities of the plurality of power conversion circuits are substantially the same as each other, and the display also indicates the number of power conversion circuits that can be disconnected.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 shows the configuration of a power conversion device 91 according to the first embodiment of the present invention. FIG. 1 illustrates an example in which three inverter circuits are arranged in parallel. In the drawings of the respective embodiments, the same reference numerals denote the same or corresponding parts, and therefore, detailed description thereof will not be repeated. In the figure, 1 is a DC voltage source such as a battery, and 17 is its output voltage line. 2a, 2
b and 2c are connected in parallel to the DC voltage source 1 and also connected in parallel to the load 3, and are first, second, and third power conversion circuits that convert the voltage of the DC voltage source 1 into AC. And the first power conversion circuit 2a
2 will be described with reference to FIG.

Reference numeral 30 denotes a voltage sensor for detecting the output voltage (same as the voltage of the load 3) connected in parallel to the power conversion circuit;
Reference numeral 31 denotes a voltage command generation circuit that outputs an output voltage command value of the entire power conversion circuit connected in parallel; 32, a subtractor that subtracts the output of the voltage sensor 30 from the output of the voltage command generation circuit 31; A voltage controller that controls the outputs of the power conversion circuits 2a to 2c so that the output becomes zero;
Reference numeral 34 denotes a current command generation circuit that outputs a current command value of the power conversion circuits 2a to 2c, and 35 denotes an operation command generation circuit that outputs a device start / stop command. A portion excluding the power supply 1 and the load 3 in FIG.

FIG. 2 is a block diagram showing a detailed configuration of the power conversion circuit 2a of FIG. 1. Reference numeral 60 denotes an inverter circuit composed of a power semiconductor element; 61, an individual current sensor for detecting an output current of the inverter circuit 60; Is a reactor, and 13 is a capacitor.
A C filter is configured to shape the output voltage waveform of the inverter circuit 60 into a waveform close to a sine wave. 14 is a subtractor for subtracting the signal of the individual current sensor 61 from the output signal 20 of the current command generating circuit 34, 15 is a current controller that operates so that the output of the subtractor 14 becomes zero, and 16 is according to the output of the current controller 15. This is a pulse generation circuit that controls the control phase of the inverter circuit 60. Pulse generation circuit 1
The operation / non-operation 6 is controlled by the output 19 of the operation command generation circuit 35. The power conversion circuit 2a is a current-type inverter circuit that controls an output current according to a current command signal.

Next, the operation will be described. A voltage command generating circuit 31 generates an arbitrary AC voltage command. The difference between the command voltage and the signal of the voltage sensor 30 is the voltage controller 3
3 is input. The voltage controller 33 is constituted by a proportional or proportional / integral or proportional / integral / differential control circuit, and operates so that the difference between the voltage command and the signal of the voltage sensor 30 becomes close to zero. Since the voltage sensor 30 detects the voltage after the plurality of power conversion circuits are connected in parallel, the current command generation circuit 34 regards the plurality of power conversion circuits connected in parallel as one circuit, and Output the specified current command value. The current command generation circuit 34 outputs a collective current command value (I), and outputs (I / N) obtained by dividing the current command value (I) by the number of inverters to each power conversion circuit. Then, each power conversion circuit performs an output according to the command value.

The circuit of FIG. 1 eliminates the need for a circuit for detecting the total output current of the power converters connected in parallel and calculating and instructing the shared current as described with reference to the related art. A simpler configuration can be achieved. The cross current between the power conversion circuits connected in parallel is reduced to a level lower than a problematic level by the filter including the reactor 12 and the capacitor 13 shown in FIG.

Embodiment 2 FIG. In the power conversion device according to the second embodiment, the power conversion circuits connected in parallel with different capacities have different capacities (at least a part of them). FIG. 3 is a configuration diagram of a power conversion device 92 according to the second embodiment, and FIG. 4 is a partial detailed configuration diagram. In the figure, it is assumed that at least two of the power conversion circuits 2a to 2c have different rated current values. Reference numeral 34a denotes a constant-rate distribution current command generation circuit that outputs a different current command value to each of the power conversion circuits 2a to 2c. The other parts are the same as those in the configuration shown in FIG. 1 and will not be described in detail.

FIG. 4 is a diagram showing a detailed configuration of the current command generating circuit 34a. In FIG. 4, 100, 101, 10
Reference numeral 2 denotes a data setter indicating the rated current carrying capacity of each of the power conversion circuits 2a, 2b, 2c, and 103 denotes an adder for summing all the rated current carrying capacity. 104, 105, 106
Is a divider that obtains a sharing ratio (also referred to as a load factor) of each of the power conversion circuits 2a, 2b, and 2c by dividing the rated energizing current capacity values 100, 101, and 102 by the output of the adder 103. 107a, 107b and 107c are multipliers for multiplying the sharing ratio output from the dividers 104, 105 and 106 by the command value of the total current sent from the voltage controller 33 to calculate a current command value for each power conversion circuit. It is. The circuit shown in FIG. 4 is a constant rate distribution circuit according to the present invention.

For example, assume that the capacities of the power conversion circuits 2a, 2b, 2c are 50A, 100A, 150A. And when the command value from the voltage controller 33 is 75A. The power conversion circuit 2a has 75 · 50 / (50 + 1)
00 + 150) = 12.5A The power conversion circuit 2b has 7
A command of 75 · 150 / (300) = 37.5A is sent to the 5 · 100 / (300) = 25A power conversion circuit 2c.

By providing the configuration (constant-rate distribution circuit) shown in FIG. 4, even if the current capacities of the power conversion circuits connected in parallel are different from each other, a current command value proportional to the ratio of each rated current can be output. It is possible to control such that the burden ratio of each power conversion circuit is always a constant ratio.

Embodiment 3 For maintenance, the power conversion circuit in operation may be partially stopped or disconnected (referred to as disconnection), or the disconnected power conversion circuit may be reconnected. In the case of FIG. 1 of the first embodiment, the current distribution rate must be reset every time the power is disconnected and reconnected. In the case of FIG. 3 of the second embodiment, the rated current data setting device 100, Since the settings of 101 and 102 must be changed each time, disconnection and reconnection cannot be performed easily. FIGS. 5 and 6 show the configuration of a power conversion device 93 that solves this problem. In FIG. 5, reference numeral 36 denotes an operation detection circuit, which is provided by each of the power conversion circuits 2a, 2b, and 2c.
Receiving a signal indicating whether each power conversion circuit is operating or not, the number of operating power conversion circuits (when the capacity of each power conversion circuit is the same) or the total rated current of the operating power conversion devices The capacity (when the rating of each power conversion circuit is not the same) is output to the current command generation circuit 34 or the constant rate distribution current command circuit 34a (FIG. 5 shows the case of the current command generation circuit 34).

FIG. 6 shows the details of the power conversion circuit 2a of FIG. 5. Reference numeral 21a denotes a state output circuit which outputs, for example, an "H" state signal 22a when the power conversion circuit 2a is operating normally. . The state signals 22a, 22b, and 22c are input to the operation detection circuit 36, and the above-described result is obtained. As a result, the current command generating circuit 34 outputs a current command value corresponding to the operating power conversion circuit, and the current value is automatically corrected even if disconnection and reconnection are performed on the way (in the present invention). Therefore, the disconnection and reconnection work becomes extremely easy.

To facilitate understanding, first, a specific example in which the capacity of each power conversion circuit is the same, for example, 50 A, will be described. If the current supplied to the load 3 is 75 A, the operation detection circuit 36 outputs N = 3 during operation of all three units, and each power conversion circuit outputs 75 A.
A current command of / 3 = 25 A is output. When one of them stops, N = 2 is output, and 75A / 2 =
The current command is changed to 37.5A.

Next, a case where the rated capacities of the respective power conversion circuits are different will be described with reference to specific examples. As described in the second embodiment, when the current values of the currents supplied to the loads are 75 A, when the respective capacities are 50 A, 100 A, and 150 A, as described above, all the three power conversion circuits are in operation. Is that the operation detection circuit 36 is (50 + 100 + 150 = 30
0) is output. Then, current command values of 12.5, 25, and 37.5 are output to the respective power conversion circuits. Now, when the power conversion circuit of the rated 100A stops operation, the operation detection circuit 36 outputs (50 + 150 = 2
00) is output. 75.50 / 200 = 18.75 A is provided in the power conversion circuit 2a.
A current command of 75 · 150/200 = 56.2 A is output to C.

Embodiment 4 FIG. In FIG. 1 of the first embodiment, since a current command according to the output signal of the voltage controller 33 is output to each power conversion circuit, a command exceeding the capacity of the power conversion circuit at the time of overload or the like is issued. Then, the power conversion circuit may be destroyed due to the overcurrent. FIG. 7 shows a configuration of a power conversion device 94 that has solved such a problem.
Shown in In the figure, reference numeral 35a denotes an operation command generation circuit with a current command monitoring circuit, and its configuration is shown in FIG.

In FIG. 8, reference numeral 109 denotes an output 20 of the current command generation circuit 34 and a total rated current value 20X of the power conversion circuit.
When the current command value 20 exceeds the total rated current capacity 20X, a signal to stop the operation of the power converter (immediately requires the operation time of the comparator 109) or at least an alarm signal is issued. Reference numeral 110 denotes a latch circuit that holds (latches) this signal when the above-described signal is output from the comparator 109. The overload operation characteristic of the power conversion circuit thus configured is shown at 101 in FIG. Although not described in detail, the power conversion circuits 2a to 2c formed by semiconductor power elements are protected against extremely large overcurrent by the characteristics of a known semiconductor protection fuse. This is indicated by the dotted line 100 in FIG. In the circuits of FIGS. 7 and 8, overload protection of the power converter can be performed with a simple configuration without using a load current sensor or a total current sensor.

Embodiment 5 Power conversion circuits 2a to 2c
Does not fail immediately when its output current becomes overloaded, but has a predetermined short-time overload withstand characteristic according to the degree of the overload current. Therefore, FIG. 10 shows a partial configuration of the power conversion device 95 in which the time until the stop is delayed by effectively utilizing the short-time overload characteristic instead of immediately stopping the overload when the overload occurs. FIG. 11 shows the protection characteristics. In the figure, 113 is a delay circuit,
When the comparator 109 outputs a signal, the comparator 109 operates so as not to output a signal to the latch circuit 110 until a time corresponding to an overload allowable time of the power conversion circuit (preset in the delay circuit 113).

As a result, overload protection coordination with the power conversion circuit can be achieved, and the system can be provided with a short-time overload tolerance. Incidentally, generally, the overload withstand capability at the rated load is several seconds to several minutes, which is much longer than the response time of the voltage controller. A characteristic example of the overload characteristic of the power conversion device having such a configuration is shown in 102 of FIG. This characteristic is improved because the time until the operation is longer than that of the characteristic 101 in FIG. 9 of the fourth embodiment.

Here, although not shown, the output signal 20 of the current command generation circuit 34 becomes larger than the set rated current value 20X, and when the comparator 109 outputs a signal, the difference depends on the degree of the difference. The output signal may be output to the delay circuit 113, and the delay circuit 113 may operate with a delay time according to the degree of the difference. The overload characteristic of the power converter in this case is, for example, as shown by a characteristic line 103 in FIG. 12, and the overload characteristic of the power conversion circuit can be used to the limit.

Embodiment 6 FIG. 13 and 14 show the configuration of a power conversion device 96 according to Embodiment 6 of the present invention. In FIG. 13, reference numeral 23 denotes a current control state monitoring circuit, the detailed configuration of which is shown in FIG. The output signal of the subtractor 14 and the preset set value α are input to the comparator 114. The comparator 114 determines that the power conversion circuits 2a to 2c are operating normally if the output of the subtractor 14 is within the range of plus or minus α. If the output of the subtractor 14 is out of the range of plus or minus α, the power conversion circuits 2a to 2a
2c determines that it is not operating normally and outputs a signal,
After this signal is latched by the latch circuit 115, the signal 2
Output as 2. The signal 22 is sent to the operation detection circuit 36 as described with reference to FIG.
Also sent to the pulse generation circuit 16 to stop the inverter operation pulse.

According to the configurations shown in FIGS. 13 and 14, the power converter in which the current cannot flow according to the current command stops itself and outputs the stopped state to the operation detecting circuit 36. Operation can be continued without being affected by the conversion circuit.

Embodiment 7 In the third embodiment, when one unit is disconnected during operation, the load is distributed to the remaining power conversion circuits. Therefore, if the rated load was just before the original disconnection, if the unit was disconnected, the overload would occur immediately. There is a problem that the system may stop operating.
That is, it is better to know in advance whether or not the vehicle can be disconnected, for example, when the vehicle is disconnected and maintenance is performed during operation.

FIG. 15 shows a configuration of a power conversion device 97 according to the seventh embodiment which has solved such a problem. 3 in the figure
7 is a parallelism judging circuit, the details of which are shown in FIGS.
Shown in FIG. 16 shows the case where the rating of each power conversion circuit is the same, and FIG. 17 shows the case where the rating capacity of each power conversion circuit is not the same.

First, FIG. 16 will be described. In FIG. 16, reference numeral 120 denotes a multiplier for multiplying the current command signal 20 output from the current command generating circuit 34 by the current operating number 36a output from the operation detecting circuit 36, and 121 subtracts 1 from the current operating number 36a. A subtraction circuit 122 is a multiplier for multiplying the output of the subtraction circuit 121 by the set value of the rated energizing current of the power conversion circuit, thereby obtaining an allowable current of the system when the current operation number is minus one.
Reference numeral 123 compares the outputs of the above-described two multiplier circuits 120 and 122, and outputs a signal when the multiplier 122 is larger (when the modulus of the allowable current of the system when the current operation number is minus 1 is larger than the current load). Output comparator, 124
Is a disconnectable circuit display (display) for displaying disconnect permission when there is an output signal of the comparator 123.

Next, FIG. 17 will be described. 20a, 2
0b and 20c are current command values output from the current command generating circuit 34a of the second embodiment shown in FIG. 120
Is an adder for adding these signals to obtain a current output current value (total). 36a is the total current value (total current capacity) of the currently operating power conversion circuit. And 3
Reference numeral 6b denotes a rated current of the power conversion circuit to be disconnected, which is input from a keyboard (not shown) or the like. 121
Is a subtractor for subtracting the capacity 36b of the power conversion circuit to be disconnected from the total current capacity 36a to obtain a total rated current value after the disconnection. Descriptions of 123 and 124 are the same as those described above with reference to FIG. As a result, the disconnectable circuit display indicates whether or not the power conversion circuit desired to be disconnected can be disconnected.

By confirming the lighting of the display,
It is possible to check in advance whether one of the power conversion circuits connected in parallel or the power conversion circuit desired to be disconnected can be disconnected during operation.

Embodiment 8 FIG. The configuration of FIG. 16 of the seventh embodiment is further modified so that it is possible to know how many power conversion circuits can be disconnected during operation in a power conversion device having inverters of the same rating in parallel. The configuration of the power conversion device 98 is the same as that of the seventh embodiment, except that the disconnection possibility determination circuit 37 shown in FIG.
Is replaced by In FIG. 18, reference numeral 125 denotes a subtractor for subtracting a current command value per unit, which is an output of the current command generation circuit 34, from a rated energizing current value per power conversion circuit and calculating a margin per unit. is there.

A multiplier 126 multiplies the margin by the current number 36a to calculate a margin of the system, and a 127 divides the margin of the system by the rated energizing current per unit to calculate the margin. Divider. Reference numeral 128 denotes an integer output circuit that outputs only the integer part of the division result of the divider 127, and reference numeral 129 denotes a numerical indicator that numerically displays the result of the integer output circuit 128. By checking the number of spare units displayed on the numerical indicator 129, it is possible to know how many units can be disconnected, and it is possible to safely execute the disconnection operation. In the case where the ratings of the inverters shown in FIG. 17 of the seventh embodiment are different, the total rated current capacity of the power conversion circuit (plural) to be disconnected is input as the rated current value 36b of the inverter to be disconnected. Good.

[0046]

As described above, the power conversion device of the present invention does not require a current sensor for detecting the total current of a plurality of power conversion circuits connected in parallel, so that the effect that the circuit configuration is simple can be obtained. .

Further, even when power conversion circuits having different current capacities are connected in parallel, the load ratio of each power conversion circuit can be made substantially the same, so that the power capacities can be used to the utmost efficiency.

Also, even if the number of power conversion circuits used during operation changes, the current command value is readjusted in accordance with the changed number, so that operation is always performed at an optimum load factor. .

If the current command value exceeds the rated current capacity during operation, the operation is immediately stopped, so that the power converter is always protected.

If the state in which the current command value exceeds the rated current capacity continues for a predetermined time during operation, the operation is stopped, so that the power converter is always protected.

If the current command value exceeds the rated current capacity during the operation, the operation is stopped after a time delay corresponding to the excess amount, so that the power converter is always protected.

Further, the current command value is compared with the output current of the power converter, and when the difference is equal to or more than a predetermined value, the power converter is stopped, so that an abnormal output does not cause an abnormality in the load. .

Further, since it is determined and displayed whether or not the power conversion circuit can be disconnected during operation, the disconnection work can be performed safely.

Since the number of converter circuits that can be disconnected during operation is displayed, the efficiency of the disconnection operation can be increased.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a power conversion device according to a first embodiment of the present invention.

FIG. 2 is a partial detailed view of FIG.

FIG. 3 is a configuration diagram of a power conversion device according to a second embodiment of the present invention.

FIG. 4 is a partial detailed view of FIG. 3;

FIG. 5 is a configuration diagram of a power conversion device according to a third embodiment.

FIG. 6 is a partial detailed view of FIG. 5;

FIG. 7 is a configuration diagram of a power conversion device according to a fourth embodiment.

FIG. 8 is a partial detailed view of FIG. 7;

9 is an overload characteristic diagram of the power converter of FIG.

FIG. 10 is a partial detailed configuration diagram of a power conversion device according to a fifth embodiment.

11 is an overload characteristic of the power converter of FIG.

FIG. 12 shows overload characteristics when the configuration of the power converter according to the fifth embodiment is changed.

FIG. 13 is a configuration diagram of a power conversion device according to a sixth embodiment.

FIG. 14 is a partial detailed view of the power converter of FIG.

FIG. 15 is a configuration diagram of a power conversion device according to a seventh embodiment.

16 is a partial detailed configuration diagram of the power conversion device of FIG.

FIG. 17 is a partial configuration diagram of a power conversion device according to an eighth embodiment.

FIG. 18 is a partial configuration diagram of the eighth embodiment.

FIG. 19 is a configuration diagram of a conventional power converter.

[Explanation of symbols]

1 DC power supply, 2a, 2b, 2c power conversion circuit, 3
AC load, 15 current controller, 16 pulse generation circuit, 18 output terminal of filter circuit, 21a
State output circuit, 23 current control state monitoring circuit, 30
Voltage sensor, 31 voltage command generation circuit, 32 subtractor, 33 voltage controller, 34 current command generation circuit, 34a constant rate distribution current command circuit, 35 operation command generation circuit, 35a operation command generation circuit with current command monitoring circuit, 36 operation detection Circuit, 60 inverter circuit, 6
DESCRIPTION OF SYMBOLS 1 Individual current sensor, 91-97 Power conversion device, 10
0, 101, 102 data setting device, 109 comparator,
110 latch circuit, 123 comparator, 124 latch circuit.

Claims (9)

[Claims] 1. An inverter circuit for converting DC power input to an input terminal into AC power by a semiconductor element, a filter circuit connected to an output terminal of the inverter circuit, and a current for controlling an output current of the inverter circuit. A power conversion circuit including a controller, and a plurality of the power conversion circuits connected in parallel;
A voltage sensor for detecting a voltage at an output terminal of the power conversion circuit connected in parallel; an output of the filter circuit by controlling the plurality of power conversion circuits by a given voltage command signal and a signal of the voltage sensor; A power converter, comprising: a voltage controller that controls a voltage at an end; and a current command generation circuit that commands each output current value of the plurality of power conversion circuits based on an output signal of the voltage controller. 2. A current capacity of at least one of the plurality of power conversion circuits is different from a current capacity of another power conversion circuit, and the current command generation circuit has a load ratio of each power conversion circuit substantially equal to each other. The power conversion device according to claim 1, further comprising a constant rate distribution circuit that outputs a current command value. 3. The plurality of power conversion circuits each have an operation detection circuit that outputs a signal indicating whether or not the operation is in progress. 3. The power conversion circuit according to claim 1, further comprising an adjustment circuit that calculates a total current capacity of the power conversion circuit and adjusts the current command value based on the total current capacity. 4. Comparing a current command value output by the current command generation circuit with a current capacity of a corresponding power conversion circuit,
When any one of the current command values exceeds the current capacity of the corresponding power conversion circuit, a current command value monitoring circuit that transmits a signal for stopping operation of the power conversion device is provided. The power converter according to any one of claims 1 to 3. 5. The power conversion circuit according to claim 1, wherein the current command value output from the current command generation circuit is compared with a current capacity of each corresponding power conversion circuit. 4. A circuit according to claim 1, further comprising a current command value overload monitoring circuit for transmitting a signal for stopping the operation of the power converter when the state of exceeding the current capacity continues for a predetermined time. The power converter according to claim 1. 6. The predetermined time is determined in advance according to a difference between the current command value and the current capacity when the current command value exceeds the current capacity of a corresponding power conversion circuit. The power conversion device according to claim 5, wherein the power conversion device is used. 7. The power conversion circuit includes a current sensor for detecting an output current of each power conversion circuit, and the current of the power conversion circuit corresponding to a current command value output from the current command generation circuit. 2. A current control state monitoring circuit for comparing the output value of the sensor and outputting a signal for stopping the operation of the power converter when the difference exceeds a predetermined level. 3. The power converter according to 2. 8. A current command value output from the current command generation circuit and an output state of the operation detection circuit determine whether some of the power conversion circuits can be disconnected in a current operation state. 4. The power converter according to claim 3, further comprising a disconnection possibility determination circuit, and a display for displaying a determination result of the disconnection possibility determination circuit. 9. The power conversion circuit according to claim 8, wherein the current capacities of the plurality of power conversion circuits are substantially the same as each other, and the display also displays the number of power conversion circuits that can be disconnected. 3. The power converter according to claim 1.