JP2887013B2 - Parallel operation control device for three-phase AC output converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
When the three-phase AC output converter operates in parallel with another three-phase AC power supply (including the three-phase AC output converter), the parallel operation of the three-phase AC output converter that controls the current balance between the converter and the other power supply The present invention relates to a control device.

[0002]

2. Description of the Related Art FIGS.
FIG. 19 is a diagram rewritten in the same format as that of the conventional parallel operation system of AC output converters disclosed in Japanese Patent Publication No. 6137 and Japanese Patent Publication No. 56-13101. FIG. 19 shows a parallel configuration of two AC output converters. 20 and 21 are equivalent circuit diagrams during operation, FIG. 20 and FIG. 21 are vector diagrams during parallel operation of two AC output converters, and FIG. 22 is a configuration diagram illustrating a parallel operation system of AC output converters.

Before describing the configuration of a conventional parallel operation system for AC output conversion, as shown in FIG. 19, two AC power supplies (hereinafter simply referred to as power supplies) 1 and 2 share a common load 4.
Are considered in parallel operation. The output voltages of the power supplies 1 and 2 are E ₁ and E ₂ , the internal impedances of the power supplies 1 and 2 are equal to Z, and the output currents of the power supplies 1 and 2 are I ₁ and I ₂ . In addition, load 3
Is connected to the common connection point A (common output voltage) by E
_Assuming that _A is _A , the resistance component of the internal impedance Z is R, and the reactance is X, the internal impedance Z can be expressed by the following equation. Z = R + jX (1) In this case, the absolute value | Z | of the internal impedance and the internal impedance angle φ are as follows.

(Equation 1) φ = tan ⁻¹ (X / R) (3) In the circuit of FIG. 19, the following expression is satisfied. E ₁ −ZI ₁ = E ₂ −ZI ₂ = E _A (4)

If the cross current is defined as the difference between its own output current and the average of the individual output currents, the cross current ΔI _{1 as} viewed from the power source ₁ and the cross current ΔI _{2 as} viewed from the power source ₂ are given by the following equations. ΔI ₁ = I ₁ −1/2 (I ₁ + I ₂ ) = 1/2 (I ₁ −I ₂ ) (5) ΔI ₂ = I ₂ −1/2 (I ₁ + I ₂ ) = 1/2 ( I ₁ −I ₂ ) (6) From equation (4), the following equation is established. E ₁ −E ₂ = Z (I ₁ −I ₂ ) (7) From the equations (5), (6) and (7), the following equation is established. ΔI ₁ = −ΔI ₂ = 1/2 (E ₁ −E ₂ ) / Z (8) From the equation (8), the cross currents ΔI ₁ and ΔI ₂ are equal to the difference voltage E
Internal impedance angle φ with respect to ₁ −E ₂ and E ₂ −E ₁
It can be seen that only the lag phase occurs.

Further, the following equation is established from the equation (4). E _A = 1/2 (E ₁ + E ₂ ) −Z (I ₁ + I ₂ ) (9) Generally, the internal impedance is sufficiently small with respect to the load impedance. I do. E _A ≒ 1/2 (E ₁ + E ₂ ) (10)

Now, the output voltages E ₁ and E _{2 of} the power supplies ₁ and ₂ have the same phase and differ in absolute value by ΔE (that is, | E ₁ | − |
E ₂ | = ΔE), the vector relationship based on the output voltage E ₁ is as shown in FIG. That is, the cross current vector [Delta] I ₁ is delayed by the internal impedance angle φ with respect to the differential voltage vector (E ₁ -E _2), the common output voltage vector E _A is almost in phase with the output voltage vector E _1, E ₂ dual supply . Therefore, the direction of the cross current vector ΔI _{1 in} the case where the phases match and the absolute values are different is parallel to the direction of the virtual vector E _AX delayed from the common output voltage vector E _A by the internal impedance angle φ (virtual). Perpendicular to the virtual vector E _AY perpendicular to the vector E _AX ).

Next, the output voltages E ₁ and E _{2 of} the power supplies ₁ and ₂
Assuming that the absolute values match and the phases differ by θ, the vector relationship based on the output voltage E ₁ is as shown in FIG. In this case, the difference voltage vector (E ₁ −E ₂ ) is delayed by (90 ° −1 / 2θ) with respect to the output voltage vector E ₁ of the power supply 1, and the cross current vector ΔI ₁ is the difference voltage vector (E ₁ −E ₂ ) is delayed by the internal impedance angle φ. Common output voltage vector E _A
Lags the output voltage vector E ₁ by approximately θθ, and lags the output voltage vector E ₂ by approximately θθ. Therefore, the direction of the cross current vector ΔI ₁ when the absolute values match and the phases are different is perpendicular to the direction of the virtual vector E _AX delayed from the common output voltage vector E _A by the internal impedance angle φ (virtual). Parallel to the virtual vector E _AY perpendicular to the vector E _AX ).

As can be seen from the consideration of the two vector diagrams, the virtual vector E _AX (or the virtual vector E _AY perpendicular _thereto ) delayed from the common output voltage E _A by the internal impedance angle φ is used as a reference. Cross flow vector ΔI ₁
The reference vector E _AX component parallel with respect to [Delta] I _1x (E of
A component perpendicular to _AY ) and a component ΔI _1Y (parallel to E _AY ) are detected, and the absolute value of the output voltage of the power supply is controlled so that the parallel component ΔI _1X becomes zero. For example, the output voltage absolute value deviation between power supplies can be eliminated,
If the output voltage phase control of the power supplies is performed so that the vertical component ΔI _1Y becomes zero, the output voltage phase deviation between the power supplies can be eliminated.

FIG. 22 is a block diagram showing a conventional parallel operation system of AC output converters. In FIG. 22, a first inverter device 1 is operated in parallel with a second inverter device 2 of the same configuration through an output bus 3 while a load is being applied. 4 is supplied with power. The first inverter device 1 includes an inverter body 100, a filter reactor 101, and a capacitor 102 as main components, converts the power of the DC power supply 5 into AC, and is connected to the output bus 3 through an output switch 103a.

The voltage control circuit 403 includes a voltage setting circuit 40
7 and the signal of the voltage detection circuit 300, the PWM circuit 4
00, the pulse width modulation of the inverter body 100 is performed to control the internally generated voltage.

The detection signal I _1A is obtained from the output current I ₁ of the first inverter device by the current detector 200a, and the difference from the detection signal I2a similarly obtained from the second inverter device 2 is:
That is, the signal ΔI ₁ corresponding to the cross current is obtained by the cross current detection circuit 151. Then, the voltage E _AX delayed by the internal impedance angle φ from the common output voltage E _A from the phase shifter 105, 90
° to form the voltage E _AY advanced by -φ. Arithmetic circuit 15
2 outputs a signal ΔQ proportional to a component ΔI _1X parallel to E _AX of the cross current ΔI ₁ , and the arithmetic circuit 153 outputs a signal ΔP proportional to a component ΔI _1Y parallel to E _AY of the cross current ΔI ₁ .

The signal ΔQ proportional to ΔI _1X is supplied to the voltage control circuit 403 as an additional target value, and by adjusting the internally generated voltage of the inverter main body 100 by about several percent, the output voltage absolute value of both inverters is adjusted. Match and ΔQ
It works to make zero.

Meanwhile, the signal ΔP which is proportional to [Delta] I _1Y described above through an amplifier 154 constituting the PLL circuit, by performing the fine adjustment of the frequency of the reference oscillator 155, and controls the phase of the internally generated voltage of the inverter main body 100 Operate so that the output voltage phases of both inverters coincide with each other and ΔP becomes zero.

In this manner, the absolute value and phase of the voltage are controlled so that ΔQ and ΔP are both zero.
There is no cross flow between the inverters, and stable load sharing is performed.

The parallel operation control means of the conventional AC output converter described here is for the case where the AC output converter is a single-phase inverter. However, even in the case of a three-phase AC output converter, the configuration of the PWM circuit is adapted for three phases. The means for controlling the absolute value and phase of the voltage is the same, only by changing it.

[0016]

Since the conventional parallel operation system of the three-phase AC output converter is constituted as described above, there are the following two problems. The first problem is that it is difficult to improve the control response speed because the shared current is balanced by controlling only the phase of the internally generated voltage of the inverter and the absolute value of the voltage. That is not possible. The second problem is that two components orthogonal to the cross flow (the component parallel to E _AX and the component E
_A cross-current control cannot be performed at a high speed because a filter is necessary for detecting the separation into components parallel to _AY ). For this reason, there is a limit to the application to a high-speed voltage control system such as instantaneous waveform control that maintains the output of the inverter as a high-quality sine wave with little distortion.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a parallel operation control device for a three-phase AC output converter that balances a shared current at a high speed.

[0018]

A parallel operation control device for a three-phase AC output converter according to the first invention connects the outputs of a plurality of three-phase AC output converters to a common bus and shares the load current. In the parallel converter system operating in parallel while performing the operation, each of the above converters performs switching a plurality of times during one cycle by the arm of each phase constituting the converter, and outputs the instantaneous value of the output voltage to the synchronous rotation coordinate of two. In addition to the instantaneous voltage control type converter controlled by the two components, the cross current of the current flowing between the respective converters is detected, and the virtual current is added to the cross current.
A voltage command value to be applied to the instantaneous voltage control means is corrected by a signal obtained by multiplying the impedance value by a signal obtained by multiplying the voltage between the converters, and the output thereof is output.
By changing the voltage, the output voltage of the converter is controlled, and the component mainly caused by the phase difference of the cross current of the current flowing between the respective converters is supplied to the reference sine wave generating means of the synchronous rotation coordinates. It is characterized by acting.

Further, the parallel operation control device for a three-phase AC output converter according to the second invention connects the outputs of a plurality of three-phase AC output converters to a common bus and operates the parallel operation while sharing the load current. In each of the above-described parallel converter systems, each of the converters controls the instantaneous value of the output voltage by performing two or more switching operations during one cycle by the arm of each phase constituting the converter by using two components of the synchronous rotation coordinates. The instantaneous voltage control type converter detects a cross current of the current flowing between the respective converters, and a signal obtained by multiplying the cross current by a virtual impedance value generates a current flowing between the converters. The voltage command value applied to the instantaneous voltage control means is corrected so that the cross current of the current is suppressed, and the output voltage is changed to control the output voltage of the converter. The component perpendicular to the virtual vector which is delayed by the virtual impedance angles of the output transducer, is characterized in that so as to act on the reference sine wave generator means of the synchronous rotating coordinate.

Further, the parallel operation control device for a three-phase AC output converter according to the third invention connects the outputs of the plurality of three-phase AC output converters to a common bus, and performs the parallel operation while sharing the load current. In each of the above-described parallel converter systems, each of the converters controls the instantaneous value of the output voltage by performing two or more switching operations during one cycle by the arm of each phase constituting the converter by using two components of the synchronous rotation coordinates. The instantaneous voltage control type converter detects the cross current of the current flowing between the respective converters, and adds the virtual impedance to the cross current.
The voltage command value to be applied to the instantaneous voltage control means is corrected by the signal obtained by multiplying the output value by changing the output voltage so that the cross current of the current flowing between the converters is suppressed.
Te, and controls the output voltage of the converter, primarily the components due to the phase difference of the cross current component of the current flowing between the converter mutual above each phase control loop for synchronizing the synchronous rotational coordinates with other AC power source Characterized in that it is made to act on.

Further, the parallel operation control device for a three-phase AC output converter according to the fourth invention connects the outputs of a plurality of three-phase AC output converters to a common bus, and performs the parallel operation while sharing the load current. In each of the above-described parallel converter systems, each of the converters controls the instantaneous value of the output voltage by performing two or more switching operations during one cycle by the arm of each phase constituting the converter by using two components of the synchronous rotation coordinates. The instantaneous voltage control type converter detects a cross current of the current flowing between the respective converters, and a signal obtained by multiplying the cross current by a virtual impedance value generates a current flowing between the converters. The voltage command value applied to the instantaneous voltage control means is corrected so that the cross current of the current is suppressed, and the output voltage is changed to control the output voltage of the converter. The component perpendicular to the virtual vector which is delayed by the virtual impedance angles of the output transducer, is characterized in that so as to act on the phase control loop for synchronizing the synchronous rotational coordinates with other AC power source.

Further, in the parallel operation control device for a three-phase AC output converter according to the fifth invention, the output of the three-phase AC output converter is connected to a common bus line with another three-phase AC power supply, and the load current is shared. In the parallel converter system operating in parallel while performing the operation, the above-mentioned converter is configured such that the arm of each phase constituting the converter performs switching a plurality of times during one cycle to convert the instantaneous value of the output voltage into two components of the synchronous rotation coordinate. In addition to the instantaneous voltage control type converter controlled by the above, the cross current of the current flowing between the converter and the AC power supply is detected, and the virtual current is added to the cross current.
A voltage command value given to the instantaneous voltage control means is corrected by a signal obtained by multiplying the impedance value by a signal obtained by multiplying the voltage value by a signal obtained by multiplying the current value between the converter and the AC power supply.
The output voltage is changed to control the output voltage of the converter, and a component mainly caused by a phase difference of a cross current of a current flowing between the converter and the AC power supply is generated by generating a reference sine wave of the synchronous rotation coordinate. It is characterized by acting on the means.

Further, in the parallel operation control device for a three-phase AC output converter according to the sixth invention, the output of the three-phase AC output converter is connected to a common bus with other three-phase AC power supplies, and the load current is shared. In a parallel converter system operating in parallel while operating, each of the converters has one arm of each phase constituting the converter.
An instantaneous voltage control type converter that performs switching a plurality of times during a cycle to control an instantaneous value of an output voltage by two components of a synchronous rotation coordinate, and a cross current of a current flowing between the converter and the AC power supply. And a voltage command value given to the instantaneous voltage control means is corrected by a signal obtained by multiplying the cross current by the virtual impedance value so that the cross current of the current flowing between the converter and the AC power supply is suppressed. The output voltage of the converter is controlled by changing the output voltage, and the component perpendicular to the virtual vector delayed by the virtual impedance angle of the three-phase AC output converter with respect to the bus voltage of the load current is synchronized with the synchronous voltage. The present invention is characterized in that it is made to act on a reference sine wave generating means of the rotation coordinates.

[0024]

In the parallel operation control device for a three-phase AC output converter according to the first aspect of the present invention, not the average value control but the instantaneous voltage control means on the synchronous rotation coordinates is provided with a virtual impedance corresponding to the cross current of the current flowing between the converters. The signal obtained by multiplying the value
A signal obtained by correcting the voltage command value so that the cross current is suppressed.
To change the output voltage of the instantaneous voltage control means to convert the phase of the reference sine wave signal used for coordinate conversion between the synchronous rotation coordinate and the three-phase signal into a component caused by the phase difference of the cross-flow converter output voltage. By making adjustments accordingly, the voltage control means operates instantaneously so as to reduce the cross current.

In the parallel operation control device for a three-phase AC output converter according to the second invention, the instantaneous voltage control means on the synchronous rotation coordinate is obtained by multiplying the cross current of the current flowing between the converters by the virtual impedance value. A signal in which the voltage command value is corrected so that the cross current is suppressed by the signal is given to change the output voltage of the instantaneous voltage control means, and the output voltage of the converter is changed.
Controls pressure, the reference sine wave generator of the synchronous rotating coordinate, acts a component perpendicular to the virtual vector which is delayed by the virtual Lee <br/> impedance angle of the three-phase AC output transducer against bus voltage of the load current Thus, the cross current of the current flowing between the converters is suppressed.

In the parallel operation control device for a three-phase AC output converter according to the third invention, a cross current component of the current flowing between the converters is detected, and a virtual impedance value is assigned to the cross current component.
Given by a signal obtained by multiplying the instantaneous voltage control means as cross current component of the current flowing between the converter each other is suppressed
That by the voltage command value to change the output of the correction basil, the components controlling the output voltage of the converter, mainly due to the phase difference of the cross current component of the current flowing between the converter mutual said each synchronous rotating coordinate In a phase control loop that synchronizes with another AC power supply.

In the parallel operation control device for a three-phase AC output converter according to the fourth aspect of the present invention, a cross current of the current flowing between the converters is detected, and a signal obtained by multiplying the cross current by a virtual impedance value is obtained. The output voltage of the converter is controlled by correcting the voltage command value given to the instantaneous voltage control means and changing the output so as to suppress the cross current of the current flowing between the converters, thereby controlling the synchronous rotation coordinates. the phase control loop for synchronizing with other AC power source, by applying a component perpendicular to the virtual vector which is delayed by the virtual impedance angles of the three-phase AC output transducer against bus voltage of the load current, flowing between the converter mutual Suppresses the cross current.

In the parallel operation control device for a three-phase AC output converter according to the fifth aspect of the invention, the cross current of the current flowing between the converter and another AC power supply is detected, and the current is obtained by multiplying the cross current by a virtual impedance value. Signal and the AC power
Correcting the voltage command value to be provided to the instantaneous voltage control means as cross current component is suppressed current flowing between the source by varying its output, controls the output voltage of the converter, primarily the converter and the AC The component caused by the phase difference of the cross current of the current flowing between the power supplies is caused to act on the reference sine wave generating means of the synchronous rotation coordinates.

In the parallel operation control device for a three-phase AC output converter according to the sixth aspect of the present invention, a cross current of a current flowing between the converter and another AC power supply is detected, and the current is obtained by multiplying the cross current by a virtual impedance value. Signal and the AC power
Correcting the voltage command value to be provided to the instantaneous voltage control means as cross current component is suppressed current flowing between the source by varying its output, controls the output voltage of the converter, a reference sine wave of the synchronous rotating coordinate The generation means is provided with 3
Temporary delay by virtual impedance angle of phase AC output converter
By applying a component perpendicular to the virtual vector, the cross current of the current flowing between the converter and another AC power supply is suppressed.

[0030]

[Embodiment 1] FIG. 1 shows one embodiment according to the first and second inventions. The same numbers are assigned to the functions corresponding to those in FIG. 22 described above. FIG. 22 shows an inverter device that controls the average value of the output voltage, whereas FIG. 1 controls the instantaneous value of the output voltage. Since the type of the inverter device is the same, the same number does not always mean the circuit having the same function.
FIG. 1 shows a single connection diagram of a parallel operation system of a three-phase AC converter. A symbol “￣” above a character is a matrix indicating three-phase output signals, and is referred to as a bar. Further, マ ト リ ク ス represents a matrix indicating signals on the synchronous rotation coordinates by the dq axes, and is referred to as a cup. For example, the voltage V is represented by the following equation.

(Equation 2)

In the figure, the first inverter device 1 supplies power to the load 4 while operating in parallel with the second inverter device 2 having the same configuration and simplified through the output bus 3. Reference numeral 5 denotes a DC power supply connected to the first inverter device 1, and reference numeral 6 denotes a DC power supply connected to the second inverter device 2. The numbers after 100 are the components of the inverter device. The numbers without subscripts and the subscripts a and d to z are the components of the first inverter device 1, and the subscript number b is the component of the second inverter. It is a component of the device 2.

Reference numeral 100 denotes an inverter body, for example, a transistor or MOSFET capable of high-frequency switching.
And the like, as shown in FIG.
Since each arm of the phase bridge inverter switches at a high frequency of about 10 to several hundred times the output frequency (for example, 60 Hz), the DC voltage is converted into a rectangular high-frequency AC voltage including a sine wave fundamental. 10
Numerals 1 and 102 denote a reactor and a capacitor constituting a low-pass filter, which remove harmonics from a rectangular high-frequency AC voltage generated by the inverter main body 100, obtain a sine wave output voltage, and output the sine wave output voltage through an output switch 103a. It is connected to the output bus 3.

Reference numeral 200a denotes a current sensor for detecting the output current bar I ₁ of the _first inverter device, and reference numeral 201 denotes a current sensor for detecting the output current bar I _A1 of the inverter body 100. Reference numeral 300 denotes a voltage sensor for detecting a voltage bar V ₁ of the capacitor 102 (the output bus voltage during parallel operation).

Reference numeral 400 denotes a PWM circuit for determining the switching timing of the inverter main body 100. For example, a triangular wave comparison type PWM for switching the inverter main body 100 at the intersection of the voltage command signal for the fundamental wave to be output from the inverter main body 100 and the triangular wave carrier. Circuit. 40
1 is a current control circuit for controlling the output current bar I _A1 of the inverter main body 100, 402 is a limiter circuit for limiting the output current command value of the inverter main body 100, and 403 is a voltage control circuit for controlling the voltage bar V ₁ of the capacitor 102. , 4
04 is a capacitor 10 for generating a desired output voltage.
A capacitor current reference generating circuit 405 for outputting a current value to be passed to the second inverter device 405 is a cross current for inserting a virtual impedance between the first inverter device 1 and the second inverter device 2 to operate to limit the cross current. A limiting virtual impedance circuit; 406, a current detection circuit for detecting a load current value to be shared with the cross current output by the No. 1 inverter device 1; 407, a circuit for generating an output voltage command value of the No. 1 inverter device; Is a coordinate transformation reference generator for producing synchronous rotation coordinates.

Also, 500, 501, 502, 503,
Reference numeral 504 denotes an adder / subtractor, 600, 601, 602, and 603 denote three-phase / two-phase conversion circuits for converting three-phase (U, V, W) signals into signals on synchronous rotating coordinates by dq axes;
-The signals on the synchronous rotation coordinates by the q axis are converted into three phases (U, V,
W) is a two-phase / three-phase conversion circuit that converts the signal into a signal of W).

The second inverter device 2 has the same configuration as the first inverter device 1 and has an output connected in parallel with the first inverter device 1 through the output bus 3.
An output switch of the inverter device 2, and a current sensor 200 b for detecting an output current bar I ₂ of the inverter device 2.

FIG. 3 is a block diagram showing details of the current detection circuit 406. 406s and 406t are adders / subtractors, and 406u is an amplifier circuit having a gain of 1 / n, where n is the number of paralleled inverter devices. Adder 40
In 6s, the output current bars I ₁ and 2 of the _first inverter device 1
No. adds the output current bar I ₂ of the inverter apparatus 2 obtains the load current bar I _L, by inputting the signal to the amplifier circuit 406U, the load current bar I _L parallel number n (in this case n
= 2 calculates the value bar I _L / n divided by), which No.1 inverter device 1 is output as the load current bar I _L1 ^* to be shared. Also, the current bar I _L1 to be shared with the output current bar I ₁ of the first inverter device 1 is calculated by the subtractor 406t.
The difference of ^* , that is, the cross current Δ bar I ₁ is calculated and output.

Next, the operation will be described. In this embodiment, in the case of a three-phase inverter or converter, control using a synchronous rotating coordinate system based on dq axes, which can obtain more excellent characteristics, can be obtained. Have applied the system. So first, 3
The relationship between the phase signal and the signal on the synchronous rotation coordinates by the dq axes and the coordinate conversion will be described.

The coordinate conversion reference generator 408 generates the following six three-phase sine wave signals that serve as the reference for coordinate conversion.

[0040]

(Equation 3)

The current sensor 301, the current detection circuit 406,
Assuming that the three-phase output signals of the voltage sensor 300 are represented as bar X, when these are multiplied by the following conversion matrix bar C, they are converted into DC signal cups X on the dq axes.

(Equation 4)

The result of the control operation performed on the dq axes is multiplied by the next inverse transformation matrix by the two-phase / three-phase conversion circuit 604, thereby returning the result to the three-phase system again.
Given to the circuit.

(Equation 5)

By performing such a conversion, when the output voltage command bar V ^* is given by the following equation,

(Equation 6) The value on the dq axis is as follows.

(Equation 7)

When the capacitance of the capacitor 102 is C _P , the current command cup I _C ^{* to} be supplied to the capacitor is expressed by the following equation.

(Equation 8)

Thus, on the dq axes, the three-phase output voltage reference and the capacitor current reference are DC constant values,
Since the control on the three-phase coordinates of U, V, and W is the additional value control, an error is likely to occur even in a steady state. On the other hand, the control on the dq axes is a constant value control. Control with less noise.

Next, the instantaneous voltage control of the inverter will be described. This inverter device is provided with a current minor loop, and the current control circuit 401
The reactor 101 such that the signal cup I _{A1 obtained} by coordinate-transforming the output current bar I _A1 of 0 to the d-q axis by the three-phase / two-phase conversion circuit 600 matches the current command cup I _A1 from the limiter circuit 402. Output the voltage to be applied to. Since the output bus 3 has a voltage from the capacitor 102 and the No. 2 inverter device 2, in order to apply a desired voltage to the reactor 101, the inverter body 100 calculates the sum of the voltage of the output bus 3 and the voltage to be applied to the reactor 101. Need to occur.

Therefore, the voltage bar V ₁ of the capacitor 102 detected by the voltage sensor 300 is converted to the three-phase / two-phase conversion circuit 60.
The adder 500 adds the signal cup V ₁ coordinate-converted to the dq axis at ₁ and the output of the current control circuit 401, and the two-phase / 3-phase conversion circuit 604 converts the signal into three phases. Then, it is given to the triangular wave comparison type PWM circuit 400 as a voltage command.

The capacitor current reference generation circuit 404 generates a current reference cup I which is 90 ° ahead of the voltage command cup V ₁ ^* of the capacitor 102 as a current to flow through the capacitor.
_C ^* is generated according to the capacitance 102 of the capacitor. It will be described later that the voltage command cup V ₁ ^* of the capacitor 102 is obtained from the output of the subtractor 504. The voltage control circuit 403
Capacitor 102 voltage command cup V ₁ ^* and capacitor 1
02 voltage deviation of the cup V ₁ of the inputs the operated signal by the subtractor 503, and outputs a correction current signal inverter main body 100 to be output in order to reduce the deviation.

The output current command value cup I _A1 ^* of the inverter body 100 is the output of the capacitor current reference generation circuit 404 and the voltage control circuit 403 and the load current sharing command value of the first inverter device 1 output by the current detection circuit 406. Bar I
_L1 ^* and a signal cup I _L1 ^* that coordinate transformation d-q axis in 3-phase / 2-phase conversion circuit 602 calculates by an adder 502,
The result is a signal limited by the limiter circuit 402. Therefore, in the no-load state, the inverter body 1
00 establishes a no-load voltage by supplying current to flow through capacitor 102. In this case, the voltage control circuit 403 corrects an excess or deficiency in the output of the capacitor current reference generation circuit 404 caused by an error in current control or an error between the design value and the actual value of the capacitance of the capacitor 102.

Next, when the load 4 is turned on, a command is given from the current detection circuit 406 to the current minor loop so as to share one half of the load current bar I _L , and each inverter reduces the load current by one. / 2 at a time. Here, the limiter circuit 402 transmits a command value to the current control circuit 401 so that the inverter main body 100 does not supply an overcurrent such as an inrush current at the time of starting the load.
The current limit is limited to 00 or less.

With this configuration, the inverter is protected from overcurrent by its own current minor loop, and the output voltage is always sinusoidal by quickly following the distortion or sudden change in load current. Can be kept. A feature of this method is that such a control is performed each time the high frequency PWM of the inverter is switched, so that the response is very fast. For example, if a switching frequency of 10 kHz is used, control is performed every 100 μsec. Therefore, a transient phenomenon such as a sudden change in load can be completed in about 10 times of 100 μsec, and excellent control performance can be obtained.

When the response and the accuracy of the voltage control system of the first inverter device 1 and the response of the voltage control system of the second inverter device 2 are exactly the same, the cross current can be eliminated by the above-described control system configuration. There is a slight difference in the output voltage due to variations in control gain, main circuit constant, and the like. Also,
Since the instantaneous voltage control is performed, most of the internal impedance of the inverter is the impedance of the wiring, and a slight difference in output voltage makes it easy for a large cross current to flow. Therefore, it is difficult to perform stable parallel operation with less cross flow. For example, assuming that the voltage sensors of the first inverter device 1 and the second inverter device 2 have errors of -0.5% and + 0.5%, respectively, the output voltage difference at the time of the single operation becomes 1%, and the impedance is temporarily set. If the wiring impedance between them is 1% or less, the cross current flows 100% or more.

In the present embodiment, the cross current is suppressed by configuring the control circuit so that impedance exists only for the cross current flowing between the inverters as follows. The cross-current limiting virtual impedance circuit 405 is
Δcup I ₁ × cup Z _im (cup Z _im is a virtual impedance transfer function) is calculated, and this signal is subtracted by a subtractor 5.
04, the output cup V of the output voltage reference generation circuit 407
^* , And this is set as the voltage command cup V ₁ ^* of the capacitor 102. The voltage of the capacitor 102 instantaneously follows the voltage command cup V ₁ ^* by the above-described voltage control system.

FIG. 4 is a block diagram in which FIG. 1 is simplified and represented by a scalar quantity. Referring to FIG. 4, the inverter has the output impedance of the cup Z _im only with respect to the cross current by the cross current limiting virtual impedance circuit 405. The operation of a low impedance voltage source for current components other than cross current will be described. In the figure, 700a, 70
0b indicates transfer functions from the voltage command values V ₁ ^* and V ₂ ^{* of the} _first inverter device 1 and the second inverter device 2 to the output voltage, respectively, and the other numbers have already been described in FIG. The same functions are given the same numbers. Some symbols have already been used, but the following symbols are defined again.

V _B : Output bus voltage V ^* : Output voltage command value V ₁ : No. 1 inverter capacitor voltage command value V ₂ : No. 2 inverter capacitor voltage command value _IL : Load current I ₁ : No. 1 inverter output current I _2: 2 No. inverter output current [Delta] I _1: 1 No. inverter cross current _{(= I 1 -1/2 I L)} ΔI 2: 2 No. inverter cross current _{(= I 2 -1/2 I L)} G 1: 1 No. inverter voltage Control system transfer function G ₂ : No. 2 inverter voltage control system transfer function Z _im : Cross-current limiting virtual impedance value ＾ mark: matrix on synchronous rotation coordinates by dq axes ￣ mark: matrix on three-phase coordinates

Next, using these symbols, a relational expression showing the effect of the virtual impedance for restricting the cross current will be derived. For simplicity, consider a scalar quantity. From Kirchhoff's law, the following equation holds. I _L = I ₁ + I ₂ (23) From the equation (23), ΔI ₁ and ΔI ₂ are as follows.
((5), (6) the same as the _{formula) ΔI 1 = I 1 -1/2 I} L = 1/2 (I 1 -I 2) ... (24) ΔI 2 = I 2 -1/2 I L = 1/2 (I ₂ −I ₁ ) (25) ΔI ₂ = −ΔI ₁ (26) From the equations (4) and (26), V ₁ ^* and V ₂ ^* are as follows. ^{_{V 1 * = V * -Z im}} × ΔI 1 ... (27) V 2 * = V * -Z im × ΔI 2 = V * + Z im × ΔI 1 ... (28)

From the definitions of G ₁ and G ₂ , the following equation holds. V _B = V ₁ ^* × G ₁ (29) V _B = V ₂ ^* × G ₂ (30) From the equations (27) to (30), the following equation is established. ^{_{V B = V * × G 1}} -Z im × ΔI 1 × G 1 ... (31) V B = V * × G 2 -Z im × ΔI 1 × G 2 ... (32) (31), (32) formula Thus, when ΔI ₁ is obtained, the following expression is obtained. ΔI ₁ = (V ^* / Z) × [(G ₁ −G ₂ ) / (G ₁ + G ₂ )] (33) When the equation (31) + (32) is obtained and divided by 2, the following equation is obtained. Become. V _B = V ^* × [(G ₁ + G ₂ ) / 2] −Z _im × ΔI ₁ × [(G ₁ −G ₂ ) / 2] (34)

From equation (33), the cross current can be suppressed by the virtual impedance value Z _im . Since the gain of G ₁ and G ₂ can be made substantially equal to 1 at the output frequency by configuring the voltage control system with the above-described instantaneous voltage control type or the like, the equation (33) becomes the following equation. ΔI ₁ ≒ [V ^* × (G ₁ −G ₂ )] / (2 × Z _im ) (35) Assuming that the output voltage difference between the individual inverters in the single operation is ΔV, the following equation (33) is obtained. It becomes an expression. ΔI ₁ ≒ ΔV / (2 × Z _im ) (36) For example, when ΔV is 1%, if Z _im = 50% is selected,
The cross current is ΔV / (2 × Z) = 1/100 = 1%.

Next, in the equation (34), the second term on the right side is obtained by substituting the equation (35). Z _im × ΔI ₁ × [(G ₁ −G ₂ ) / 2] ≒ [V ^* × (G ₁ −G ₂ )] ² / (4 × V ^* ) = (ΔV) ² / (4 × V ^* ) (37) Since ΔV is as small as about 1%, it can be considered that (ΔV) ² ≒ 0. Therefore, the expression (34) becomes only the first term on the right side, and becomes the following expression. V _B ≒ V ^* (G ₁ + G ₂ ) / 2 (38) From the equation (38), the bus voltage V _B during the parallel operation is an average output voltage value of each inverter device during the independent operation.
It can be seen that there is no influence of the virtual impedance value Z _im .

Z _im may be any transfer function as long as it has an appropriate impedance value for limiting the cross current at the output frequency. For example, if this circuit is a proportional circuit, Z _im is a resistor, if it is a differential circuit, Z _im is a reactor, if it is an integrating circuit, Z _im is a capacitor, and if it is a combination circuit of proportional, integral, and differential, it is Z _{im. im} operates as a circuit combining a resistor, a capacitor, and a reactor. In addition, Z _im can stably limit the cross current even in a circuit including a non-linear element such as an asymmetrical limiter or the like, as long as it has an appropriate impedance value for limiting the cross current at the output frequency.

In the above description of the effect of the virtual impedance for restricting the cross current, for simplicity, the description has been made ignoring that the current and the voltage are vector quantities. However, the same relationship holds even with vector quantities. . Further, the cup Z _im does not need to have the same transfer function as long as it has an appropriate impedance value for limiting the cross flow in both the d-axis component and the q-axis component.

FIG. 5 shows a specific example of the current detection circuit 406 for detecting the cross current and the current to be shared by the inverter device. Although this circuit is a known means, its operation will be briefly described. For example 300A of the load current I _L Inv-
, INV-2 and INV-3 have I ₁ = 90 A, I ₂ = 100 A, and I ₃ = 11, respectively.
Consider a case where 0A is output. The output current of each inverter is output to the same current sensor CT-1, CT-2, CT-3.
, And load resistors R11, R21, R31 having the same resistance value are connected to
V, 10 V and 11 V are obtained. This voltage is a voltage corresponding to the output current of the inverter device. Resistors R12, R22, R12, R22,
Connecting R32 as shown in the figure, the voltage of each of these resistors _{^{1/3 (9 + 10 +}} 11) = 10V is obtained. _^1/3 of the voltage load current I _L, that is, the voltage of each of the inverter corresponding to the current value to be shared.

Therefore, with respect to the inverter INV-1, a current to be shared between the points X1 and X2 and a voltage corresponding to a cross current between the points X1 and X3 are obtained.
These signals may be isolated and taken into the control circuit. To stop the inverter INV-1, first, the switch S12 is turned on, and the resistors R22 and R32 are turned on.
Is set to 15V, and all loads are transferred to the other two inverters. Next, the switch S11 may be turned on and the inverter device may be stopped at the same time.

In the above description of the specific example of the current detection circuit 406, for the sake of simplicity, the description has been made ignoring that the current and the voltage are vector quantities, but the same relationship holds even with vector quantities.

The instantaneous voltage control system and the cross current limiting control described above are configured on the dq axes. The coordinate transformation reference generator 408 generates six three-phase sinusoidal signals for coordinate transformation reference which are indispensable for control on the dq axes (Equations (13) and (14)). FIG. 6 is a block diagram showing the configuration of the coordinate transformation reference generator 408. The configuration and operation will be described below with reference to the drawings.

[0066] In FIG. 6, 408d is a voltage detector for detecting a bus voltage cups V _B. 408h is a phase comparator, 408j is an amplifier, 408m is a voltage frequency conversion circuit, and 408n is a counter, and these constitute a phase locked control loop. 408k is an output switch 103a
Is a switch that operates on the A side when is off and on the B side when it is on. Reference numeral 408p denotes a sine wave generator that generates six three-phase sine wave signals serving as a reference for coordinate conversion according to the count value of the counter 408n. A phase shifter 408e creates a virtual vector delayed by an angle of the virtual impedance 仮 想 cup Z _im from the bus voltage. 408f is cross flow Δcup I
₁ is a component detector that detects a component perpendicular to this virtual vector. 408g is an amplifier.

The voltage frequency conversion circuit 408 m
8M1, voltage frequency converter 408M2, is composed of a frequency reference generator 408M3, the input Vf _B,
The frequency f is adjusted by about several percent.

Therefore, when the output switch 103a is off, the bus voltage and the count value of the counter 408n are set in the phase-locked control loop (408h, 408j, 408m, 408).
n), the sine wave generator 408p generates six three-phase sine wave signals synchronized with the bus voltage.

When the output switch 103a is on,
The switch 408k is set to the B side, and the component output from the component detector 408f is “a component perpendicular to the virtual vector delayed by an angle of the virtual impedance from the bus voltage (frequency component of the output current)”, that is, “cross current. is (already described in the prior art) component "due to the phase difference, is input to the voltage-frequency conversion circuit 408m via the amplifier 408 g, is added to the frequency reference 408M3, used in the coordinate transformation by performing fine adjustment of the frequency Fine-tune the phase of the reference sine wave signal. Since the reference sine wave signal is synchronized with the output voltage, finely adjusting the reference sine wave signal is equivalent to finely adjusting the phase of the output voltage.

Since the output current is composed of the cross current and the load current to be shared, the “frequency component of the output current” is “the frequency component (1/2 I _LY ) of the load current to be shared” and the “phase difference of the cross current”. With the components (ΔI _1Y , ΔI _2Y ) resulting from
The output voltage phase of the first inverter device 1 is 1/2 I _LY + ΔI
_{According to 1Y} , the output voltage phase of the second inverter device 2 is 1 /
The phase is advanced or delayed according to 2 I _LY + ΔI _2Y . Here, since ΔI _1Y = −ΔI _2Y , the output voltage phase of the first inverter device 1 is
The phase is advanced or delayed relatively according to the polarity and magnitude of 2 × ΔI _1Y . Therefore, the inverter body 100 generates an output voltage having the same phase as the bus voltage before the parallel connection (the output switch 103a is turned off) before the parallel connection (the output switch 103a is turned off).
Is ON), the phase of the output voltage is finely adjusted so that the component caused by the phase difference of the cross current becomes zero.

Note that the voltage frequency conversion circuit 408 m
The configuration shown in FIG. That is, the absolute value and polarity (positive / negative) of the input Vf _B are detected by 408 m 4 and 408 m 5, the frequency f _B corresponding to the absolute value is obtained from the voltage-frequency converter 408 m 2, and the frequency addition / subtraction circuit 408 m 7 controls the oscillator 408 m 6 Addition and subtraction are performed with the frequency f ₀ . This circuit configuration is characterized in that the frequency accuracy of the output voltage can be easily increased by using a high-precision oscillator.

Embodiment 2 FIG. Next, FIG. 8 relates to the third and fourth inventions, in which another power source 7 is connected to the output bus of the first embodiment via a switch 8, and the first inverter device 1 and the second inverter device are connected. 2 is configured to operate in the same phase as the power supply 7, and when the first inverter device 1 or the second inverter device 2 fails, or when an inspection is performed, the output switch 1
03a and 103b off, switch 8 on, power supply 7
Is a system for supplying power to the load 4 without interruption. The difference from the inverter device of the first embodiment is that the coordinate transformation reference generator 40
9.

FIG. 9 is a block diagram showing the configuration of the coordinate transformation reference generator 409. A voltage detector 409q and a phase comparator 4 are added to the coordinate transformation reference generator 409 described in the first embodiment.
09r, a power failure detection circuit 409s, a switch 409t, and an amplifier 409v are added, and the other subscripts that are the same as the subscripts of the alphabet 408 are the same components.

Here, the voltage detector 409q calculates
The voltage cup Vs of the power supply 7 is detected, and a power failure detection circuit 409 is provided.
s turns on the switch 409t when the power supply 7 is normal, and turns off when the power is cut off. Therefore, when the power supply 7 is normal, the phase comparator 409r, the amplifier 409v, and the voltage frequency conversion circuit 4
The phase of the output bus voltage is the same as that of the power supply 7 by the phase-locked control loop composed of the power supply 7 and the counter 409n.
The signal from the switch 409k is added to the output of the phase comparator 409r by the adder 409u, and given as an auxiliary signal to the phase synchronization control loop.
Before the paralleling, an output voltage having the same phase as the bus voltage is generated, and after the paralleling, the phase of the output voltage is finely adjusted so that the component caused by the phase difference of the cross current becomes zero.

Embodiment 3 FIG. Further, FIG. 10 shows that in the second embodiment, the first inverter device 1 and the second inverter device 2
Is provided with a synchronization circuit 9 for operating the power supply 7 in phase with the power supply 7.

FIG. 11 is a block diagram showing the structure of the synchronization circuit 9. The output bus voltage cup V _B and the voltage cup Vs of the power supply 7 are detected by the voltage detectors 9d and 9e, respectively, and the phase difference is obtained by the phase comparator 9f.
The signal V _fs amplified by is supplied to the first inverter device 1 and the second inverter device 2 via the switch 9j. The power failure detection circuit 9g is a switch 9j when the power supply 7 is normal.
On, and off when the power goes out.

The difference from the inverter device of the second embodiment is the configuration of the coordinate conversion reference generator 410. FIG. 12 is a block diagram showing the configuration of the coordinate transformation reference generator 410.
Except that the adder 410m1 has three inputs, the same subscript as the subscript of the alphabet of the coordinate transformation reference generator 408 shown in the first embodiment is the same component. The output V _fs of the synchronizing circuit 9 is connected to the voltage frequency conversion circuit 4.
Since the input is 10 m, the same operation as in the second embodiment can be expected.

Although the synchronization circuit and the coordinate conversion reference generator shown in FIGS. 11 and 12 _exchange V _fs as analog signals, as described with reference to FIG. 7, the frequency according to the absolute value of V _fs Figure 1 shows a synchronization circuit using
3. The voltage frequency conversion circuit 410m in the coordinate conversion reference generator 408 may have the configuration shown in FIG.

Embodiment 4 FIG. Next, FIG. 15 relates to the fifth and sixth aspects of the present invention, in which the current detection circuit in the second embodiment uses the current bar Is of the power supply 7 detected by the current detector 200c.

(Equation 9) Is obtained as a current detection circuit 411. With this configuration, the first inverter device 1 and the second inverter device 2 can instantaneously limit the cross current flowing between the first inverter device 1 and the second inverter device 2, so that the switch 8 is always turned on.
Parallel operation can be performed for the load 4.

Embodiment 5 FIG. FIG. 16 is a circuit diagram showing the power supply 7 detected by the current detector 200c in the current detection circuit according to the third embodiment.
Using the current bar Is of

(Equation 10) Is obtained as a current detection circuit 411. With this configuration, similarly to the fourth embodiment, the first inverter device 1 and the second inverter device 2 can operate the cross current flowing between the first inverter device 1 and the second inverter device 2 in parallel.

In each of the embodiments described with reference to FIGS. 1, 8, 15, and 16, the command value of the current minor loop is added to the parallel capacitor 102 of the output filter of the inverter.
, The controllability is improved, but the capacitor current reference generating circuit 404 in FIGS. 1, 8, 15, and 16 may be omitted.
This is because the voltage control circuit 403 operates so that the output voltage of the first inverter device 1 matches the output voltage reference cup V ₁ ^*, and as a result, generates a signal replacing the capacitor current reference signal. This is because the control system operates without any trouble. In this case, the voltage control circuit 403
When the amplification factor is sufficiently large, the deviation in the voltage control is reduced.

In the above description, the case where the configuration of the control circuit is an instantaneous voltage control system having a current minor loop has been described. However, the voltage control which can control the output voltage at high speed without having a current minor loop is described. In the system, the AC output converters can be stably operated in parallel by the cross current limiting virtual impedance circuit.

In the above description, the case where the three-phase inverter is used in parallel operation has been described. However, other converters may be combined with a high-frequency inverter and a cycloconverter as shown in FIG. The same principle can be applied to a converter capable of instantaneous voltage control such as a high-frequency link type converter for converting to a low-frequency sine wave.

In the converter shown in FIG.
By switching from 1 to Q4, a square wave as shown in FIG. Next, a saw-tooth wave synchronized with the switching of the inverter is generated as shown in FIG. 7B, and an intersection between the sawtooth wave and the output voltage command signal indicated by the line X1-X2 in the figure is obtained as shown in FIG. .
Based on this signal and the polarity of the inverter voltage R2S2,
By selecting the switch of the cycloconverter as shown in FIG. 7E, the signals X1-X2 are obtained as shown in FIG.
Can be obtained between NU in FIG.
Similarly, control between NV and between NW can be performed to obtain a three-phase output.

In order to realize the principle shown in FIGS. 1, 8, 10, 15, and 16, a discrete circuit using an analog operational amplifier or the like may be used, or digital control by a microprocessor or digital signal processor may be used. It can also be realized by software processing.

In the above description, two inverters having the same capacity have been described for simplicity, but the present invention can also be applied to parallel operation of n converters having different capacities. In this case, CT-1, CT-2, CT-3, etc. and resistors R11, R2 in FIG.
1, R31, etc. are changed according to the capacity.
If the same voltage is obtained at the terminals such as 1, R21, R31, all converters share the burden in proportion to the capacity.

[0087]

As described above, the first to sixth inventions
According to, the flow between converters or between the converter and AC power supply
Detected cross current, and the virtual impedance value is added to the cross current.
To the instantaneous voltage control means by a signal obtained by multiplying
Since the voltage command value is corrected, even if the voltage
Output voltage feedback signal of each converter
The current of each converter
Dispersion of the sharing control is eliminated, and the instantaneous value of
It has the effect of suppressing it. Further, according to the first invention,
By causing a component resulting from the phase difference of the cross current of the current flowing between the respective converters to act on the reference sine wave generating means of the synchronous coordinates, by suppressing the cross current flowing between the converters, With a simple circuit configuration, there is an effect of quickly suppressing the cross current.

According to the second aspect of the present invention, the component perpendicular to the vector delayed by the output impedance angle of the three-phase AC output converter with respect to the bus voltage of the load current is converted to the reference sine wave generating means of the synchronous rotation coordinates. By acting on the first
It has the same effect as the invention.

According to the third aspect of the present invention, the component caused by the phase difference of the cross current of the current flowing between the converters is
By acting on the phase control loop for synchronizing the synchronous rotation coordinates with another AC power supply, in addition to the effects of the first invention, the load can be applied without interruption of the power supply when a three-phase AC output converter such as an inverter device fails or is inspected. Can be supplied to

According to the fourth aspect of the present invention, the phase control loop for synchronizing the synchronous rotation coordinate with another AC power supply has a vector delayed by the output impedance angle of the three-phase AC output converter with respect to the bus voltage of the load current. In this case, a component perpendicular to the current is applied to suppress the cross current of the current flowing between the converters.

According to the fifth aspect of the present invention, the cross current of the current flowing between the three-phase AC output converter and another AC power supply is detected,
By this detection signal, the output of the instantaneous voltage control means is changed so that the cross current of the current flowing between the converter and the AC power supply is suppressed, and the output voltage of the converter is controlled.
In addition to the effect of the first invention, a component mainly caused by the phase difference of the cross current of the current flowing between the converter and the AC power supply is applied to the reference sine wave generating means of the synchronous rotating coordinate system. Since the cross current flowing between the output converter and another power supply can be instantaneously limited, an effect that the load can be operated in parallel can be obtained.

Further, according to the sixth aspect of the invention, the cross current of the current flowing between the converters is detected, and the detection signal is used to suppress the cross current of the current flowing between the converters. The output of the converter is controlled by changing the output of the instantaneous voltage control means, and the component perpendicular to the vector delayed from the bus voltage of the load current by the output impedance angle of the three-phase AC output converter is calculated as By acting on the reference sine wave generating means of the synchronous rotation coordinates, the same effect as in the fifth invention can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment according to the first and second inventions.

FIG. 2 is a circuit diagram showing an embodiment of a converter used in the first embodiment.

FIG. 3 is a block diagram of the current detection circuit of FIG. 1;

FIG. 4 is a simplified block diagram of FIG. 1;

FIG. 5 is a circuit diagram showing an embodiment of the current detection circuit of FIG. 1;

FIG. 6 is a block diagram of the coordinate transformation reference generator of FIG. 1;

FIG. 7 is a block diagram of the voltage frequency conversion circuit of FIG. 6;

FIG. 8 is a block diagram showing a second embodiment according to the third and fourth inventions.

FIG. 9 is a block diagram of the coordinate transformation reference generator of FIG. 8;

FIG. 10 is a block diagram showing a third embodiment according to the third and fourth inventions.

FIG. 11 is a block diagram showing the synchronization circuit of FIG. 10;

FIG. 12 is a block diagram of the coordinate transformation reference generator of FIG. 10;

FIG. 13 is a block diagram showing another synchronization circuit of FIG. 10;

FIG. 14 is a block diagram of another voltage frequency conversion circuit in FIG. 12;

FIG. 15 is a block diagram showing a fourth embodiment according to the fifth and sixth inventions.

FIG. 16 is a block diagram showing Embodiment 5 according to the fifth and sixth inventions.

FIG. 17 is a circuit diagram showing an example of another converter used in the present invention.

FIG. 18 is an operation explanatory diagram of another converter used in the present invention.

FIG. 19 is an equivalent circuit diagram of a conventional AC output converter during parallel operation.

FIG. 20 is a vector diagram at the time of parallel operation of the conventional AC output converter.

FIG. 21 is another vector diagram of the conventional AC output converter during parallel operation.

FIG. 22 is a block diagram showing a configuration of a conventional system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inverter device 1 2 Inverter device 3 Output bus 4 Load 403 Voltage control circuit 405 Cross-current limiting virtual impedance 406 Current detection circuit 408 Coordinate transformation reference generator

Claims (6)

(57) [Claims] 1. In a parallel converter system in which outputs of a plurality of three-phase AC output converters are connected to a common bus and parallel operation is performed while sharing load current, each of the converters constitutes a converter. The instantaneous voltage control type converter in which the arm of each phase performs switching a plurality of times during one cycle to control the instantaneous value of the output voltage by two components of the synchronous rotation coordinates, detecting a cross current component of the current flowing in the virtual impedance value squared to the cross current component
Flip the signal obtained, given the instantaneous voltage control means as cross current component of the current flowing between the converter each other is suppressed
The converter controls the output voltage of the converter by correcting the voltage command value, and converts the component mainly caused by the phase difference of the cross current of the current flowing between the respective converters into the reference sine wave of the synchronous rotation coordinate. A parallel operation control device for a three-phase AC output converter, wherein the device operates on a generating means. 2. In a parallel converter system in which the outputs of a plurality of three-phase AC output converters are connected to a common bus and the parallel operation is performed while sharing the load current, each of the converters constitutes a converter. The instantaneous voltage control type converter in which the arm of each phase performs switching a plurality of times during one cycle to control the instantaneous value of the output voltage by two components of the synchronous rotation coordinates, A voltage command given to the instantaneous voltage control means so that the cross current of the current flowing between the converters is detected and the cross current of the current flowing between the converters is suppressed by a signal obtained by multiplying the virtual current by the virtual impedance value. The output voltage of the converter is controlled by correcting the value of the three-phase AC output converter with respect to the bus voltage of the load current.
A parallel operation control device for a three-phase AC output converter, wherein a component perpendicular to a virtual vector delayed by a virtual impedance angle is applied to the reference sine wave generating means of the synchronous rotation coordinates. 3. In a parallel converter system in which outputs of a plurality of three-phase AC output converters are connected to a common bus, and the parallel operation is performed while sharing the load current, each of the converters constitutes a converter. The instantaneous voltage control type converter in which the arm of each phase performs switching a plurality of times during one cycle to control the instantaneous value of the output voltage by two components of the synchronous rotation coordinates, detecting a cross current component of the current flowing in the virtual impedance value squared to the cross current component
Flip the signal obtained, given the instantaneous voltage control means as cross current component of the current flowing between the converter each other is suppressed
The output voltage of the converter is controlled by correcting the voltage command value, and the component mainly caused by the phase difference of the cross current of the current flowing between the converters is converted to the synchronous rotation coordinates by another AC. A parallel operation control device for a three-phase AC output converter, wherein the device operates on a phase control loop synchronized with a power supply. 4. In a parallel converter system in which outputs of a plurality of three-phase AC output converters are connected to a common bus, and the parallel operation is performed while sharing the load current, each of the converters constitutes a converter. The instantaneous voltage control type converter in which the arm of each phase performs switching a plurality of times during one cycle to control the instantaneous value of the output voltage by two components of the synchronous rotation coordinates, A voltage command given to the instantaneous voltage control means so that the cross current of the current flowing between the converters is detected and the cross current of the current flowing between the converters is suppressed by a signal obtained by multiplying the virtual current by the virtual impedance value. The output voltage of the converter is controlled by correcting the value of the three-phase AC output converter with respect to the bus voltage of the load current.
Parallel operation control of a three-phase AC output converter, wherein a component perpendicular to a virtual vector delayed by a virtual impedance angle is applied to a phase control loop for synchronizing the synchronous rotation coordinates with another AC power supply. apparatus. 5. A parallel converter system in which an output of a three-phase AC output converter is connected to a common bus with another three-phase AC power supply and operates in parallel while sharing a load current, wherein the converter is a converter. And the instantaneous voltage control type converter in which the arm of each phase performs switching a plurality of times during one cycle to control the instantaneous value of the output voltage by two components of the synchronous rotation coordinates. The instantaneous voltage is detected so that the cross current of the current flowing between the AC power supply is detected, and a signal obtained by multiplying the cross current by the virtual impedance value suppresses the cross current of the current flowing between the converter and the AC power supply. by correcting the voltage command value to be provided to the control means, the variable
Controlling the output voltage of the converter, and causing a component mainly due to the phase difference of the cross current of the current flowing between the converter and the AC power supply to act on the reference sine wave generating means of the synchronous rotation coordinates. A parallel operation control device for a three-phase AC output converter. 6. A parallel converter system in which an output of a three-phase AC output converter is connected to a common bus with another three-phase AC power supply and operates in parallel while sharing a load current, wherein each of the converters comprises: An instantaneous voltage control type converter in which an arm of each phase constituting the converter performs switching a plurality of times during one cycle to control an instantaneous value of an output voltage by two components of a synchronous rotation coordinate. And a cross current of the current flowing between the AC power supplies is detected, and a signal obtained by multiplying the cross current by a virtual impedance value suppresses the cross current of the current flowing between the converter and the AC power supply. The output voltage of the converter is controlled by correcting the voltage command value applied to the instantaneous voltage control means, and the virtual vector is delayed from the bus voltage of the load current by the virtual impedance angle of the three-phase AC output converter. A parallel operation control device for a three-phase AC output converter, wherein a vertical component is caused to act on a reference sine wave generating means of the synchronous rotation coordinates.