JPH11143562A - Controller for active filter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the compensating ratio of higher harmonic from being lowered even when the fundamental wave of load current is unbalanced. SOLUTION: This device is provided with a load current fundamental wave anti-phase component arithmetic circuit which consists of an anti-phase three-phase two-phase conversion circuit 20 which converts an anti-phase component of load current detection value from a three-phase into a two-phase, a 1st anti-phase component arithmetic circuit 21 which calculates an anti-phase effective component and anti-phase ineffective component of load current from the output signal and an output signal of a phase-locked loop, a 1st anti-phase detection lowpass filter 22 which takes out a direct current component of the anti-phase effective component signal, a 2nd anti-phase detection lowpass filter 23 which takes out a direct current component of the anti-phase ineffective component signal, a 2nd anti-phase component arithmetic circuit 24 which operates an anti-phase fundamental wave component of the load current in two-phase from an output signal of each-phase detection lowpass filter and an output signal of the phase-locked loop and an anti-phase component two-phase three- phase conversion circuit 25 which converts the output signal form two-phase into three-phase. An output signal of a fundamental wave adder 26 which adds each output signal of a two- phase three-phase conversion circuit 15 and the anti-phase component two-phase three-phase conversion circuit is inputted as a subtraction element of a 1st a subtracted 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an active filter device, and more particularly to a control device for an active filter device which does not lower the harmonic compensation ratio even when the fundamental wave of the load current is unbalanced. It is about.

[0002]

2. Description of the Related Art FIG. 6 is a schematic diagram showing a configuration example of a control device of a conventional active filter device. In FIG. 6, a three-phase AC power supply 1 has a load 2 for generating a harmonic current.
Are connected.

An inverter 4 is connected in parallel to the load 2 via a reactor 3. Further, the DC voltage of the inverter 4 is charged by the capacitor 5.

On the other hand, the first current detector 6 detects the load 2
_Is detected. Further, the output current i _C of the inverter 4 is detected by the second current detector 7. further,
The voltage detector 8 detects the AC voltage v _S of the three-phase AC power source 1.

On the other hand, a phase locked loop (hereinafter referred to as PLL (Ph)
case Locked Loop) circuit)
A phase signal θ synchronized with the AC voltage of the three-phase AC power supply 1 detected by the voltage detector 8 is generated. Further, the first three-phase to two-phase conversion circuit 10 calculates the current detection value of the load 2 by the first current detector 6 from the three-phase to α by the following (Equation 1).
Phase and β phase.

[0006]

(Equation 1)

Further, the first arithmetic circuit 11 uses the phase signal θ from the PLL circuit 9 to calculate d
An operation called q conversion is performed to separate the current of the load 2 into an effective component i _LP and an ineffective component i _LQ . And this d
By the q conversion, the fundamental component of the current of the load 2 becomes a DC signal, and the harmonic component becomes an AC signal.

[0008]

(Equation 2)

On the other hand, the first low-pass filter 12 is provided with a DC component i of the effective component signal i _LP from the first arithmetic circuit 11.
_Take out _LFP . Also, the second low-pass filter 13
_Extracts the DC component i _LFQ of the invalid component signal i _LQ from the first arithmetic circuit 11.

Further, the second arithmetic circuit 14 uses the phase signal θ from the PLL circuit 9 to perform an operation called an inverse dq transform shown in the following (Equation 3), and the direct current from the first low-pass filter 12 The component i _LFP and the DC component i _LFQ from the second low-pass filter 13 are converted into a two-phase signal of α-phase and β-phase, and a fundamental wave component of the current of the load 2 is calculated.

[0011]

(Equation 3)

Further, the two-phase to three-phase conversion circuit 15 converts the two-phase signals _LF and i _LF from the second arithmetic circuit 14i into a fundamental wave signal i _F which is a three-phase signal by the following (Equation 4).
Convert to

[0013]

(Equation 4)

Incidentally, the first three-phase to two-phase conversion circuit 10, the first arithmetic circuit 11, the first low-pass filter 12, the second low-pass filter 13, the second
From the arithmetic circuit 14 and the two-phase to three-phase conversion circuit 15 constitute a load current fundamental wave arithmetic circuit for obtaining a fundamental wave signal i _F.

On the other hand, the first subtractor 16 subtracts the fundamental signal i _F from the two-phase to three-phase conversion circuit 15 from the current detection value i _L of the load 2 by the first current detector 6 to obtain a load. The harmonic component of the two currents is calculated as a current command i _C ^* of the inverter 4.

The second subtractor 17 subtracts a current detection value i _C of the inverter 4 from the second current detector 7 from an output signal i _C ^* from the first subtractor 16. Further, PWM (Pulse Width Modulat)
(ion) The circuit 18 generates a gate signal so that the current command i _C ^* of the inverter 4 matches the current detection value i _C of the inverter 4 and supplies the gate signal to the switching element of the inverter 4.

FIG. 7 is a diagram showing an example of waveforms of respective parts in the control device of the active filter device of FIG. FIG.
In, (a) represents a three-phase alternating current waveform of the AC voltage v _S of the power supply 1, (b) the waveform of the source current i _S, (c) the load current i
_L waveform, a (d) shows the output current i _C of the waveform of the inverter 4, (e) is a waveform of the fundamental wave signal i _F, (f) the current command i _C ^* of the waveform of the inverter 4.

In practice, each waveform has three phases, but only one phase is shown here. Next, FIG.
The control device of the active filter device of FIG. 6 will be described with reference to FIG.

For example, when the load 2 is a six-pulse rectifier, the current i _{L of the} load 2 has a square waveform as shown in FIG. The purpose of the active filter device is load 2
A current that cancels the harmonic component of the current i _L is generated so that the power supply current i _S has a waveform including only the fundamental wave component as shown in FIG. Therefore, the active filter device needs to detect a harmonic component of the current i _L of the load 2 and output the same.

The control method will be described below. First, the current i _{L of the} load 2 is detected, and dq conversion is performed by the first three-phase to two-phase conversion circuit 10 and the first arithmetic circuit 11. By the dq conversion, the fundamental component of the current i _L of the load 2 is represented by a DC component, and the harmonic component is represented by an AC component.

In order to extract only the fundamental wave component of the current i _L of the load 2, the DC component is extracted by the first and second low-pass filters 12 and 13. Then, the DC component is subjected to inverse dq conversion by the second arithmetic circuit 14, and further, the two-phase to three-phase conversion circuit 1
5 by converting a three-phase, it is possible to calculate the fundamental component i _F of the load 2 current i _L. This fundamental wave component i _F
Is a waveform consisting of only the fundamental wave component as shown in FIG.

Then, (i _L −
As i _F ), a harmonic component of the current i _L of the load 2 is calculated, and is calculated as a current command i _C ^* of the inverter 4. FIG. 7F shows the current command i _C ^* of the inverter 4.

Further, when the output current i _C of the inverter 4 is fed back and a gate signal is generated by the PWM circuit 18 so as to match the current command i _C ^{* of} the inverter 4, the harmonic component of the load 2 is reduced by the inverter 4. A canceling current can be applied. The output current i _C of the inverter 4 is shown in FIG.
(D). As a result, the power supply current i _S is reduced as shown in FIG.
As shown in (1), only the fundamental wave component is present, and the active filter device can compensate for the harmonic current of the load 2.

[0024]

As described above, in the control device of the conventional active filter device, the harmonic current generated by the load 2 is compensated to make the power supply current i _S only the fundamental wave component. it can.

However, when the three-phase load current to be subjected to harmonic compensation is unbalanced, the conventional device as shown in FIG.
This is because the load current fundamental wave operation circuit in FIG. 6 detects only the positive-phase fundamental wave component of the three-phase fundamental wave components and does not detect the negative-phase fundamental wave component.

Hereinafter, such a problem will be described with reference to FIG. FIG. 8 is a diagram illustrating a positive-phase component and a negative-phase component of a fundamental wave unbalanced current flowing when an unbalanced load is connected to a system.

As shown in the circuit diagram of FIG. 8A, when a load is connected to the R and S phases of the system power supply and no load is connected to the T phase, the load current is applied to the R phase by the current ILR. Flows, and the current ILS flows in the S phase, but the current ILT in the T phase becomes zero, and an unbalanced fundamental wave current that is not three-phase balanced flows. At this time, the current ILR and the current ILS have the same amplitude and are equal to each other.
0 degrees out of phase.

FIG. 8 (b) is a diagram for explaining the above state with a phasor. The load current fundamental wave shown in (i) has a current ILR and a current ILS having the same amplitude and 180 degrees out of phase.
Only, and there is no T-phase current ILT.

The phasor in (i) is a vector synthesis of the positive phase component of the load current fundamental wave shown in (ii) and the positive phase component of the load current fundamental wave shown in (iii). In the control device of the conventional active filter device of FIG. 6, the fundamental wave component of the load current is calculated by using the above-described (Equation 1) and (Equation 2), the first and second low-pass filters 12 and 13, and (Equation 3). Since it is calculated by (Equation 4), in the load state of FIG.
_F is only the positive phase component of the load current fundamental wave of (ii) in FIG.

Therefore, in the current command i _C ^* of the inverter 4 calculated by the first subtractor 16 in FIG. 6, the component of the fundamental phase of the load current which remains in the negative phase remains within the rated range of the active filter device. This compensates for the remaining fundamental and negative harmonic components.

As a result, if the load 2 has a large amount of the negative phase component of the fundamental wave, there is a problem that the compensation rate of the harmonic component is reduced. Further, in the conventional device of FIG. 6, since no DC power supply is added, the DC voltage of the inverter 4 gradually decreases due to loss. If the DC voltage of the inverter 4 is too low, the output voltage of the inverter 4 is low,
The harmonic compensation current cannot be output.

Therefore, in the control device of the active filter device, an active component is added to the current command i _C ^* of the inverter 4 to transfer active power to and from the three-phase AC power supply 1 so that the DC voltage is constant. You need to control.

Further, the harmonic current of the load 2 increases,
When the current command i _C ^* of the inverter 4 exceeds the rated compensation capacity, the inverter 4 outputs a current exceeding the rated value, and the operation of the device is stopped by the protection operation.

Therefore, the current command i _C ^{* of the} inverter 4
Must be adjusted so that does not exceed the rated compensation capacity.
In addition, the control device of the active filter device is provided with a fundamental wave component i of the load current with the development of digital technology in recent years.
It is conceivable that the detection of _F is realized by digital control using a microprocessor.

When the fundamental wave component i _F is output as a digital signal, the fundamental wave component i _F becomes a discontinuous value for each sampling period (calculation period) of the microprocessor. The accompanying harmonic is added to the current command i _C ^* of the inverter 4.

This is a problem caused by digitizing the control device of the conventional active filter device. Further, due to the time delay required for the operation of the load current fundamental wave operation circuit and the delay element of the first current detector 6, the fundamental wave component i _F causes a phase delay with respect to the actual fundamental wave component of the load current i _L. Occurs.

Thus, the current command i _C of the inverter 4 is obtained.
^* , The fundamental wave component remains, and the active filter device compensates for the remaining fundamental wave negative-phase component and harmonic component within the rated range.

For this reason, there arises a problem that the compensation rate of the harmonic component by the active filter device is reduced.
A first object of the present invention is to provide a control device for an active filter device which does not lower the harmonic compensation ratio even when the fundamental wave of the load current is unbalanced.

A second object of the present invention is to provide an active circuit capable of controlling the DC voltage of the inverter constant without lowering the harmonic compensation ratio even when the fundamental wave of the load current is unbalanced. A control device for a filter device is provided.

A third object of the present invention is to reduce the harmonic compensation ratio even when the fundamental wave of the load current is unbalanced, and to increase the harmonic current of the load to be included in the current command. To provide a control device for an active filter device capable of adjusting a current command so that a harmonic output current does not exceed a rated harmonic compensation capacity when a harmonic component exceeds a rated harmonic compensation capacity. It is in.

A fourth object of the present invention is to reduce the harmonic compensation ratio even when the fundamental wave of the load current is unbalanced and to use a digital control device constituted by a microprocessor or the like. It is an object of the present invention to provide a control device of an active filter device capable of suppressing generation of harmonics accompanying a sampling period generated in the active filter device.

A fifth object of the present invention is to reduce the harmonic compensation ratio even when the fundamental wave of the load current is unbalanced, and to detect the load current fundamental wave and the load current harmonic due to a calculation delay. It is an object of the present invention to provide a control device for an active filter device which reduces the residual of the fundamental wave component contained in the active filter device and prevents the reduction of the harmonic compensation effect.

[0043]

To achieve the above object, according to the present invention, a phase synchronization circuit for generating a phase signal synchronized with a three-phase AC power supply and a three-phase AC power supply are provided. First to convert the load current detection value from three-phase to two-phase
Based on the output signal from the first three-phase to two-phase conversion circuit and the output signal from the phase locked loop circuit,
A first arithmetic circuit for calculating an effective component and an invalid component of the load current, a first low-pass filter for extracting a DC component of the effective component signal from the first arithmetic circuit, and an invalid component signal from the first arithmetic circuit A second low-pass filter that extracts the DC component of the load current, a fundamental wave component of the load current based on an output signal from the first low-pass filter, an output signal from the second low-pass filter, and an output signal from the phase locked loop. A two-phase arithmetic circuit, a two-phase three-phase conversion circuit that converts an output signal from the second arithmetic circuit from a two-phase to a three-phase, and a two-phase three-phase conversion circuit from a load current detection value And a first subtracter for calculating a harmonic component of the load current by subtracting the output signal from
In a control device of an active filter device configured to be a current command of an inverter connected in parallel to a load,
A negative-phase three-phase / two-phase conversion circuit that converts the negative phase component of the load current detection value from three-phase to two-phase, based on an output signal from the negative-phase three-phase / two-phase conversion circuit and an output signal from the phase locked loop circuit A first negative-phase component operation circuit for calculating a negative-phase effective component and a negative-phase invalid component of the load current; and a first negative-phase component component DC signal from the first negative-phase component operation circuit. A negative-phase detection low-pass filter, a second negative-phase detection low-pass filter that extracts a DC component of the negative-phase invalid component signal from the first negative-phase component calculation circuit, and an output signal from the first negative-phase detection low-pass filter. A second anti-phase component operation circuit that calculates the anti-phase fundamental wave component of the load current in two phases based on the output signal from the second anti-phase detection low-pass filter and the output signal from the phase locked loop; The output signal from the negative phase component operation circuit 2 is A negative-phase component two-phase to three-phase conversion circuit, and a load current fundamental wave negative-phase component operation circuit comprising: an output signal from the two-phase to three-phase conversion circuit and a negative phase component to the two-phase to three-phase conversion circuit An output signal from a fundamental wave adder for adding the output signal is input as a subtraction element of the first subtractor.

Therefore, in the control device for the active filter device according to the first aspect of the present invention, since the load current fundamental wave anti-phase component operation circuit is provided, even when the load current fundamental wave is an unbalanced load, each of the control devices can be used. Since the unbalanced fundamental wave component of the load current for each phase can be detected and the harmonic current for each phase can be calculated as a current command value, the active filter device does not reduce the harmonic compensation rate. it can.

According to the second aspect of the present invention, the first aspect of the present invention is provided.
In the control device of the active filter device of the invention of the invention,
A DC voltage control circuit including a third subtractor that outputs a difference between the DC voltage detection value of the inverter and the DC voltage command, and an amplifier that amplifies an output signal from the third subtractor is added. Is added to the output signal from the first low-pass filter.

Therefore, in the control device of the active filter device according to the second aspect of the present invention, the DC voltage of the inverter is detected, the difference between the detected value and the DC voltage command is obtained, and the signal obtained by amplifying the difference is used as the first signal. By adding to the fundamental component effective component of the load current, which is the output from the low-pass filter, the same operation as in the case of the first aspect of the present invention is obtained, and the fundamental component is added to the current command, Since the inverter can exchange active power with the three-phase AC power supply, the DC voltage of the inverter can be controlled to be constant.

According to a third aspect of the present invention, in the control device for the active filter device according to the first aspect of the present invention, the output signal from the negative-phase component two-phase to three-phase conversion circuit is converted from three-phase to two-phase. 2 based on the output signal from the second three-phase to two-phase conversion circuit, the output signal from the second three-phase to two-phase conversion circuit and the output signal from the phase locked loop circuit, A third arithmetic circuit for calculating as a component,
A second adder for adding an output signal from the first low-pass filter and an effective component from the third arithmetic circuit; an output signal from the second low-pass filter and an invalid component from the third arithmetic circuit; A third adder for adding the effective component and the invalid component of the load current, which are the outputs from the first arithmetic circuit, the output signal from the second adder, and the output signal from the third adder. A current command gain calculation circuit that calculates a current command adjustment gain such that the current command becomes the rated compensation capacity if the current command is equal to or greater than the rated compensation capacity; and A current command adjustment circuit comprising a multiplier for multiplying the output signal from the first subtractor by the current command adjustment gain is added, and the output signal from the multiplier is used as the final current command for the inverter. I have to

Therefore, in the control device of the active filter device according to the third aspect of the present invention, the active component and the inactive component of the load current, which are the output signals from the first arithmetic circuit,
A current command is calculated from the output signal from the first low-pass filter, the output signal from the second low-pass filter, and the output signal from the third arithmetic circuit. By calculating a gain so that the command becomes the rated compensation capacity and multiplying the gain by the current command, the same operation as in the invention of claim 1 can be obtained, and the current command of the inverter is rated. Since the adjustment can be performed within the compensation capacity, the capacity compensated by the active filter device can be rated.

Further, according to the fourth aspect of the present invention, the first aspect is provided.
In the control device of the active filter device of the invention of the invention,
A fundamental wave low-pass filter for removing harmonic components of an output signal from the fundamental wave adder is added, and an output signal from the fundamental wave low-pass filter is input as a subtraction element of the first subtractor.

Therefore, in the control device for an active filter device according to the present invention, the output signal from the fundamental wave adder is input to the fundamental wave low-pass filter, and the output signal from the fundamental wave low-pass filter is subjected to the first subtraction. In addition to providing the same operation as the case of the first aspect of the present invention by inputting as a subtraction element of the circuit, a digital circuit constituted by a microprocessor or the like is used as a circuit for calculating a fundamental three-phase signal. Also when used, harmonics that occur depending on the sampling period can be suppressed.

According to a fifth aspect of the present invention, in the control device of the active filter device according to the first aspect of the present invention, the first setter, the first phase adder, the second setter, A second phase adder, and the first phase adder converts the output signal from the phase locked loop and the output setting signal from the first setting device as phase signals to be input to the second arithmetic circuit. Using the added signal, a second phase adder adds an output signal from the phase locked loop and an output setting signal from the second setting unit as a phase signal to be input to the second anti-phase component operation circuit. The used signal is used.

Therefore, in the control device of the active filter device according to the fifth aspect of the present invention, the output signal from the phase locked loop is used as the phase signal input to the second arithmetic circuit and the second antiphase component arithmetic circuit. By using the signals corrected by the first setting device and the second setting device,
In addition to having the same effect as in the case of the first aspect of the present invention, the fundamental wave component of the load current to be detected is reduced by the time delay required for the operation of the load current fundamental wave operation circuit and the delay element of the load current detector. Since the phase lag of the actual fundamental wave component of the load current can be eliminated, the fundamental wave component can be removed from the load current without phase lag, and the harmonic detection signal that does not leave the fundamental wave component of the load current active It can be used as a current reference of the filter device, and can increase the harmonic compensation rate of the active filter device.

[0053]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) FIG. 1 is a schematic diagram showing a configuration example of a control device of an active filter device according to the present embodiment. The same parts as those in FIG. Here, only the different parts will be described.

That is, as shown in FIG. 1, the control device of the active filter device according to the present embodiment comprises an anti-phase three-phase to two-phase conversion circuit 20, a first anti-phase component operation circuit 21, Anti-phase detection low-pass filter 22, second anti-phase detection low-pass filter 23, and second anti-phase component operation circuit 24
, An anti-phase component two-phase to three-phase conversion circuit 25, and a fundamental wave adder 2
6 and a load current fundamental wave anti-phase component operation circuit surrounded by a dashed line is added to FIG.

The negative-phase three-phase / two-phase conversion circuit 20 converts the negative-phase component of the current detection value i _L of the load 2 by the first current detector 6 from three-phase to two-phase. The first anti-phase component operation circuit 21 outputs the output signal i _LN from the anti-phase three-phase to two-phase conversion circuit 20.
, I _LN and the output signal θ from the PLL circuit 9 to calculate a negative-phase effective component i _LNP and a negative-phase invalid component i _LNQ of the load current.

The first negative-phase detection low-pass filter 22 is
The negative-phase effective component signal i from the first negative-phase component calculation circuit 21
_Extract the DC component i _{LNFP of LNP} . The second negative-phase detection low-pass filter 23 _extracts the DC component i _LNFQ of the negative-phase invalid component signal i _LNQ from the first negative-phase component calculation circuit 21.

The second anti-phase component operation circuit 24 outputs the output signal i _LNFP from the first anti-phase detection low-pass filter 22,
Output signal i from the second negative-phase detection low-pass filter 23
_{Based on LNFQ} and output signal θ from PLL circuit 9,
Calculates the negative-phase fundamental wave component of the load current in two phases.

The negative-phase component two-phase to three-phase conversion circuit 25 outputs the output signals i _LNF , i _LNF from the second negative-phase component operation circuit 24.
Is converted from two-phase to three-phase. The fundamental wave adder 26 adds the output signal i _F from the two-phase to three-phase conversion circuit 15 and the output signal i _NF from the negative-phase two-phase to three-phase conversion circuit 25.

[0059] Then, and an output signal i _FM from the fundamental wave adder 26, so that the input as a subtraction element of the first subtractor 16. Next, the operation of the control device of the active filter device according to the present embodiment configured as described above will be described.

The description of the operation of the same parts as in FIG. 6 is omitted, and only the operation of the different parts will be described here. In FIG. 1, an anti-phase three-phase to two-phase conversion circuit 20 in a load current fundamental wave anti-phase component calculation circuit converts a current detection value i _L of the load 2 from three phases to α phase and β phase by the following (Equation 5). To two phases.

[0061]

(Equation 5)

That is, (Equation 5) replaces i _LV and i _LW in (Equation 1) for performing the operation of the first three-phase to two-phase conversion circuit 10 described in the conventional apparatus of FIG. 6 (Equation 5). )
The two-phase load current signals i _LN and i _LN are calculated.

The first anti-phase component operation circuit 21 uses the phase signal θ from the PLL circuit 9 to calculate d
An operation called q conversion is performed to separate the current of the load 2 into an effective component i _LNP and an invalid component i _LNQ .

[0064]

(Equation 6)

That is, this (Equation 6) is the same algorithm as (Equation 2) for performing the operation of the first arithmetic circuit 11 described in the conventional device of FIG. Due to this dq conversion, the fundamental component of the current of the load 2 having a negative phase becomes a DC signal,
The fundamental wave positive phase component and the harmonic component become AC signals.

The first low-pass filter 22 takes out the DC component i _LNFP of the negative-phase effective component signal i _LNP from the first negative-phase component operation circuit 21,
_Extracts the DC component i _LNFQ of the negative-phase invalid component signal i _LNQ from the first negative-phase component operation circuit 21.

The first anti-phase component operation circuit 24 performs an operation called an inverse dq transform shown in the following (Equation 7) using the phase signal θ from the PLL circuit 9, and a first anti-phase detection low-pass filter the output signal i _LNFP from 22, an output signal i _LNFQ from the second reversed phase detector low pass filter 23, converted to two-phase signals of α phase and β phase.

[0068]

(Equation 7)

The anti-phase component two-phase to three-phase conversion circuit 25 converts the output signals i _LNF and i _LNF from the second anti-phase component operation circuit 24 into a fundamental wave signal as a three-phase signal by the following (Equation 8). Convert to i _NF .

[0070]

(Equation 8)

The fundamental wave adder 26 outputs an output signal (a three-phase fundamental wave reversed-phase signal) i _NF from the reversed-phase component two-phase to three-phase conversion circuit 25.
A, by adding the output signal (three-phase fundamental signal) i _F from the two-phase three-phase conversion circuit 15, and outputs a corrected basic wave three-phase signal i _FM.

As described above, the negative-phase component of the load current described in FIG. 8 can be detected as the three-phase fundamental negative-phase signal i _NF. By adding to the wave signal i _F , a fundamental component of each of the three phases of the load current is calculated as a corrected fundamental three-phase signal i _FM .

[0073] The first subtracter 16, from the first current detector 6 according to the load 2 current detection value i _L, and subtracts the correction fundamental three-phase signal i _FM, the second subtractor 17, The current detection value i _C of the inverter 4 by the second current detector 7 is subtracted from the output signal i _C ^* from the first subtractor 16.

Then, the PWM circuit 18 outputs the signal i _C
^A gate signal is generated so that ^* and the current detection value i _C of the inverter 4 match, and is provided to the switching element of the inverter 4.

As described above, the control device of the active filter device of the present embodiment is provided with the load current fundamental wave anti-phase component calculation circuit, so that when the load 2 is an unbalanced load (the load current If the waves are unbalanced)
The fundamental component of the load current for each phase can be detected,
Since the harmonic current for each phase can be calculated as a current command value, the active filter device can prevent the harmonic compensation rate of the load current from being reduced.

(Second Embodiment) FIG. 2 is a schematic diagram showing a configuration example of a control device of an active filter device according to the present embodiment. The same parts as those in FIG. The description will be omitted, and only different portions will be described here.

That is, as shown in FIG. 2, the control device of the active filter device of the present embodiment comprises a DC voltage reference setter 34, a third subtractor 35, an amplifier 36,
A DC voltage control circuit surrounded by a dashed line and comprising a first adder 37 is added to FIG.

The DC voltage reference setting unit 34 sets a DC voltage reference signal V _D ^* as a DC voltage command. The third subtractor 35 detects the DC voltage detection value V _{D of the} inverter 4.
And the DC voltage reference signal V from the DC voltage reference setter 34
Output the difference from _D ^* .

The amplifier 36 amplifies the output signal from the third subtractor 35. The first adder 37 converts the output signal i _AVR from the amplifier 36 into the first low-pass filter 1.
2 to the output signal i _LFP .

Next, the operation of the control device of the active filter device of the present embodiment configured as described above will be described. The description of the operation of the same part as that of FIG. 1 is omitted, and only the operation of the different part will be described here.

In FIG. 2, the third subtractor 35 compares the DC voltage detection value V _D of the inverter 4 with the DC voltage reference signal V _D ^* from the DC voltage reference setter 34, and compares the difference with the amplifier 36. , And adds the amplified signal i _AVR to the fundamental wave effective component i _LFP of the load current i _L from the first low-pass filter 12.

In this case, the amplified signal i _AVR is V _D ^* > V
When the _D is positive, when the V _D ^* <V _D is negative. V _D
^* > When V _D, the effective component included in the load current fundamental wave component i _F from the two-phase / three-phase conversion circuit 15 increases by i _AVR ,
As a result, a fundamental wave effective component corresponding to −i _AVR is added to the current command i _C ^* , the inverter 4 receives active power, and the DC voltage of the inverter 4 increases.

When V _D ^* <V _D , the effective component included in the load current fundamental wave component i _F from the two-phase / three-phase conversion circuit 15 decreases by | i _AVR |, and as a result, the current command i _C ^*
, A fundamental wave effective component corresponding to | i _AVR | is added, the inverter 4 outputs active power, and the DC voltage of the inverter 4 decreases.

As described above, the control device for the active filter device of the present embodiment detects the DC voltage of the inverter 4 and calculates the difference between the detected value and the DC voltage command.
A signal obtained by amplifying the difference is supplied to a first low-pass filter 12.
Is added to the fundamental wave effective component of the load current, which is the output from, so that in addition to the same effect as in the first embodiment, an effective component is added to the current command, Since the inverter 4 can exchange active power with the three-phase AC power supply 1, the DC voltage of the inverter 4 can be controlled to be constant.

(Third Embodiment) FIG. 3 is a schematic diagram showing a configuration example of a control device of an active filter device according to the present embodiment. The same parts as those in FIG. The description will be omitted, and only different portions will be described here.

That is, as shown in FIG. 3, the control device of the active filter device according to the present embodiment includes a second three-phase to two-phase conversion circuit 40, a third arithmetic circuit 41, and a second adder. A current command adjustment circuit surrounded by a dashed line and including a current adder 42, a third adder 43, a current command gain calculation circuit 48, and a multiplier 49 is added to FIG.

The second three-phase to two-phase conversion circuit 40 converts the output signal i _NF from the negative-phase component two-phase to three-phase conversion circuit 25 from three-phase to two-phase. The third arithmetic circuit 41 outputs the output signals i _LNP and i _LNP from the second three-phase to two-phase conversion circuit 40,
Based on the output signal θ from the PLL circuit 9, the negative phase component of the load current is calculated as a positive phase active component i _LNPP and an invalid component i _LNPQ .

The second adder 42 outputs the output signal i _LFP from the first low-pass filter 12 and the third arithmetic circuit 41
And the active ingredient i _LNPP from Third adder 43
Is the output signal i _LFQ from the second low-pass filter 13
And the invalid component i _LNPQ from the third arithmetic circuit 41.

The current command gain calculating circuit 48
Effective component i of the load current which is the output from the arithmetic circuit 11
_LP and invalid component i _LQ , output signal i _LPNFP from second adder 42, output signal i from third adder 43
_A current command is calculated based on _LPNFQ, and if the current command is equal to or greater than the rated compensation capacity, a current command adjustment gain K is calculated so that the current command becomes the rated compensation capacity.

The multiplier 49 is provided in the current command gain calculation circuit 4
8 from the first subtractor 1
6 is multiplied by the output signal. Then, the output signal from the multiplier 49 is set as the final current command i _C ^{* of the} inverter 4 so that the current command is within the rated compensation capacity.

Next, the operation of the control device of the active filter device of the present embodiment configured as described above will be described. The description of the operation of the same part as that of FIG. 1 is omitted, and only the operation of the different part will be described here.

In FIG. 3, a second three-phase to two-phase conversion circuit 4
0 is a value obtained by calculating the three-phase fundamental-wave negative-phase signal i _NF from the negative-phase component two-phase to three-phase conversion circuit 25 by the same algorithm as in the above (Equation 1) and converting it into a two-phase signal of i _LNP and i _LNP I do.

The third arithmetic circuit 41 performs the dq conversion using the phase signal θ from the PLL circuit 9 by the same algorithm as in the above (Equation 2), and performs the load from the second three-phase to two-phase conversion circuit 40. The two negative-phase fundamental currents i _LNP and i _LNP are separated into a positive-phase converted effective component i _LNPP and a positive-phase converted invalid component i _LNPQ .

The second adder 42 outputs the output signal i _LFP from the first low-pass filter 12 and the third arithmetic circuit 41
Adding the active ingredient i _LNPP from, and outputs a signal i _LPNFP.

The third adder 43 adds the output signal i _LFQ from the second low-pass filter 13 and the invalid component i _LNPQ from the third arithmetic circuit 41, and outputs a signal i _LPNFQ . The current command gain calculation circuit 48 is a first calculation circuit 1
Active component i _LP and reactive component i of load current from 1
Calculating the _LQ, an output signal i _LPNFP from the second adder 42, a current command from an output signal i _LPNFQ from the third adder 43.

When the current command is smaller than the rated compensation capacity, a current command adjustment gain K = 1 is output.
When the current command is larger than the rated compensation capacity, the current command adjustment gain K = (rated compensation capacity / current command) is output.

That is, if the current command is 125%,
The current command adjustment gain K = 100/125 = 0.8 is output. Then, the multiplier 49 multiplies the output signal (current command) from the first subtractor 16 by the current command adjustment gain K from the current command gain calculation circuit 48, and finally obtains the current command i _{C of the} inverter 4. ^*

Thus, the current command of the inverter 4 can be set within the rated compensation capacity. As mentioned above,
In the control device of the active filter device of the present embodiment, the effective component i _LP and the invalid component i _LQ of the load current, which are the output signals from the first arithmetic circuit 11, and the output signal i from the first low-pass filter 12 _A current command is calculated from the _LFP , the output signal i _LFQ from the second low-pass filter 13, and the effective component i _LNPP and the invalid component i _LNPQ from the third arithmetic circuit 41, and the current command is _equal to or greater than the rated compensation capacity. Then, a current command adjustment gain K is calculated such that the current command becomes the rated compensation capacity, and the current command is multiplied by the current command adjustment gain K to obtain a final current command i of the inverter 4.
_{Since C} ^* is obtained, the same effect as in the first embodiment can be obtained, and in addition, the current command of the inverter 4 can be adjusted within the rated compensation capacity.

(Fourth Embodiment) FIG. 4 is a schematic diagram showing a configuration example of a control device of an active filter device according to the present embodiment. The same parts as those in FIG. The description will be omitted, and only different portions will be described here.

That is, as shown in FIG. 4, the control device of the active filter device according to the present embodiment has a configuration in which a fundamental low-pass filter 50 is added to FIG.
The fundamental wave low-pass filter 50 is connected to the fundamental wave adder 26.
Removing harmonic components of the output signal i _FM from.

The output signal i _FMM from the fundamental wave low-pass filter 50 is input as a subtraction element of the first subtractor 16. Next, the operation of the control device of the active filter device according to the present embodiment configured as described above will be described.

The description of the operation of the same parts as in FIG. 1 is omitted, and only the operation of the different parts will be described here. 4, the fundamental wave pass filter 50 inputs the corrected basic wave three-phase signal i _FM from the fundamental wave adder 26, by removing the harmonic component produced depending on the control unit, modifying the fundamental wave The three-phase signal i _FMM is output.

The first subtractor 16 subtracts the modified fundamental three-phase signal i _FMM from the current detection value i _L of the load 2 by the first current detector 6, and the second subtractor 17 The current detection value i _C of the inverter 4 by the second current detector 7 is subtracted from the output signal i _C ^* from the first subtractor 16.

Then, the PWM circuit 18 outputs the signal i _C
^A gate signal is generated so that ^* and the current detection value i _C of the inverter 4 match, and is provided to the switching element of the inverter 4.

Thus, even when a digital circuit using a microprocessor or the like is used as a circuit for calculating the modified fundamental three-phase signal i _FMM , it is possible to suppress harmonics generated depending on the sampling period. it can.

As described above, in the control device of the active filter device of the present embodiment, the output signal from the fundamental wave adder 26 is input to the fundamental wave low-pass filter 50, and the output signal from the fundamental wave low-pass filter 50 is Since the input is made as a subtraction element of the first subtractor 16,
In addition to obtaining the same effects as those of the first embodiment, the sampling period can also be increased when a digital circuit constituted by a microprocessor or the like is used as a circuit for calculating a fundamental three-phase signal. Can be suppressed.

(Fifth Embodiment) FIG. 5 is a schematic diagram showing a configuration example of a control device of an active filter device according to the present embodiment. The same parts as those in FIG. The description will be omitted, and only different portions will be described here.

That is, as shown in FIG. 5, the control device of the active filter device according to the present embodiment comprises a first setter 61, a first phase adder 62, and a second setter 63.
And a second phase adder 64 are added to FIG.

The output signal from the PLL circuit 9 and the output setting signal from the first setting unit 61 are added by the first phase adder 62 as the phase signal to be input to the second arithmetic circuit 14. The output signal from the PLL circuit 9 and the output setting signal from the second setting unit 63 are used as a phase signal to be input to the second anti-phase component operation circuit 24 by a second phase adder. The configuration is such that the signal added at 64 is used.

Next, the operation of the control device of the active filter device of the present embodiment configured as described above will be described. The description of the operation of the same part as that of FIG. 1 is omitted, and only the operation of the different part will be described here.

In FIG. 5, the first phase adder 62
The output signal θ from the PLL circuit 9 and the output setting signal from the first setting unit 61 are added, and the added signal is added to the second signal.
As a phase signal to the arithmetic circuit 14.

The second phase adder 64 adds the output signal θ from the PLL circuit 9 and the output setting signal from the second setting unit 63, and outputs the added signal to the second opposite phase. It is input as a phase signal to the component operation circuit 24.

On the other hand, the second arithmetic circuit 14 uses the phase signal θ from the first phase adder 62 to
An operation called conversion is performed, and the DC component i _LFP from the first low-pass filter 12 and the DC component i _LFQ from the second low-pass filter 13 are converted into two-phase signals of α-phase and β-phase. The fundamental component of the current 2 is calculated.

The first anti-phase component operation circuit 24 performs the above-mentioned operation called the inverse dq transform using the phase signal θ from the second phase adder 64 to obtain the first anti-phase detection low-pass signal. the output signal i _LNFP from the filter 22, the output signal i _LNFQ from the second reversed phase detector low pass filter 23,
The signal is converted into a two-phase signal of α-phase and β-phase.

The [0115] above, the delay element of the load current time required for calculation of the fundamental arithmetic circuit delay and a load current detector (first current detector 6), the actual corrections fundamental component i _FM of the load current i _L Can be prevented from causing a phase lag with respect to the fundamental wave component.

As described above, in the control device of the active filter device of the present embodiment, the output signal from PLL 9 is used as the phase signal to be input to second operation circuit 14 and second antiphase component operation circuit 24. Since the signals corrected by the first setting device 61 and the second setting device 63 are used, the same effect as that of the first embodiment can be obtained, and the load current fundamental wave Due to the time delay required for the operation of the arithmetic circuit and the delay element of the load current detector,
Since the fundamental wave component of the load current to be detected can be prevented from causing a phase delay with respect to the actual fundamental wave component of the load current, the fundamental wave component can be removed from the load current without a phase delay,
The harmonic detection signal in which the fundamental component of the load current does not remain can be used as the current reference of the active filter device, and the harmonic compensation rate of the active filter device can be increased.

(Other Embodiments) The DC voltage reference setter 34 and the third subtractor 3 in the second embodiment are described.
5, a DC voltage control circuit including an amplifier 36 and a first adder 37; a second three-phase to two-phase conversion circuit 40 and a third arithmetic circuit 41 in the third embodiment; Second
, A third adder 43, a current command gain calculation circuit 48, and a current command adjustment circuit including a multiplier 49. The fundamental wave low-pass filter 50 in the fourth embodiment, In the fifth embodiment, the first setting device 61, the first phase adder 62, and the second setting device 6
3 and the circuit including the second phase adder 64 may be appropriately combined with the configuration added to FIG. In this case, it is possible to simultaneously achieve the functions and effects of the combined embodiments.

[0118]

As described above, according to the control device for an active filter device of the first aspect of the present invention, the load current fundamental wave anti-phase component operation circuit is added, so that the load current fundamental wave is reduced. In the case of unbalance, the unbalanced fundamental wave of the load current for each phase can be detected, and the harmonics of the load current can be detected as in the case of the balanced state. It is possible to prevent the harmonic suppression effect from being reduced.

Further, according to the control device of the active filter device of the present invention, the DC voltage of the inverter is detected, and the difference between the detected value and the DC voltage command is amplified and added to the load current fundamental wave effective component. Therefore, in addition to obtaining the same effect as in the case of the first aspect of the present invention, an effective component of the fundamental wave is added to the current command, and the inverter transfers active power to and from the three-phase AC power supply. Therefore, the DC voltage of the inverter can be controlled to be constant.

Further, according to the control device of the active filter device of the present invention, when the current command exceeds the rated compensation capacity, a gain is calculated so that the current command becomes the rated compensation capacity, and the gain is calculated. Since the current command is multiplied, the same effect as that of the first aspect of the invention can be obtained. In addition, the current command of the inverter is within the rated compensation capacity, and the capacity compensated by the active filter device is reduced. It becomes possible to be rated.

Further, according to the control device of the active filter device of the present invention, the output signal from the fundamental wave adder is input to the fundamental wave low-pass filter, and the output signal from the fundamental wave low-pass filter is converted to the first signal. Since the input is performed as a subtraction element of the subtractor, the same effect as in the case of the first aspect of the invention is obtained. In addition, as a circuit for calculating a fundamental three-phase signal, a microprocessor or the like is used. Since it is possible to suppress the generation of harmonics due to quantization that occurs when a digital circuit is configured using a control device, the control device of the active filter device can be easily digitized.

According to the control device for an active filter device of the invention of claim 5, the second arithmetic circuit and the second arithmetic circuit
Since a signal obtained by correcting the output signal from the phase locked loop by the first setting device and the second setting device is used as the phase signal to be input to the antiphase component calculation circuit of
In addition to obtaining the same effect as in the case of the first aspect of the present invention, the fundamental wave component of the load current detected by the time delay required for the operation of the load current fundamental wave arithmetic circuit and the delay element of the load current detector. Since the phase lag of the load current of the actual fundamental wave component can be compensated, the fundamental wave component can be removed from the load current without a phase lag, and only the harmonic in which the fundamental wave component of the load current does not remain can be detected to detect the active filter device. It is possible to increase the harmonic compensation rate.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment of a control device for an active filter device according to the present invention.

FIG. 2 is a schematic diagram showing a second embodiment of the control device of the active filter device according to the present invention.

FIG. 3 is a schematic diagram showing a third embodiment of the control device of the active filter device according to the present invention.

FIG. 4 is a schematic diagram showing a fourth embodiment of the control device of the active filter device according to the present invention.

FIG. 5 is a schematic diagram showing a fifth embodiment of the control device of the active filter device according to the present invention.

FIG. 6 is a schematic diagram showing a configuration example of a control device of a conventional active filter device.

FIG. 7 is a diagram showing an example of waveforms of respective parts of a control device of a conventional active filter device.

FIG. 8 is a diagram for explaining a problem of a control device of the conventional active filter device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Three-phase AC power supply, 2 ... Load, 3 ... Reactor, 4 ... Inverter, 5 ... Capacitor, 6 ... 1st current detector, 7 ... 2nd current detector, 8 ... Voltage detector, 9 ... PLL Circuit: 10: first three-phase to two-phase conversion circuit, 11: first arithmetic circuit, 12: first low-pass filter, 13: second low-pass filter, 14: second arithmetic circuit, 15: two-phase Three-phase conversion circuit, 16: first subtractor, 17: second subtractor, 18: PWM circuit, 20: anti-phase three-phase to two-phase conversion circuit, 21: first anti-phase component operation circuit, 22 ... A first negative-phase detection low-pass filter, 23 a second negative-phase detection low-pass filter, 24 a second negative-phase component operation circuit, 25 a negative-phase component two-phase to three-phase conversion circuit, 26 a fundamental wave adder, 34: DC voltage reference setter 35: Third subtracter 36: Amplifier 37 ······························································································································· 49, a multiplier; 50, a fundamental wave low-pass filter; 61, a first setter; 62, a first phase adder; 63, a second setter; 64, a second phase adder.

Claims (5)

[Claims] 1. A phase synchronization circuit for generating a phase signal synchronized with a three-phase AC power supply, and a first three-phase circuit for converting a detected current value of a load connected to the three-phase AC power supply from three phases to two phases A two-phase conversion circuit; and a first calculation circuit for calculating an effective component and an invalid component of a load current based on an output signal from the first three-phase to two-phase conversion circuit and an output signal from the phase synchronization circuit. A first low-pass filter that extracts a DC component of an effective component signal from the first arithmetic circuit; a second low-pass filter that extracts a DC component of an invalid component signal from the first arithmetic circuit; The output signal from the low-pass filter and the second
A second arithmetic circuit for calculating the fundamental wave component of the load current in two phases based on the output signal from the low-pass filter and the output signal from the phase locked loop, and the output signal from the second arithmetic circuit A two-phase to three-phase conversion circuit that converts the two-phase to three-phase, and subtracting an output signal from the two-phase to three-phase conversion circuit from the load current detection value to calculate a harmonic component of the load current. A subtractor, wherein the output signal from the first subtractor is used as a current command for an inverter connected in parallel to the load. An anti-phase three-phase to two-phase conversion circuit that converts the anti-phase component of the three-phase to two-phase, based on an output signal from the anti-phase three-phase to two-phase conversion circuit and an output signal from the phase synchronization circuit, Negative phase active component and negative phase of load current A first anti-phase component operation circuit that calculates an effective component; a first anti-phase detection low-pass filter that extracts a DC component of the anti-phase effective component signal from the first anti-phase component operation circuit; A second negative-phase detection low-pass filter that extracts a DC component of the negative-phase invalid component signal from the negative-phase component calculation circuit; an output signal from the first negative-phase detection low-pass filter; and the second negative-phase detection low-pass filter A second negative-phase component arithmetic circuit that calculates the negative-phase fundamental wave component of the load current in two phases based on the output signal from the phase-locked loop and the output signal from the phase-locked loop; A negative-phase component two-phase to three-phase conversion circuit for converting an output signal from the circuit from two-phase to three-phase; and a load current fundamental wave negative-phase component calculation circuit comprising: an output signal from the two-phase to three-phase conversion circuit And the negative-phase component two-phase to three-phase conversion circuit An output signal from a fundamental wave adder for adding the output signal of the first subtractor is input as a subtraction element of the first subtractor. 2. The control device for an active filter device according to claim 1, wherein a third subtractor that outputs a difference between a DC voltage detection value of the inverter and a DC voltage command; and a third subtractor. And an amplifier for amplifying an output signal from the amplifier; and a DC voltage control circuit comprising: an amplifier for adding an output signal from the amplifier to an output signal from the first low-pass filter. Control device for filter device. 3. The control device for an active filter device according to claim 1, wherein a second three-phase two-phase converter converts an output signal from the negative-phase component two-phase to three-phase conversion circuit from three-phase to two-phase. A negative-phase component of the load current is calculated as a positive-phase active component and an invalid-phase component based on an output signal from the second three-phase to two-phase conversion circuit and an output signal from the phase synchronization circuit. A third arithmetic circuit; an output signal from the first low-pass filter;
A second adder for adding an effective component from the arithmetic circuit of the third embodiment, and an output signal from the second low-pass filter and the third adder.
A third adder for adding an invalid component from the arithmetic circuit; an effective component and an invalid component of the load current output from the first arithmetic circuit; an output signal from the second adder; A current command is calculated based on the output signal from the third adder and a current command for calculating a current command adjustment gain such that the current command becomes the rated compensation capacity if the current command is equal to or greater than the rated compensation capacity. A gain operation circuit, a multiplier for multiplying the output signal from the first subtractor by a current instruction adjustment gain from the current instruction gain operation circuit, and a current instruction adjustment circuit comprising: A control device for an active filter device, wherein an output signal is a final current command of the inverter. 4. The control device for an active filter device according to claim 1, further comprising: a fundamental wave low-pass filter for removing a harmonic component of an output signal from the fundamental wave adder; Wherein the output signal is input as a subtraction element of the first subtractor. 5. The control device for an active filter device according to claim 1, wherein the first setter, the first phase adder, the second setter, and the second phase adder are provided. A signal obtained by adding the output signal from the phase synchronization circuit and the output setting signal from the first setting unit by the first phase adder as a phase signal to be input to the second arithmetic circuit. The output signal from the phase locked loop and the output setting signal from the second setting device are added by the second phase adder as a phase signal to be input to the second antiphase component operation circuit. A control device for an active filter device, wherein a signal is used.