JPH10112938A - Active filter device and control thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of a transformer which is essential in a series active filter and control the transformer easily. SOLUTION: This is a device for controlling a series type active filter 5 connected to a power supply system 1 through a transformer. The device includes a higher harmonic waveform holding means 7e which holds the higher harmonic waveforms to be compensated for and a pulse width modulation means 7g which modulates the pulse width of the active filter 5 based on the higher harmonic waves held in the higher harmonic waveform holding means 7e, and so controls the series type active filter 5 that the band of the transformer may be set in correspondence with the higher harmonic waves except for basic waves of the power supply 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active filter device and a control method thereof, and more particularly, to a device and a method for controlling a series active filter connected to a power supply system via a transformer.

[0002]

2. Description of the Related Art At the input stage of an inverter circuit, a capacitor input type rectifier circuit shown in FIG. 6 is generally used in home electric appliances such as air conditioners. In FIG. 6, for each phase of the three-phase AC power supply including the system impedance,
Each phase of the three-phase full-wave rectifier circuit is connected via an AC reactor, a smoothing capacitor is connected between output terminals of the three-phase full-wave rectifier circuit, and a load is connected in parallel with the smoothing capacitor.

In the device having this configuration, the voltage waveform of the u-phase of the three-phase AC power supply is sinusoidal as shown in FIG. 7, and the line voltages Vuv and Vuw between the u-phase of the three-phase AC power supply and other phases.
Is also sinusoidal as shown in FIG.
The corresponding diode of the three-phase full-wave rectifier circuit is turned on only during the period when v and Vuw are higher than the terminal voltage Vdc of the smoothing capacitor. Therefore, the u-phase AC power supply current Is
As shown in FIG. 8, u has a pulse-like distortion waveform having a large valley in a half cycle, and the crest value increases and the power factor decreases. Of course, 5th, 7th, 11th
There are many harmonic components such as the following. And now,
2. Description of the Related Art Since inverter circuits are widely used in home electric appliances, there is a strong demand for reducing harmonic components of AC power supply current.

As a method for reducing the harmonic component of the AC power supply current, an active filter has attracted attention. Here, the active filter is roughly classified into a parallel type and a series type according to a connection method with a power supply system. As shown in FIG. 10, the parallel type active filter is connected in parallel between the output terminal of each phase of the three-phase AC power supply and the AC reactor. A pair of power transistors are connected in series corresponding to the respective phases, and a series connection circuit of these power transistors is connected in parallel between terminals of the capacitor, and a connection point AC reactor of the power transistors in each series connection circuit is connected. Connected to the output terminals of each phase of the three-phase AC power supply.

When the active filter having this configuration is employed, the AC power supply system voltage is directly applied to the power transistor constituting the active filter, and the peak value of the output current is large. When a capacitor input type rectifier circuit widely used in home appliances such as an air conditioner is applied, it is necessary to prevent a compensation current by an active filter from flowing into a stage preceding the rectifier circuit. That is, if the output current of the active filter is ICu, the system impedance of the AC power supply is ZSu, and the impedance of the AC reactor at the preceding stage of the full-wave rectifier circuit is ZLu, the compensation current ICuS flowing to the power supply side is ICuS = ｛ZLu / ( Since ZSu + ZLu)｝ ICu, it is necessary to use an AC reactor having a sufficiently large impedance Lu with respect to the system impedance ZSu in order to set ICuS = ICu in order to obtain a sufficient power supply harmonic reduction effect. FIG.
As shown in the equivalent circuit for one phase, the active filter is controlled as a current source. Therefore, when a voltage-type main circuit configuration is employed, the output of the AC reactor ZCu is also provided.
It is necessary to provide.

FIG. 12 shows the harmonic distribution, and FIG. 13 shows the waveform of each component. On the other hand, a series type active filter is connected in series to a power supply system via a transformer as shown in FIG. This active filter only needs to control voltage harmonics smaller than the fundamental wave, and the output current peak value during the active filter operation is also smaller than the output current peak value of the parallel type active filter.

Further, the series type active filter is operated as a voltage source as shown in FIG. 14 showing an equivalent circuit for one phase. Therefore, the series type active filter can be constituted only by the active filter of the voltage type main circuit, and a separate AC reactor is provided. No need.
FIG. 15 shows the harmonic distribution, and FIG. 16 shows the waveform of each component.

[0008]

As described above, the series-type active filter does not require the addition of an AC reactor and can reduce the capacity of elements such as a power transistor, but requires a transformer. Because
It was thought that it was difficult to apply it directly to an air conditioner where cost reduction was desired.

In a series-type active filter used for three-phase high power, unbalance compensation is performed together with harmonic compensation, so that the negative phase component of the fundamental wave is also included in the compensation target, and The band must be set from the power supply frequency, and the capacity of the active filter increases accordingly.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has an active filter device capable of achieving downsizing of a transformer, which is indispensable in a series active filter, and simplifying control. And a control method thereof.

[0011]

According to a first aspect of the present invention, there is provided an active filter device for controlling a series-type active filter connected to a power supply system via a transformer.
The series active filter is controlled so as to set the band of the transformer corresponding to the harmonics other than the fundamental wave of the power supply.

According to a second aspect of the present invention, there is provided an active filter device for controlling a series type active filter connected to a power supply system via a transformer, wherein the harmonic waveform holding means holds a harmonic waveform to be compensated. And pulse width modulation means for pulse width modulating the active filter based on the harmonics held in the harmonic waveform holding means.

According to a third aspect of the present invention, there is provided an active filter device for controlling a series type active filter connected to a power supply system via a transformer, wherein a harmonic waveform holding means for holding a harmonic waveform to be compensated. And pulse width modulation means for pulse width modulating the active filter based on the harmonics held in the harmonic waveform holding means, and setting the transformer band corresponding to harmonics other than the fundamental wave of the power supply In order to control the series type active filter as much as possible.

According to a fourth aspect of the present invention, the active filter device employs a three-phase power source as a power source, and further includes voltage detecting means for detecting a voltage between any one phase or one line. And a harmonic waveform amplitude setting means for setting the amplitude of the harmonic waveform based on the detected voltage amplitude and supplying the amplitude to the pulse width modulation means. Is what it is.

According to a fifth aspect of the present invention, there is provided an active filter device which supplies a harmonic compensation voltage to an air conditioner via an inverter circuit as a power supply system. In the control method of the active filter device according to the sixth aspect, in controlling the series-type active filter connected to the power supply system via the transformer, the control of the transformer is performed in accordance with harmonics other than the fundamental wave of the power supply. This is a method of controlling a series-type active filter to set a band.

According to a seventh aspect of the present invention, there is provided a method for controlling an active filter device, wherein a harmonic waveform to be compensated is held in controlling a series type active filter connected to a power supply system via a transformer. This is a method of performing pulse width modulation on an active filter based on a held harmonic. The control method of the active filter device according to claim 8 is
In controlling a series-type active filter connected to a power supply system via a transformer, a harmonic waveform to be compensated is held, and the active filter is pulse-width modulated based on the held harmonic. In addition, this method controls the series-type active filter so as to set the band of the transformer corresponding to harmonics other than the fundamental wave of the power supply.

According to a ninth aspect of the present invention, in the active filter device, a series type active filter is inserted on the AC side with reference to a rectifier circuit connected between a power supply system and a load.
The compensation band corresponds to one of the fifth harmonic and the seventh harmonic of the power supply, and controls a series active filter connected to the power supply system via a transformer. According to a tenth aspect of the present invention, the amplitude of the compensation voltage of the fifth harmonic or the seventh harmonic is set so as to flatten a predetermined range including the peak point of the line voltage at the preceding stage of the rectifier circuit.

An active filter device according to claim 11 is
A series-type active filter is inserted on the DC side with reference to a rectifier circuit connected between a power supply system and a load, and a compensation band corresponding to a sixth harmonic of the power supply is supplied to the power supply via a transformer. It controls a series-type active filter connected to the system. According to a twelfth aspect of the present invention, the amplitude and the phase of the compensation voltage of the sixth harmonic are set so as to flatten the rectified voltage ripple of the rectifier circuit.

According to a thirteenth aspect of the present invention, there is provided a method of controlling an active filter device, wherein a compensation band corresponds to one of a fifth harmonic and a seventh harmonic of a power supply and is connected to a power supply system via a transformer. This is a method for controlling the active filter. A method for controlling an active filter device according to claim 14, wherein the amplitude of the compensation voltage of the fifth harmonic or the seventh harmonic is set so as to flatten a predetermined range including the peak point of the line voltage at the preceding stage of the rectifier circuit. It is.

According to a fifteenth aspect of the present invention, a series type active filter is inserted on the DC side with reference to a rectifier circuit connected between a power supply system and a load, and a compensation band is set to the sixth order of the power supply. This is a method of controlling a series type active filter corresponding to harmonics. A control method of an active filter device according to a sixteenth aspect is a method of setting the amplitude of the compensation voltage of the sixth harmonic so as to flatten the rectified voltage ripple of the rectifier circuit.

[0021]

According to the active filter device of the first aspect,
In controlling the series-type active filter connected to the power supply system via the transformer, the series-type active filter is controlled to set the band of the transformer in accordance with harmonics other than the fundamental wave of the power supply. Therefore, it is possible to reduce the magnetic flux density of the transformer core without increasing the cross-sectional area of the transformer core, and thus to downsize the transformer to achieve a reduction in size and cost of the active filter device as a whole. Can be.

According to the active filter device of the present invention, when controlling a series-type active filter connected to a power supply system via a transformer, a harmonic waveform to be compensated is controlled by a harmonic waveform holding means. Since the active filter is pulse-width-modulated by the pulse width modulation means based on the harmonics held by the harmonic waveform holding means, the control of the active filter can be simplified, and Since the control of the active filter can be achieved by an inexpensive microcomputer, a detector, and the like, the cost of the entire active filter device can be reduced.

In the active filter device according to the third aspect, when controlling a series-type active filter connected to a power supply system via a transformer, a harmonic waveform holding for holding a harmonic waveform to be compensated is provided. Means, including pulse width modulation means for pulse width modulation of the active filter based on the harmonics held in the harmonic waveform holding means,
Since the series-type active filter is controlled to set the band of the transformer corresponding to the harmonics other than the fundamental wave of the power supply, the control of the active filter can be simplified, and as a result, inexpensive microcomputers and detectors The control of the active filter can be achieved by, for example, the cost can be reduced as a whole of the active filter device.
In addition, the magnetic flux density of the transformer core can be reduced without increasing the cross-sectional area of the transformer core, and the transformer can be downsized to achieve the downsizing and cost reduction of the active filter device as a whole.

In the active filter device according to the fourth aspect, a three-phase power source is employed as a power source, and further includes voltage detecting means for detecting a voltage between any one phase or one line, and the harmonic waveform holding means includes a detecting means. And outputting a corresponding harmonic waveform in synchronization with the voltage phase, and further comprising a harmonic waveform amplitude setting means for setting the amplitude of the harmonic waveform based on the detected voltage amplitude and supplying the amplitude to the pulse width modulation means. Since it includes, the number of voltage detecting means can be reduced, and further simplification and cost reduction of the active filter device as a whole can be achieved.

In the active filter device according to the fifth aspect, since a device for supplying a harmonic compensating voltage to the air conditioner via an inverter circuit is employed as a power supply system, the influence on the input harmonic distribution is reduced. The effect of load fluctuation is slow,
Even if high-speed control based on the instantaneous value is not applied, there is no concern about a decrease in the compensation performance, so that the device can be configured using an inexpensive microcomputer, etc., and the cost of the active filter device as a whole can be reduced. Can be.

According to the control method of an active filter device of the present invention, in controlling a series type active filter connected to a power supply system via a transformer, it is possible to cope with harmonics other than a fundamental wave of a power supply. In order to set the transformer band by controlling the series active filter, the magnetic flux density of the transformer core can be reduced without increasing the cross-sectional area of the transformer core. Thus, the size and cost of the active filter device as a whole can be reduced.

According to the control method of an active filter device of the present invention, in controlling a series type active filter connected to a power supply system via a transformer, a harmonic waveform to be compensated is held. Since the active filter is pulse-width-modulated based on the retained harmonics, the control of the active filter can be simplified, and the control of the active filter can be achieved with an inexpensive microcomputer or detector. Therefore, the cost can be reduced as a whole of the active filter device.

According to the control method of an active filter device of the present invention, in controlling a series-type active filter connected to a power supply system via a transformer, a harmonic waveform to be compensated is held. Then, the active filter is pulse-width-modulated based on the retained harmonics, and furthermore, the series active filter is controlled to set the transformer band corresponding to the harmonics other than the fundamental wave of the power supply. Therefore, the control of the active filter can be simplified, and the control of the active filter can be achieved with an inexpensive microcomputer, detector, etc., so that the cost of the active filter device as a whole can be reduced, and the transformer core The magnetic flux density of the transformer core can be reduced without increasing the cross-sectional area of the transformer, and the transformer can be downsized. It is possible to achieve miniaturization and cost reduction of the overall active filter device Te.

In the active filter device according to the ninth aspect, the series active filter is inserted on the AC side with reference to a rectifier circuit connected between the power supply system and the load, and the power supply is connected via the transformer. In controlling the series-type active filter connected to the system, the series-type active filter is set so that the compensation band corresponds to one of the fifth harmonic and the seventh harmonic of the power supply and the band of the transformer is set. Since the control is performed, the magnetic flux density of the transformer core can be reduced without increasing the cross-sectional area of the transformer core, and the transformer is downsized to achieve a reduction in size and cost of the active filter device as a whole. Can be
In addition, the capacitance of the switching element constituting the serial active filter can be reduced.

In the active filter device according to the tenth aspect, the amplitude of the compensation voltage of the fifth harmonic or the seventh harmonic is expressed by
Since the predetermined range including the peak point of the line voltage is set so as to be flat, the amplitude of the voltage to be compensated by the series type active filter can be reduced in addition to the effect of the ninth aspect. The capacitance of the switching element forming the filter can be further reduced.

In the active filter device according to the eleventh aspect, the series active filter is inserted on the DC side with reference to a rectifier circuit connected between the power supply system and the load, and the power supply is connected via a transformer. In controlling the series-type active filter connected to the system, the series-type active filter is controlled to set the band of the transformer in accordance with the compensation band corresponding to the sixth harmonic of the power supply. The magnetic flux density of the transformer core can be reduced without increasing the cross-sectional area of the transformer core, and thus the transformer can be downsized to achieve downsizing and cost reduction of the active filter device as a whole. The capacitance of the switching element constituting the active filter can be reduced.

In the active filter device according to the twelfth aspect, the amplitude and the phase of the compensation voltage of the sixth harmonic are set so as to flatten the rectified voltage ripple of the rectifier circuit. In addition, the amplitude of the voltage to be compensated for by the series-type active filter can be reduced, and the capacitance of the switching element constituting the series-type active filter can be further reduced.

According to the method for controlling an active filter device of the thirteenth aspect, a series type active filter is inserted on the AC side with reference to a rectifier circuit connected between a power supply system and a load, and a compensation band is set for the power supply. Since the series active filter connected to the power supply system via the transformer is controlled in correspondence with one of the fifth harmonic and the seventh harmonic, without increasing the cross-sectional area of the transformer core. The magnetic flux density of the transformer core can be reduced, and the transformer can be reduced in size to achieve downsizing and cost reduction of the active filter device as a whole, and furthermore, the capacity of the switching element constituting the series active filter. Can be reduced.

According to the control method of the active filter device of the fourteenth aspect, the amplitude of the compensation voltage of the fifth harmonic or the seventh harmonic can be reduced by flattening a predetermined range including the peak point of the line voltage in the preceding stage of the rectifier circuit. Claim 1 because it is set to be
In addition to the effect of 3, the amplitude of the voltage to be compensated by the series-type active filter can be reduced, and the capacitance of the switching element constituting the series-type active filter can be further reduced.

According to the method for controlling an active filter device of the present invention, a series type active filter is inserted on the DC side with reference to a rectifier circuit connected between a power supply system and a load. In controlling the series-type active filter connected to the power supply system via
Since the series active filter is controlled to set the band of the transformer so that the compensation band corresponds to the sixth harmonic of the power supply, the magnetic flux density of the transformer core can be reduced without increasing the cross-sectional area of the transformer core. The size of the transformer can be reduced, and the size of the transformer can be reduced, so that the size and cost of the active filter device as a whole can be reduced. Further, the capacity of the switching element constituting the series active filter can be reduced.

According to the active filter device of the sixteenth aspect, the compensation voltage of the sixth harmonic is set to flatten the rectified voltage ripple of the rectifier circuit.
In addition to the effect of 5, the amplitude of the voltage to be compensated by the series-type active filter can be reduced, and the capacitance of the switching element constituting the series-type active filter can be further reduced.

[0037]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an electric circuit diagram schematically showing the overall configuration of a system incorporating the active filter device of the present invention, and FIG. 2 is a block diagram also showing a device for controlling the active filter device.

In the system shown in FIG. 1, each terminal of the three-phase AC power supply 1 is connected to each phase of the three-phase full-wave rectifier circuit 2, and a smoothing capacitor 3 is connected between the output terminals of the three-phase full-wave rectifier circuit 2. And a load 4 is connected in parallel with the smoothing capacitor 3. An active filter main circuit 5 in which a series connection circuit of a pair of power transistors corresponding to the respective phases is connected in parallel between terminals of the capacitor,
It is connected to each terminal of the three-phase AC power supply via a transformer 6. Specifically, a connection point between power transistors of each series connection circuit is connected to a corresponding terminal of a three-phase AC power supply via a transformer 6.

In FIG. 2, a three-phase AC power supply 1 has a circuit configuration including an inverter main circuit 4 a and a load 4 b connected thereto via a series active filter main circuit 5 and a rectifier circuit 2. Thus, an active filter control device 7 is added. The inverter main circuit 4a and the load 4b constitute the load 4 in FIG.
The active filter control device 7 includes a phase voltage detector 7a for detecting a phase voltage of the three-phase AC power supply 1, a zero-cross detector 7b for detecting a zero-cross of the detected phase voltage, and a basic circuit based on the detected phase voltage. A fundamental wave voltage effective value calculating unit 7c for calculating an effective value of the wave voltage, a synchronizing unit 7d for outputting a synchronizing signal by performing a phase lock loop process or the like based on the detected zero cross, and compensating for compensating a harmonic. A compensation waveform holding unit 7e for holding a waveform, and a compensation waveform holding unit 7e
A compensation waveform generator (harmonic waveform amplitude setting means) which determines the amplitude of each harmonic of the compensation waveform by using as input the compensation waveform and the effective value of the fundamental wave voltage output from ) 7f and a PWM unit 7g that performs pulse width modulation with the compensation waveform output from the compensation waveform generation unit 7f as input and outputs an ON / OFF signal for each power transistor of the series active filter main circuit 5.
And

The operation of the series-type active filter device having the above-described configuration is as follows. First, when it is assumed that the voltage applied to the transformer 6 is V, the frequency is f, and the number of windings is N, it is known that there is a relationship of Equation 1.

[0041]

(Equation 1)

Here, φm is the magnitude of the magnetic flux generated in the transformer core. Further, assuming that the cross-sectional area through which the magnetic flux passes is S, the magnetic flux density Bm of the transformer core is represented by Equation 2.

[0043]

(Equation 2)

Usually, the saturation magnetic flux density of the iron core is about 1T, and the specifications of the transformer are determined so as not to exceed this. Here, paying attention to Equations 1 and 2, if the frequency f is increased to reduce the magnetic flux φm generated in the transformer core, the magnetic flux density Bm of the transformer core can be reduced without increasing the cross-sectional area S of the transformer core. You can see that it can be done.
The present invention focuses on this point, and can reduce the size of the transformer by restricting the harmonic compensation band of the active filter to the fifth order or higher, and reduce the cost of the series-type active filter as a whole. Can be achieved. Here, the reason for limiting the harmonic compensation band to the fifth or higher order is that even-order harmonics are not generated if the load is balanced, and the 3n-order harmonics (here, n
This is because the frequency f is increased without substantially affecting harmonic compensation, noting that a natural number does not occur.

Further, it goes without saying that a line voltage detector may be employed instead of the phase voltage detector 7a. Furthermore, a single-phase AC power supply can be used instead of the three-phase AC power supply 1. In this case, considering that a balanced load does not generate even-order harmonics, a harmonic compensation band is considered. May be restricted to the third order or higher.

The active filter control device 7 shown in FIG.
Are the voltage harmonics (eg, 5
(7th order, 11th order) waveforms are held, the fundamental wave amplitude is obtained by Fourier calculation of the detected value of the input voltage waveform, and the compensation waveform is calculated based on the held voltage harmonic waveform and the fundamental wave amplitude. Then, the power transistor is synchronized with the power supply, and the power transistor is ON / OFF-controlled by pulse width modulation of the power transistor.

Also, by performing such processing, there is no need to perform complicated arithmetic processing based on the instantaneous waveform of the power supply, and an expensive detector, a computer capable of high-speed processing, and the like can be eliminated. 7. Overall cost reduction can be achieved. Furthermore, since only the harmonics are held as the output waveform of the active filter, the fundamental wave voltage is not output and applied to the transformer, and the above-described small and inexpensive transformer can be employed. .

Further, since the output waveform and the power supply are synchronized to enable voltage output based on the held compensation waveform, the period of Fourier calculation (frequency of amplitude calculation) is, for example, about 1 second. The required control can be achieved using a low-speed and inexpensive microcomputer. This will be described in more detail.

When the active filter is not provided (see FIG. 6), the full wave is applied only during the period when the power supply voltage takes a value close to the peak value, that is, during the period when the power supply voltage becomes higher than the terminal voltage Vdc of the smoothing capacitor. The diode of the rectifier circuit conducts, and the current has a pulse-like distortion waveform as shown in FIG. As a result, power supply harmonic components increase. In order to solve this inconvenience, for example, by applying a voltage VDu + Vn shown by a solid line in FIG. 4B to the u phase shown in FIG. 3 (the broken line is the u-phase voltage of the three-phase AC power supply),
As shown in FIG. 4A, a long conduction period of the u-phase diode can be ensured. Here, Vn is the voltage at the neutral point of the power supply as viewed from the intermediate tap C0 provided artificially in the smoothing capacitor.

The voltages VDv + Vn and VDw + Vn for compensating the reverse bias of the other phases (v-phase and w-phase) may be advanced by 120 ° and −120 °, respectively. Also,
By applying the condition of VDu + VDv + VDw = 0, a voltage Vn shown in (c) of FIG. 4 is obtained, and a voltage Vn shown in (b) of FIG. 4 and a voltage Vn shown in (c) of FIG. 4 are obtained. VDu can be obtained as shown in FIG.

By performing a Fourier transform on this, the following equation (3) is obtained.
Get.

[0052]

(Equation 3)

Where θ is the power supply voltage phase. In Equation 3, the fundamental wave component is the power supply voltage VSu (more precisely, the power supply voltage minus the impedance drop of the power supply system based on the load current), and the harmonic component is the voltage VCu to be compensated in series by the active filter. See (e) in 4｝
Respectively.

Therefore, it is sufficient that the waveform of the voltage VCu shown in FIG. 4E is held in the compensation waveform holding section 7e in FIG. From Equation 3, the relationship between the power supply voltage effective value VS of the fundamental wave and the voltage Vdc between terminals of the smoothing capacitor is Vdc = (π / 21/2) VS. Therefore, the amplitude of each harmonic of the compensation waveform can be determined using this relationship.

In the case of a single-phase power supply, a compensation waveform can be obtained in the same manner. FIG. 5 is a waveform diagram showing a simulation result of a system using the series type active filter device. By adopting the compensation voltage waveform VCu shown in (c ′) in FIG. 5, (a ′) (b) in FIG. ´)
As shown in FIG. 5, the power receiving end voltage VTu and the current ISu can be made substantially sinusoidal, and the harmonic components are significantly reduced as compared with FIGS. 5A and 5B in which the active filter device is not used. can do.

The system shown in FIG. 17 is a three-phase full-wave rectifier circuit 2.
It differs from the system of FIG. 1 only in that a DC reactor (passive filter) 8 is connected between the filter and the smoothing capacitor 3, and other components are the same as those of the system of FIG. 1. The configuration of the device for controlling the active filter device is the same as that of the device shown in FIG.

Therefore, when this system is adopted, the power supply current can be made closer to a rectangular wave (constant current operation) by inserting the DC reactor 8, and the same operation as the above system can be achieved. be able to. Further, in the system shown in FIG. 17, when the harmonic compensation band of the active filter is limited to only the fifth order, the voltage applied to u-phase voltage Vsu of the three-phase AC power supply by series active filter main circuit 5. (Compensation voltage) Vcu ', u-phase voltage Vlu, line voltage Vu
v, Vuw and u-phase current Isu of the three-phase AC power supply are shown in FIG.
As shown in FIG. That is, for example, when the voltage (compensation voltage) Vcu ′ shown in FIG. 18A is applied to the u-phase voltage Vsu of the three-phase AC power supply by the series-type active filter main circuit 5 for the u-phase, FIG. The u-phase voltage Vlu shown in the middle (a) is the u-phase voltage of the three-phase full-wave rectifier circuit 2.
The line voltages Vuv and Vuw supplied to the phase are flattened in a predetermined region including the original peak point as shown in FIG. 18B, and as a result, as shown in FIG. 18C. In addition, a longer conduction period of the u-phase diode can be ensured. Further, in this case, the output ripple after the diode smoothing becomes smaller as compared with the case where the serial type active filter is not used, and the voltages Vuv-Vdc and Vuw-Vdc applied to the DC reactor 8 when the diode is turned on are substantially reduced during the ON period. Can be constant and extremely small. For this reason,
The input current waveform Isu has a rectangular waveform, and the peak value can be reduced as compared with the rectifier circuit.

The compensation voltages of the other phases (v phase, w phase) may be advanced by 120 ° and -120 °, respectively. Further, when the harmonic compensation band of the active filter is limited to only the seventh order, the voltage (compensation voltage) Vcu ′ applied to the u-phase voltage Vsu of the three-phase AC power supply by the series-type active filter main circuit 5, u-phase voltage V
lu, the line voltages Vuv, Vuw and u of the three-phase AC power supply.
The phase current Isu is as shown in FIG.

19 and 18, when the harmonic compensation band of the active filter is limited to only the seventh order, the same as when the harmonic compensation band of the active filter is limited to only the fifth order. It can be seen that the action can be achieved. FIG. 20 is a waveform diagram showing a full-wave rectified voltage waveform as a simulation result of a system using the series-type active filter device, where only the fundamental wave is applied, the fifth harmonic is applied, and the seventh harmonic is applied. 20 and the case where the eleventh harmonic is applied, respectively, in FIGS.
(C) and (d). Then, the phase and amplitude Vc of each harmonic as the compensation voltage were determined so as to flatten (smooth) the vicinity of the peak value of the full-wave rectified voltage. In particular,
At the time of three-phase 200 V input, the amplitude Vc when only the fundamental wave is applied, when the fifth harmonic is applied, when the seventh harmonic is applied, and when the eleventh harmonic is applied is 0 Vrms in effective value. , 8.1 Vrms, 7.5 Vrms,
It was 3.5 Vrms.

Then, as shown in FIG. 24A, a circuit configuration in which the active filter 5 is connected as a voltage source between the three-phase AC power supply 1 and the three-phase full-wave rectifier circuit 2 is adopted. As a result of performing a simulation using the amplitude Vc set as described above, simulation results shown in FIGS. 25 to 28 were obtained. FIG. 30 shows the results of FFT analysis of the AC power supply current Isu in each case. In each of FIGS. 25 to 29,
(A) shows the u-phase AC power supply current Isu, and (b) shows the terminal voltage Vdc of the smoothing capacitor 3. FIG.
At 0, a, b, c, and d indicate the case where only the fundamental wave is applied, the case where the fifth harmonic is applied, the case where the seventh harmonic is applied, and the case where the eleventh harmonic is applied, respectively. . In addition, the input power from the three-phase AC power supply 1 is 2.5
kW and an input voltage of 200 V were employed.

As is apparent from the simulation results, the peak value of the power supply current is flattened (smoothed).
During the diode-on period, the power supply current approaches a constant current operation, that is, a square wave having a pulse width of 2/3 of a half cycle. Of course, the ripple of the DC voltage (the voltage between the terminals of the smoothing capacitor 3) is also greatly reduced. Further, as is clear from the simulation results, it is understood that good harmonic reduction can be achieved by using the fifth harmonic or the seventh harmonic as the compensation waveform. When the fifth harmonic is applied, not only the fifth harmonic component but also the seventh harmonic component of the power supply current is reduced. When the seventh harmonic is applied, the seventh harmonic of the power supply current is reduced. Not only the wave component but also the fifth harmonic component is reduced. The total distortion rate was about 50% when the capacitor input type rectifier circuit was adopted,
When the fifth harmonic was applied, it was reduced to about 28%, and when the seventh harmonic was applied, it was reduced to about 31%.

Assuming that the input voltage is v (the effective value is V) and the input current is i (the effective value is I), the power factor cos φ is expressed by Equation 4.

[0063]

(Equation 4)

Since the input power and the input voltage are determined as described above, the power factor cosφ is determined based on the effective value I of the input current. That is, the lower the total distortion rate is, the lower the effective value I of the input current is, and the power factor cos φ is improved. When the fifth harmonic is applied, the power factor is 0.957.
When the seventh harmonic is applied, the power factor is 0.953.
Met.

Further, it was found that the voltage amplitude required to obtain the smoothing effect as shown in FIG. 20 was less than about 4% of the system line voltage. Therefore, the capacity of the switching element can be significantly reduced, and the size of the transformer can be reduced because the power is small. The system of FIG. 21 differs from the system of FIG. 17 in that a transformer 6 is provided to apply a compensation voltage between the three-phase full-wave rectifier circuit 2 and the DC reactor 8 (DC side) by the series active filter main circuit 5. Significantly different from the system. of course,
Since the compensation voltage is applied on the DC side, the series-type active filter main circuit 5 may be composed of a single capacitor and a switching element connected in a single-phase full bridge, and the configuration can be simplified. Also, the transformer 6 may be one phase, and the configuration can be simplified. However, as shown in FIG. 22, as the series-type active filter main circuit 5, one capacitor and two capacitors connected in series with each other are connected in parallel with each other, and two capacitors connected in series with each other in parallel with each other. A connection point between two capacitors connected in series with each other;
A configuration may be employed in which a compensation voltage is output from a connection point between two switching elements connected in series to each other.

The configuration of the device for controlling the active filter device is different from that of the device of FIG. 2 only in that only a single phase is required. In the system shown in FIG. 21, the harmonic compensation band of the active filter is limited to only the sixth order. When this system is adopted, the line voltage of each phase, the compensation voltage, the DC voltage, the compensated voltage, and the u of the three-phase AC power supply
The phase current Isu is as shown in FIG. That is,
For example, the voltage Vc output by the series active filter main circuit 5 {see FIG.
23, the voltage Vrec at the previous stage of the DC reactor 8 becomes as shown in FIG. 23A, and as a result, as shown in FIG. Can be approximated to a rectangular state, and the peak value can be reduced as compared with the rectifier circuit.

In this case, the voltage Vrec-Vdc applied to the DC reactor 8 when the diode is turned on can be made to have a very small maximum amplitude during the on-time as compared with the case where no active filter is used. Therefore, an effect similar to that of the system of FIG. 17 is obtained. FIG. 20E shows a diode smoothing voltage waveform when the harmonic compensation band is limited to the sixth order, and the voltage amplitude required to obtain the smoothing effect as shown in FIG. Is about 7
It turns out that less than% is enough. Therefore, the capacity of the switching element can be significantly reduced, and the size of the transformer can be reduced because the power is small.

FIG. 20 (e) is a waveform diagram showing a full-wave rectified voltage waveform as a simulation result of a system using the series-type active filter device, in which a sixth harmonic is applied. Then, the phase and the amplitude Vc as the compensation voltage were determined so as to flatten (smooth) the vicinity of the peak value of the full-wave rectified voltage. Specifically, three-phase 200
At the time of V input, the amplitude Vc when the sixth harmonic is applied
Was 18 Vrms in effective value.

Then, as shown in FIG. 24B, a circuit configuration in which an active filter is connected as a voltage source between the three-phase full-wave rectifier circuit 2 and the DC reactor 8 is employed. As a result of performing a simulation by using the amplitude Vc set to the above, the simulation result shown in FIG. 29 was obtained. Also, the FFT of the AC power supply current Isu
The analysis results are shown in FIG. In FIG. 29,
(A) shows the u-phase AC power supply current Isu, and (b) shows the terminal voltage Vdc of the smoothing capacitor 3. In addition, the input power from the three-phase AC power supply 1 is 2.5
kW and an input voltage of 200 V were employed.

As is apparent from the simulation results, the peak value of the power supply current is flattened (smoothed).
During the diode-on period, the power supply current approaches a constant current operation, that is, a square wave having a pulse width of 2/3 of a half cycle. Of course, the ripple of the DC voltage (the voltage between the terminals of the smoothing capacitor 3) is also greatly reduced. Further, as is clear from the simulation results, it is understood that good harmonic reduction can be achieved by employing the sixth harmonic as the compensation waveform. Also, the total distortion rate was about 50% when the capacitor input type rectifier circuit was adopted, but was reduced to about 30% when the sixth harmonic was applied.

Further, when the sixth harmonic was applied, the power factor was 0.956. With these systems,
As well as reducing the harmonics, the power factor is also calculated as follows: power factor = active power / apparent power (where apparent power = total rms of input voltage x total rms of input current total rms = each harmonic FIG. 30 shows the result of the fast Fourier transform analysis of the power supply current because the effective value of the input current is reduced because the square root of the sum of squares of the effective value is obtained.
Can be improved as shown in FIG. In FIG. 30, the horizontal axis indicates the order of the harmonics. In each order, in order from the left, only the rectifier circuit is used, when the fifth harmonic is applied, when the seventh harmonic is applied,
This shows the case where the eleventh harmonic is applied and the case where the sixth harmonic is applied.

When the main circuit of the series type active filter is connected to the AC side as shown in FIG. 17, as a result of the trial production, the power of the fundamental wave flows into the main circuit side of the series type active filter via the transformer 6. As a result, the voltage of the capacitor connected to the main circuit of the series active filter rises,
The following has been found to occur: (1) When the fifth harmonic is output from the active filter, the capacitor voltage becomes a high voltage at which the compensation effect cannot be obtained. (2) When the seventh harmonic is output from the active filter, the capacitor voltage becomes close to the optimum voltage at which the compensation effect can be obtained. In addition, the system shown in FIG.
Even when the power supply current waveform was set to a sine wave in the 37th order, it was found from the results of the trial production that the capacitor voltage was close to the optimum voltage at which the compensation effect was obtained.

For this reason, in the case of (1), it is necessary to provide a discharge resistor at both ends of the capacitor to the extent that the inflowing power is consumed. Also, as a measure to deal with the problem (1),
Excess power for increasing the capacitor voltage can be regenerated to the power supply side by adding an active converter circuit. In the system in which the main circuit of the series type active filter is connected to the DC side as shown in FIG. 21, the above does not occur. Therefore, it is necessary to separately provide a rectifier circuit for securing the capacitor voltage of the active filter circuit. was there.

When the capacitance of the smoothing capacitor of the conventional capacitor input type rectifier circuit is reduced, FIG.
As shown in the leftmost bar graph corresponding to each capacitance in the middle (a) to (c), there is a problem that the distortion rate of the power supply current increases and the DC voltage ripple increases. In consideration of this point, by applying an appropriate compensation voltage (compensation voltage for compensating up to the 37th harmonic) to the AC side using the system shown in FIGS. 1 and 2, the voltage waveform at the preceding stage of the diode bridge is made rectangular. It is preferable to make it wavy,
Since the DC voltage ripple can be reduced, when the capacitance of the smoothing capacitor is reduced to about 1/10, the DC voltage ripple can be reduced sufficiently, and the cost of the entire system decreases with the reduction in the capacitance of the smoothing capacitor. Can be achieved. In addition, as shown in the rightmost bar graph corresponding to each capacitance in FIG. 31, the power supply current distortion rate can be reduced by the action of the active filter. Further, when only the single-order harmonic is compensated, the second bar graph from the left corresponding to each capacitance in FIG. 31 (when a compensation voltage for compensating only the fifth-order harmonic is applied) is obtained. As shown in the third bar graph from the left corresponding to the capacitance (when a compensation voltage for compensating only the sixth harmonic is applied), the power supply is compared with the case where a compensation voltage for compensating up to the 37th harmonic is applied. Although the distortion rate of the current increases, there is almost no change due to the reduction of the capacitance of the smoothing capacitor.The transformer can be downsized, and the DC voltage ripple is sufficiently small, so that further cost reduction can be achieved. it can.

[0075]

According to the first aspect of the present invention, it is possible to reduce the magnetic flux density of the transformer core without increasing the cross-sectional area of the transformer core. This has a specific effect of achieving a reduction in cost and cost.

According to the second aspect of the present invention, the control of the active filter can be simplified, and the control of the active filter can be achieved by an inexpensive microcomputer, detector, and the like. It has a unique effect that it can be performed.
According to the third aspect of the present invention, the control of the active filter can be simplified, and the control of the active filter can be achieved with an inexpensive microcomputer, detector, or the like. Therefore, the cost of the entire active filter device can be reduced. In addition, the magnetic flux density of the transformer core can be reduced without increasing the cross-sectional area of the transformer core, and the transformer can be downsized to achieve the downsizing and cost reduction of the active filter device as a whole. It has a unique effect.

The invention according to claim 4 has a specific effect that the number of voltage detecting means can be reduced, and further simplification and cost reduction can be achieved as a whole of the active filter device. According to the fifth aspect of the present invention, the load fluctuation affecting the input harmonic distribution is slow, and there is no concern about a decrease in the compensation performance without applying high-speed control based on the instantaneous value. It is possible to configure the device, and it is possible to reduce the cost of the active filter device as a whole.

According to the sixth aspect of the present invention, the magnetic flux density of the transformer core can be reduced without increasing the cross-sectional area of the transformer core. This has a specific effect that cost reduction can be achieved. According to the seventh aspect of the present invention, the control of the active filter can be simplified, and the control of the active filter can be achieved by an inexpensive microcomputer, detector, or the like. Therefore, the cost of the entire active filter device can be reduced. It has a unique effect.

According to the eighth aspect of the present invention, the control of the active filter can be simplified, and the control of the active filter can be achieved by an inexpensive microcomputer, detector, or the like. In addition, the magnetic flux density of the transformer core can be reduced without increasing the cross-sectional area of the transformer core, and the transformer can be downsized to achieve downsizing and cost reduction of the active filter device as a whole. It has a unique effect that it can be performed.

According to the ninth aspect of the present invention, the magnetic flux density of the transformer core can be reduced without increasing the cross-sectional area of the transformer core, and the transformer can be downsized to reduce the size of the active filter device as a whole. It is possible to achieve a special effect that cost reduction can be achieved and the capacity of the switching element constituting the series active filter can be reduced.

According to a tenth aspect of the present invention, in addition to the effect of the ninth aspect, the amplitude of the voltage to be compensated by the series active filter can be reduced, and the capacitance of the switching element constituting the series active filter can be further increased. This has a unique effect that it can be reduced. According to the eleventh aspect of the present invention, the magnetic flux density of the transformer core can be reduced without increasing the cross-sectional area of the transformer core, and thus the transformer is downsized to reduce the size and cost of the active filter device as a whole. It is possible to achieve a specific effect that the capacitance of the switching element constituting the series-type active filter can be reduced.

According to the twelfth aspect of the present invention, in addition to the effect of the eleventh aspect, the amplitude of the voltage to be compensated by the series-type active filter can be reduced, and the capacity of the switching element constituting the series-type active filter can be further increased. This has a unique effect that it can be reduced. The invention of claim 13 can reduce the magnetic flux density of the transformer core without increasing the cross-sectional area of the transformer core,
As a result, the size of the transformer can be reduced and the size of the active filter device as a whole can be reduced, and the cost can be reduced. In addition, there is a specific effect that the capacity of the switching element constituting the series active filter can be reduced.

According to a fourteenth aspect of the present invention, in addition to the effect of the thirteenth aspect, the amplitude of the voltage to be compensated by the series type active filter can be reduced, and the capacity of the switching element constituting the series type active filter can be further increased. This has a unique effect that it can be reduced. The invention according to claim 15 can reduce the magnetic flux density of the transformer core without increasing the cross-sectional area of the transformer core,
As a result, the size of the transformer can be reduced and the size of the active filter device as a whole can be reduced, and the cost can be reduced. In addition, there is a specific effect that the capacity of the switching element constituting the series active filter can be reduced.

According to a sixteenth aspect of the present invention, in addition to the effect of the fifteenth aspect, the amplitude of the voltage to be compensated by the series-type active filter can be reduced, and the capacity of the switching element constituting the series-type active filter can be further increased. This has a unique effect that it can be reduced.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram schematically showing an overall configuration of a system incorporating an active filter device of the present invention.

FIG. 2 is a block diagram also showing a device for controlling the active filter device.

FIG. 3 is an equivalent electric circuit diagram showing a relationship among an AC power supply for one phase, a series-type active filter, a rectifier circuit, and a smoothing capacitor.

4 is a diagram showing waveforms of various parts of the electric circuit of FIG. 3 and a conduction period of a diode.

FIG. 5 is a waveform diagram showing a simulation result of a system using a three-phase full-wave rectifier circuit and a series active filter device.

FIG. 6 is an electric circuit diagram showing a rectifier circuit of a capacitor input type.

FIG. 7 is a diagram showing a u-phase voltage waveform of a three-phase AC power supply.

FIG. 8 is a diagram showing u-phase AC power supply current of a three-phase AC power supply.

FIG. 9 is a diagram showing a harmonic distribution of an AC power supply current.

FIG. 10 is an electric circuit diagram showing a configuration of a system using a parallel type active filter.

11 is a diagram showing an equivalent circuit for one phase of the system of FIG. 10;

FIG. 12 is a diagram illustrating a harmonic distribution of a current ILu flowing in a preceding stage of the rectifier circuit.

FIG. 13 is a diagram showing waveforms of respective components of a system using a parallel type active filter.

FIG. 14 is a diagram showing an equivalent circuit for one phase of the system of FIG. 1;

FIG. 15 is a diagram showing a harmonic distribution.

FIG. 16 is a diagram showing waveforms of respective components of a system using a serial type active filter.

FIG. 17 is an electric circuit diagram schematically showing the overall configuration of a system in which the active filter device of the present invention is incorporated on the AC side.

FIG. 18 is a diagram showing waveforms at various parts of the electric circuit of FIG. 17 when a fifth harmonic is applied.

FIG. 19 is a diagram showing waveforms of respective parts of the electric circuit of FIG. 17 when a seventh harmonic is applied.

FIG. 20 is a diagram showing a simulation result of a full-wave rectified voltage waveform.

FIG. 21 is an electric circuit diagram schematically showing an overall configuration of a system in which the active filter device of the present invention is incorporated on the DC side.

FIG. 22 is an electric circuit diagram showing another configuration example of the active filter device.

FIG. 23 is a diagram showing waveforms at various parts of the electric circuit of FIG. 21 when a sixth harmonic is applied.

FIG. 24 is a diagram showing a simulation circuit configuration.

FIG. 25 is a diagram showing a simulation result of a capacitor input type rectifier circuit.

FIG. 26 is a diagram showing a simulation result when a fifth harmonic is applied.

FIG. 27 is a diagram showing a simulation result when a seventh harmonic is applied.

FIG. 28 is a diagram illustrating a simulation result when an eleventh harmonic is applied.

FIG. 29 is a diagram showing a simulation result when a sixth harmonic is applied.

FIG. 30 is a diagram showing an FFT analysis result, a total distortion factor, and a power factor of a power supply current.

FIG. 31 is a diagram showing changes in a power factor, a total distortion factor of a power supply current, and a DC voltage ripple due to a capacitance of a smoothing capacitor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Three-phase AC power supply 4a Inverter main circuit 5 DC-type active filter main circuit 6 Transformer 7a Phase voltage detection part 7e Compensation waveform holding part 7f Compensation waveform generation part 7g PWM part 1 Three-phase AC power supply 5 DC-type active filter main circuit 6 Transformer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02M 7/48 H02M 7/48 R

Claims (16)

[Claims] An apparatus for controlling a series-type active filter (5) connected to a power supply system (1) via a transformer (6), the apparatus being adapted to reduce harmonics other than a fundamental wave of the power supply (1). An active filter device characterized by controlling a series type active filter (5) to set a band of a transformer (6) in a corresponding manner. 2. An apparatus for controlling a series type active filter (5) connected to a power supply system (1) via a transformer (6), wherein the harmonic waveform holds a harmonic waveform to be compensated. Holding means (7e) and harmonic waveform holding means (7
e) pulse width modulating means (7) for pulse width modulating the active filter (5) based on the harmonics held in
g). 3. An apparatus for controlling a series type active filter (5) connected to a power supply system (1) via a transformer (6), wherein the harmonic waveform holds a harmonic waveform to be compensated. Holding means (7e) and harmonic waveform holding means (7
e) pulse width modulating means (7) for pulse width modulating the active filter (5) based on the harmonics held in
g) and controlling the series active filter (5) to set the band of the transformer (5) in accordance with harmonics other than the fundamental wave of the power supply (1). . 4. A power supply (1) is a three-phase power supply,
Voltage detecting means (7) for detecting a voltage between phases or one line.
a), the harmonic waveform holding means (7e) outputs a corresponding harmonic waveform in synchronization with the detected voltage phase, and sets the amplitude of the harmonic waveform based on the detected voltage amplitude to perform pulse width modulation. 4. The active filter device according to claim 2, further comprising a harmonic waveform amplitude setting means (7f) for supplying to the means (7g). 5. The power supply system (1) includes an inverter circuit (4).
The active filter device according to any one of claims 1 to 4, wherein an operating voltage is supplied to the air conditioner via a). 6. A method for controlling a series type active filter (5) connected to a power supply system (1) via a transformer (6), the method comprising controlling harmonics other than a fundamental wave of the power supply (1). A control method for an active filter device, comprising: controlling a series active filter (5) to set a band of a transformer (6) in a corresponding manner. 7. A method for controlling a series type active filter (5) connected to a power supply system (1) via a transformer (6), wherein a harmonic waveform to be compensated is held, A method for controlling an active filter device, comprising performing pulse width modulation on an active filter (5) based on a held harmonic. 8. A method for controlling a series type active filter (5) connected to a power supply system (1) via a transformer (6), wherein a harmonic waveform to be compensated is held, Pulse width modulation of the active filter (5) based on the held harmonics, and furthermore, a series type to set the band of the transformer (6) corresponding to the harmonics other than the fundamental wave of the power supply (1). A method for controlling an active filter device, comprising controlling an active filter (5). 9. An apparatus for controlling a series type active filter (5) connected to a power supply system (1) via a transformer (6), the series type active filter (5).
Is inserted on the AC side with reference to the rectifier circuit (2) connected between the power supply system (1) and the load, and the compensation band is set to the fifth harmonic and the seventh harmonic of the power supply (1). An active filter device characterized by controlling a series type active filter (5) in correspondence with one of them. 10. The active filter according to claim 9, wherein the amplitude of the compensation voltage of the fifth harmonic or the seventh harmonic is set so as to flatten a predetermined range including the peak point of the line voltage at the preceding stage of the rectifier circuit. apparatus. 11. Power supply system (1) via a transformer (6)
For controlling a series-type active filter (5), which is connected to a serial-type active filter (5).
Is inserted on the DC side with reference to the rectifier circuit (2) connected between the power supply system (1) and the load, and the compensation band is connected in series with the sixth harmonic of the power supply (1). An active filter device for controlling an active filter (5). 12. An amplitude and a phase of a compensation voltage of a sixth harmonic,
The active filter device according to claim 11, wherein the rectifier circuit (2) is set to flatten the voltage ripple after rectification. 13. A power supply system (1) via a transformer (6).
A method for controlling a series-type active filter (5) connected to a serial-type active filter (5)
Is inserted on the AC side with reference to the rectifier circuit (2) connected between the power supply system (1) and the load, and the compensation band is set to one of the fifth harmonic and the seventh harmonic of the power supply (1). A control method for an active filter device, characterized by controlling a series active filter (5) in a corresponding manner. 14. The active filter according to claim 13, wherein the amplitude of the compensation voltage of the fifth harmonic or the seventh harmonic is set so as to flatten a predetermined range including the peak point of the line voltage at the preceding stage of the rectifier circuit. How to control the device. 15. Power supply system (1) via a transformer (6)
A method for controlling a series-type active filter (5) connected to a serial-type active filter (5)
Is inserted on the DC side with reference to a rectifier circuit (2) connected between a power supply system (1) and a load, and a series active filter is provided with a compensation band corresponding to the sixth harmonic of the power supply (1). (5) A method for controlling an active filter device, characterized by controlling (5). 16. The amplitude and phase of the compensation voltage of the sixth harmonic are
The control method of an active filter device according to claim 15, wherein the rectification circuit (2) is set to flatten the voltage ripple after the rectification.