KR20170027178A - Power conversion system having filters utilizing the phase of voltage harmonics - Google Patents

Power conversion system having filters utilizing the phase of voltage harmonics Download PDF

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Publication number
KR20170027178A
KR20170027178A KR1020150123787A KR20150123787A KR20170027178A KR 20170027178 A KR20170027178 A KR 20170027178A KR 1020150123787 A KR1020150123787 A KR 1020150123787A KR 20150123787 A KR20150123787 A KR 20150123787A KR 20170027178 A KR20170027178 A KR 20170027178A
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South Korea
Prior art keywords
phase
converter
filter
harmonic
filter unit
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KR1020150123787A
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Korean (ko)
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설승기
온성재
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서울대학교산학협력단
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Priority to KR1020150123787A priority Critical patent/KR20170027178A/en
Priority to PCT/KR2016/001633 priority patent/WO2017039090A1/en
Publication of KR20170027178A publication Critical patent/KR20170027178A/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H02M1/126—Arrangements for reducing harmonics from ac input or output using passive filters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/06—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
    • H02M7/08—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode arranged for operation in parallel
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F37/00—Fixed inductances not covered by group H01F17/00
    • H02M2001/0064—

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

Embodiments of the present invention relate to a power conversion apparatus having a filter using a phase of voltage harmonics. The power conversion apparatus comprises: a converter unit including a plurality of three-phase converter which are connected in parallel in three or a multiple of three; a filter unit; and a load unit. The converter unit includes first to third converters having outputs of phases a, b, and c, respectively. The filter unit includes at least one among a normal harmonic filter unit, a reverse harmonic filter unit, and an image harmonic filter unit. The filter unit can be composed of a passive element. The power conversion apparatus not only can restrain current harmonics flowing to a three-phase current load/power source, but also can significantly reduce current harmonics autonomously flowing in each converter.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a power conversion apparatus having a filter using an image of voltage harmonics,

The present invention relates to a power conversion apparatus having a filter for suppressing harmonic components, and more particularly, to a power conversion apparatus including a filter unit using phases of respective voltage harmonics of a three-phase converter operating in parallel at three or three multiples, .

Various circuit configurations have been considered in order to connect large-capacity energy sources such as new and renewable energy to the system. For PWM converters, power and power factor controls are widely used because they are free, relatively efficient, and have low current harmonics. In addition, PWM inverters are widely used to drive large capacity motors.

The PWM voltage waveform contains many voltage harmonics and is usually connected to a passive filter between the power supply (load) and the PWM converter in order to meet the stringent harmonic specifications of the system or to suppress the harmonic current to the motor Is used. In the case of power converters with several MVA to several tens of MVA, these filters, especially the magnetic core, account for a significant portion of the volume and cost of the system. Therefore, various filters to effectively suppress current harmonics with only a small volume and a minimum number of passive elements Are used.

1 (a) to 1 (c) are three examples of filters widely used in existing grid-connected power converters. 1 (a) is a filter made only of an inductor. In the case of the inductor, the higher the frequency, the larger the impedance, which can suppress the current harmonics. However, to meet the stringent harmonic specifications of the system, a significantly larger inductor is required. 1 (b) is an LCL filter composed of two inductors and one capacitor, and is widely utilized in a grid-connected converter. The LCL filter can attenuate -60 dB / dec at a frequency higher than the resonant frequency of the filter. Therefore, the LCL filter can attenuate current harmonics sufficiently even with passive elements of a smaller size than a filter using an inductor alone as shown in FIG. 1 (a).

However, the resonance by the added capacitor causes the stability problem of the power conversion system, and careful design is needed considering this. In the case of the LLCL filter shown in FIG. 1 (c), an inductor connected in series with the capacitor is added in the LCL filter structure in view of the fact that the magnitude of the current harmonic is larger in the switching frequency band than in the other frequency band. The added inductor allows very high attenuation in certain frequency bands to meet grid current harmonic limits with smaller passive components.

2 (a) is a circuit diagram for explaining an interleaving operation, 2 (b) represents a phase difference of a triangle wave of each converter, and 2 (c) represents a cancellation of current pulsation due to a phase difference of a triangle wave. .

Referring to FIGS. 2 (a) to 2 (c), the phase of the current harmonic between the converters can be changed by shifting the phase of the triangular wave of the converter connected in parallel as shown in FIG. 2 (a) have. As a result, current pulsations having different phases are offset from each other at the output current as shown in FIG. 2 (c), so that the harmonic characteristic of the power source (load) side current can be improved.

However, the interleaving operation has no effect on the converter's own current harmonics. Current harmonics in the converter itself increase additional losses in the filter, increase conduction loss and switching loss in the power semiconductors, and increase the rated current of the power semiconductors required for the power conversion circuit. Therefore, when interleaving, a considerable size filter is required to reduce the converter's own current harmonics.

Fig. 3 (a) shows a coupled inductor used in interleaving operation in many applications, and Fig. 3 (b) is a circuit diagram showing a coupled inductor. Fig. 3 (c) is also a circuit diagram showing the connection between the coupling inductors and the converter output on any one phase when the coupling inductor is used in three parallel-connected three-phase converters.

The coupling inductor utilizes the phase difference between converter current harmonics when interleaving. In this filter structure derived from a DC-DC converter, windings are connected to a magnetic core as shown in FIG. 3 (a). The flux due to the Fundamental Term for power transfer among the converter currents cancel each other in the magnetic core, while in the case of harmonic currents having different phases, the magnetic flux is superimposed in the core. This provides a very small impedance for the fundamental wave current, while it provides a large impedance for the phase-shifted harmonic currents by interleaving, thereby suppressing the converter's own current harmonics.

The structure of the magnetic core for implementing the coupling inductor when the N converters are connected in parallel is various. For example, a combinatorial cascade structure as shown in FIG. 3 (c) is often used. This structure avoids the problem that the magnetic core is saturated by the fundamental current, but the number of cores required for parallel connection of N converters increases to N (N-1) / 2. For example, when three converters are operated in parallel, three magnetic cores are required on one phase as shown in FIG. 3 (c), requiring nine magnetic cores in total for a three-phase system.

4 is a common-mode filter widely used for suppressing the circulating current of the Zero sequence component during EMI (Electro-Magnetic Interference) filtering and converter parallel operation. The common mode filter uses the phase difference existing between the three phases. Using the phase difference between the three phases, the magnetic flux due to the fundamental wave current is canceled in the magnetic core, and in the case of the image minute current having the same magnitude and phase in the three phases, the magnetic flux is superimposed on each other in the core, The minute current can be effectively suppressed even with a small-sized magnetic core. However, the attenuation effect can not be obtained for current harmonics other than the image minute current.

5 is a graph showing the voltage harmonics of the output voltage of the three-phase converter of the power inverter according to the fraction of the voltage harmonic. Here, 'phase difference' refers to a positive sequence component, a negative sequence component, and an image component classified according to the phase difference between three-phase voltages. Referring to FIG. 5, the phase of the converter output voltage at a predetermined output frequency 51 is determined by the control of the control unit, and the image minute voltage harmonic 52 exists at a multiple of the output frequency. Also, in the case of the voltage harmonics 53 appearing around the frequency which is an integral multiple of the switching frequency of the converter, a normal minute and a negative phase image are displayed.

That is, when the coupling inductor as shown in FIG. 3 is connected to power conversion devices whose triangular waves are phase-shifted with each other as shown in FIG. 2, the phase-shifted current harmonic can be reduced. However, in the case of the three-parallel converter, since a large number of magnetic cores are required depending on the structure of the coupling inductor, or the practical implementation is difficult, the common-mode inductor shown in FIG. 4 is usually used only for the two- , It is possible to effectively reduce the harmonic current of the image minute current, but the harmonic of the normal minute or reverse phase current can not be reduced in addition to the image minute current harmonic.

In order to solve the above problems, according to the present invention, a phase of a voltage harmonic divided into a normal component, a reverse phase, and a video image and a phase shift of a voltage harmonic by interleaving are simultaneously used according to a phase difference between three- It is an object of the present invention to realize a passive filter that greatly attenuates current harmonics. The goal is to reduce the size and cost of passive components to suppress current harmonics in power conversion systems using three-phase PWM converters. This method not only suppresses the current harmonics flowing to the three-phase AC load / power supply, but also greatly reduces the current harmonics flowing through each converter itself.

According to an aspect of the present invention, there is provided a power conversion apparatus having a filter using phase difference of voltage harmonics, including a converter section including a plurality of parallel-connected three-phase converters, a filter section, and a load section, phase, c-phase, and wherein the filter unit includes at least one of a normal harmonic harmonic filter unit, a reverse-phase harmonic filter unit, and an image harmonic-harmonic filter unit, Device.

In the power conversion apparatus having a filter using a phase component of a voltage harmonic according to an embodiment, the normal harmonic filter unit may include a phase a of the first converter, a phase c of the second converter, and a b phase output of the third converter, A phase of the first converter, a phase of the first converter, a phase of the first converter, a phase of the first converter, a phase of the first converter, a phase of the first converter, And a third steady-state filter receiving the a-phase output of the third converter.

The inverse phase component harmonic filter unit may be configured to convert the a phase of the first converter, the b phase of the second converter, and the c phase output of the third converter into an input A c-phase of the first converter, a-phase of the second converter, a b-phase of the second converter and a b-phase of the first converter, which receives the b-phase output of the third converter, And a third reverse phase filter receiving the a phase output of the third converter.

According to an embodiment of the present invention, there is provided a power conversion apparatus having a filter using a phase component of a voltage harmonic, wherein the image component harmonic filter unit comprises: a first image minuter filter receiving the a-, b-, and c- 2 phase converter, a b-phase, and a c-phase output of the second converter, and a third image filter that receives the a-phase, b-phase, and c-phase outputs of the third converter.

The phase connection order of each of these converters can be varied in various forms while having various functions.

In the power conversion apparatus having the filter using the phase component of the voltage harmonic according to an embodiment, the filter unit may include a normal harmonic filter unit, a reverse phase harmonic filter unit, and an image harmonic filter unit. The normal phase harmonic filter unit, the reverse phase harmonic frequency filter unit, and the video signal harmonic frequency filter unit may include a circular core or an EI core, a CI core, a cylindrical core, And a core in which three EI cores for the normal, negative, and negative harmonic filter portions are integrated into one magnetic core, respectively.

The triangular wave of the second converter is shifted by 120 degrees from the triangular wave of the first converter and the triangular wave of the third converter is shifted by 120 degrees from the triangular wave of the first converter. 1 converter with a phase angle of 120 [deg.] With respect to the triangular wave of the converter.

The power conversion apparatus may further include a controller for adjusting the phase of the triangular waves of the first to third converters in the power conversion apparatus having the filter using the phase difference of the voltage harmonic according to an exemplary embodiment.

In a power conversion apparatus having a filter utilizing a phase fraction of a voltage harmonic according to an embodiment, the power conversion apparatus further includes an additional filter unit, wherein the additional filter unit may include one or more inductors or capacitors.

The power converter according to an embodiment of the present invention has a filter using a phase difference of voltage harmonics, wherein the additional filter unit includes a point of common coupling (PCC) formed at an output terminal of the filter unit, As shown in FIG.

According to the embodiment of the present invention, the harmonic filter and the power conversion device using the phase of the voltage harmonic are composed of three converters connected in parallel and a magnetic core in which the alternating current ends of the respective converters are properly connected.

The magnetic flux due to the harmonic current component is superimposed on each other in the core to effectively suppress most of the current harmonics, while the magnetic flux due to the fundamental current component is canceled out in the core. Since the magnitude of the current harmonic is usually very small compared to the fundamental wave current, the size of the magnetic core can be very small because the size of the magnetic core is designed only considering the harmonic current. In addition, it is easy to implement because it can apply the forms of magnetic cores that have been used previously. When a capacitor is used as shown in FIGS. 1 and 2, a harmonic current reduction effect can be obtained.

1 (a) to 1 (c) are three examples of filters widely used in existing grid-connected power converters.
2 (a) is a circuit diagram for explaining an interleaving operation, 2 (b) shows a phase difference between two triangular waves, and 2 (c) shows a cancellation of a current pulsation due to a phase difference.
Fig. 3 (a) shows a coupled inductor used in interleaving operation in many applications, and Fig. 3 (b) is a circuit diagram showing a coupled inductor. 3 (c) is a circuit diagram showing a case where coupling inductors are connected to a 3-parallel converter in a combinatorial cascade structure.
FIG. 4 is a common-mode filter widely used for suppressing an image circulating current during EMI (Electro-Magnetic Interference) filtering and converter parallel operation.
5 is a graph showing the voltage harmonics of the output voltage of the three-phase converter of the power inverter according to the fraction of the voltage harmonic.
6 is a block diagram of a power conversion apparatus 1000 having a filter using a phase difference of voltage harmonics according to an embodiment of the present invention, and FIG. 7 is a block diagram of a filter unit 200 of the power conversion apparatus 1000 .
8 (a), 8 (b) and 8 (c) show the pager of the normal voltage harmonic in the switching frequency bands of the first converter 110, the second converter 120 and the third converter 130 Phasor).
9 (a) to 9 (c) show an example of the first to third image partial filters 211 to 213 when the image component harmonic filter unit 210 is a common mode filter using a circular core.
10 (a) to 10 (c) show an example of the first to third normal frequency filters 221 to 223 when the normal harmonic filter unit 220 is a common mode filter using a circular core.
Figs. 11A to 11C show examples of the first to third antiphase filters 231 to 233 when the antiphase harmonic filter unit 230 is a common mode filter using a circular core.
12 (a) to 12 (c) illustrate a case where each of the normal harmonic filter unit 210, the reverse-phase harmonic filter unit 220, the image harmonic harmonic filter unit 230, As shown in Fig.
13 (a) and 13 (b) show experimental results of implementing the filter unit 200 using the EI core.

Embodiments described herein may be wholly hardware, partially hardware, partially software, or entirely software. A "unit," "module," "device," or "system" or the like in this specification refers to a computer-related entity such as a hardware, a combination of hardware and software, or software. A processor, an object, an executable, a thread of execution, a program, and / or a computer, for example, a computer, but is not limited to, a computer. For example, both an application running on a computer and a computer may correspond to a part, module, device or system of the present specification.

Hereinafter, the structure and characteristics of the present invention will be described with reference to examples, but the present invention is not limited to these examples. Where similar reference numerals are used in the several figures, like reference numerals refer to the same or similar functions for various embodiments.

In the following description, the term " converter " is an interchangeable component of an inverter, and the term " converter " may include a converter or an inverter.

6 is a block diagram of a power conversion apparatus 1000 having a filter using a phase difference of voltage harmonics according to an embodiment of the present invention, and FIG. 7 is a block diagram of a filter unit 200 of the power conversion apparatus 1000 .

Referring to FIG. 6, a power conversion apparatus 1000 having a filter using phase harmonics includes a converter unit 100 including a plurality of parallel-connected three-phase converters, a filter unit 200, and a load unit 300 . The load section 300 may be an electric motor as an AC load.

The converter unit 100 may include first to third converters 110 to 130 connected in parallel. Each converter also has an a-phase, b-phase, and c-phase output. In the following description and drawings, the a-phase output of the first converter is denoted by a1 and the c-phase output of the second converter is denoted by c2 in order to clarify the description. Therefore, b3 represents the b-phase output of the third converter.

The triangular wave of the second converter 120 is shifted by 120 degrees from the triangular wave of the first converter 110 and the triangular wave of the third converter 130 is shifted by 120 degrees from the triangular wave of the first converter 110 And can be controlled by the control unit 102. For example, the control unit 102 may adjust the switching timings of the converters 110-120 to adjust the phase of the voltage harmonics of the respective converters.

8 (a), 8 (b) and 8 (c) show the switching frequencies of the first converter 110, the second converter 120 and the third converter 130,

Figure pat00001
And the phasor diagram of the harmonics of the normal voltage in the band. 8A, 8B and 8C, the second converter 120 is adjusted so as to be shifted by 120 degrees with respect to the first converter 110, and the third converter 130 is adjusted And the first converter 110 is adjusted to be ahead by 120 degrees with respect to the first converter 110. The leading and lagging of this 120 ° phase can be reversed between the converters, and thus the order of connection of the converters to the normal, negative, and negative image filters may change.

The converters 110 to 130 connected in parallel generate a three-phase voltage and a video voltage from the DC power supply unit 101 according to a control signal for controlling the current of each converter. Each of the converters 110-130 outputs the load power equally divided and may share a control unit for interleaving operation or may have a control unit for each converter. If there is a control unit for each converter, there may be a communication link for synchronization between the control units. The converters 110 to 130 are circuits for three-phase AC / DC power conversion, and various circuit configurations such as multi-level converters are possible.

Although three converters 110 to 130 are shown in FIG. 6, this is merely an example of the present invention, and may further include additional multiples of three.

7, the filter unit 200 may include at least one of an image component harmonic filter unit 210, a normal component harmonic filter unit 220, and a reverse phase component harmonic filter unit 230. In a preferred embodiment, the filter unit 200 may be configured only as a passive element.

Phase harmonic filter unit 210 and the normal-harmonic harmonic filter unit 220 and the inverse-phase harmonic filter unit 230 may be connected in series, and the order of connection of the filter units 210-230 is shown in FIG. 7 It is not limited to bars.

The image signal harmonic filter unit 210 includes a first image signal filter 211 receiving the a-phase, b-phase, and c-phase outputs of the first converter 110, a second image filter 212 for receiving the c-phase output, and a third image filter 213 for receiving the a-phase, b-phase, and c-phase outputs of the third converter. Each filter 211-213 can reduce the image component harmonic component of the AC signal transmitted from each of the converters 110-130.

9 (a) to 9 (c) show a case where the image component harmonic filter unit 210 is a common mode filter using a circular core. 9 (a) to 9 (c) show an example of the first to third image partitioning filters 211 to 213, respectively.

The normal harmonic filter unit 220 includes a first steady state filter 221 for receiving the a phase of the first converter, the c phase of the second converter, and the b phase of the third converter 221, the b phase of the first converter, A c phase of the first converter, a b phase of the second converter, and an a phase output of the third converter are input to the second normalizer filter 222 receiving the a phase of the second converter, the c phase output of the third converter, And a third stationary filter 223.

10 (a) to 10 (c) show the first to third normal frequency filters 221 to 233, respectively, in the case where the normal harmonic filter unit 220 is a common mode filter using a circular core. As shown in Fig. That is, the filters shown in Figs. 10 (a) to 10 (c) are the same as those of the current harmonics due to the voltage harmonics shown in Fig. 8,

Figure pat00002
It is possible to attenuate the normal-minute current harmonics in the band.

If the parallel-connected converters share the same power, since the magnitude of the fundamental wave current is the same, the magnetic flux due to the fundamental wave current is canceled in the core through the connection as shown in FIG. 10, In the case of harmonics, magnetic fluxes are superimposed on each other in the core, and the magnetic core can provide a large impedance. Therefore, according to the embodiment, since the magnetic flux due to the fundamental wave current is not formed in the core, it can be realized as a magnetic core of a small size, while the magnetic flux due to the current harmonic superimposes on each other to effectively suppress the current harmonic.

The connection of each filter of the reverse phase component harmonic filter unit 230 can be determined as follows.

The inverse phase component harmonic filter unit 230 includes a first inverse-phase filter 231 receiving the a-phase of the first converter, the b-phase of the second converter, and the c-phase output of the third converter, the c- A second inverse-phase filter 232 for receiving the a-phase of the second converter, the b-phase output of the third converter, and the c-phase of the first converter, the a-phase of the second converter, and the b- And a third reverse phase component filter 233.

11 (a) to 11 (c) illustrate the case where the anti-phase harmonic filter unit 230 is a common mode filter using a circular core. FIGS. 11 ). ≪ / RTI > That is, the filters shown in Figs. 11 (a) to 11 (c) are the switching harmonics of the current harmonics due to the voltage harmonics shown in Fig. 8,

Figure pat00003
It is possible to attenuate the antiphase current harmonic in the band.

Accordingly, the normal harmonic filter unit 220 and the inverse-phase harmonic filter unit 230 are connected to the switching frequency

Figure pat00004
It is possible to reduce the normal harmonic and the reverse-phase current harmonic in the band.

In one example, the filter unit 200 may include both the normal harmonic filter unit 220, the inverse-phase harmonic filter unit 230, and the image harmonic filter unit 210. In this case, image minus, normal minus, and reverse phase harmonic can be reduced. When the normal harmonic filter unit 220, the inverse-phase harmonic filter unit 230, and the image harmonic-wave filter unit 210 are formed as circular cores, the image harmonic, the normal harmonic, and the reverse- The harmonics can be reduced.

In the above description, the normal harmonic filter unit 220, the inverse-phase harmonic filter unit 230, and the image harmonic-harmonic filter unit 210 are formed of circular cores. However, in another embodiment, And the image minus filter units 210-230 may be composed of EI cores. Further, the present invention is not limited to the circular core and the EI core.

12 (a) to 12 (c) show an example of the filter unit 200 configured using the EI core. 12 (a), 12 (b), 12 (b) and 12 (c), the normal harmonic filter unit 12 (c)).

In one embodiment, the power conversion apparatus 1000 having a filter that uses the phase fraction of the voltage harmonic may further include the additional filter unit 400. [ The additional filter section 400 may be configured to include one or more inductors or capacitors. For example, the additional filter unit 400 may include the conventional filters described with reference to Figs. 1 (a) to 1 (c). In particular, the additional filter unit 400 can reduce the current harmonics in the three-fold switching frequency band (3f sw , 6f sw , 9f sw ...).

6, the additional filter unit 400 is connected to the PCC 201 (the point of common coupling 201) formed at the output end of the filter unit 200 and the load unit 300 or to the respective converters It is possible. For example, the additional filter unit 400 may be connected to the outputs of 211 to 213 or 221 to 223 or 231 to 233.

13 (a) and 13 (b) show experimental results of implementing the filter unit 200 using the EI core. Fig. 13 (a) shows the load current waveform, and Fig. 13 (b) shows the converter current waveform. Referring to FIG. 13 (a), through 120 ° interleaving, most of the current harmonics cancel each other to show a low total harmonic distortion (THD). Also, referring to FIG. 13 (b), the phase-shifted normal-phase and quadrature-phase current harmonics and the image minute current are effectively suppressed through the proposed filter, so that a current close to a sinusoidal wave similar to the system- .

The power conversion apparatus according to the present invention can be widely used in a large-capacity power conversion system that requires parallel operation of an AC-DC power conversion apparatus, or in applications requiring miniaturization of the entire power conversion system having an EMI filter through triangular wave phase shift .

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

1. A power conversion apparatus having a filter using a phase harmonic of voltage harmonics, comprising a converter section including a plurality of three-phase converters connected in parallel at a multiple of 3 or 3, a filter section, and a load section,
The converter section includes first to third converters each having an a-phase, a b-phase, and a c-phase output,
Wherein the filter unit includes at least one of a normal harmonic filter unit, a reverse-phase harmonic filter unit, and an image harmonic filter unit,
Wherein the filter unit is composed of a passive element.
The method according to claim 1,
Wherein the normal harmonic filter unit comprises:
A first normal frequency filter receiving the a-phase of the first converter, the c-phase of the second converter, and the b-phase output of the third converter;
A second normal frequency filter receiving the b-phase of the first converter, the a-phase of the second converter, and the c-phase output of the third converter; And
And a third constant-frequency filter receiving the c-phase of the first converter, the b-phase of the second converter, and the a-phase output of the third converter.
The method according to claim 1,
The inverse-phase component harmonic-
A first reverse-phase filter receiving the a-phase of the first converter, the b-phase of the second converter, and the c-phase output of the third converter;
A second reverse phase filter receiving the c-phase of the first converter, the a-phase of the second converter, and the b-phase output of the third converter; And
And a third phase-reversal frequency filter for receiving the b-phase of the first converter, the c-phase of the second converter, and the a-phase output of the third converter.
The method according to claim 1,
Wherein the image component harmonic filter unit comprises:
A first image min filter receiving the a-phase, b-phase, and c-phase outputs of the first converter;
A second image min filter receiving the a-phase, b-phase, and c-phase outputs of the second converter; And
And a filter using a phase division of a voltage harmonic having a third image min filter receiving the a-phase, b-phase, and c-phase outputs of the third converter.
The method according to claim 1,
Wherein the filter unit includes a normal harmonic filter unit, a reverse-phase harmonic filter unit, and an image minus harmonic filter unit.
The method according to claim 1,
The EI core, the EI core, the CI core, the cylindrical core, and the three EI cores for the normal, antiphase, and image component harmonic filter units are connected to the first, second, Wherein the core is formed of at least one of a core integrated into a magnetic core and a core integrated into a magnetic core.
The method according to claim 1,
The second converter has a triangular wave phase shifted by 120 degrees from the first converter,
Wherein the third converter has a triangular wave phase that is 120 DEG ahead of the first converter.
The method according to claim 1,
Further comprising a controller for adjusting a phase of a triangular wave of the first to third converters.
The method according to claim 1,
Further comprising an additional filter section,
Characterized in that the additional filter section comprises at least one inductor or capacitor.
9. The method of claim 8,
Wherein the additional filter unit comprises:
Wherein the filter is formed between a point of common coupling (PCC) formed at an output terminal of the filter unit and an output terminal of the filter unit or between the load unit and the filter unit.
KR1020150123787A 2015-09-01 2015-09-01 Power conversion system having filters utilizing the phase of voltage harmonics KR20170027178A (en)

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Cited By (2)

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US10622882B2 (en) 2018-09-18 2020-04-14 Korea Institute Of Energy Research Control of power conversion device for decreasing total harmonic distortion
KR102143442B1 (en) * 2020-03-24 2020-08-11 (주)온담엔지니어링 Apparatus for reducing harmonics of the power network

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US10630215B2 (en) 2017-11-20 2020-04-21 General Electric Company System and method for operating a doubly fed induction generator system to reduce harmonics
WO2020144795A1 (en) * 2019-01-10 2020-07-16 三菱電機株式会社 Choke coil and noise filter using same

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WO1993023914A1 (en) * 1992-05-11 1993-11-25 Electric Power Research Institute Harmonic blocking converter system
JP3444011B2 (en) * 1995-03-22 2003-09-08 株式会社明電舎 Active filter for electric power
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KR100532059B1 (en) * 2003-02-25 2005-11-30 엘에스산전 주식회사 Apparatus for generating voltage sag and swell
JP5701380B2 (en) * 2010-06-10 2015-04-15 シャフナー・エーエムファウ・アクチェンゲゼルシャフト Correlated magnetic device for canceling harmonic components

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10622882B2 (en) 2018-09-18 2020-04-14 Korea Institute Of Energy Research Control of power conversion device for decreasing total harmonic distortion
KR102143442B1 (en) * 2020-03-24 2020-08-11 (주)온담엔지니어링 Apparatus for reducing harmonics of the power network

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