KR102297964B1 - Method and apparatus for controling 3 phase 4 wire grid-connected uninterruptible power supply device - Google Patents

Abstract

The present invention relates to a control method of an uninterruptible power supply device with a 3-phase and 4-wire structure and a device thereof. According to an embodiment of the present invention, the control device of the uninterruptible power supply device with the 3-phase and 4-wire structure comprises: a PFC converter controller using a DC voltage of a capacitor bank included in the uninterruptible power supply device and an input phase current of the uninterruptible power supply device to control a PFC converter included in the uninterruptible power supply device; and a DC-AC inverter controller using an output phase voltage and an output phase current of the uninterruptible power supply device to control a DC-AC inverter included in the uninterruptible power supply device.

Description

A method for controlling an uninterruptible power supply having a three-phase, four-wire structure and an apparatus therefor

The present invention relates to a method for controlling an uninterruptible power supply having a three-phase four-wire structure and an apparatus therefor. More specifically, it relates to a control apparatus having a simple structure capable of reducing control execution time even when an unbalanced upper and lower load is connected to an uninterruptible power supply, and a method performed in the apparatus.

Conventionally, a proportional integral controller (PI controller) is mainly used to control the uninterruptible power supply. The control method using such a PI controller is a controller suitable for controlling the DC component, and in order to control the AC component, for example, conversion such as DQ conversion must be necessarily preceded. Accordingly, there is a need for a method capable of controlling the AC component without conversion. In addition, the control method using the PI controller operates stably when a balanced load is connected. However, when an unbalanced load is connected, the structure of the controller becomes complicated and the execution time of the control operation becomes long. Accordingly, there is a need for a control method having a simple structure in which the execution time of the control operation can be shortened even when an unbalanced load is connected.

In addition, the input harmonic currents that can occur in the uninterruptible power supply device can cause problems such as overheating of the power cable of the power system using the same power supply, overheating of the capacitor, reduction in cable capacity, malfunction of the uninterruptible power supply, and failure of components constituting the uninterruptible power supply. can cause Therefore, there is a need for a method for actively removing such harmonic currents.

Furthermore, voltage imbalance of the capacitor bank may also cause problems such as failure of the uninterruptible power supply. Therefore, a control method capable of maintaining the balance of the voltages of the capacitor banks is required.

Korean Patent Registration No. 10-2233773 (published on February 17, 2016)

A technical problem to be solved through some embodiments of the present invention is to provide an apparatus capable of controlling an AC component without conversion and a method performed by the apparatus.

Another technical problem to be solved through some embodiments of the present invention is to provide a control apparatus having a simple structure and a method performed by the apparatus, in which the execution time of a control operation can be shortened even when an unbalanced load is connected.

Another technical problem to be solved through some embodiments of the present invention is to provide an apparatus for actively canceling harmonic currents and a method performed in the apparatus.

Another technical problem to be solved through some embodiments of the present invention is to provide an apparatus for maintaining the balance of the voltage of a capacitor bank and a method performed in the apparatus.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

An apparatus for controlling an uninterruptible power supply apparatus according to an embodiment of the present invention for solving the above technical problem is an apparatus for controlling an uninterruptible power supply apparatus having a three-phase four-wire structure, the capacitor bank included in the uninterruptible power supply apparatus Using a DC voltage and an input phase current of the uninterruptible power supply device, a PFC converter controller for controlling a PFC converter included in the uninterruptible power supply device, and an output phase voltage and an output phase current of the uninterruptible power supply device to the uninterruptible power supply device a DC-AC inverter controller for controlling the included DC-AC inverter, wherein the PFC converter controller uses a difference between a command DC voltage and a DC voltage of the capacitor bank to change the DC voltage of the capacitor bank to the command DC A first control unit for outputting a control value of the DC voltage of the capacitor bank to reach the voltage, and adding an effective component of the output load current to the control value of the DC voltage of the capacitor bank output by the first control unit as a feed-forward, A first current determination unit that determines a command Q-axis current, and determines a command D-axis current so that the power factor of the PFC converter is controlled to a first reference value, the command D-axis current determined by the first current determination unit, and the command Q-axis a converter configured to convert a current and output a command input phase current, and based on a difference between the command input phase current and the input phase current corresponding to the command input phase current, the input so that the input phase current reaches the corresponding command input phase current A second control unit configured to output a control value of the phase current, and to have a gain greater than or equal to a reference value in the fundamental wave of the input phase current, and a command input phase voltage corresponding to the control value of the input phase current output by the second control unit to the input phase current and a first modulation voltage output unit configured to output a first modulation voltage in addition to the feed forward, wherein the DC-AC inverter controller is configured to: Based on a difference between a command output phase voltage and the output phase voltage corresponding to the command output phase voltage Thus, the command corresponding to the output phase voltage a third control unit configured to output the control value of the output phase voltage to reach the output phase voltage, but to have a gain greater than or equal to a reference value in the fundamental wave of the output phase voltage; the control value of the output phase voltage output by the third control unit A second current determiner that determines the command output phase current by adding the output load current corresponding to the feed-forward, and based on the difference between the command output phase current and the output phase current corresponding to the command output phase current, the output phase current corresponds to A fourth control unit configured to output the control value of the output phase current so as to reach the command output phase current, which has a gain greater than or equal to a reference value in the fundamental wave of the output phase current, and the control value of the output phase current output by the fourth control unit and a second modulation voltage output unit configured to output a second modulation voltage by adding the corresponding command output phase voltage as a feed-forward.

In one embodiment, the PFC converter controller detects a plurality of harmonics constituting the command Q-axis current determined by the first current determination unit, and analyzes the magnitude of each of the plurality of harmonics by a harmonic analysis unit and the harmonic analysis The additionally analyzed may further include a harmonic blocking unit for selectively blocking a frequency of a harmonic having a frequency equal to or greater than a reference level among the plurality of harmonics constituting the command Q-axis current.

In one embodiment, the capacitor bank, based on the neutral wire connected to the capacitor bank of the uninterruptible power supply having the three-phase four-wire structure, the upper capacitor bank located at the upper end of the neutral wire and the lower capacitor bank located at the lower end of the neutral wire Including, wherein the PFC converter controller controls the difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank to be less than or equal to a second reference value, the DC voltage of the upper capacitor bank and the lower capacitor bank Further comprising a first capacitor bank controller for outputting a difference in DC voltage, wherein the first capacitor bank controller, the difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank is the command output by the converter In addition to the input phase current, it may be transmitted to the second control unit.

In one embodiment, the DC-AC inverter controller controls the difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank to be less than or equal to a second reference value, the DC voltage of the upper capacitor bank and the lower end Further comprising a second capacitor bank controller for outputting a difference in the DC voltage of the capacitor bank, the second capacitor bank controller, the difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank the second current Subtracting the command output phase current determined by the determination unit may be transmitted to the fourth control unit.

In one embodiment, if the input power is normal, the first capacitor bank controller is activated and the second capacitor bank controller is deactivated, if the input power is abnormal, the first capacitor bank controller is deactivated and the second capacitor The bank controller may be activated.

1 illustrates an exemplary environment to which an apparatus for controlling an uninterruptible power supply according to an embodiment of the present invention is applied.
FIG. 2 is an exemplary diagram of a PFC converter controller of the control device of the uninterruptible power supply device described with reference to FIG. 1 .
FIG. 3 is another exemplary diagram of the PFC converter controller described with reference to FIG. 2 .
FIG. 4 is another exemplary diagram of the PFC converter controller described with reference to FIG. 2 .
5 is an exemplary diagram of a DC-AC inverter controller of the uninterruptible power supply device described with reference to FIG. 1 .
6 is another exemplary diagram of the DC-AC inverter controller described with reference to FIG. 5 .

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the technical spirit of the present invention is not limited to the following embodiments, but may be implemented in various different forms, and only the following embodiments complete the technical spirit of the present invention, and in the technical field to which the present invention belongs It is provided to fully inform those of ordinary skill in the art of the scope of the present invention, and the technical spirit of the present invention is only defined by the scope of the claims.

In adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated in different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used with the meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not to be interpreted ideally or excessively unless clearly defined in particular. The terminology used herein is for the purpose of describing the embodiments and is not intended to limit the present invention. As used herein, the singular also includes the plural unless specifically stated otherwise in the phrase.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the components from other components, and the essence, order, or order of the components are not limited by the terms. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but another component is between each component. It should be understood that elements may be “connected,” “coupled,” or “connected.”

As used herein, “comprises” and/or “comprising” refers to the presence of one or more other components, steps, operations and/or elements mentioned. or addition is not excluded.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 illustrates an exemplary environment to which an apparatus for controlling an uninterruptible power supply according to an embodiment of the present invention is applied. 1 shows only a preferred embodiment for achieving the object of the present invention, some components may be added or deleted as necessary. In addition, each component of the uninterruptible power supply 200 and the control apparatus 100 of the uninterruptible power supply device shown in FIG. 1 represents functional elements that are functionally separated, and a plurality of components are integrated with each other in an actual physical environment. It should be noted that it may be implemented in the form of Hereinafter, each component of the uninterruptible power supply 200 and the control apparatus 100 of the uninterruptible power supply apparatus shown in FIG. 1 will be described.

The uninterruptible power supply 200 may refer to a device that converts to AC 220V, which is generally used, using various power sources such as commercial power and batteries. In general, the uninterruptible power supply 200 may include a PFC converter 210 , a DC-DC converter 220 , a capacitor bank 230 , and a DC-AC inverter 240 .

The PFC converter 210 may refer to a type of AC-DC converter for improving the power factor and improving the efficiency of electric energy. The PFC converter 210 may serve to receive AC power and convert it into DC power. Next, the DC-DC converter 220 may drop the DC voltage applied from the PFC converter 210 to a DC voltage for charging the battery, and the battery voltage when the PFC converter 210 stops operating due to an abnormality in the input power. can be boosted to a DC voltage of the capacitor bank 230 required for the DC-AC inverter to operate. Next, the capacitor bank 230 may serve to smooth and store the DC voltage supplied from the PFC converter 210 or the DC-DC converter 220 . Next, the DC-AC inverter 240 may convert the DC voltage smoothed and stored in the capacitor bank 230 into an AC voltage. In addition to the components constituting the uninterruptible power supply 200 described above, all known components may be included in the uninterruptible power supply 200 , and in addition to the operation of the components of the power conversion device 200 described above, each component is uninterruptible. It should be noted that various operations performed by the power supply 200 may be performed.

In some embodiments related to the uninterruptible power supply 200 , the uninterruptible power supply 200 may refer to the uninterruptible power supply 200 having a three-phase, four-wire structure.

The apparatus 100 for controlling the uninterruptible power supply may control signals exchanged by components constituting the uninterruptible power supply 200 . For example, the PFC converter controller 110 of the control device 100 uses the DC voltage of the capacitor bank 230 included in the uninterruptible power supply 200 and the input phase current of the uninterruptible power supply 200, the PFC converter 210 can be controlled. For another example, the inverter controller 120 of the control device 100 may control the DC-AC inverter 240 included in the uninterruptible power supply device by using the output phase voltage and the output phase current of the uninterruptible power supply device 200 . may be A more detailed description related thereto will be described later in detail with reference to FIGS. 2 to 6 .

2 to 4 are exemplary diagrams of the PFC converter controller 110 of the control device 100 of the uninterruptible power supply device described with reference to FIG. 1 . Hereinafter, each component constituting the PFC converter controller 110 will be described in more detail.

)과 콘덴서 뱅크의 DC 전압(

)의 차이를 이용하여, 콘덴서 뱅크의 DC 전압이 지령 전압에 도달하도록 콘덴서 뱅크의 DC 전압의 제어값을 출력할 수 있다. 상술한 제1 제어부(111)는 비례 적분 제어기(i.e. PI 제어기)로 구현될 수 있다. 본 실시예에 따르면, 지령 DC 전압 및 콘덴서 뱅크의 DC 전압은 DC 성분이므로, 응답 특성이 양호한 비례 적분 제어기가 DC 성분을 제어하기 위해 이용될 수 있다. 다만, 상술한 예시에 본 발명이 한정되는 것은 아니고 제1 제어부(111)는 다른 제어기로 구현될 수도 있음을 유의해야 한다. 비례 적분 제어기와 관련된 구체적인 설명은 본 발명의 요지를 흐리지 않기 위해 생략하기로 한다.The first control unit 111 is a command DC voltage (

) and the DC voltage of the capacitor bank (

), it is possible to output a control value of the DC voltage of the capacitor bank so that the DC voltage of the capacitor bank reaches the command voltage. The above-described first control unit 111 may be implemented as a proportional integral controller (ie, a PI controller). According to this embodiment, since the command DC voltage and the DC voltage of the capacitor bank are DC components, a proportional integral controller with good response characteristics can be used to control the DC component. However, it should be noted that the present invention is not limited to the above-described examples and the first control unit 111 may be implemented as another controller. A detailed description related to the proportional integral controller will be omitted so as not to obscure the gist of the present invention.

)을 피드 포워드로 더하여, 지령 Q축 전류(

)를 결정할 수 있다. 또한, 제1 전류 결정부(112)는 PFC 컨버터의 역률이 제1 기준치로 제어되도록 지령 D축 전류(

)를 결정할 수도 있다. 이때, 제1 기준치는 역률을 1로 제어하기 위해 0으로 고정될 수 있다.The first current determining unit 112 is an effective component (() of the output load current to the DC voltage control value of the capacitor bank output by the first control unit 111

) is added as feedforward, and the command Q-axis current (

) can be determined. In addition, the first current determining unit 112 commands the D-axis current (

) can also be determined. In this case, the first reference value may be fixed to 0 in order to control the power factor to 1.

,

,

)를 출력할 수 있다. 여기서, 변환부(113)는 지령 D축 전류 및 지령 Q축 전류를 3상 전류로 변환하기 위해 예를 들어, DQ 변환 및 정지/회전 좌표계 변환 등을 수행할 수 있다.The conversion unit 113 converts the command D-axis current and the command Q-axis current determined by the first current determination unit, and converts the command input phase current (

,

,

) can be printed. Here, the conversion unit 113 may perform, for example, DQ conversion and stop/rotation coordinate system conversion, etc. to convert the command D-axis current and the command Q-axis current into three-phase current.

The input phase current corresponding to each phase may be controlled by using the three-phase command input phase current converted by the converter 113 . Hereinafter, for convenience of description, a control operation performed on R will be described.

)의 차이에 기초하여, 입력 상전류가 대응되는 지령 입력 상전류에 도달하도록 입력 상전류의 제어값을 출력하되, 입력 상전류의 기본파에서 기준 수치 이상의 이득을 갖도록 구성될 수 있다. 예를 들어, 제2 제어부(114)는 비례 공진 제어기(i.e. PR 제어기)로 구현될 수 있다. 본 실시예에 따르면, 입력 상전류에 대한 변환 없이도, AC 성분을 직접 제어할 수 있다. 이상적인 비례 공진 제어기는 입력 상전류의 기본파에서 무한대의 이득을 갖도록 설계될 수 있지만, 미리 설정된 기준 수치 이상의 이득을 갖는 제어기가 본 발명에 적용될 수도 있음을 유의해야 한다. 다만, 상술한 예시에 본 발명이 한정되는 것은 아니고, 제2 제어부(114)는 다른 제어기로 구현될 수도 있음을 유의해야 한다. 비례 공진 제어기와 관련된 구체적인 설명은 본 발명의 요지를 흐리지 않기 위해 생략하기로 한다.The second control unit 114 controls the input phase current corresponding to the command input phase current and the command input phase current (

), the control value of the input phase current is output so that the input phase current reaches the corresponding command input phase current, but may be configured to have a gain greater than or equal to a reference value in the fundamental wave of the input phase current. For example, the second control unit 114 may be implemented as a proportional resonance controller (ie, a PR controller). According to this embodiment, it is possible to directly control the AC component without converting the input phase current. An ideal proportional resonant controller may be designed to have infinite gain in the fundamental wave of the input phase current, but it should be noted that a controller having a gain greater than or equal to a preset reference value may be applied to the present invention. However, it should be noted that the present invention is not limited to the above-described example, and the second control unit 114 may be implemented as another controller. A detailed description related to the proportional resonance controller will be omitted so as not to obscure the gist of the present invention.

)을 입력 상전류의 제어값에 피드 포워드로 더하여, 제1 모듈레이션 전압(

)을 출력할 수 있다. 여기서, 출력된 제1 모듈레이션 전압을 이용됨으로써, PWM 모듈레이션을 통한 스위칭 소자의 동작이 수행될 수 있다.The first modulation voltage output unit 115 includes a command input phase voltage (

) is added to the control value of the input phase current as feed-forward, and the first modulation voltage (

) can be printed. Here, by using the output first modulation voltage, the operation of the switching element through PWM modulation may be performed.

According to the present embodiment, in controlling the PFC converter 210, since the AC current of each phase can be directly controlled without coordinate transformation, the execution time of the control operation can be shortened. Furthermore, by using a proportional resonance controller including a resonance controller capable of passing only a specific frequency, a harmonic current included in the input current may be eliminated. Hereinafter, components that can be added to the PFC converter controller 110 will be described in detail with reference to FIGS. 3 to 4 .

Referring to FIG. 3 , the PFC converter controller 110 may further include a harmonic analysis unit 116 and a harmonic blocking unit 117 . Hereinafter, specific operations performed by the harmonic analysis unit 116 and the harmonic blocking unit 117 will be described.

The harmonic analysis unit 116 may detect a plurality of harmonics constituting the command Q current determined by the first current determination unit 112 and analyze the magnitude of each of the plurality of harmonics. In some embodiments related to the harmonic analysis unit 116 , a Fast Fourier Transformer (FFT) may be used to implement the harmonic analysis unit 116 . However, this is an example, and all known techniques for analyzing a plurality of frequencies constituting the command Q-axis current may be applied to the present invention. In this case, a plurality of harmonics other than the 60Hz frequency, which is a fundamental frequency, may be detected, and the magnitude of each of the plurality of harmonics may be analyzed. According to the present embodiment, it is possible to block the detected harmonics by actively analyzing the command Q-axis current, without the need to determine the harmonics of a specific order in advance in order to block the plurality of harmonics. Therefore, it is possible to solve the control time delay and resource waste that may be caused by blocking the harmonics of the order that do not actually exist.

The harmonic blocking unit 117 may selectively block harmonics having a frequency equal to or greater than a reference level among a plurality of harmonics constituting the command Q-axis current analyzed by the harmonic analysis unit 116 . In some embodiments, the harmonic blocking unit 117 may be implemented as a BSF (Band-Stop Filter), but it should be noted that all known methods for blocking a specific frequency may be applied to the present invention as it is.

According to the present embodiment described with reference to FIG. 3 , it is possible to minimize harmonic currents that may be generated through the proportional controller part of the proportional resonance controller. At this time, in order to minimize the influence of harmonics included in the active component of the output phase current, the harmonic analysis unit 116 and the harmonic blocking unit 117 may be applied to the command Q-axis current determined by the first current determining unit 112 . . In addition, according to the present embodiment, by analyzing the harmonics generated by the harmonic analysis unit 116, it is possible to block the input harmonic current that is actively generated regardless of the type of load connected to the uninterruptible power supply.

In some embodiments, the capacitor bank of the uninterruptible power supply device, the neutral wire of the uninterruptible power supply device having a three-phase four-wire structure is connected to the capacitor bank center, based on this, the upper capacitor bank located on the upper side of the neutral wire and the lower end located on the lower side of the neutral wire It may include a capacitor bank. Here, the PFC converter controller 110 may further include a first capacitor bank controller 118 . Hereinafter, a detailed operation performed by the first capacitor bank controller 118 will be described.

) 및 하단 콘덴서 뱅크의 DC 전압(

)의 차이가 제2 기준치 이하가 되도록 제어하되, 상단 콘덴서 뱅크의 DC 전압 및 하단 콘덴서 뱅크의 DC 전압의 차이를 출력할 수 있다. 여기서, 제1 콘덴서 뱅크 제어기(118)는 상단 콘덴서 뱅크의 DC 전압 및 하단 콘덴서 뱅크의 DC 전압의 차이를 변환부(113)가 출력한 지령 입력 상전류에 더해 제2 제어부(114)에 전송할 수 있다. 몇몇 실시예에서, 제1 콘덴서 뱅크 제어기(118)를 구현하기 위해 예를 들어, 비례 적분 제어기가 이용될 수 있다.The first capacitor bank controller 118 is the DC voltage (

) and the DC voltage of the lower capacitor bank (

), but controlled to be less than or equal to the second reference value, the difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank may be output. Here, the first capacitor bank controller 118 may transmit the difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank to the second controller 114 in addition to the command input phase current output by the converter 113 . . In some embodiments, for example, a proportional integral controller may be used to implement the first capacitor bank controller 118 .

In some other embodiments related to the first capacitor bank controller 118 , the second reference value may mean zero. That is, the DC voltage of the upper capacitor bank and the voltage of the lower capacitor bank may be controlled to be the same. According to the present embodiment, since the DC component is removed from the input component of the PFC converter or DC-AC inverter, generation of circulating current in the uninterruptible power supply device can be suppressed, and a failure in the uninterruptible power supply device can be prevented. Hereinafter, a DC-AC inverter controller will be described in detail with reference to FIGS. 5 and 6 .

5 and 6 are exemplary views of the DC-AC inverter controller 120 of the uninterruptible power supply device described with reference to FIG. 1 . Hereinafter, each component constituting the DC-AC inverter controller 120 will be described in more detail.

) 및 출력 상전류(

)를 제어할 수 있다. 이하, 설명의 편의를 위해 U상에서 수행되는 제어 동작에 대해 설명하기로 한다.The DC-AC inverter controller 120 outputs the phase voltage (

) and output phase current (

) can be controlled. Hereinafter, for convenience of description, a control operation performed on the U phase will be described.

)과 지령 출력 상전압에 대응되는 출력 상전압의 차이에 기초하여, 출력 상전압이 대응되는 지령 출력 상전압에 도달하도록 출력 상전압의 제어값을 출력하되, 출력 상전압의 기본파에서 기준 수치 이상의 이득을 갖도록 구성될 수 있다. 예를 들어, 제3 제어부(121)는 비례 공진 제어기(i.e. PR 제어기)로 구현될 수 있다. 본 실시예에 따르면, 출력 상전압에 대한 변환 없이도, AC 성분을 직접 제어할 수 있다. 이상적인 비례 공진 제어기는 출력 상전압의 기본파에서 무한대의 이득을 갖도록 설계될 수 있지만, 미리 설정된 기준 수치 이상의 이득을 갖는 제어기가 본 발명에 적용될 수도 있음을 유의해야 한다. 다만, 상술한 예시에 본 발명이 한정되는 것은 아니고, 제3 제어부(121)는 다른 제어기로 구현될 수도 있음을 유의해야 한다. 비례 공진 제어기와 관련된 구체적인 설명은 본 발명의 요지를 흐리지 않기 위해 생략하기로 한다.The third control unit 121 is a command output phase voltage (

) and the output phase voltage corresponding to the command output phase voltage, output the control value of the output phase voltage so that the output phase voltage reaches the corresponding command output phase voltage, but a reference value in the fundamental wave of the output phase voltage It may be configured to have more than one benefit. For example, the third control unit 121 may be implemented as a proportional resonance controller (ie, a PR controller). According to this embodiment, it is possible to directly control the AC component without converting the output phase voltage. An ideal proportional resonant controller can be designed to have infinite gain in the fundamental wave of the output phase voltage, but it should be noted that a controller having a gain greater than or equal to a preset reference value may be applied to the present invention. However, it should be noted that the present invention is not limited to the above-described example, and the third control unit 121 may be implemented as another controller. A detailed description related to the proportional resonance controller will be omitted so as not to obscure the gist of the present invention.

)을 의미할 수 있다.In some embodiments related to the third control unit 121, the control value of the output phase voltage output by the third control unit is the capacitor charging current command (

) can mean

)에 대응되는 출력 부하 상전류(

)를 피드 포워드로 더하여, 지령 출력 상전류(

)을 결정할 수 있다. The second current determining unit 122 is a capacitor charging current command of the LC filter output from the third control unit 121 (

) corresponding to the output load phase current (

) as feed-forward, the command output phase current (

) can be determined.

The fourth control unit 123 outputs a control value of the output phase current so that the output phase current reaches the corresponding command output phase current based on the difference between the command output phase current and the output phase current corresponding to the command output phase current, but the fundamental wave of the output phase current It may be configured to have a gain greater than or equal to the reference value. For example, the fourth control unit 123 may be implemented as a proportional resonance controller (i.e. a PR controller). According to this embodiment, it is possible to directly control the AC component without converting the output phase current. An ideal proportional resonant controller can be designed to have infinite gain in the fundamental wave of the output phase current, but it should be noted that a controller having a gain greater than or equal to a preset reference value may be applied to the present invention. However, it should be noted that the present invention is not limited to the above-described example, and the fourth control unit 123 may be implemented as another controller. A detailed description related to the proportional resonance controller will be omitted so as not to obscure the gist of the present invention.

)을 피드 포워드로 더하여, 제2 모듈레이션 전압을 출력할 수 있다. 여기서, 출력된 제1 모듈레이션 전압을 이용됨으로써, PWM 모듈레이션을 통한 스위칭 소자의 동작이 수행될 수 있다.The second modulation voltage output unit 124 is a command output phase voltage (

) may be added as a feed forward to output a second modulation voltage. Here, by using the output first modulation voltage, the operation of the switching element through PWM modulation may be performed.

According to the present embodiment, in controlling the DC-AC inverter 240 , since the AC current and AC voltage of each phase can be directly controlled without coordinate transformation, the execution time of the control operation can be shortened. In addition, in controlling the DC-AC inverter 240, since the AC current and AC voltage of each phase can be directly controlled without coordinate transformation, voltage drop of each phase does not occur, even when the unbalanced upper and lower parts are connected to the uninterruptible power supply. It can control the uninterruptible power supply device stably. Hereinafter, components that can be added to the DC-AC inverter controller 120 will be described in detail with reference to FIG. 6 .

In some embodiments, the capacitor bank of the uninterruptible power supply device, based on the neutral wire of the uninterruptible power supply device having a three-phase four-wire structure, may include an upper capacitor bank located above the neutral line and a lower capacitor bank located below the neutral line. Here, the DC-AC inverter controller 120 may further include a second capacitor bank controller 125 . Hereinafter, a detailed operation performed by the second capacitor bank controller 125 will be described.

) 및 하단 콘덴서 뱅크의 DC 전압(

)의 차이가 제2 기준치 이하가 되도록 제어하되, 상단 콘덴서 뱅크의 DC 전압 및 하단 콘덴서 뱅크의 DC 전압의 차이를 출력할 수 있다. 여기서, 제2 콘덴서 뱅크 제어기(125)는 상단 콘덴서 뱅크의 DC 전압 및 하단 콘덴서 뱅크의 DC 전압의 차이를 제2 전류 결정부(122)가 출력한 지령 출력 상전류에 감산해 제4 제어부(123)에 전송할 수 있다. 몇몇 실시예에서, 제2 콘덴서 뱅크 제어기(125)를 구현하기 위해 예를 들어, 비례 적분 제어기가 이용될 수 있다.The second capacitor bank controller 125 is the DC voltage of the upper capacitor bank (

) and the DC voltage of the lower capacitor bank (

), but controlled to be less than or equal to the second reference value, the difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank may be output. Here, the second capacitor bank controller 125 subtracts the difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank from the command output phase current output by the second current determiner 122 and the fourth controller 123 can be sent to In some embodiments, for example, a proportional integral controller may be used to implement the second capacitor bank controller 125 .

In some other embodiments related to the second capacitor bank controller 125 , the second reference value may mean zero. That is, the DC voltage of the upper capacitor bank and the voltage of the lower capacitor bank may be controlled to be the same. According to the present embodiment, since the DC component is removed from the input component of the PFC converter or DC-AC inverter, generation of circulating current in the uninterruptible power supply device can be suppressed, and a failure in the uninterruptible power supply device can be prevented.

In some embodiments related to the control device according to an embodiment of the present invention, when the input power is normal, the first capacitor bank controller 118 is activated, the second capacitor bank controller 125 is deactivated, and the input power is turned off. If abnormal, the first capacitor bank controller 118 may be deactivated, and the second capacitor bank controller 125 may be activated.

The capacitor bank controller including the first capacitor bank controller 118 and the second capacitor bank controller 125 is preferably operated in a PFC converter that is basically a power supply of the capacitor bank. That is, when the input power is normal, the second capacitor bank controller 125 for controlling the capacitor bank in the DC-AC inverter may be unnecessary. However, the PFC converter may stop operating when the input power is abnormal due to the characteristics of the uninterruptible power supply device. According to this embodiment, even when the input power for stopping the operation of the PFC converter is abnormal, the capacitor bank can be continuously controlled so that the balance between the upper capacitor bank and the lower capacitor bank is maintained.

According to the control device of the uninterruptible power supply device described with reference to FIGS. 1 to 6 so far, the AC component can be controlled without conversion, and even when an unbalanced load is connected to the uninterruptible power supply device, the execution time of the control operation can be shortened. A control device having a simple structure that can be implemented may be provided. Also, by actively canceling harmonics, circulating current in the uninterruptible power supply can be eliminated. Furthermore, even when the input power is abnormal, the voltage balance of the capacitor bank can be maintained.

On the other hand, each component of the control device of the uninterruptible power supply device according to the embodiment of the present invention described so far is software (Software) or hardware such as FPGA (Field Programmable Gate Array) or ASIC (Application-Specific Integrated Circuit) (Hardware). However, the components are not meant to be limited to software or hardware, and may be configured to reside in an addressable storage medium, or may be configured to execute one or more processors. A function provided in the components may be implemented by a more subdivided component, or may be implemented as a single component that performs a specific function by combining a plurality of components.

So far, various embodiments of the present invention and effects according to the embodiments have been described with reference to FIGS. 1 to 6 . Effects according to the technical spirit of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the specification.

In the above, even though all the components constituting the embodiment of the present invention are described as being combined or operating in combination, the technical spirit of the present invention is not necessarily limited to this embodiment. That is, within the scope of the object of the present invention, all the components may operate by selectively combining one or more.

Although embodiments of the present invention have been described with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention pertains can practice the present invention in other specific forms without changing the technical spirit or essential features. can understand that there is Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention should be interpreted by the claims below, and all technical ideas within the equivalent range should be interpreted as being included in the scope of the technical ideas defined by the present invention.

Claims (5)

An apparatus for controlling an uninterruptible power supply having a three-phase four-wire structure, the apparatus comprising:
a PFC converter controller for controlling the PFC converter included in the uninterruptible power supply device by using the DC voltage of the capacitor bank included in the uninterruptible power supply device and the input phase current of the uninterruptible power supply device; and
A DC-AC inverter controller for controlling the DC-AC inverter included in the uninterruptible power supply by using the output phase voltage and the output phase current of the uninterruptible power supply,
The PFC converter controller,
a first control unit for outputting a control value of the DC voltage of the capacitor bank using a difference between the command DC voltage and the DC voltage of the capacitor bank so that the DC voltage of the capacitor bank reaches the command DC voltage;
The effective component of the output load current is added as a feed-forward to the control value of the DC voltage of the capacitor bank output by the first control unit to determine the command Q-axis current, and the power factor of the PFC converter is controlled to the first reference value. a first current determining unit for determining the D-axis current;
a conversion unit for converting the command D-axis current and the command Q-axis current determined by the first current determination unit to output a command input phase current;
Based on the difference between the command input phase current and the input phase current corresponding to the command input phase current, the input phase current outputs the control value of the input phase current so that the input phase current reaches the corresponding command input phase current, in the fundamental wave of the input phase current a second control unit configured to have a gain greater than or equal to a reference value; and
A first modulation voltage output unit for outputting a first modulation voltage by adding a command input phase voltage corresponding to the control value of the input phase current output by the second control unit as a feed-forward to the input phase current;
The DC-AC inverter controller,
outputting a control value of the output phase voltage such that the output phase voltage reaches the corresponding command output phase voltage based on a difference between the command output phase voltage and the output phase voltage corresponding to the command output phase voltage, a third control unit configured to have a gain greater than or equal to a reference value in the fundamental wave of the output phase voltage;
a second current determination unit configured to determine a command output phase current by adding an output load current corresponding to the control value of the output phase voltage output by the third control unit as a feed-forward;
Based on the difference between the command output phase current and the output phase current corresponding to the command output phase current, output the control value of the output phase current so that the output phase current reaches the corresponding command output phase current, a fundamental wave of the output phase current a fourth control unit configured to have a gain greater than or equal to the reference value; and
A second modulation voltage output unit for outputting a second modulation voltage by adding the command output phase voltage corresponding to the control value of the output phase current output by the fourth control unit as a feed-forward,
The PFC converter controller,
a harmonic analysis unit detecting a plurality of harmonics constituting the command Q-axis current determined by the first current determining unit and analyzing the magnitude of each of the plurality of harmonics; and
Further comprising a harmonic blocking unit selectively blocking the frequency of a harmonic greater than or equal to a reference size among the plurality of harmonics constituting the command Q-axis current analyzed by the harmonic analysis unit,
The control unit of the uninterruptible power supply. delete According to claim 1,
The capacitor bank is
Based on the neutral wire connected to the capacitor bank of the uninterruptible power supply having the three-phase four-wire structure, an upper capacitor bank located at the upper end of the neutral wire and a lower capacitor bank located at the lower end of the neutral wire,
The PFC converter controller,
A first capacitor that controls the difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank to be less than or equal to a second reference value, and outputs the difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank Further comprising a bank controller,
The first capacitor bank controller,
The difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank is added to the command input phase current output by the converter and transmitted to the second control unit,
The control unit of the uninterruptible power supply. 4. The method of claim 3,
The DC-AC inverter controller,
A second capacitor that controls the difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank to be less than or equal to a second reference value, and outputs the difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank Further comprising a bank controller,
The second capacitor bank controller,
The difference between the DC voltage of the upper capacitor bank and the DC voltage of the lower capacitor bank is subtracted from the command output phase current determined by the second current determining unit and transmitted to the fourth control unit,
The control unit of the uninterruptible power supply. delete

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