KR101704377B1 - The each phase output voltage controller for 3 phase space vector pulse width modulation inverter - Google Patents

Abstract

The present invention relates to an output voltage controller for a three-phase space vector pulse width modulation inverter, capable of controlling an operation of the three-phase inverter comprising an uninterruptible power supply device. Specially, introduced is an output voltage controller for a three-phase space vector pulse width modulation inverter, capable of minimizing an output voltage unbalance rate generated by a single phase load and an impedance error of an output transformer by dividing the phase and the output voltage of each phase with a D axis control method and a Q axis control method after DQ conversion with regard to each phase. The present invention includes a phase generator which generates a bypass single phase from a bypass voltage, a DQ converter which generates a virtual voltage on a virtual DQ coordinate system, a voltage controller which generates a command voltage, and a space vector PWM signal generator which generates a PWM control signal in response to the command voltage.

Description

[0001] The present invention relates to a three-phase space vector pulse width modulation (PWM) inverter,

The present invention relates to a three-phase space vector pulse width modulation inverter output voltage controller for controlling the operation of a three-phase inverter constituting an uninterruptible power supply, and in particular, Phase space-time vector pulse-width modulation inverter output that minimizes the impedance error of the output transformer and the output voltage imbalance rate caused by the single-phase load by dividing the output voltage and phase of each phase by D-phase and Q-phase control methods To a voltage controller.

Uninterruptible power supplies are widely used for protecting loads from abnormal power sources such as power outage, momentary power failure, and voltage drop, and their demand is increasing with the development of the IT industry. Uninterruptible power supply (UPS) is the most important electrical characteristic to supply high quality power of constant voltage and constant frequency to load regardless of input power quality. The most important function of an inverter used in a three-phase uninterruptible power supply is the stability of the output voltage.

The most important function of an inverter for a three-phase uninterruptible power supply lies in the stability of the output voltage. Regardless of the quality of the input power supply, it is the most important electrical characteristic to supply a good quality power supply with constant voltage and constant frequency to the load.

However, when looking at the load of the uninterruptible power supply, various information devices and computer systems are composed of loads using almost one phase power. These 1-phase loads create an unbalanced load condition of the 3-phase inverter, resulting in unbalance of the output voltage. Generally, the inverter output voltage control of the 3 phase uninterruptible power supply unit performs DQ conversion of 3-phase alternating voltage to 2-phase and PI control by using synchronous coordinate system. This control is performed under the condition that 3-phase output voltage equilibrates Therefore, in the case of an inverter with a Delta-Y transformer, there is a limit to precise control of the output voltage imbalance caused by the impedance difference of each phase of the transformer and the unbalance of the 1-phase load.

Generally, inverter output voltage control of a three-phase uninterruptible power supply unit is generally performed by performing DQ conversion of a three-phase AC voltage to a two-phase DC voltage using a synchronous coordinate system and performing PI (Proportional-Integral) control, It is assumed that the phase output voltages are balanced with each other. However, since a single-phase load is generally used, the output voltage imbalance of each phase occurs due to the unbalance of the load. Therefore, the DQ control system alone has a limitation to precisely control the unbalanced voltage of each phase.

Furthermore, when using a delta wye (Δ-Y) transformer at the output of the inverter, a phase difference of 30 ° occurs between the primary and secondary of the output transformer. Since the voltage at the primary side is controlled by the voltage difference between the two phases, The voltage on the primary side may become unstable when the phase voltage is detected.

To solve this problem, it is necessary to control the inverter output voltage each time.

1 shows an embodiment of a conventional uninterruptible power supply.

Referring to FIG. 1, a conventional uninterruptible power supply 100 includes a three-phase inverter 110, a transformer 120, a filter 130, a first switch 140, a second switch 150, Subsystem 160. The < / RTI >

Phase AC voltage output from the three-phase inverter 110 operating in response to the PWM control signal PWM is supplied to the load 170 via the delta-wire transformer 120, the filter 130 and the first change-over switch 140, . The control subsystem 160 outputs the three phase inverter voltage Vabc, inv fed back from the filter 130 to the phase? Byp of the three phase bypass voltage Vabc, byp applied to the second switch 150 And generates a PWM control signal PWM for controlling the operation of the three-phase inverter 110 in synchronization with each other. The output characteristic of the inverter 110 will be determined by the PWM control signal PWM. Here, the three-phase bypass voltage Vabc, byp is a voltage applied from the outside of the uninterruptible power supply 100, for example, a commercial power source supplied from KEPCO.

Fig. 2 shows the internal configuration of the conventional control subsystem shown in Fig.

2, the conventional control subsystem 160 includes a virtual two-phase converter 210, a dq converter 220, an LPF unit 230, a voltage control unit 240, and a space vector PWM signal generator 250 ).

2 shows a two-phase converter 210 of the virtual three-phase inverter voltage (V _{a, inv,} V _{b, inv,} V _{c, inv)} a may be seen to process at the same time, the actual three-phase inverter voltage (V _{a , inv, Vb, inv} , _Vc , _inv ) are respectively processed and integrated for simplification of the drawings, and will be applied to the following description.

,

)을 생성한다. dq 변환기(220)는 3상 바이패스 전압(Vabc,byp)의 위상(θbyp)과 동기화 된 단상의 출력전압(

,

)을 가상의 DQ 좌표계 상에서 가상의 전압(

,

)으로 변환한다. The virtual two-phase converter 210 performs _a virtual two-phase conversion on each of the three-phase inverter voltages V _{a, inv} , V _{b, inv} , V _{c, and inv} to generate a single phase Output voltage (

,

). dq converter 220 generates a single phase output voltage synchronized with the phase? byp of the three-phase bypass voltage Vabc, byp

,

) On a virtual DQ coordinate system

,

).

,

)이 LPF부(230; 231, 232)를 거쳐 인가되는 가상의 2상 전압(

,

)을 다시 3상 전압으로 변환하여 지령전압(

,

,

)을 생성한다. The voltage control unit 240 outputs the output of the dq converter 220 synchronized with the phase? Byp of the three-phase bypass voltage Vabc, byp

,

) Is supplied to the LPF unit 230 (231, 232) via a virtual two-phase voltage

,

) Is again converted into a three-phase voltage and the command voltage

,

,

).

,

,

)을 이용하여 제어신호(PWM)를 생성한다. The space vector PWM signal generator 250 generates a command voltage

,

,

To generate a control signal PWM.

2, the voltage control unit 240 includes a first adder 241, a second adder 242, a first PI control unit 243, a second PI control unit 244, a DQ converter 245, Phase converter 246.

,

) 중 하나의 가상의 전압(

)은 동기좌표계에서 항상 영(zero)이 되도록 제어되어야 위상차가 없게 되므로, 제1덧셈기(241)에서 하나의 가상의 전압(

) 값을 영(0)으로 뺀 차이값을 제1PI제어기(243)에 전달한다. The virtual voltage input to the voltage control unit 240

,

) Of one of the virtual voltages

Is controlled to be zero in the synchronous coordinate system so that there is no phase difference. Therefore, the first adder 241 adds one virtual voltage

) Value is subtracted from zero (0) to the first PI controller 243.

,

) 중 나머지 하나의 가상의 전압(

)은 제2덧셈기(242)에서 기준 출력전압의 크기(

)와의 오차값을 연산하여 제2PI제어기(244)에 전달한다. The virtual voltage input to the voltage control unit 240

,

) Of the remaining one of the virtual voltages

Is input to the second adder 242 by the magnitude of the reference output voltage

And transmits the calculated error value to the second PI controller 244.

)를 생성하고, 제2PI제어기(244)는 제2덧셈기(242)로부터 출력되는 오차값을 이용하여 Q축 제어신호(

)를 생성한다. The first PI controller 243 uses the difference value output from the first adder 241 to generate a D-axis control signal (

And the second PI controller 244 generates a Q-axis control signal (i.e., a Q-axis control signal) using the error value output from the second adder 242

).

) 및 Q축 제어신호(

)의 2상 전압을 3상 전압으로 역변환하여 지령전압(

,

,

)을 생성한다. The two-phase to three-phase converter 246 converts the phase of the three-phase bypass voltage?

) And a Q-axis control signal (

) Is inversely converted to a three-phase voltage to generate a command voltage (

,

,

).

However, in this control method, the DQ output voltage control is controlled through the virtual phase voltage for each phase. Therefore, it is necessary to control only the Q-axis, which is the effective voltage, and in particular, the output voltage control of the three-phase inverter having the delta- Since the voltage is fed back from the secondary side of the transformer, the voltage control on the primary side of the transformer may become unstable when errors in the phase and voltage control occur.

(0001) Patent No. 10-1022425

In order to precisely control the output voltage of a three-phase inverter having a delta-wire output transformer, the present invention is directed to a method and apparatus for precisely controlling a three-phase inverter output voltage using a one-phase DQ conversion output voltage controller, Phase transformer and the unbalanced load using the output of the output voltage controller of each phase, which is virtually converted, and the voltage and phase difference generated by the unbalanced load can be precisely compensated. And to provide a vector pulse width modulation inverter output voltage controller.

According to another aspect of the present invention, there is provided a three-phase space-vector pulse-width modulation inverter output voltage controller including a three-phase inverter, a delta-wire transformer for transforming the output of the three- Phase inverter and a second switch for switching a three-phase bypass voltage input from a commercial power supply, wherein the PWM control unit controls the operation of the three-phase inverter The three-phase space vector pulse width modulated inverter output voltage controller that generates the signals for each phase includes a phase generator, a DQ converter, a voltage controller, and a PWM signal generator.

The phase generator generates a bypass single phase phase from a bypass voltage input to the second switch. The DQ converter generates a virtual voltage on a virtual DQ coordinate system using a virtual phase shift voltage obtained by shifting the phases of the bypass single-phase, three-phase inverter, and three-phase inverter voltages by 90 °. The voltage controller converts the virtual voltage output from the DQ converter to the D-axis and the Q-axis using the bypass single phase phase to correct the phase error, and generates a command voltage of the same phase that compensates for the unbalanced voltage . The space vector PWM signal generator generates the PWM control signal in response to the command voltage.

The three-phase space vector pulse width modulation inverter output voltage controller according to the present invention performs DQ conversion on each phase (a, b, c) so that the D axis compensates phase errors of each phase and the Q axis compensates each phase unbalance voltage. In the output voltage control and phase compensation of a three-phase inverter with Δ-Y output transformer, it is possible to control the voltage and phase on the primary side of the Δ-Y output transformer precisely by feeding back the voltage on the secondary side of the transformer The impedance error of the Δ-Y output transformer and the unbalance ratio of the three-phase inverter output voltage that can be generated by the 1-phase load can be remarkably improved. Further, when such a controller is applied to a single-phase inverter, it is possible to control the effective power and the reactive power of the inverter output, respectively, and to perform more precise phase-locked control.

1 shows an embodiment of a conventional uninterruptible power supply.
Fig. 2 shows the internal configuration of the conventional control subsystem shown in Fig.
3 shows an internal configuration of a three-phase space vector pulse width modulation inverter output voltage controller according to the present invention.

In order to fully understand the present invention and the operational advantages of the present invention and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings, which are provided for explaining exemplary embodiments of the present invention, and the contents of the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

3 shows an internal configuration of a three-phase space vector pulse width modulation inverter output voltage controller according to the present invention.

FIG. 3A is a block diagram of a three-phase space vector pulse width modulation inverter output voltage controller, and FIG. 3B is a block diagram of a voltage controller constituting the three-phase space vector pulse width modulation inverter output voltage controller shown in FIG. 3A.

3A, a three-phase space vector pulse-width modulated inverter output voltage controller 160 (hereinafter referred to as a control subsystem) includes an all-pass filter 310, a DQ converter 320, a voltage controller 330, a space vector PWM signal Generator 340 and a phase generator 350.

3 shows the control subsystem 160 is a three-phase inverter voltage (V _{a, inv,} V _{b, inv,} V _{c, inv)} a may be seen to process at the same time, the actual three-phase inverter voltage (V _{a, inv} , V _{b, inv} , V _{c, inv} ) are respectively processed and integrated for simplification of the drawings, and the same applies to the following description.

The phase generator 350 generates three bypass single-phase phases? A,? B,? C from the three-phase bypass voltage?

)을 생성한다. The full-band pass filter 310 generates a virtual phase shift voltage (V _{a, inv} , V _{b, inv} , V _{c, inv} ) shifted by 90 ° through the all pass filter

).

)으로, 전대역 통과필터(310)로부터 출력되는 위상천이전압(

)을 Q축으로 하여 바이패스의 단상 위상(θa)과 동기화된 가상의 DQ 좌표계 상에서 가상의 전압(

,

)을 생성한다. DQ converter 320 converts the inverter output voltages Va, inv Vb, inv Vc, and inv to the D-axis

), And the phase shift voltage ("

) On the basis of the imaginary DQ coordinate system synchronized with the single-phase phase &thetas; a of the bypass,

,

).

,

)으로부터 위상 오차를 보정하고 불평형 전압을 보상한 위상이 동일한 지령전압(

,

,

)을 생성한다. The voltage controller 330 compares the phase difference? A with the bypass single phase phase? A and outputs a virtual voltage (?

,

) And compensates for the unbalanced voltage. The phase difference between the command voltage

,

,

).

,

,

)에 응답하여 제어신호(PWM)를 생성한다. The space vector PWM signal generator 340 generates a command voltage

,

,

In response to the control signal PWM.

3B, the voltage controller 330 includes a first adder 331, a second adder 332, a phase error compensation PI controller 333, an unbalanced voltage compensation PI controller 334, a third adder 335 And a two-phase-to-three-phase converter 336.

,

) 중 하나의 가상의 전압(

)은 동기좌표계에서 항상 영(zero)이 되도록 제어되어야 하므로, 제1덧셈기(331)에서 하나의 가상의 전압(Vim,d) 값을 영(0)으로 뺀 차이값을 연산한다. 전압제어기(330)에 입력되는 가상의 전압(

,

) 중 나머지 하나의 가상의 전압(

)은 제2덧셈기(332)에서 기준 출력전압의 크기(

)와의 오차값을 연산한다. The virtual voltage input to the voltage controller 330

,

) Of one of the virtual voltages

Must be controlled to be zero in the synchronous coordinate system. Therefore, the first adder 331 calculates a difference value obtained by subtracting one virtual voltage (Vim, d) by zero (0). The virtual voltage input to the voltage controller 330

,

) Of the remaining one of the virtual voltages

Is output from the second adder 332 to the magnitude of the reference output voltage

).

The phase error compensation PI controller 333 detects the phase on the D axis of the difference value output from the first adder 331 and outputs the phase compensation control value. The unbalanced voltage compensation PI controller 334 detects the unbalanced voltage on the Q axis of the error value output from the second adder 332 and outputs the voltage compensation control value.

The PI (Proportional-Integral) controller basically has the form of a feedback controller and measures the output of the object to be controlled and compares it with a desired reference value or a setpoint to obtain an error ), And calculates a control value necessary for controlling the object by using the error. A control value (MV) of an arbitrary moment (t) can be expressed by the following equation.

Here, the first term on the right side of the equal sign is a proportional term that gives a control action proportional to the magnitude of the error value (e) t at an arbitrary moment (t), the second term is a steady-state ) (E) τ), which is a function of the integral term. t and tau are variables representing an arbitrary time. Kp and Ki are called gains, and the process of calculating the appropriate gain through mathematical, empirical, or empirical methods is called tuning. The configuration and operation characteristics of the PI controller as described above are generally known, and therefore will not be described in detail here.

The third adder 335 generates a phase? ^{E obtained} by _adding the phase compensation control value output from the phase error compensation PI controller 333 and the phase difference? Y generated in the delta phase transformer.

,

,

)을 생성한다. 3개의 바이패스 단상 위상(θa, θb, θc) 중 하나의 바이패스 단상 위상(θa)은 실선으로 되어 있고, 나머지 2개의 바이패스 단상 위상(θb, θc)은 점선으로 도시되어 있는 이유는, 3개의 바이패스 단상 위상(θa, θb, θc)이 동시에 적용되는 것이 아니라는 것을 의미하며, 예를 들면, 도 3b에서는 실선으로 표시된 하나의 바이패스 단상 위상(θa)이 적용되고 있는 것을 나타내는 것이다. The two-phase-to-three phase converter 336 multiplies the phase? ^E output from the third adder 335 and the voltage compensation control value output from the unbalanced voltage compensating PI controller 334 by three bypass single phase phases? A, θb, θc) are applied to the three phase command voltages (

,

,

). One bypass phase phase? A of the three bypass single phase phases? A,? B and? C is a solid line and the remaining two bypass single phase phases? B and? C are shown by dotted lines, Means that the three by-pass single-phase phases? A,? B and? C are not applied at the same time. For example, in FIG. 3b, one bypass single-phase phase? A indicated by a solid line is applied.

The first adder 331 and the second adder 332 function to detect an error between virtual D-axis and Q-axis for each phase. The phase error compensation PI controller 333 and the unbalanced voltage compensation PI controller (334) controls the compensation of the output phase and the magnitude of the output voltage with respect to the D-axis and Q-axis errors.

The three-phase space vector pulse width modulation inverter output voltage controller according to the present invention performs DQ conversion on each phase (a, b, c) so that the D axis compensates phase errors of each phase and the Q axis compensates each phase unbalance voltage. In the output voltage control and phase compensation of a three-phase inverter with Δ-Y output transformer, it is possible to control the voltage and phase on the primary side of the Δ-Y output transformer precisely by feeding back the voltage on the secondary side of the transformer The impedance error of the Δ-Y output transformer and the 3-phase inverter output voltage imbalance rate that can be caused by the 1-phase load can be remarkably improved.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

110; 3-phase inverter
120: Transformer
130: filter
140: 1st switch
150: 2nd switch
160: control subsystem
210: virtual two-phase converter
220: dq converter
230: LPF unit
240:
250: Space vector PWM signal generator
310: full-band pass filter
320: DQ converter
330: Voltage controller
331: first adder
332: second adder
333: phase error compensation PI controller
334: Unbalanced voltage compensation PI controller
335: third adder
336: Two-phase-to-three phase converter
340: Space vector PWM signal generator
350: phase generator

Claims (3)

A three-phase inverter, a delta-wire transformer for transforming the output of the three-phase inverter to a filter, a first switching switch for switching the three-phase inverter voltage output from the filter to transfer the voltage to a load, And a second switch for switching the three-phase space vector pulse width modulation inverter output voltage controller to generate a PWM control signal for controlling the operation of the three-phase inverter for each phase,
A phase generator for generating a bypass single phase phase from the bypass voltage;
A DQ converter for generating a virtual voltage on a virtual DQ coordinate system using a virtual phase shift voltage obtained by shifting the phases of the bypass single-phase, three-phase inverter, and three-phase inverter voltages by 90 °;
A voltage controller for converting the virtual voltage output from the DQ converter into a D-axis and a Q-axis using the bypass single phase and correcting a phase error, and generating a command voltage having an identical phase compensating for an unbalanced voltage; And
A space vector PWM signal generator for generating the PWM control signal in response to the command voltage; To
Phase space-vector pulse-width modulation inverter output voltage controller.
The method according to claim 1,
A full-band pass filter for generating the virtual phase shift voltage by shifting the phase of the three-phase inverter voltage by 90 °; To
Phase space-vector pulse-width modulation inverter output voltage controller. The apparatus of claim 1, wherein the voltage controller comprises:
A first adder for generating a difference value obtained by subtracting zero from one virtual voltage of the virtual voltages input to the voltage controller;
A second adder for generating an error value with respect to a magnitude of a predetermined reference output voltage from the remaining one virtual voltage of the virtual voltages input to the voltage controller;
A phase error compensation PI controller for detecting a phase on the d axis of the difference value output from the first adder to generate a phase compensation control value;
An unbalanced voltage compensation PI controller for detecting an unbalanced voltage on the Q axis of the error value output from the second adder to generate a voltage compensation control value;
A third adder for generating phase information of the phase compensation control value output from the phase error compensation PI controller and a phase difference generated in the delta-wire transformer; And
A two-phase-to-three phase converter for generating a command voltage having the same phase by applying the bypass phase phase to the output phase of the third adder and the voltage compensation control value output from the unbalance phase compensation PI controller; To
Phase space-vector pulse-width modulation inverter output voltage controller.

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