KR20050067701A - Controlling system of single-phase active power filter(apf) using rotating reference frames and mehtod thereof - Google Patents

Abstract

Disclosed is a control system and method for a single phase active power filter using a rotational coordinate system. According to the present invention, by detecting the single-phase current through the CT (CT) mounted as the input power of the nonlinear load, and induce a virtual phase current using the delay characteristics of the low pass filter from the single-phase current, A harmonic detector for detecting a distorted load current i _L using a rotational coordinate system synchronized with two phase currents and a power supply frequency and for commanding a corresponding compensation current; A hysteresis current that receives a compensation current command value (i _ref ) corresponding to the compensation current and compares the output current (i _C ) and the compensation current command value (i _ref ) of the inverter with each other to perform current correction within a reference value. Controller; And a gate driver for driving control of the amount of current supplied to the nonlinear load in response to the current correction of the hysteresis current controller.

The harmonic detector at this time is the actual current of the single phase current ( ) Phase A first low pass filter (LPF), delayed by a delay; The virtual current provided through the first low pass filter LPF ) And the actual current ( )end D-axis current component when rotating at speed ) And the q component current component ( A normal component coordinate transformation unit for calculating; D-axis current component calculated by the normal component coordinate conversion unit ( ) And the q component current component ( A second low pass filter (LPF) for extracting only the direct current component of the filter; The virtual current provided through the first low pass filter LPF ) And the actual current ( ) Is- D-axis current component when rotating at speed ) And the current component of the q-axis ( An inverse component coordinate transformation unit for calculating; D-axis current component calculated by the inverse component coordinate transformation unit ( ) And the current component of the q-axis ( A third low pass filter (LPF) for extracting only the direct current component of the filter; And a d-axis current component of a DC component extracted through the second low pass filter (LPF) D) current component of the direct current component extracted through the third low pass filter (LPF) ) By subtracting the d-axis current component ( ), And the q-axis current component of the direct current component extracted through the second low pass filter (LPF) ) And the q-axis current component of the direct current component extracted through the third low pass filter (LPF) ) And add the q-axis current component ( ) And the d- and q-axis current components ( , ) Is the actual current axis ( And an inverse transform unit for performing the inverse transform on the to generate the compensation current command value (i _ref ),

As the control algorithm for the single-phase active power filter, which is a method of harmonic reduction caused by single-phase nonlinear loads, is proposed, the conventional method requires at least half-cycle time to detect harmonics. You can create a coordinate system like this, which gives you the effect of instantaneous calculations.

In addition, unlike the conventional method of creating a virtual phase by delaying the actual load current, a current having a different phase and magnitude is generated by using a delay characteristic of a low pass filter, and two currents having a different phase are used by a rotational coordinate system. After detecting the fundamental wave current, the compensation current command value including only the harmonic component can be obtained by removing the fundamental wave component from the load current, thereby providing the effect of real-time control.

Description

CONTROLLING SYSTEM OF SINGLE-PHASE ACTIVE POWER FILTER (APF) USING ROTATING REFERENCE FRAMES AND MEHTOD THEREOF}

The present invention relates to a control method of a single-phase active power filter, and more particularly, to extract a harmonic component of a distorted load current, that is, a current generated by a nonlinear load using a diode rectifier. The present invention relates to a control system and method for a single-phase active power filter using a rotational coordinate system that can compensate for this in real time.

In general, loads using semiconductor power converters such as thyristor converters and diode rectifiers, such as SMPS, UPS, computer systems, etc., operate as non-linear loads and are a major cause of serious harmonics on the power supply side. Such harmonic currents cause distortion of the power supply voltage and increase capacity of power system devices such as generators, transmission lines, transformers, and the like, and may cause heat and vibration to various power devices, causing insulation breakdown or shortening of lifespan. In addition, malfunctions of various electronic devices such as measurement equipment or EMI may occur in communication systems.

The passive filter used to remove the harmonics is inexpensive, but only the harmonics of a certain order can be compensated for selectively, so it is difficult to obtain satisfactory performance when a wide range of harmonics occur in the power supply stage. There is always a possibility of causing this. As a solution of the passive filter, a three-phase active power filter has been developed.

To compensate for harmonics, the 3-phase active power filter calculates the reactive power of the load to determine the command value of the compensation current, or determines the command value of the input current using the error between the reference value and the detection value of the DC capacitor voltage. However, when a three-phase active power filter is installed at a point of common coupling (PCC), which is an installation point of an active power filter that meets the IEEE-519 harmonic standard, voltage distortion occurs due to switching of a converter.

In order to prevent this, a single phase active power filter having a high correlation with current harmonics may be used, but research on single phase active power filters is substantially insufficient compared to three phase active power filters.

SUMMARY OF THE INVENTION The present invention was created to solve this problem, and an object of the present invention is to improve the PF by eliminating harmonic components on the power supply side operating as a nonlinear load and compensating reactive power, and to reduce the possibility of interference between the loads. The present invention provides a control system and method for a single phase active power filter using a rotating coordinate system.

A control system of a single-phase active power filter using a rotational coordinate system according to an aspect of the present invention for achieving the above object, detects a single-phase current through the (CT) mounted as an input power source of the non-linear load, and from the single-phase current Deriving a virtual phase current using the delay characteristics of a low pass filter, detecting a distorted load current i _L using a rotational coordinate system synchronized with two phase currents and a power supply frequency, and corresponding compensation A harmonic detector for commanding a current; A hysteresis current that receives a compensation current command value (i _ref ) corresponding to the compensation current and compares the output current (i _C ) and the compensation current command value (i _ref ) of the inverter with each other to perform current correction within a reference value. Controller; And a gate driver for driving control of the amount of current supplied to the nonlinear load in response to the current correction of the hysteresis current controller.

Preferably, the harmonic detector, the actual current of the single-phase current ( ) Phase A first low pass filter (LPF), delayed by a delay; The virtual current provided through the first low pass filter LPF ) And the actual current ( )end D-axis current component when rotating at speed ) And the q component current component ( A normal component coordinate transformation unit for calculating; D-axis current component calculated by the normal component coordinate conversion unit ( ) And the q component current component ( A second low pass filter (LPF) for extracting only the direct current component of the filter; The virtual current provided through the first low pass filter LPF ) And the actual current ( ) Is- D-axis current component when rotating at speed ) And the current component of the q-axis ( An inverse component coordinate transformation unit for calculating; D-axis current component calculated by the inverse component coordinate transformation unit ( ) And the current component of the q-axis ( A third low pass filter (LPF) for extracting only the direct current component of the filter; And a d-axis current component of a DC component extracted through the second low pass filter (LPF) D) current component of the direct current component extracted through the third low pass filter (LPF) ) By subtracting the d-axis current component ( ), And the q-axis current component of the direct current component extracted through the second low pass filter (LPF) ) And the q-axis current component of the direct current component extracted through the third low pass filter (LPF) ) And add the q-axis current component ( ) And the d- and q-axis current components ( , ) Is the actual current axis ( It is characterized in that the inverse conversion unit for generating the compensation current command value (i _ref ) by performing an inverse transformation for the).

On the other hand, the control method of a single-phase active power filter using a rotary coordinate system according to an aspect of the present invention for achieving the above object, a) the actual current of the single-phase current through the first low pass filter ( Phases Delay by Generating c); b) the virtual current ( ) And the actual current ( ) To coordinate D-axis current component when rotating at speed ) And the q component current component ( Calculating c); c) through the second low pass filter the d-axis current component ( ) And the q component current component ( Extracting only a direct current component of a); d) the virtual current ( ) And the actual current ( ) To- D-axis reverse phase current component when rotating at speed ) And q-axis reverse phase current component Calculating c); e) through the third low pass filter the d-axis reverse phase current component ( ) And q-axis reverse phase current component Extracting only a direct current component of a); f) d-axis current component of the direct current component ( D) reverse phase current component of the direct current component ) By subtracting d-axis current value ( Calculating c); g) q-axis current component of the direct current component ( ) And the q-axis reverse phase current component of the direct current component ( ) And the q-axis current value ( Calculating c); h) the d- and q-axis current values ( , ) Is the actual current axis ( Generating the compensation current command value (i _ref ) by performing an inverse transform on the? And i) the compensation current command value (i _ref) input receives supply of the output current (i _C) and the compensation current command value (i _ref) of the drive are compared with the reference value, the current correction in the to occur non-linear load current Characterized in that the step consisting of controlling.

Preferably, the step h) is h-1) the d-axis and q-axis current components ( , ) Is the actual current axis ( Inversely perform the current setpoint ( Calculating c); h-2) the actual current ( At the current setpoint ( Subtracting) and assuming the result as the compensation current command value (i _ref ).

Alternatively, the step h) is h-1) the d-axis and q-axis current values ( , ) Is the actual current axis ( ) By performing inverse conversion on the current setpoint ( Calculating c); h-2) the current setpoint ( ) Active ingredient ( Extracting; h-3) the actual current ( At the current setpoint ( ) Active ingredient ( Subtracting) and assuming the result as the compensation current command value (i _ref ).

In addition, step i) is i-1) the actual compensation current supplied to the non-linear load ( Calculating c); i-2) The compensation current command value i _ref (t) and the actual compensation current ( Calculating an error e (t) between i-3) switching the inverter in response to the error e (t) of the command current.

The control method of the single-phase active power filter using the rotary coordinate system according to the present invention having such a feature will be described in detail with reference to the accompanying drawings. 1 is a system configuration for explaining a control device of a single-phase active power filter using a rotary coordinate system according to the present invention. As shown, an input power supply Vs is supplied to the nonlinear load 101, and an inverter 109 is connected in parallel with the power input terminal of the nonlinear load 101 to compensate for a harmonic component of current. A harmonic detector 103 is mounted to detect the distorted load current i _L by mounting the CT as an input power source of the nonlinear load 101 and to command a corresponding compensation current. command value (i _ref), an input receiving the output current (i _C) and compensate the command current (i _ref), the cross-comparison reference value hysteresis current controller 105, so that the current correction in the place, and the of the inverter 109, And a gate driver 107 for driving control of the inverter 109 in response to an output signal of the hysteresis current controller 105.

The compensation current command value i _ref is generated by the harmonic detector 103, and the harmonic detector 103 induces a virtual phase current by using a delay characteristic of a low pass filter. Compensation current command value i _ref is calculated by performing forward time calculation using a rotational coordinate system synchronized with the phase current and the power source frequency. FIG. 2 is a block diagram showing a functional module for detecting a harmonic current in such a single phase circuit and calculating a compensation current command value i _ref . 4 is a flowchart for explaining a method for calculating the compensation current command value i _ref .

First, enter the step S401, the actual current drawn into the non-linear load 101, i _{L, Re} ( ) And after passing through the low pass filter (LPF) Delay and reduce the current signal i _{L, LPF} ( ) I _{L, Re} ( ) And i _{L, LPF} ( ) Is defined by equations (1) and (2).

Here, i _{L, Re} is With axial current, i _{L, LPF} is Each defined by the axial current, as in Equation 3;

to be. Actual supply to the non-linear load 101 Virtual current provided through the axial current and low pass filter 201 The axial current forms a waveform having a predetermined phase value as shown in FIG. At this time, using the two components of the equation (4) as shown in Figure 6 (a) Axis Get a coordinate system with axes.

Shown Is Represents a component of a current rotating at a speed of Is- It represents the component of the current rotating at the speed of, and names the current as the normal component and the reverse phase component, respectively. And in step S403, Axial current and The axial current may be converted into a d-axis current and a q-axis current, and the normal component coordinate conversion unit 203 performs calculation based on Equation 4. The calculation uses only the fundamental wave components i _α1 and i _β1 of Equations 1 and 2 above.

Therefore, through the normal component coordinate conversion unit 203 for the normal rotation as shown in Figure 6b Perform coordinate transformation. this is;

Is, Wow _Denotes the DC and AC components of i _dpos , respectively.

therefore,

I _dpos through step S405 Wow I _qpos can be separated into DC component and AC component as divided by. In other words,

In Equation 8 Wow Is represented by the following equations (8) and (9).

On the other hand, the coordinate transformation of the inverse phase component in step S407 is the angular velocity Through the inversion unit 213 and the normal component coordinate transformation unit 211 to invert the. Where, for reverse -> δｑ coordinate transformation as an equation,

to be. In addition, the d- axis current of the negative sequence is represented by Equation 11;

here,

to be. In addition, q- axis current is represented by (12).

here,

to be. In step S409, the above , Represents the DC component of the negative sequence, , Represents an AC component, respectively.

In this way, a two-phase system was constructed using the new phase to obtain the current command value (i _ref ). However, since only compensation for the load current (i _{L, Re} ) is made, after detecting the fundamental wave component of the load current, The harmonic component can be extracted by subtracting the mood wave component from the total load current. At this time, the low pass filters 205 and 209 extract only DC values of i _{d, pos} , i _{q, pos} , i _{d, neg} , i _{q, neg} signals provided through the normal component coordinate conversion units 203 and 211, and S411. In step d using the equations (6) and (12), the d- axis current value ) In other words,

In step S413, the q-axis current value (the DC component of the q-axis current) ) Is obtained by the sum of the equations (8) and (14). In other words,

to be. And dq by the inverse transformation unit 207 in step S415 -> If you convert,

to be. In addition, to calculate the current command value, Only axial components are used, No axial component is used, Is expressed by Equation 18 through step S417.

On the other hand, in the case of filtering only harmonics according to the current command value through the step S419 and filtering the harmonics to compensate for the invalid component, in the first embodiment of the present invention 1) to compensate for both the reactive current component and the distorted current component Remove only the active component of the fundamental wave current from the total load current as follows. That is, the current command value is shown in equation (19).

here, Is Active ingredient.

Also, in the second embodiment of the present invention, 2) in the case of filtering only the distorted components of the active current and the reactive current, Remove it. That is, the current command value at this time is as shown in equation (21).

Meanwhile, the hysteresis current controller 105 is used to control the current of the inverter 109 so that the output current supplied to the nonlinear load 101 can estimate the compensation current command value i _ref . If the current is larger than the bandwidth of the command current, the current size is lowered. If the current is smaller than the command current, the current is increased to control the inverter 109. The current value of the compensation current command value i _ref , that is, the error e (t) between the command current iref (t) and the actual compensation current ic (t), controls the switch operation of the inverter.

If the error of the two signals reaches the upper limit of the hysteresis band, the switch of the inverter will operate to decrease the current. On the contrary, if the error reaches the lower limit, the inverter will operate to increase the current. Therefore, as shown in FIG. 3, the hysteresis current controller 105 is switched so that the output current does not exceed the command current value and the upper limit value (or the lower limit value) in the hysteresis band having an upper limit value and a lower limit value around the command current value. At this time, the switching frequency is expressed by Equation 22;

Where h is the hysteresis limit, Vdc is the DC-Link voltage of the inverter, and L is the value of the inductance of the inverter output stage.

Therefore, the parallel active power filter compensates the harmonic components of the current generated by the nonlinear load 101, thereby providing a stable power supply.

7 to 10 are experimental waveform diagrams showing simulation and experimental results of the present invention. First, the compensation of harmonic currents by the active power filter is performed in a single phase system as described above. The simulation package (PSIM) was used to simulate the RL load as a current source. Figure 7 shows the operating waveforms in a single phase power system with a harmonic current source load. The load current is shown in Fig. 7 (a), the command value of the compensation current determined by the proposed algorithm is Fig. 7 (b), and the actual compensation current which is the output current of the inverter is shown in 7 (c). The power supply current after compensation is shown in Fig. 7 (d).

8 shows an FFT analysis of load current and power supply current. As can be seen from the waveform, it can be seen that the lower harmonic components are well reduced. As a result of measuring THD (Total Harmonic Distortion) up to 25th, the pre-compensation load current contains 18.41% of harmonic components as shown in FIG. It can be seen that there is little compensation left and the remaining harmonic components. The THD after compensation is lowered to 3.05%, meeting the harmonic regulation of IEEE-519.

 Supply Voltage Voltage frequency 110 [ V rms] 60 [Hz]  Sampling Frequency 20 [kHz]  Cut-off Frequency (1) Cut-off Frequency (2) 70 [Hz] 20 [Hz]  DC-Link Capacitance (C_dc) 4700 [㎌]  Load Inductance (L_L) 15 [mH]  Load Resistance (R_L) 12.8 [Ω]  Inverter side Inductance (L_c) 1.8 [mH]

The nonlinear load used in the experiment was a single-phase full-wave rectifier circuit connected to the RL series load. The circuit parameters of the system used are shown in Table 1. The cutoff frequency of LPF , which is required to make the second phase for complex calculation, was 70 [Hz]. Inverter DC-Link capacitor used 4700 [kW], diode rectifier output stage, 15 [mH] inductor (L _L ) and 12.8 [kW] resistor (R _L ). As the inductor L _c of the inverter output stage, 1.8 [mH] was used. In the harmonic detection algorithm, 20 [Hz] was used as the cutoff frequency of LPF used to separate DC components.

9A shows waveforms of the load currents i _{L and Re} and the compensation command current i _ref . 9b shows the inverter output current i _c and the power supply current waveform after compensation (10 A / div, 4 ms / div). The harmonic spectrum of the load current and the power supply current after compensation represents the load current, and is shown in Figs. 9C and 9D, respectively. Therefore, the THD of the load current is 17.94%, and the harmonic component of the compensated power supply current is 3.25%, which satisfies the harmonic regulation of IEEE-519. 10A shows the waveform of the currents at the start of the control circuit. In order to verify the dynamic characteristics of the proposed active power filter, eh 10b is measured the waveform of load current and power current when the load is changed from 50% to 100%. It can be seen that the waveforms of the power current before and after the load remain sinusoidal.

As described above, the control system and method of the single-phase active power filter using the rotational coordinate system according to the present invention by presenting a control algorithm for the single-phase active power filter which is a method of harmonic reduction caused by a single-phase nonlinear load, In the conventional method, it takes minimum half-cycle time to detect harmonics, and it is possible to make instantaneous calculations by using a virtual phase to create a coordinate system as used in three phases.

In addition, unlike the conventional method of creating a virtual phase by delaying the actual load current, a current having a different phase and magnitude is generated by using a delay characteristic of a low pass filter, and two currents having a different phase are used by a rotational coordinate system. After detecting the fundamental wave current, the compensation current command value including only the harmonic component can be obtained by removing the fundamental wave component from the load current, thereby providing the effect of real-time control.

1 is a configuration diagram showing a control system of a single phase active power filter according to the present invention.

FIG. 2 is a diagram illustrating a harmonic detector of FIG. 1. FIG.

FIG. 3 is a graph for explaining the hysteresis current controller of FIG. 1.

4 is a flowchart for explaining the main operation of the present invention.

5 is a capture screen of an oscilloscope for explaining a phase difference between a real current and a virtual current.

6A and 6B are graphs for explaining axis transformation by the phase difference between the actual current and the virtual current.

7 is an operational waveform diagram of each terminal of the single-phase power system according to the present invention.

8 is a waveform diagram showing harmonic spectra before and after compensation.

9A is an analog output waveform of the load current and the compensation current command value, 9b is an output waveform showing the power current before and after compensation, 9c is a waveform showing the frequency spectrum of the load current, and 9d is a harmonic spectrum of the power current after compensation. The waveform diagram shown.

Fig. 10A is a waveform of current at the time of starting a control circuit, and 10b is a diagram of waveform of power supply current in a variable load.

<Description of Symbols for Main Drawings>

101: non-linear load 103: harmonic detector

105: hysteresis current controller 107: gate driver

109: inverter 201, 205, 209: low pass filter

203, 211: normal component coordinate transformation unit 207: inverse transformation unit

Claims (9)

In the control device of the power filter for compensating the current harmonic components of the non-linear load connected in parallel with the inverter, Detects the single-phase current of the input power supply of the non-linear load through a current detector, and derives a virtual phase current using the delay characteristic of a low pass filter from the single-phase current, and synchronizes the two phase currents and the power frequency. A harmonic detector for detecting the distorted load current i _L and commanding a compensation current corresponding thereto using a rotational coordinate system; A hysteresis current that receives a compensation current command value (i _ref ) corresponding to the compensation current and compares the output current (i _C ) and the compensation current command value (i _ref ) of the inverter with each other to perform current correction within a reference value. Controller; And And a gate driver for driving control of the amount of current supplied to the nonlinear load in response to the current correction of the hysteresis current controller. The method of claim 1, wherein the harmonic detector, Actual current of the single-phase current ( ) Phase A first low pass filter (LPF), delayed by a delay; The virtual current provided through the first low pass filter LPF ) And the actual current ( )end D-axis current component when rotating at speed ) And the q component current component ( A normal component coordinate transformation unit for calculating; D-axis current component calculated by the normal component coordinate conversion unit ( ) And the q component current component ( A second low pass filter (LPF) for extracting only the direct current component of the filter; The virtual current provided through the first low pass filter LPF ) And the actual current ( ) Is- D-axis current component when rotating at speed ) And the current component of the q-axis ( An inverse component coordinate transformation unit for calculating; D-axis current component calculated by the inverse component coordinate transformation unit ( ) And the current component of the q-axis ( A third low pass filter (LPF) for extracting only the direct current component of the filter; And D-axis current component of the DC component extracted through the second low pass filter (LPF) D) current component of the direct current component extracted through the third low pass filter (LPF) ) By subtracting the d-axis current component ( ), And the q-axis current component of the direct current component extracted through the second low pass filter (LPF) ) And the q-axis current component of the direct current component extracted through the third low pass filter (LPF) ) And add the q-axis current component ( ) And the d- and q-axis current components ( , ) Is the actual current axis ( A control system for a single phase active power filter using a rotational coordinate system, characterized in that the inverse transform unit for performing the inverse transform to generate the compensation current command value (i _ref ). The method of claim 2, wherein the compensation current command value (i _ref ) is a DC component of the d-axis and q-axis current ( , ) Is the actual current axis ( Inversely perform the current setpoint ( ) And the actual current ( At the current setpoint ( Subtracting) and assuming the result as the compensation current command value (i _ref ), a control system for a single-phase active power filter using a rotary coordinate system. The method of claim 2, wherein the compensation current command value (i _ref ) is a DC component of the d-axis and q-axis current ( , ) Is the actual current axis ( ) By performing inverse conversion on the current setpoint ( ) And the current command value ( ) Active ingredient ( ) And the actual current ( At the current setpoint ( ) Active ingredient ( ) Subtracts the result by the compensation current command value (i _ref ), the control system for a single-phase active power filter using a rotary coordinate system. 2. The hysteresis current controller of claim 1, wherein the hysteresis current controller comprises the compensation current command value i _ref (t) and the actual compensation current (i). The control system of a single-phase active power filter using a rotational coordinate system, characterized in that for switching the inverter in response to the error (e (t)). In the control method of the power filter for compensating the current harmonic component of the non-linear load connected in parallel with the inverter, a) the actual current of the single phase current through the first low pass filter ( Phases Delay by Generating c); b) the virtual current ( ) And the actual current ( ) To coordinate D-axis current component when rotating at speed ) And the q component current component ( Calculating c); c) through the second low pass filter the d-axis current component ( ) And the q component current component ( Extracting only a direct current component of a); d) the virtual current ( ) And the actual current ( ) To- D-axis reverse phase current component when rotating at speed ) And q-axis reverse phase current component Calculating c); e) through the third low pass filter the d-axis reverse phase current component ( ) And q-axis reverse phase current component Extracting only a direct current component of a); f) d-axis current component of the direct current component ( D) reverse phase current component of the direct current component ) By subtracting d-axis current value ( Calculating c); g) q-axis current component of the direct current component ( ) And the q-axis reverse phase current component of the direct current component ( ) And the q-axis current value ( Calculating c); h) the d- and q-axis current values ( , ) Is the actual current axis ( Generating the compensation current command value (i _ref ) by performing an inverse transform on the? And i) the output current (i _C) and the compensation current command value (i _ref) the mutual comparison reference value supplied to the current correction in the to occur non-linear load current of the inverter receiving the compensation current command value (i _ref) Control method of a single-phase active power filter using a rotational coordinate system, characterized in that consisting of a step of controlling. The method of claim 6, wherein step h) is performed by h-1) the d-axis and q-axis current components ( , ) Is the actual current axis ( Inversely perform the current setpoint ( Calculating c); h-2) the actual current ( At the current setpoint ( Subtracting) and assuming the result as the compensation current command value (i _ref ). 7. The method of claim 6, wherein the step h) comprises h-1) the d-axis and q-axis current values ( , ) Is the actual current axis ( ) By performing inverse conversion on the current setpoint ( Calculating c); h-2) the current setpoint ( ) Active ingredient ( Extracting; h-3) the actual current ( At the current setpoint ( ) Active ingredient ( Subtracting) and assuming the result as the compensation current command value (i _ref ). 7. The method of claim 6, wherein step i) comprises i-1) actual compensation current supplied to the nonlinear load ( Calculating c); i-2) The compensation current command value i _ref (t) and the actual compensation current ( Calculating an error e (t) between i-3) A control method of a single phase active power filter using a rotational coordinate system, characterized in that the switching control of the inverter in response to the error (e (t)) to the command current.