KR100305688B1 - Phase detection device of ac waveform and method thereof - Google Patents

Abstract

PURPOSE: A phase detection device of AC waveform and method thereof is provided to prevent a malfunction owing to waveform fluctuation and to exactly detect a phase angle at a bad circumstance, by detecting the phase angle at a current time with simple hardware and software regardless of fluctuation of an AC waveform. CONSTITUTION: A voltage division circuit part(21) divides an AC input voltage(Vi). A photo-coupler(22) separates a ground between the voltage division circuit part(21) and a next stage and couples the divided voltage to a next stage. A limit circuit part(23) limits a voltage from the photo-coupler(22) to output a logic signal to a processor(24). The processor(24) calculates a high-level sustain time from a rising time to a falling time based on a rising time of a logic level as a reference time and divides a different time between the high-level sustain time and a half-period time by 2 in order to obtain the rising time. The processor adds the rising time and the high-level sustain time to obtain the falling time, and detects a phase angle using the falling time.

Description

Phase detection device of AC waveform and its method

The present invention relates to a phase detection device and method thereof for an AC waveform, and in particular, to enable a simple hardware and software to accurately detect an image (phase angle) at a current time regardless of the variation of the AC waveform, The present invention relates to an AC waveform phase detection device and a method thereof, which can prevent a malfunction and also enable accurate phase detection even in a harsh environment such as an industrial site with heavy load fluctuations.

In general, the fields in which phase detection devices for AC waveforms such as power supplies are used include power converters such as UPS, active filters, special purpose compensation devices such as low voltage compensators, demodulation circuits, and synchronous signal generation circuits. For example, the AC waveform phase detection device is applied to various fields of the industry.

1 is a block diagram of a phase detection apparatus for a conventional AC waveform. Referring to FIG. 1, a phase detection apparatus for a conventional AC waveform is outputted by comparing an input AC waveform with an arbitrary reference wave. It is used to feed back the stable oscillation by using VCO as input of VCO.

FIG. 1 is a block diagram of a PLL which is widely used as a phase detection method throughout the industry. The input power Vi and the reference power Vr are multiplied using a multiplexer, which is a phase comparator 11, and the output value When the error voltage is averaged by using the low pass filter 12 and the value is applied to the input of the VCO 13, the oscillation frequency (phase) is converted in the VCO. At this time, by using the output of the converted VCO 13 as a reference power, the error between the input power is reduced and the error value becomes "0" when the frequency of the input power and the reference power are the same and the phase is 90 degrees out of phase. The oscillation is stable and the phase of the input voltage is detected by converting the VCO output value.

However, in the conventional phase detection method, when the input power is stabilized and the size does not change, accurate detection results can be obtained. However, when the state of the input power is unstable or severe, a phenomenon such as an instantaneous low voltage or an instantaneous voltage rise occurs. In this case, the error value is changed so that accurate phase detection is impossible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and therefore, an object of the present invention is to enable accurate detection of a phase (phase angle) at the present time with simple hardware and software, regardless of an AC waveform variation. The present invention provides a method and method for detecting phases of an AC waveform which can prevent malfunction due to waveform variation and also enable accurate phase detection even in a harsh environment such as an industrial site with heavy load fluctuations.

1 is a block diagram of a phase detection apparatus for a conventional AC waveform.

2 is a block diagram of an AC waveform phase detection device according to the present invention.

3 is an AC waveform diagram for explaining phase detection with respect to the AC waveform.

4 is a flow chart showing a phase detection method of an AC waveform according to the present invention.

Explanation of symbols on the main parts of the drawings

21: voltage divider circuit 22: photo coupler

23: limit circuit 24: processor

As a technical means for achieving the above object of the present invention, the apparatus of the present invention comprises: a voltage distribution circuit unit for dividing and outputting an input power of AC to a size required at a rear stage; A photocoupler separating the ground between the voltage distribution circuit portion and the next stage and coupling the divided voltage from the voltage distribution circuit portion to the next stage; A limit circuit unit configured to provide a logic signal by limiting a voltage through the photocoupler to a predetermined level to a subsequent processor; The high level holding time from the rising time to the falling time is calculated using the rising time as the reference time, and the rising time is obtained by dividing the difference time between the high level holding time and the half cycle time by two. A processor for obtaining a falling time by adding the rising time and the high level holding time, and detecting a phase angle using the falling time; Characterized in having a.

In addition, as another technical means for achieving the object of the present invention, the method of the present invention, the voltage divider circuit portion for dividing the input power of the AC to the size required in the rear stage, and the ground between the voltage divider circuit portion and the next stage separated A photocoupler for coupling the divided voltage to the next stage, a limit circuit unit for limiting the voltage through the photocoupler to a predetermined level, and phase detection of an AC waveform performed by a processor based on a logic signal from the limit circuit unit. A method, comprising: a first step of calculating a high level holding time from a rising time to a falling time with a logic level from the limit circuit unit as a reference time; A second step of obtaining a rise time by dividing the difference time between the high level holding time obtained in the first step and the half cycle time of the AC waveform by 2; A third step of obtaining a fall time by adding the rise time and the high level holding time obtained in the second step; A fourth step of detecting a phase by converting the fall time obtained in the third step into a phase angle; Characterized in that made.

Hereinafter, an AC waveform phase detection device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram of an AC waveform phase detection device according to the present invention. Referring to FIG. 2, the AC waveform phase detection device according to the present invention is required to have an AC input power Vi at a rear end thereof. The voltage divider circuit 21 for dividing and outputting the photocoupler 22 which separates the ground between the voltage divider circuit 21 and the next stage and couples the divided voltage from the voltage divider circuit 21 to the next stage. And a limit circuit section 23 for providing a logic signal by limiting the voltage through the photocoupler 22 to a predetermined level, and the logic level from the limit circuit section 23 rises at time t1. A high level holding time (Δt) from the rising time t1 to the falling time t2 is calculated as a reference time, and the time between the high level holding time (Δt) and the half cycle (2 / T) time is calculated. The rise time (t1) is divided by the difference time (T / 2- △ t) by two. And it is composed of a processor 24 for adding the rise time (t1) and high-level holding time (△ t) is obtained for the falling time (t2), detecting the phase angle using the falling time (t2).

In addition, the processor 24 obtains the falling time t2 of the logic signal provided from the limit circuit unit 23, that is, the image at the current time by the following equation (1).

Here, 0.5 (T over 2-DELTA t) + DELTA t is t1.

3 is an AC waveform diagram for explaining phase detection with respect to an AC waveform, and FIG. 4 is a flowchart showing a method for detecting an AC waveform phase according to the present invention.

Operation according to the device of the present invention configured as described above will be described in detail below based on the accompanying drawings.

Referring to FIGS. 2, 3, and 4, first, the voltage distribution circuit unit 21 shown in FIG. 2 divides an AC power source having an arbitrary frequency into a voltage having a magnitude required at a rear end thereof. It is provided to the limit circuit part 23 through the coupler 22.

The photocoupler 22 separates the ground between the power supply side of the voltage distribution circuit section 21 and the control side of the limit circuit section 23 and simultaneously transfers the voltage from the voltage distribution circuit section 21 to the limit circuit section 23. Combine.

The limit circuit unit 23 is configured as a schmitt trigger, which provides a logic signal generated by limiting a voltage provided through the photocoupler 22 to a predetermined level, which is set in advance, to the processor 24. The processor 24 detects an image at the current time, that is, the falling time t2 of the logic signal, as shown in the flowchart shown in FIG. 4, which will be described in detail below.

First, in the first steps 41 and 42, the rising time t1 at which the logic level from the limit circuit unit 21 rises from the low level " 0 " to the high level " 1 " The time from the rising time t1 to the falling time t2 at which the logic signal falls from the high level to the low level, that is, the high level holding time DELTA t at which the logic signal is maintained at the high level is calculated.

In the second step 43, the difference time T / 2-Δt between the high level holding time DELTA t obtained in the first step 42 and the half cycle (2 / T) time of the input AC waveform is calculated. Dividing by 2, the rise time t1 from the time when the input AC waveform is zero-crossed to the time when the logic signal rises from a low level to a high level can be obtained.

In the third step 44, the logic signal falls from the high level to the low level from the time when the zero crossing is performed by adding the rising time t1 obtained in the second step 43 and the high level holding time DELTA t. Find the fall time (t2) to.

In the fourth step 45, a phase is detected by converting the fall time t2 obtained in the third step 44 into a phase angle, which is expressed by Equation 2 below.

Here, 1 / f * 0.5 is a time corresponding to a half cycle of the AC waveform. If the AC waveform is 60 Hz, the 1 / f * 0.5 is 8.33 msec.

According to the present invention, it is possible to accurately calculate the phase angle at the current time irrespective of the change in the input voltage, so that it can be applied to industrial sites with high fluctuation load, and the circuit configuration for phase detection is simple, thereby reducing the possibility of its own malfunction. In addition, the method for image detection is not only fixed in hardware as in the conventional method, but in the present invention, by adding software, the algorithm for more accurate image detection is improved and the scalability for the future is excellent.

According to the present invention as described above, by allowing a simple hardware and software to accurately detect the phase (phase angle) at the current time irrespective of the fluctuation of the AC waveform, it is possible to prevent malfunction due to the waveform fluctuations, Accurate phase detection is effective even in harsh environments such as industrial sites with heavy load fluctuations.

The above description is only a description of one embodiment of the present invention, the present invention is capable of various changes and modifications within the scope of the configuration.

Claims (4)

A voltage divider circuit 21 for dividing and outputting an AC input power Vi into a size required at a later stage; A photocoupler 22 separating the ground between the voltage divider circuit 21 and the next stage and coupling the divided voltage from the voltage divider circuit 21 to the next stage; A limit circuit unit 23 for providing a logic signal by limiting the voltage through the photocoupler 22 to a predetermined level to a processor at a later stage; The logic level from the limit circuit section 23 calculates the high level holding time Δt from the rising time t1 to the falling time t2 using the rising time t1 as a reference time, and the high level. The rise time t1 is obtained by dividing the difference time T / 2-Δt between the holding time Δt and the half cycle (2 / T) time by two, and the rising time t1 and the high level holding time Δ a processor 24 for adding the t) to obtain the fall time t2 and detecting the phase angle using the fall time t2; Phase detection device of the AC waveform, characterized in that it comprises a. 2. The processor 24 according to claim 1, wherein the processor 24 sets the fall time t2 of the logic signal provided from the limit circuit section 23, i.e., the image at the present time.

An AC waveform phase detection device, characterized by the equation. A voltage divider circuit 21 for dividing an AC input power Vi into a size required at a later stage, and a port separating the ground between the voltage divider circuit 21 and the next stage and coupling the divided voltage to the next stage. AC waveform performed in the processor 24 based on the coupler 22, the limit circuit section 23 for limiting the voltage through the photocoupler 22 to a predetermined level, and the logic signal from the limit circuit section 23 In the phase detection method of A first step of calculating the high level holding time Δt from the rising time t1 to the falling time t2 with the logic level from the limit circuit section 21 as the reference time as the rising time t1 ( 41,42); The rise time t1 is divided by two by dividing the difference time T / 2-Δt between the high level holding time DELTA t obtained in the first step 42 and the half cycle 2 / T time of the AC waveform by two. Obtaining a second step 43; A third step (44) of obtaining a fall time (t2) by adding the rising time (t1) and the high level holding time (Δt) obtained in the second step (43); A fourth step 45 of detecting a phase by converting the fall time t2 obtained in the third step 44 into a phase angle; Phase detection method of the AC waveform, characterized in that consisting of. The method of claim 3, wherein in the fourth step 45, the phase angle at the fall time t2 is determined.

Phase detection method of an AC waveform, characterized by the equation.

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