KR20080053777A - Apparatus for detecting reverse connetion of three-phase input source - Google Patents

Abstract

An apparatus for detecting a reverse phase of three-phase input power is provided to reduce a manufacturing cost by determining the reverse phase through a flip-flop. An apparatus for detecting a reverse phase of three-phase input power includes a power input unit(100), a rectification unit(110), and a flip-flop(120). The power input unit receives 3-phase AC power from the outside. The rectification unit receives two signals among signals with different phases inputted to the power input unit and converts the two signals into constant voltage. The flip-flop compares the phases of the two signals converted by the rectification unit, determines whether the phases are normal or not, and then outputs the determination result.

Description

 Apparatus for detecting reverse connetion of three-phase input Source}

1 is a block diagram schematically showing the configuration of an apparatus for detecting a reverse phase of a three-phase AC power source according to an embodiment of the present invention;

2 is a circuit diagram illustrating an apparatus for detecting a reverse phase of a three-phase AC power source according to an embodiment of the present invention;

3 is a graph showing a three-phase AC power signal according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: power input unit 110: rectifier

115: stabilizer 120: flip-flop

130: output unit 132: switching unit

134: light emitting unit 140: power supply unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse phase detection device for an input power source, and more particularly to a reverse phase detection device for a three phase AC power source.

Three-phase AC power is used in a variety of fields, including industrial sites that require a high power output is possible than the single phase power source. It is particularly useful for machine tools, fans, and compressors that use rotating magnetic fields. However, unlike single-phase AC power that does not need to distinguish the phase of the input power, a three-phase AC power source causes a serious problem when the input order of the three-phase power is changed during wiring. Serious damage to the entire system can occur, for example, by changing the direction of rotation of the motor or by stopping the machine tool from operating. However, the actual three-phase AC power is applied to large-scale business sites, and the distance from the main power input unit, it is difficult for the operator to manually check the reverse phase of the three-phase power in the process.

Due to this difficulty, there are largely a current based method and a voltage based method as a method of checking whether a three-phase AC power source is connected in reverse phase. The three phases R, S, and T phases are sinusoidal waves having a phase difference of 120 degrees. That is, in order to check whether the input order of the three phases is correct, the order of all three phases can be determined by only holding one phase of three phases and determining the order of the remaining two phases.

First, the current-based method uses a current sensor to detect the current in the R, S, and T phases supplied to the power supply. Specifically, the R, S, and T phase currents are half-wave rectified and converted into DC voltage. After the current value is recognized in the voltage waveform corresponding to the R phase, the T-phase current value is checked at the time when it becomes '0'. It can be seen that if a positive waveform is present, it is reversed, otherwise it is normal (normal). The method of detecting the reversed phase state based on the current has a disadvantage that the current sensor is relatively expensive, and the reversed state of the AC power can be detected after driving the compressor to which the three-phase AC power is applied. If the compressor is operated by supplying three-phase AC power connected in the reversed phase without recognizing the reversed phase, there is a problem that may cause damage to the entire system including the compressor.

On the other hand, the voltage-based reverse phase detection method has the advantage that it can detect whether or not the reverse phase state without driving the compressor operating by the actual three-phase AC power source. Representatively, a method of detecting a reverse phase based on voltage is to connect a resistor (R), a coil (L), and a capacitor (C) with a three-phase power supply and star to determine whether the phase is reverse according to the voltage waveform at the neutral point. have. The resistor, coil, and capacitor-based method connects a coil on R, a resistor on S, and a capacitor on T. The coil delays the phase by 90 degrees, the resistance maintains the phase, and the capacitor advances the phase by 90 degrees. When the R, S, and T phases are output in order, the single phase waveform is detected at the neutral point. . On the other hand, when a reverse phase phenomenon occurs in which the order of some of the three phases is reversed, 0 V is detected at the neutral point by the waveform having the reverse phase. However, as described above, the method of detecting the reverse phase in reality is that the resistor, the coil, and the capacitor cannot have the ideal gain and phase response characteristics as described above, and even in this case, '0'V is not output exactly at the neutral point. There is a problem that this is high.

One of the conventionally proposed techniques for detecting the reverse phase of a three-phase AC power input, using a photodiode and a photo transistor to half-wave rectified the voltage of the R, S, and T phases to form a DC voltage and then detect a reverse phase state. This is disclosed in Korean Patent Laid-Open Publication No. 2005-105645. It first detects the S phase after 8.25 ms of time after the R phase is detected, and detects the signal by repeating four times in 250 ms units when the S phase is detected. After that, if the high value is not detected more than three times in four times during the detection of the S phase, the process is processed as an error once and the S phase error count is increased. After that, the T phase is detected after 13.75 ms based on the time when the high value of the R phase is detected, and at this time, the signal is repeatedly detected four times in a unit of 250 μs. If the T value is not detected more than three times out of four times, the T phase error count is increased by processing one error. If the error counts of the S and T phases are equal to or greater than the error reference value, it is assumed that the three phase signals are not continuously detected and an error flag is generated. At this time, in determining the state of the image, the toughness is imparted by implementing a high value at the time when the size of the image becomes at least 1/2 of the maximum value. This has the advantage that the accuracy can be improved compared to the existing method, but even if the detection of the waveform several times to detect the reverse phase there is a limit that there is a risk of malfunction due to sudden waveform distortion or serious noise. In addition, in addition to the basic elements such as photodiodes and phototransistors required for implementing the algorithm proposed in the prior art, additional elements such as sampling devices and counters are required, which increases the manufacturing cost. Even when using a microprocessor in a general manner, the cost is higher than using a logic gate or flip-flop. That is, the manufacturing cost is high, the application range is limited in the application to the integrated product.

The present invention is derived from such a background, and aims to prevent the entire system from being damaged by the reverse phase input of the three-phase AC power supply by accurately detecting the reverse phase input before driving the system.

Furthermore, an object of the present invention is to provide a reverse phase sensing device of a low-cost three-phase AC power source.

Additionally, an object of the present invention is to prevent an error in a detection result due to spark or noise in detecting reverse phase of an input three-phase AC power.

In order to achieve the above object, a reverse phase detection apparatus for a three-phase AC power source according to an aspect of the present invention selects any two signals among three-phase AC power signals to be input and flips a signal that must be in phase in a normal state of the two. The data terminal of the flop is applied, and a signal having a late phase is applied to the clock terminal to determine whether the phase is reversed based on the output value of the flip flop.

According to the present invention according to this aspect of the present invention, it is possible to accurately detect whether the reverse phase before driving the system to prevent the entire system from being damaged by the reverse phase of the three-phase AC power supply, and to reverse the phase image using the flip-flop By determining whether there is an effect that can reduce the production cost of the reverse phase detection device of the three-phase AC power source.

According to a further aspect of the present invention, the rectifier for receiving a three-phase AC power is converted into a constant voltage further comprises a stabilization unit including a plurality of zener diodes having a breakdown voltage so that the output is a constant voltage if the input AC power is a predetermined value or more. As a result, an error can be prevented from occurring in the detection result due to spark or noise.

The foregoing and additional aspects of the invention are described in detail below to enable those skilled in the art to readily understand and reproduce through the embodiments described with reference to the accompanying drawings.

1 is a block diagram schematically illustrating a configuration of an apparatus for detecting a reverse phase of a three-phase AC power source according to an embodiment of the present invention. As shown, the reverse phase detection apparatus according to the present invention receives two signals from the power input unit 100 receives a three-phase AC power from the outside, and signals of different phases input to the power input unit 100. The rectifier 110 converts the constant voltage and the two signals converted by the rectifier 110 into two inputs, and includes a flip-flop 120 that outputs an on / off signal depending on whether it is normal or reversed.

The other illustrated power supply unit 140 supplies the control power required for driving the reversed phase sensing apparatus according to the present invention. In the present embodiment, one of the three phases (R, T, C) other than any two phases selected among the AC power source is rectified to a predetermined voltage and applied to the power supply unit 140.

The power input unit 100 receives a three-phase (R, T, C) AC power source having a phase difference of 120 degrees from the outside. This is a known configuration.

The rectifier 110 receives two signals arbitrarily selected from signals of different phases input to the power input unit 100 and converts them into constant voltages. 2 is a circuit diagram illustrating an apparatus for detecting a reverse phase of a three-phase AC power supply according to an embodiment of the present invention. In this embodiment, signals input to L2 and L3 are assumed to be two signals selected arbitrarily.

First, a high voltage signal (phase T) input to L3 is a voltage of a desirable degree to be applied to the input terminal of the flip-flop 120 later by the resistors R13, R14, R15, and R16 for limiting the current. Voltage drop. First , a voltage drop occurs by the zener diode Q6 having a large breakdown voltage, and a constant voltage of about 5V is output by Q7. In the present embodiment, Q6 has a breakdown voltage of about 47V. However, it is not limited thereto. As described above, the numerical value of the constant voltage output through the rectifier 110 is not limited to 5V, but may be a value input to the input terminal to the flip-flop 120, which will be described later.

In addition, a signal (S phase) input to L2 may have a voltage drop caused by the resistors R1, R2, and R3 and the zener diode Q3 for current limiting, and a constant voltage of 5V may be output by Q4.

In addition to the two signals arbitrarily selected as described above, the signal (phase R) input to L1 is also output at a constant voltage by the diodes D1, D2, D3, and D4. At this time, the remaining voltages which are not outputted as the constant voltage among the high voltages input to L1 are charged to C4 and C5. On the other hand, when the input voltage is low, the voltages charged in C4 and C5 are discharged through the discharge resistors R9, R10, R11, and R12. Through the charge / discharge of C4 and C5, the AC power input to L1 may be stably output at a constant voltage.

According to an additional aspect of the present invention, the rectifier 110 may further include a stabilization unit 115 for absorbing noise power fluctuations such as distortion of an input AC power waveform or an abnormal abnormal variation. As shown in FIG. 2, the stabilization unit 115 includes zener diodes Q1, Q2, and Q3 including Zener diodes Q1 having a high breakdown voltage with a part of voltage for a high voltage signal input through L2. , Q2, Q3) and a voltage drop occurs. That is, the constant voltage signal may be output when the voltage of the signal input through the L2 terminal is greater than or equal to the breakdown voltage of the Zener diodes Q1, Q2 and Q3. As a result, it is possible to prevent the constant voltage from being output to the spark or noise input that occurs momentarily, and to prevent an error in the inverse detection result due to noise such as waveform distortion or spark.

In addition, by outputting a shaped DC voltage using a zener diode and passing a low pass filter, the robustness can be increased by substantially eliminating a large amount of abrupt waveform distortion or noise that may exist in the generated 5V input voltage.

The flip-flop 120 compares the phases of the two signals converted by the rectifier 110 to determine whether it is normal or reversed, and outputs the determination result.

According to a characteristic aspect of the present invention, the flip-flop 120 is applied to the data terminal an output signal of which the phase should be faster in the normal state of the two signals, and an output signal from the terminal from which the signal having a late phase is output to the clock terminal. It is characterized in that the D flip-flop (U2).

3 is a graph showing a three-phase AC power signal according to an embodiment of the present invention. As shown in the figure, the S phase input to the L2 terminal is 120 degrees ahead of the T phase input to the L3. The illustrated t1, t2, t3, t4 are arbitrary times set according to whether the two waveforms are positive (H) or negative (L) values. Table 1 shows only four parts of time for each waveform type, but since three-phase AC power signals are sinusoids with a constant period, they cycle in the same cycle as t1-> t2-> t3-> t4-> t1-> t2. do. The output values for the signals applied to the flip-flop 120 for each time are shown in the table.

DATA (S phase) Clock (T phase) Q t1 H L t2 H H H t3 L H t4 L L

In the present embodiment, the flip-flop 120 may be a D flip-flop of the upward edge trigger. The output value to the output terminal Q is the output value when the clock value becomes L-> H value, which is already input to the Data terminal at the time t1. That is, the output value at the time t2 to which the clock is applied becomes the H value input to the D terminal at the time t1. According to the operation principle of the flip-flop, the value output to the output terminal Q is always a high value when the three-phase AC power input is normal.

The reverse phase of the three-phase signal is when the input order of the three-phase waveforms is changed. In this case, the T phase is input to the L2 terminal and the S phase is input to the L3 terminal. That is, when there is a reverse phase input, the T phase shown in the graph of FIG. 3 is applied to the data terminal D of the flip-flop 120, and the S phase is applied to the clock terminal. This case is shown as a table | surface as follows.

DATA (T phase) Clock (S phase) Q t1 L H L t2 H H t3 H L t4 L L

In the same way as in normal operation, the output at the time t1, which is the time when the clock value is applied, is the value already input to the DATA terminal, and the L value is output. Accordingly, it can be seen that the output value of the D flip-flop 120 is always a low value when a reverse phase occurs.

The output unit 130 outputs the determination result output from the flip-flop 120 to the outside. In the output unit 130 according to an aspect of the present invention, the light emitting unit 134 and the collector end are connected to the light emitting unit, and the base end is connected to the output terminal of the D flip-flop 120, and the D flip-flop 120 is provided. If the value output to the output terminal of the high value includes a switching unit 132 is turned on.

The light emitting unit 134 may be implemented as a conventional light emitting diode (LED) for converting current into light.

As illustrated in FIG. 2, the switching unit 132 includes a transistor Q9 that is turned on / off according to the output value of the D flip-flop U2 output through the Schmitt trigger U1. In addition, the Schmitt trigger (U1) is to prevent the error caused by the noise output, in this embodiment, as shown in Figure 2 the signals applied to the flip-flop 120, and the output signals are the Schmitt trigger (U1) Is implemented. In the present embodiment, when the signal applied to the base terminal of Q9 is a high value, the collector stage and the emitter stage are conducted in accordance with the switching mode operating characteristics of the transistor. Therefore, as shown in the circuit diagram of FIG. 2, a closed loop circuit in which LED1 can emit light is configured by the voltage 24V input from the power supply unit 140. At this time, as the collector terminal and the emitter terminal of Q9 become conductive, no current is applied to the base terminal of Q8, and Q8 is turned off. On the other hand, when a low signal is applied to the base terminal of Q9, Q9 is turned off and the collector terminal and emitter terminal of Q9 are cut off, and the current is supplied to the base terminal of Q8 by the voltage 24V input from the power supply unit 140. Q8 is turned on. When Q8 is on, the collector and emitter terminals of Q8 are conducting and no current is supplied to LED1.

That is, a signal applied from the output terminal of the D flip-flop U2 controls the on / off of the switching unit 132 included in the output unit 130, and LED1 according to the on / off state of the switching unit 132. A closed loop capable of driving the loop is formed. Accordingly, whether the reverse phase is detected or not can be displayed to the outside through the on / off state of the LED1.

As described in detail above, according to the present invention, it is possible to accurately detect whether or not the reverse phase is lost before driving the system to prevent the whole system from being damaged by the reverse phase input of the three-phase AC power source. As a result, it is possible to significantly reduce the production cost of the reverse phase detection device of the three-phase AC power source compared to the method of detecting the reverse phase state based on the existing current.

In addition, in detecting the reverse phase of the three-phase AC power supply, it is possible to prevent an error in the detection result due to the influence of noise such as waveform distortion or sparks.

Although the present invention has been described with reference to the preferred embodiments described with reference to the accompanying drawings, it is not limited thereto, and various modifications may be made without departing from the spirit of the present invention. Accordingly, the invention should be construed by the appended claims, which are intended to cover such obvious variations.

Claims (5)

A power input unit configured to receive three-phase AC power from the outside; A rectifying unit receiving two signals among signals of different phases input to the power input unit and converting the signals into constant voltages; A flip-flop that receives two signals converted by the rectifier as inputs and outputs an on / off signal depending on whether the signal is normal or reversed; Reverse phase detection device for a three-phase input power, characterized in that it comprises a. 2. The flip-flop of claim 1, wherein the flip-flop is a D-flop in which a signal having a higher phase in a normal state is applied to a data terminal and an output signal having a lower phase is applied to a clock terminal. Reverse phase detection device for phase input power. The method of claim 2, wherein the rectifying unit: And a stabilizing unit for absorbing noise power fluctuations such as distortion of waveforms of an AC power input or transient abnormality fluctuations. The method of claim 3, wherein the stabilizing unit: Reverse phase sensing device for a three-phase input power source, characterized in that the zener diode having a breakdown voltage. The apparatus of claim 4, wherein the reversed phase sensing device is: An output unit including a light emitting unit, a switching unit connected to the light emitting unit, a base end connected to an output terminal of the flip-flop, and a switching unit turned on when the output value of the flip-flop is high; Reverse phase detection device for a three-phase input power, characterized in that it further comprises.

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