KR100312741B1 - Phase detecting circuit of an air - conditioner - Google Patents

Abstract

A phase detection circuit of an air conditioner is disclosed. Features of the phase detection circuit of the air conditioner according to the present invention, the DC conversion unit for converting the AC power input to the DC, an AC coupling unit for removing only the DC component of the applied power and passing only the AC power, the AC coupling unit Comparing unit for detecting the zero potential point by comparing the AC power applied from the DC power applied from the DC converter, the control unit for driving the load by turning on and off the switching element when the zero potential detection signal is applied from the comparison unit Include. Therefore, the present invention as described above can accurately detect the zero potential point by comparing the waveform of the AC power supply and the DC power supply, the switching loss is reduced as the on / off operation of the switching element is made smoothly, the driving of the load is made stable .

Description

Phase detecting circuit of an air conditioner

The present invention relates to an air conditioner, and more particularly, to a phase detection circuit of an air conditioner for accurately detecting a zero potential point of an AC power source to improve power factor and attenuate harmonic currents.

Generally, the power factor of an air conditioner Improve the harmonic current In order to attenuate, the zero potential point of the AC power supply is detected, and power is supplied to each load from the zero potential point until the air conditioner is turned off to stop driving. Therefore, the power factor of the air conditioner Improve air conditioner Harmonic current To attenuate, the zero potential must be detected accurately.

1 is a view showing a phase detection circuit of a conventional air conditioner.

As shown in Figure 1, the phase detection circuit of the conventional air conditioner The AC power source AC is rectified by a bridge diode. A reactor is connected to the bridge diode. In addition, the reactor (Reactor) is connected in series with the first diode (D1), between the reactor (Reactor) and the first diode (D1) a switching element (Isolate Gate Bipolar Trangistor (GBT)) is the bridge diode ( It is connected in parallel with the output terminal of the bridge diode). The first diode D1 is connected to the load 20, and a first capacitor C1 is connected in parallel with the output terminal of the bridge diode between the first diode D1 and the load 20. do.

In addition, a first resistor R1 and a second capacitor C2 are connected in parallel to the AC power source AC, and the first resistor R1 is connected in series with the second capacitor C2. A first photocoupler PC1 is connected in parallel to the second capacitor C2. In addition, the light receiving terminal side of the first photocoupler PC1 is connected to the operating power source Vcc through a second resistor R2. The controller 10 is connected to the operating power supply Vcc through the second resistor R2, the third resistor R3 is connected to the output terminal of the controller 10, and the second photocoupler PC2 is It is connected to the third resistor R3. The base terminal of the first transistor Q1 is connected in series to the light receiving terminal side of the second photocoupler PC2, and the collector terminal of the first transistor Q1 is connected to the operating power supply Vcc through the fourth resistor R4. Is connected to. In addition, the collector terminal of the first transistor Q1 is connected to the base terminal of the second transistor Q2 through the sixth resistor R6. In addition, the collector terminal of the second transistor Q2 is connected to the operating power source Vcc through the fifth resistor R5. The emitter terminal of the second transistor Q2 is connected to the emitter terminal of the first transistor Q1. In addition, the base terminal of the second transistor Q2 is connected to the emitter terminal of the second transistor Q2 through a seventh resistor R7. The second transistor Q2 controls the switching element IGBT.

The operation of the phase detection circuit of the conventional air conditioner as described above is as follows.

2 is a waveform diagram detected by a phase detection circuit of a conventional air conditioner.

When the user turns on the operation switch (not shown), AC power AC as shown in FIG. 2A is rectified by the bridge diode, and the rectified AC power AC is connected to the reactor. The first capacitor C1 is charged through the diode D1. 2B shows the voltage charged in the first capacitor C1.

On the other hand, the AC power source AC is voltage-dropped by the first resistor R1 and applied to the second capacitor C2. 2C shows the voltage applied to the second capacitor C2. The voltage of the second capacitor C2 is applied to the first photo coupler PC1 which is a bidirectional device. At this time, the voltage applied to the first photo coupler PC1 is conducted only at a voltage other than the dress-hold voltage of −0.7 to +0.7 V of the first photo coupler PC1. This is illustrated in the waveform of FIG. 2D. That is, the first photo coupler is turned off when a voltage between -0.7 and + 0.7V is applied, and applies a high signal to the controller, and is turned on when a voltage greater than -0.7 and + 0.7V is applied to the first photo coupler. do. In this case, the section in which the first photo coupler is turned off is 2 ms. Therefore, an error of 1 dB occurs around the zero potential point.

Therefore, a signal as shown in FIG. 2D is applied from the first photocoupler PC1 to the controller 10. That is, of the controller 10 From the output When the high signal is output, the second photocoupler PC2 and the second transistor Q2 are turned off, and the first transistor Q1 and the switching element IGBT are turned on. 2E illustrates output signals of the second porter PC2, the first transistor Q1, the second transistor Q2, and the switching element IGBT according to the output signal from the controller 10. Are respectively shown.

Accordingly, as the switching element IGBT is turned on, the AC power AC applied through the first and second AC lines L1 and L2 is rectified through the bridge diode, and the reactor is reacted. Limited through. In addition, the switching device IGBT is turned on at the zero potential point of the applied AC power source AC, and the AC power source AC flows to the ground terminal through the switching device IGBT.

At this time, after a predetermined time has passed, the controller 10 applies a low signal to the second photocoupler PC2. Therefore, the second photocoupler PC2 and the second transistor Q2 are turned on, and the first transistor Q1 and the switching element IGBT are turned off. Therefore, the AC power applied as the switching element IGBT is turned off is rectified by the bridge diode and charged in the first capacitor C1. The first capacitor C1 charges an applied current and applies it to the load 20. As shown in FIG. 2F, a voltage waveform charged in the first capacitor C1 and applied to the load 20 is illustrated.

However, the phase detection circuit of the conventional air conditioner does not detect the exact zero potential point because the error of 2 에서 occurs in the period of the detection power supply, but it can detect the zero potential point in close proximity to FIG. Switching loss of the switching element as shown in the) is increased, and there is a problem that the temperature of the PCB substrate due to the switching loss is increased.

Accordingly, the present invention has been made in order to solve the above problems, to form a DC power source through rectification, DC conversion and voltage dividing, and to install a comparator to compare the waveform of the AC power source and the DC power source to accurately zero point It is an object of the present invention to provide a phase detection circuit of an air conditioner that stably operates a switching element by detecting.

1 is a circuit diagram showing a phase detection circuit of a conventional air conditioner;

2 is a waveform diagram showing a detection waveform of a phase detection circuit of a conventional air conditioner;

3 is a circuit diagram showing a preferred embodiment of the phase detection circuit of the air conditioner according to the present invention;

4 is a waveform diagram showing a detection waveform of the phase detection circuit of the air conditioner according to the present invention.

Explanation of symbols on the main parts of the drawings

10 controller 20 load

100: DC conversion unit 200: AC coupling unit

300: comparison unit R1 ~ R14: resistance

D1, D2: Diodes C1, C2, C3: Capacitor

PC1, PC2: Photocoupler Q1, Q2: Transistor

REACTOR: Reactor BRIDGE DIODE: Bridge Diode

Features of the present invention for achieving the above object, the DC conversion unit for converting the input AC power into direct current, an AC coupling unit for removing only the DC component of the applied power and passing only the AC power, in the AC coupling unit Comparing unit for detecting a zero potential point by comparing the applied AC power and the DC power applied from the DC converter, and a control unit for driving the load by turning on and off the switching element when the zero potential detection signal is applied from the comparison unit Characterized in that.

In addition, the DC converter is connected to the diode to rectify the applied AC power, a resistor connected in series with the diode to limit the power, a capacitor connected in series with the resistor to charge the applied current, and in parallel to the capacitor A zener diode converts the applied power into direct current and two resistors connected in parallel with the zener diode to divide the applied voltage.

The AC coupling unit may include a capacitor connected between two resistors for distributing an applied AC voltage and both resistors to remove a DC component and allow only an AC component to pass therethrough.

The comparator may further include a comparator configured to detect a zero potential point by comparing a resistance limiting the applied power and an applied AC power supply with a DC power supply, and output the zero potential detection signal.

The apparatus may further include a photocoupler for applying the zero potential detection signal applied by the comparator to the controller.

Therefore, the present invention as described above can accurately detect the zero potential point by comparing the waveforms of the AC power supply and the DC power supply. Therefore, as the on / off operation of the switching element is smoothly performed, the switching loss is reduced and the driving of the load is made stable.

Hereinafter, preferred embodiments of the air conditioner according to the present invention will be described in detail with reference to the accompanying drawings.

The main feature of the present invention is to detect an accurate zero potential point by comparing an applied AC power supply with a DC power supply using a comparator.

3 shows a preferred embodiment of the phase detection circuit of the air conditioner according to the present invention in which the above-described operation is carried out. In addition, the same components as the prior art will be described with the same reference numerals.

The bridge diode, the reactor, the switching element IGBT, the first and second photocouplers PC1 and PC2, the first and second transistors Q1 and Q2, and the controller 10 Since the same operation as in the prior art, detailed description is omitted.

As shown in FIG. 3, the input AC power AC passes through a bridge diode, and a reactor is disposed at an output terminal of the bridge diode. In addition, a first diode D1 is connected to the reactor, and a switching element IGBT is connected between the reactor and the first diode D1. In addition, the load 20 is connected in parallel with the first capacitor C1 through the first diode D1.

In addition, the DC converter 100 and the AC coupling unit 200 are connected to the first AC line L1. The AC coupling unit 200 is connected to the + input terminal of the comparator 300, the-input terminal is connected to the DC converter 100, and the output terminal is connected to the first photocoupler PC1.

The first photocoupler PC1 is connected to the controller 10, and a second resistor R2 is connected in parallel between the controller 10 and the first photocoupler PC1. In addition, the output terminal of the controller 10 is connected to the second photocoupler PC2 through a third resistor R3. The base terminal of the first transistor Q1 is connected to the light receiving terminal side of the second photocoupler PC2, and the fourth resistor R4 and the fifth resistor R5 are connected in parallel. The second transistor Q2 has a collector terminal connected to a fifth resistor R5, a base terminal connected to a sixth resistor R6, and an emitter terminal connected to an emitter terminal of the first transistor Q1. The seventh resistor R7 is connected between the base terminal and the emitter terminal of the second transistor Q2. In addition, a switching element IGBT is connected between the fifth resistor R5 and the collector terminal of the second transistor Q2.

The DC converter 100 charges the second diode D2 for rectifying AC power applied to the first AC line L1, the eighth resistor R8 for limiting the rectified power, and the applied power. And a fourth capacitor C4 to be applied, and a Zener diode ZD1 for converting the AC power AC applied from the fourth capacitor C4 into a direct current DC, and a direct current power supply DC applied. The ninth resistor (R9) and the tenth resistor (R10) is applied to the comparator 300 by dividing the voltage, and the AC power applied from the first AC line (L1) to the direct current (DC) Is converted to and applied to the comparator 300.

In addition, the AC coupling unit 200 divides the applied voltage to remove the DC component and passes only the AC component AC, and includes the eleventh and twelfth resistors R11 and R12 and the third capacitor C3. do.

In addition, the comparator 300 compares the DC power supply DC with the AC power supply AC and detects a zero potential point, and includes a thirteenth resistor R13 and a comparator.

Hereinafter, the operation of the phase detection circuit of the air conditioner according to the present invention configured as described above will be described in more detail with reference to FIGS. 3 and 4.

When the user operates the operation switch (not shown) and the AC power source AC is applied to the phase detection circuit, the second diode D2 of the DC converter 100 half-wave rectifies the applied AC power source AC. The fourth capacitor C4 is applied thereto. Then, the fourth capacitor C4 charges an applied current to be applied to the zener diode ZD1, and the zener diode ZD1 converts the applied alternating current AC into a direct current DC to convert the ninth resistor R9. ) And the tenth resistor R10 are applied to the comparator 300 by dividing the voltage. This is illustrated in the waveform of FIG. 4B.

In this case, the AC coupling unit 200 divides the applied power from the eleventh and twelfth resistors R11 and R12, and the third capacitor C3 removes the DC component DC from the divided power and exchanges AC. Only component AC is applied to the comparator 300. This is shown as a waveform of FIG. 4A.

Accordingly, AC (AC) output from the AC coupling unit 200 is input to the + input terminal of the comparator 200 among the waveforms shown in FIG. 4A (B). At the input terminal, a direct current (DC) output from the direct current conversion unit 100 is input, that is, (B) of FIG. 4. The comparator 200 compares the waveforms of the DC power source DC and the AC power source AC, as shown in FIG. Therefore, the comparison unit 200 outputs the waveform shown in FIG. That is, a high signal is applied to the first photocoupler PC1 at the zero potential points of the alternating current AC and DC. Therefore, the first photocoupler PC1 is turned off to apply a low signal to the controller 10. Such an output waveform of the first photocoupler PC1 is shown in Fig. 4E.

As such, when the zero point is detected by the phase detection circuit, the controller 10 applies a high signal to turn off the second photocoupler PC2 and the second transistor Q2. Accordingly, as the first transistor Q1 is turned on and the second transistor Q2 is turned off, the VCC voltage is applied to the switching device IGBT so that the switching device IGBT is turned on. This is illustrated in the waveform of FIG. 4F.

Thus, when the switching element IGBT is turned on, the AC power source AC is output to the emitter terminal of the switching element IGBT and flows to the ground terminal.

However, when the low signal is output again from the controller 10 after a predetermined time, the switching device IGBT is turned off because the second transistor Q2 is turned on. Therefore, the AC power source AC is rectified through the first diode D1 and charged by the first capacitor C1. This is shown in the waveform of Figure 4 (G).

Therefore, as illustrated in FIG. 4G, the AC power AC charged in the first capacitor C1 does not generate a switching loss because the switching device IGBT is turned on / off at the zero potential point.

The phase detection circuit of the air conditioner according to the present invention as described above can accurately detect the zero potential point by comparing the waveforms of the AC power supply and the DC power supply, so that the switching loss is smoothly switched on and off. This reduces the load and makes the drive stable.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications are possible to those skilled in the art without departing from the gist of the present invention as claimed in the claims. Such changes will fall within the scope of the claims.

Claims (5)

A DC converter converting an input AC power into DC; An AC coupling unit which removes a DC component from the applied power and passes only the AC power; A comparator for detecting a zero potential point by comparing an AC power applied by the AC coupling part with a DC power applied by the DC converter; And a control unit for driving a load by turning on and off a switching element when the zero potential detection signal is applied from the comparison unit. The method of claim 1, wherein the DC converter A diode for rectifying the applied AC power; A resistor connected in series with the diode to limit power; A capacitor for charging an applied current; A zener diode connected to the capacitor in parallel to convert applied power into direct current; And And two resistors connected in parallel with the zener diodes to divide the applied voltage. The method of claim 1, wherein the AC coupling unit Two resistors for distributing the applied alternating voltage; And And a capacitor connected between the resistors to remove the direct current component and pass only the alternating current component. The method of claim 1, wherein the comparison unit A resistor to limit the applied power source; And And a comparator for comparing the applied AC power and the DC power to detect the zero potential point and output the zero potential point detection signal. The phase detection circuit of an air conditioner according to claim 1, further comprising a photocoupler for applying a zero potential detection signal applied from said comparator to said controller.