KR20120019927A - Arc detecting circuit having transient arc detecting function and power supply apparatus for generation of atmospheric plasma by using the same - Google Patents

Abstract

PURPOSE: An arc detecting circuit having an instantaneous arc detecting function and a power supply apparatus for generating atmospheric plasma using the same are provided to determine the generation of an arc by detecting the change of an output current through an inductor for detecting a current. CONSTITUTION: A transformer(10) changes a primary voltage and current based on a predetermined winding ratio. An inductor(20) for detecting a current induces the current flowing in a primary side of the transformer. An RL serial circuit(30) forms a voltage, which is determined by impedance and an inducing current, on both ends. A rectifier circuit(40) performs the full-wave rectification of the voltage formed in both ends of an RL serial circuit. The rectifier circuit offers the rectified voltage to a comparator(50). The comparator compares the voltage outputted in the rectifier circuit with a reference voltage.

Description

ARC DETECTING CIRCUIT HAVING TRANSIENT ARC DETECTING FUNCTION AND POWER SUPPLY APPARATUS FOR GENERATION OF ATMOSPHERIC PLASMA BY USING THE SAME}

The present invention relates to an arc detection circuit having an instantaneous arc detection function and a power supply device for generating an atmospheric pressure plasma using the same. More specifically, a current detection inductor is installed on a primary side of a transformer for power supply. The arc detection circuit can detect the occurrence of an arc within one period of the output voltage from the time of the arc generation by instantaneously detecting the output current of the power supply using the current detecting inductor and determining whether the arc has occurred. And it relates to a power supply for generating atmospheric pressure plasma using the same.

Plasma is called a fourth state of matter, and an atmospheric pressure plasma processing apparatus generates plasma by high pressure discharge under atmospheric pressure. Such atmospheric pressure plasma processing apparatuses are widely used in manufacturing processes of semiconductors, liquid crystal displays, organic light emitting diodes, and the like including chemical vapor deposition (CVD), physical vapor deposition (PVD), sputtering, coating, and the like. It is widely used.

The atmospheric pressure plasma processing apparatus uses a high pressure discharge to form a plasma under atmospheric pressure, and in order to generate such a high pressure discharge, a transformer for inducing a high voltage of several tens of kV units is inevitably included.

When the atmospheric plasma processing apparatus is actually operated, an abnormal arc phenomenon such as a short occurs frequently due to the characteristics of the plasma load, and such an arc causes deterioration of characteristics and quality in the plasma load. Thus, a power supply for supplying a high voltage to an atmospheric plasma processing apparatus has a need to quickly detect such an arc phenomenon and cut off its output voltage.

Conventional atmospheric pressure plasma supply power supply by measuring the output voltage and the output current having a pulse form output from the power supply to detect the arc, the capacity by determining whether the output voltage is drastically lowered or the output current rises sharply It is determined whether an arc has occurred in the capacitive load.

However, such a conventional atmospheric pressure plasma power supply apparatus does not determine whether an arc occurs instantaneously from an output voltage and an output current having a pulse shape due to a sudden change in the output voltage and the output current, but several cycles of the pulse. It had a problem of judging whether an arc occurred at a delayed time. This time delay causes the arc phenomenon to affect the plasma load for a certain time, which adversely affects the capacitive load and the power supply for generating plasma.

The present invention is to solve the conventional technical problem described above, the current detection inductor is installed on the primary side of the step-up transformer, the current detection inductor detects the change in the output current to generate an arc An object of the present invention is to provide an arc detection circuit capable of determining instantaneously and a power supply for generating atmospheric pressure plasma using the same.

According to one aspect of the invention, the rectifier for converting the AC voltage from a commercial AC power supply to a DC voltage; An inverter unit modulating the DC voltage converted through the rectifier into an AC pulse voltage; A pulse boosting unit converting the voltage level of the AC pulse voltage output from the inverter unit according to a predetermined winding ratio; A capacitive load configured to form a plasma by applying a voltage output from the pulse boosting unit to cause a plasma reaction with respect to a target object; A current detection inductor for detecting a current input to the pulse booster by a current induction method; An arc detector for converting a current detected by the current detecting inductor into a voltage, full-wave rectifying and comparing the current to a predetermined reference voltage, and outputting the comparison result as an arc detection signal; And controlling pulse amplitude modulation on the AC pulse voltage output from the inverter unit, and controlling pulse width modulation and pulse density modulation on the AC pulse voltage output from the inverter unit to adjust the pulse resonance timing and the plasma density. And, according to the arc detection signal output from the arc detection unit is provided a power supply for atmospheric pressure plasma generation including a control unit for controlling whether or not the AC pulse voltage supplied to the pulse boosting unit from the inverter unit.

Preferably, the arc detector is composed of an inductor and a resistor connected in series with each other in both ends of the current detecting inductor, and has a predetermined impedance determined by the inductance and resistance of the inductor and the resistor, An RL series circuit for forming a voltage at both ends thereof determined by the current detected by the current detecting inductor; A rectifier circuit for performing full-wave rectification with respect to a voltage formed at both ends of the RL series circuit; And a comparator for comparing the voltage rectified by the rectifying circuit with a reference voltage and outputting the result of the comparison as an arc detection signal.

According to another feature of the invention, a transformer for converting the primary side voltage and current based on a predetermined winding ratio, and providing the converted voltage and current to the secondary side as output voltage and output current, respectively; A current detection inductor coupled to the transformer to induce a current flowing in the primary side of the transformer and inducing a primary current of the transformer and outputting the primary current; And an inductor and a resistor connected in series with both ends of the current detecting inductor, and having a predetermined impedance determined by the inductance and resistance of the inductor and the resistor, and a voltage determined by the impedance and the induced current. RL series circuits formed at both ends; A rectifier circuit for performing full-wave rectification with respect to a voltage formed at both ends of the RL series circuit; And a comparator for comparing the voltage rectified by the rectifying circuit with a reference voltage and outputting a result of the comparison as an arc detection signal. An arc detection circuit of an atmospheric pressure plasma generating power supply apparatus is provided.

Preferably, the voltage formed across the RL series circuit is determined by the combination of the rate of change of the induced current, the inductance and the resistance value.

Preferably, the inductance and resistance values of the inductor and the resistor constituting the RL series circuit are set in consideration of the voltage change slope and the magnitude of the voltage formed at both ends of the RL series circuit.

Preferably, the comparator outputs a high level signal as an arc detection signal when the rectified voltage is greater than the reference voltage, and low level when the rectified voltage is less than the reference voltage. level) signal is output as the arc detection signal.

Preferably, the arc detection signal output from the comparator is used to determine whether to cut off the power supplied to the primary side of the transformer.

Preferably, at the output of the comparator, a pullup resistor or pulldown resistor is connected to protect the circuit and obtain a clear digital logic signal.

An arc detection circuit and a power supply for generating atmospheric pressure plasma using the arc detection circuit according to the present invention detects a change in the output current in the form of induced current by a current detection inductor connected to the primary side of the transformer, thereby detecting the arc within one period of the output voltage. Can be detected instantaneously, and by converting the induced current into voltage and then full-wave rectifying, it is possible to detect where an arc occurs in the positive region or the negative region.

The present invention can thus improve the reliability of the atmospheric pressure plasma generation power supply device by detecting the occurrence of an arc and making it possible to use this arc detection signal to determine whether to cut off power to the primary side of the transformer.

1 shows an overall configuration diagram of a power supply for generating atmospheric pressure plasma according to an embodiment of the present invention.
Figure 2 shows an arc detection circuit of a power supply for generating atmospheric pressure plasma according to an embodiment of the present invention.
FIG. 3 shows a vector diagram illustrating the relationship between voltage and current in the RL series circuit shown in FIG.
4 is a waveform diagram illustrating changes in voltage and current of the secondary side of a transformer when the power supply for generating atmospheric pressure plasma according to the embodiment of the present invention is in a steady state and an arc generation state, respectively.
FIG. 5 is a waveform diagram illustrating a process of determining whether an arc occurs in the comparator illustrated in FIG. 2.

Hereinafter, with reference to the accompanying drawings will be described in more detail the configuration and operation of the power supply for generating atmospheric pressure plasma according to an embodiment of the present invention.

First, a power supply apparatus for generating atmospheric pressure plasma according to an embodiment of the present invention will be described with reference to FIG. 1. 1 is a view showing the overall configuration of a power supply for generating atmospheric pressure plasma according to an embodiment of the present invention.

As shown in FIG. 1, the apparatus for generating atmospheric pressure plasma according to the embodiment of the present invention includes an AC power source, an AC rectifier 1, an inverter 2, an inductor 3 for current detection, and a pulse boosting. The unit 4 includes a capacitive load 5, an arc detector 6, and a controller 7.

Hereinafter, the operation of the power supply for generating atmospheric pressure plasma according to the embodiment of the present invention shown in FIG. 1 will be described.

The rectifier 1 converts the AC voltage from the commercial AC power source AC into a DC voltage. The inverter unit 2 modulates the DC voltage converted through the rectifier 1 into an AC pulse voltage. The pulse booster 4 may be implemented as a kind of transformer, and converts the voltage level of the AC pulse voltage output from the inverter unit 2 according to a predetermined winding ratio.

The capacitive load 5 forms a plasma by applying a high voltage output by the pulse boosting unit 4 to cause a plasma reaction on the object to be processed.

The current detecting inductor 3 detects a current input to the pulse booster 4, and, for example, when the pulse booster 4 is implemented as a transformer, the primary side current of the transformer is converted into a current induction scheme. Detect.

The arc detector 6 converts the current detected by the current detecting inductor 3 into a voltage, and propagates and compares it with a predetermined reference voltage to determine whether an arc is generated. The arc detector 6 outputs the comparison result to the controller 7 as an arc detection signal.

The control unit 7 controls the pulse amplitude modulation (PAM) of the AC pulse voltage output from the inverter unit 2, the AC output from the inverter unit 2 to adjust the pulse resonance timing and the density of the plasma. Control pulse width modulation and pulse density modulation for pulse voltage. On the other hand, the control part 7 controls whether the AC pulse voltage supplied from the inverter part 2 to the voltage boosting part 4 is interrupted according to the arc detection signal output from the arc detection part 6. That is, when it is determined that the arc is generated by the arc detection signal, the control unit 7 cuts off the supply of the AC pulse voltage from the inverter unit 2 to the pulse boosting unit 4.

In this regard, the arc detection circuit of the power supply for generating atmospheric pressure plasma according to the embodiment of the present invention will be described in more detail with reference to FIGS. 2 to 5.

2 shows an arc detection circuit of a power supply for generating atmospheric pressure plasma according to an embodiment of the present invention.

As shown in FIG. 2, the circuit related to the arc detection function in the power supply for generating atmospheric pressure plasma according to the embodiment of the present invention includes a transformer 10, a current detecting inductor 20, a RL series circuit 30, The rectifier circuit 40 and the comparator 50 are included.

The arc detector 6 of the power supply apparatus for generating atmospheric pressure plasma shown in FIG. 1 is embodied by the RL series circuit 30, the rectifier circuit 40, and the comparator 50 among the components shown in FIG. 2.

In addition, the current detecting inductor 20 shown in FIG. 2 is substantially the same as the current detecting inductor 3 shown in FIG. 1, and the transformer 10 shown in FIG. It is substantially the same as the part (4).

A power supply for generating atmospheric pressure plasma according to an embodiment of the present invention uses a transformer 10, also referred to as a "transformer," to generate a high pressure discharge for plasma formation. Transformer is a device that converts the voltage and current of the primary side based on the winding ratio by using electromagnetic induction and transfers it to the secondary side. For example, the primary side voltage and secondary side voltage are proportional to the winding ratio, and the primary side current and secondary side current are inversely proportional to the winding ratio.

The transformer 10 converts the primary side voltage and current based on a predetermined winding ratio, and provides the converted voltage and current to the secondary side as the output voltage and the output current. Typically, the primary side voltage and current of transformer 10 is alternating current (AC).

On the other hand, as shown in Figure 2, the current detection inductor 20 is coupled to the transformer 10 to induce a current flowing in the primary side of the transformer (10). The primary side current of the transformer 10 induced by the current detecting inductor 20 is output to the RL series circuit 30 as the induction current Ia.

The RL series circuit 30 is connected to both ends of the current detecting inductor 20 and includes an inductor La and a resistor Ra connected in series with each other. The RL series circuit 30 has a predetermined impedance determined by the inductance of the inductor La and the resistor Ra and the resistance value, and the voltage determined by the impedance and the induction current Ia. (Va) is formed at both ends.

In general, the arc can occur at both the positive and negative components of the primary side current of the transformer 10, especially at the peak point of the pulse output voltage waveform. In the present invention, in order to examine both the positive and negative components of the primary side current of the transformer 10, the voltage output from the RL series circuit 30, which is a signal obtained by converting the primary side current of the transformer 10 into voltage, Rectification circuit 40 for rectifying Va) is used.

The rectifier circuit 40 performs full-wave rectification of the voltage Va formed at both ends of the RL series circuit 30, and provides the rectified voltage to the comparator 50. The comparator 50 compares the voltage output from the rectifier circuit 40 with the reference voltage Vref, and outputs the comparison result as an arc detection signal.

For example, when the voltage output from the rectifier circuit 40 exceeds the reference voltage Vref, the comparator 50 determines that an arc has occurred and outputs a high level signal as an arc detection signal. When the voltage output from the rectifier circuit 40 is smaller than the reference voltage Vref, it is determined that no arc is generated and a low level signal may be output as the arc detection signal.

The resistor Rp connected to the output terminal of the comparator 50 is a pull-up resistor, which has the purpose of protecting the circuit and obtaining a clear digital logic signal. In the present invention, the resistor Rp is merely an example of a pull-up resistor, and a pull-down resistor may be used to achieve a similar purpose as mentioned above.

Next, the relationship between the voltage and the current in the RL series circuit 30 shown in FIG. 2 will be described with reference to FIG. 3. FIG. 3 is a vector diagram illustrating a relationship between current and voltage in the RL series circuit shown in FIG. 2.

When the induced current Ia induced by the current detecting inductor 20 of FIG. 2 is referred to as a current source, the voltage Va at both ends of the RL series circuit 30 is expressed by Equation 1 below. Can be.

If both ends of the voltage Va represented by Equation 1 are expressed as the induction current Ia, the following Equation 2 is obtained.

The voltage V _L across the inductor La constituting the RL series circuit 30 shown in FIG. 2 is expressed as a derivative of the induction current Ia and has a phase 90 ° ahead of the induction current. . The voltage V _R across the resistor Ra constituting the RL series circuit 30 has the same phase as the induced current Ia.

In this situation, since the voltage Va across the RL series circuit 30 is expressed as the sum of the voltage V _L across the inductor La and the voltage V _R across the resistor Ra, the RL series circuit ( The voltage Va at both ends of 30 has a phase that is earlier than the induced current Ia by θ.

This phase difference θ between the voltage and current in the RL series circuit 30 can be obtained through an analysis method of the RL series circuit well known in the art, and the phase difference θ can be expressed by the following equation (3).

Where X = ω La and ω = 2πf.

Referring to Equation 2, the voltage V _L at both ends of the inductor La in the RL series circuit 30 is determined by the derivative of the induction current Ia and the inductance of the inductor La. Since the voltage V _R across the resistor Ra is determined by the resistance value and the value of the induced current Ia, ultimately, the voltage Va across the RL series circuit 30 is the rate of change of the induced current Ia. Is determined by the combination of inductance and resistance.

For example, in the voltage Va between the RL series circuit 30, the slope of the voltage change is affected by the inductance of the inductor La, and the magnitude of the voltage is affected by the resistance value of the resistor Ra. get affected. In other words, if the inductance is too large, the capacitive load is affected by noise, and the voltage Va at both ends of the RL series circuit 30 is sensitive. If the resistance value is too large, the voltage Va at both ends is referred to the reference voltage Vref. Compared with, it is difficult to set the reference voltage Vref in determining whether or not an arc has occurred.

Therefore, the element values, i.e., inductance and resistance values of the inductor La and the resistor Ra constituting the RL series circuit 30 should be set to appropriate values in consideration of the reliability of the capacitive load and the power supply. That is, the inductance and resistance values of the inductor La and the resistor Ra constituting the RL series circuit 30 are set in consideration of the voltage change slope of the voltage Va at both ends of the RL series circuit 30 and the magnitude of the voltage. It is desirable to.

4 is a waveform diagram illustrating changes in voltage and current of the secondary side of a transformer when the power supply for generating atmospheric pressure plasma according to the embodiment of the present invention is in a steady state and an arc generation state, respectively.

As shown in FIG. 4, when the power supply for generating atmospheric pressure plasma according to the embodiment of the present invention is in a normal state, the secondary side voltage of the transformer 10 shown in FIG. 2 has a pulse shape and has a secondary side. The current takes the form of a sine wave with the frequency of one period of the pulse.

As shown in FIG. 4, when the power supply for generating atmospheric pressure plasma according to the embodiment of the present invention is in an arc generation state, the secondary voltage of the transformer 10 shown in FIG. 2 is decreased, and the transformer 10 is reduced. The secondary side current increases rapidly. 4 illustrates a case where the secondary side current is a negative region, and the rapid increase in the secondary side current means that the magnitude of the secondary side current increases rapidly.

As described above, when the secondary current of the transformer 10 rapidly increases, although not shown in FIG. 4, similar to the waveform of the secondary current of FIG. 4, the transformer having a proportional relationship with the winding ratio of the transformer 10 ( The primary current of 10) also increases rapidly, and the induced current Ia detected by the current detecting inductor 20 will also increase rapidly. Therefore, the voltage Va at both ends of the RL series circuit 30 determined by the induced current Ia is also increased.

FIG. 2 is a waveform diagram illustrating a process of determining whether an arc occurs in the comparator illustrated in FIG. 2.

When the arc occurs as described above, the voltage Va at both ends of the RL series circuit 30 also increases rapidly, and the voltage Va at both ends of the RL series circuit 30 is applied to the rectifier circuit 40 as shown in the waveform on the right side of FIG. 5. By full-wave rectification. By configuring the voltage Va at both ends of the RL series circuit 30 to be full-wave rectified by the rectifier circuit 40, whether or not an arc is generated in any of the positive and negative regions of the secondary current of the transformer 10. It becomes possible to judge.

On the other hand, the rectified voltage waveform is compared with the reference voltage Vref by the comparator 50, and when the rectified voltage level exceeds the reference voltage Vref, the comparator 50 is a high level as an arc detection signal. Outputs a high level signal. The arc detection signal thus obtained may be used to determine whether to cut off the power supplied to the primary side of the transformer 10.

In the power supply apparatus for generating atmospheric pressure plasma according to the present invention, the primary side current of the transformer 10 is detected by the current detecting inductor 20 as the induction current Ia, and the thus detected induction current Ia is RL. By converting the voltage Va by the series circuit 30, performing full-wave rectification by the rectifier circuit 40, and then comparing the value of the voltage with a reference voltage to determine whether or not an arc is generated. Arc generation can be detected instantaneously for a time within a pulse period, and the reliability of the power supply for atmospheric pressure plasma generation can be ensured.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art, that various modifications and equivalent other embodiments are possible. will be. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

10: transformer 20: inductor for current detection
30: RL series circuit 40: rectifier circuit
50: comparator Rp: pullup resistor
Vref: reference voltage

Claims (8)

A rectifier for converting an AC voltage from a commercial AC power source into a DC voltage;
An inverter unit modulating the DC voltage converted through the rectifier into an AC pulse voltage;
A pulse boosting unit converting the voltage level of the AC pulse voltage output from the inverter unit according to a predetermined winding ratio;
A capacitive load configured to form a plasma by applying a voltage output from the pulse boosting unit to cause a plasma reaction with respect to a target object;
A current detection inductor for detecting a current input to the pulse booster by a current induction method;
An arc detector for converting a current detected by the current detecting inductor into a voltage, full-wave rectifying and comparing the current to a predetermined reference voltage, and outputting the comparison result as an arc detection signal; And
To control the pulse amplitude modulation on the AC pulse voltage output from the inverter unit, and to control the pulse width modulation and pulse density modulation on the AC pulse voltage output from the inverter unit in order to adjust the pulse resonance timing and the plasma density. And a control unit controlling whether or not the AC pulse voltage supplied from the inverter unit to the pulse boosting unit is cut off in response to the arc detection signal output from the arc detection unit. The method according to claim 1,
The arc detector,
An inductor and a resistor connected in series with both ends of the current detecting inductor, and having a predetermined impedance determined by an inductance and a resistance value of the inductor and the resistance, and detected by the impedance and the current detecting inductor. An RL series circuit for forming a voltage determined at both ends of the current;
A rectifier circuit for performing full-wave rectification with respect to a voltage formed at both ends of the RL series circuit; And
And a comparator for comparing the voltage rectified by the rectifying circuit with a reference voltage and outputting the result of the comparison as an arc detection signal. A transformer for converting the primary side voltage and current based on a predetermined winding ratio, and providing the converted voltage and current to the secondary side as output voltage and output current, respectively;
A current detection inductor coupled to the transformer to induce a current flowing in the primary side of the transformer and inducing a primary current of the transformer and outputting the primary current;
And an inductor and a resistor connected in series with both ends of the current detecting inductor, and having a predetermined impedance determined by the inductance and resistance of the inductor and the resistor, and a voltage determined by the impedance and the induced current. RL series circuits formed at both ends;
A rectifier circuit for performing full-wave rectification with respect to a voltage formed at both ends of the RL series circuit; And
And a comparator for comparing the voltage rectified by the rectifying circuit with a reference voltage and outputting the result of the comparison as an arc detection signal. The method according to claim 3,
The voltage formed at both ends of the RL series circuit is determined by the combination of the rate of change of the induced current, the inductance and the resistance value, arc detection circuit of the power supply for generating atmospheric pressure plasma. The method according to claim 3,
Inductance and resistance values of the inductor and the resistor constituting the RL series circuit are set in consideration of the voltage change slope and the magnitude of the voltage formed at both ends of the RL series circuit. Arc detection circuit. The method according to claim 3,
The comparator outputs a high level signal as an arc detection signal when the rectified voltage is greater than the reference voltage, and outputs a low level signal when the rectified voltage is less than the reference voltage. An arc detection circuit of a power supply for atmospheric pressure plasma generation, characterized in that it is output as an arc detection signal. The method according to claim 3 or 6,
The arc detection signal output from the comparator is used to determine whether to cut off the power supplied to the primary side of the transformer arc detection circuit of the power supply for generating atmospheric pressure plasma. The method according to claim 3,
At the output of the comparator, a pull-up resistor or a pull-down resistor is connected to protect the circuit and to obtain a clear digital logic signal, the arc detection circuit of the power supply for generating atmospheric pressure plasma. .

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