KR100340683B1 - Inverter co2 welder - Google Patents

Abstract

The present invention enables sufficient protection against damage of the inverter 123 applied to the power control unit 120, specifically, breakage of the IGBT, etc., compared to the conventional inverter welding machine, which is the strength of the welding quality of the inverter CO ₂ welder 100. It enables simultaneous control of constant voltage / constant current, and by hybridization of PWM control unit 130, it is strong against noise and its structure is simple to enable assembly production, and PWM control unit 130 inevitably outputs existing inverter welding machine due to welding characteristics. It is possible to double protection against breakage of IGBT of power control unit 120 which is fatally damaged when stress and instantaneous feedback sensing error occurs due to continuous short-circuit break condition of The present invention relates to a constant voltage / constant current control for improvement to realize a uniform output state.

Description

Inverter Shiotou Welding Machine {INVERTER CO2 WELDER}

The present invention relates to an inverter CO ₂ welder, and more particularly, to ensure sufficient protection against damage to the inverter applied to the power control, that is, damage to the IGBT, and to enable simultaneous control of constant voltage / constant current, and to break the IGBT of the power control. The present invention relates to an inverter CO ₂ welding machine capable of realizing a uniform output state by implementing a double protection for the lamp.

In general, welding refers to metallurgical bonding through heating or pressurization such that atomic bonding between two kinds of solid materials of the same or different types is used. Examples include arc welding, resistance welding, and laser welding. There is this.

At this time, arc welding is a welding method using arc heat generated by arc discharge, and after melting the surface of the base material and the welding part by using the heat obtained by generating an arc between the base material to be welded and the welding torch, The metal of the welding torch is melted again and welded together, and a carbon electrode or a tungsten electrode may be used instead of the welding torch.

In addition, resistance welding refers to a method of heating a joint in a molten state by using heat generated by contact resistance generated when a very large current is sent to the weld, and then welding by welding under physical pressure. It is sometimes divided into resistance welding and butt resistance welding.

In addition, laser welding is a method of welding using a strong energy beam generated by induced radiation between energy levels of atoms or molecules. Laser beam is a concentrated heat source of high energy density. Because of its strong thermal effect on the material and low thermal deformation, it is used for precise welding and cutting, and it is easy to operate because it can work in the atmosphere and can easily guide the beam away from the laser generator. .

On the other hand, the arc welding is roughly divided into an inert gas arc welding and carbon dioxide (CO ₂ ) arc welding, etc. Among these, the inert gas arc welding is a TIG (TIG) welding using a tungsten electrode again (inert-) It is divided into gas tungsten arc welding and inert-gas metal arc welding, which uses filler metal as an electrode.

In this case, the TIG welding using the tungsten electrode does not use the flux (slag) is not generated slag (slag), and thus can be very advantageously applied to metals such as Al and Mg alloy.

In addition, since the TIG welding has no transition of molten metal from the tungsten electrode, there is no instability of the arc and no generation of spatters, and the workability is good and the reliability of welding quality is very high.

MIG welding is a DC reverse polarity and has the characteristic that stable metal migration of molten metal is possible only in the case of high current density. In order to avoid melting of the electrode by resistance heat, a large current must be used. The current must be introduced just before the arc. In addition, since MIG welding has a high current density and a current / voltage characteristic is a rising characteristic, a DC welding machine having a constant voltage characteristic or a rising characteristic suitable for the self-control action of the arc length has been widely put to practical use, thereby obtaining good results.

In the MIG welding, even though a relatively high current density is used in the DC positive polarity, the arc becomes unstable because the molten metal does not become small particles but rather forms a large volume at the electrode end and forms a strong wind of ions from the anode side of the base material. Sometimes a satisfactory weld cannot be achieved.

Therefore, MIG welding is suitable for DC reverse polarity. When the DC reverse polarity increases the current value and exceeds a certain critical current value, the volume becomes microparticles and is sprayed at high speed by plasma airflow so that the spray type transition shape is obtained. In this case, the arc can be very stable and have a strong directivity, so that deep penetration can be obtained, and the welding of all postures is possible.

In the case of MIG welding, the melting speed of the welding wire is high at high current density, the voltage and current characteristics of the arc are synergistic, and the constant voltage power is used. Therefore, the melting speed itself does not need to be increased or decreased by using an automatic control device. It is controlled so that the arc length is always kept constant. In other words, the self-control action of the arc length is characterized by the self-control function by the load characteristic (high current density) and the self-control function by the power supply characteristic (constant voltage power supply). This will be possible.

On the other hand, carbon dioxide arc welding refers to welding collectively known as a shield-type arc welding using carbon dioxide (CO ₂ ) or a mixed gas mainly containing carbon dioxide as a shield gas.

MIG welding using Inner Gas as described above is mainly used for welding non-ferrous metals or alloy steels, including light metals, which are difficult to install for economic reasons, but CO2 arc welding is used for MIG welding using expensive Inert Gas. Differently, since it uses relatively inexpensive carbon dioxide, it is possible to realize welding of a high availability steel structure while maintaining high efficiency of MIG welding.

In the carbon dioxide gas welding, the use of carbon dioxide (CO ₂ ) in the shield gas is different from that of the MIG welding, and in addition, it requires a deoxidizer.

The need for deoxidizer is that the shield gas CO ₂ is at the high temperature of the arc,

This is because dissociation such as 2CO → 2CO + O ₂ generates O ₂ to generate an oxidizing atmosphere. As a result, oxidation of the molten steel occurs,

2Fe + O ₂ → 2FeO

The iron oxide FeO produced as FeO + C → Fe + CO is immediately combined with C in the steel to generate a large amount of CO gas in the molten steel to become solidified and porous including the pores of the weld metal.

As the deoxidizer, one containing an appropriate amount of deoxidizing elements such as Mn, Si or Al, Ti is used, but by addition of these deoxidizers,

FeO + Mm → Fe + MnO, 2FeO + Si → 2Fe + SiO 2 such as deoxidation result deoxidation products of MnO, SiO _2, etc. of the reaction are to be removed as slag floated.

Carbon dioxide arc welding is roughly classified into two types by the supply method of the deoxidizer, the SOLID WIRE method and the FLUX WIRE method.

Therefore, the present applicant intends to explain in detail while proposing a preferable inverter CO ₂ welding machine based on the general welding technique as described above.

The present invention has been made through the above-described proposal, the purpose of which is to ensure sufficient protection against damage of the inverter applied to the power control, that is, IGBT, etc., and to enable simultaneous control of the constant voltage / constant current and power control It is to provide an inverter CO ₂ welding machine that can realize a uniform output state by implementing a double protection against breakage of IGBT.

1 is an overall block diagram showing an inverter CO ₂ welding machine according to the present invention.

Figure 2 is a block diagram illustrating a power control unit applied to the inverter CO ₂ welding machine according to the present invention.

3 is a circuit diagram and waveform diagram for explaining the input rectifier of the power control unit applied to the inverter CO ₂ welding machine according to the present invention.

Figure 4 is an exemplary embodiment for explaining a conversion method of the inverter of the power control unit applied to the inverter CO ₂ welding machine according to the present invention.

5 is an implementation waveform diagram showing a switching operation of an IGBT element that is a configuration of an inverter applied to an inverter CO ₂ welding machine according to the present invention.

6 is a schematic view showing a main transformer, an output rectifier and a reactor applied to an inverter CO ₂ welding machine according to the present invention.

7 is a block diagram showing the subdivided PWM control unit applied to the inverter CO ₂ welding machine according to the present invention.

Explanation of symbols on the main parts of the drawings

100: inverter CO ₂ welding machine 110: input power supply

120: power controller 121: input rectifier

122: smoothing unit 123: inverter

124: main transformer 125: output rectifier

126 reactor 130 PWM control unit

131: first comparator 132: second comparator

133: third comparison unit 134: output current amplifier

135: DC converter 136: over-current blocking unit

137: pulse width control unit 138: current amplifier

140: front channel switch unit 150: main controller unit

160: input transformer 170: cooling fan

180: overvoltage cutout 190: operation delay

S1: Input Current Sensor S2: Feedback Voltage Sensor

S3: Feedback Current Sensor

The present invention for achieving the above object,

A power control unit provided with an inverter which smoothes the input power of the alternating current input AC from low current to the high current and converts it into high frequency of alternating current after smoothing to the output power of the low voltage and high current of the wide band, In the inverter CO ₂ welding machine comprising a PWM control unit for detecting the error of the voltage provided from the power control unit to generate a pulse wave and then output a uniform output current in accordance with a predetermined reference value,

An input current sensor detecting an input side current of the power control unit;

A DC converter converting the current sensed by the input current sensor into a direct current (DC);

A second comparison unit which receives the signal of the input current sensor as a DC current through the DC converter and reduces the output waveform firstly if the amount of the current exceeds a reference value;

A feedback voltage sensor for sensing an output side voltage of the power control unit;

A first comparison unit which senses the output side voltage of the power control unit through the feedback voltage sensor and compares the voltage with a reference value of the voltage to a maximum value within the output value of the second comparator;

A feedback current sensor for sensing an output side current of the power control unit;

If the value of the feedback current sensor matches the reference value of the current, the output is inverted to decrease the amount of pulse control by reducing the threshold of the amount of the input primary current supplied to the second comparator, and the value of the feedback current sensor If the deficiency is insufficient, the technical features include a third comparison unit which is non-inverted to control the output current regardless of the limit of the amount of the input primary current.

Hereinafter, a preferred embodiment of the inverter CO ₂ welding machine according to the present invention will be described with reference to the drawings.

Inverter CO ₂ welding machine 100 according to the present invention is supplied with a protective gas such as CO ₂ (carbon dioxide) and Ar (argon), Ar + CO ₂ , Ar + O ₂ (oxygen) while supplying a welding wire or aluminum It is used for precision welding of base metal such as stainless steel and iron.

That is, the welding gun is approached to the welding portion of the base material to press the torch switch so that the protective gas filled in the gas cylinder can be ejected through the gas nozzle of the welding gun, and at the same time through the inverter CO ₂ welding machine 100 of the present invention By allowing the welding wire to be adjacent to the base material by the low voltage high current, it is possible to implement the precision welding by generating the melting of the welding wire by the arc.

1 is an entire block diagram showing an inverter CO ₂ welding machine according to the invention, Figure 2 is a block diagram for explaining a power control unit 120 is applied to the inverter CO ₂ welding machine according to the invention.

As shown in FIG. 1, the inverter CO ₂ welding machine 100 according to the present invention includes an input power supply unit 110 for removing a noise signal that is likely to be mixed in an input power supply of 60 kW AC input from the outside, and The input rectifier 121 converts the input power of the AC filtered through the input power supply 110 into a direct current input power, and the input power of the DC converted through the input rectifier 121 from low current to high current. The smoothing unit 122 smoothes the output power of DC low voltage and high current so as to output a stable arc in a wide band, and detects the error of the voltage generated from the smoothing unit 122 to generate a pulse wave, Pulse width modulation (PWM) control unit 130 for controlling the output of a uniform output current in accordance with the voltage, and output of the low voltage high current of the pulse wave provided from the PWM control unit 130 An inverter 123 for converting a power source into a pulse wave of AC 50 mA, and a main transformer 124 for converting an AC 50 mA pulse wave of the inverter 123 into a low voltage large current required for welding by varying the turns ratio and the thickness of the coil; An output rectifier 125 for converting a low voltage large current of AC 50 kV outputted through the main transformer 124 into high speed rectification and converting it into a pulsated electric component, and the electric component pulsated through the output rectifier 125 Reactor 126 for smoothing with a direct current component, the front channel switch unit 140 for selecting and selecting various welding parameters such as the type of welding material to be welded and the type of gas used, the welding posture, the type of welding wire and And a main controller controlling the welding parameters selected by the operation of the front channel switch unit 140 to output the optimum desired welding voltage and the desired welding current. An input transformer 160 for converting the input power supplied from the input power supply unit 110 into a used power supply to the main controller unit 150 and the PWM control unit 130 and connected to the input transformer 160. It consists of a cooling fan 170 for discharging the heat of the inside to the outside.

In this case, the power control unit controls to smoothly convert the input power of the alternating current filtered through the input power supply unit 110 into an output power of a low voltage large current of direct current so as to output a stable arc in a wide range from low current to high current. 120 may be referred to collectively. The power controller 120 may further include an input rectifying unit 121 and an input rectifying unit 121 for converting an AC input power into an DC input power as shown in FIG. 2. The inverter 123 converts the DC input power converted through the IGBT (Insulated Gate Bipolar Transistor) element into a high frequency of 50 ㎑ AC, and converts the high frequency of the AC 50 인버터 converted through the inverter 123 into an AC low voltage. The main transformer 124 which converts into a large current power supply, and the low voltage large current power of the alternating current converted through the main transformer 124 is a direct current low voltage high current power supply. The output rectifier 125 and the output rectifier 125 smooth the power of the direct current low voltage large current converted through the output rectifier 125 to mitigate the impact of the inverter 123 due to load fluctuations. Reactor 126 that lowers the effective current of 124 can be roughly classified.

Here, the input rectifier 121 for converting the input power of the AC filtered by the input power supply 110 into the input power of the direct current may use a diode module as shown in FIG. 3. 3 is a circuit diagram and waveform diagram for explaining the input rectifier 121 of the power control unit 120 applied to the inverter CO ₂ welding machine 100 according to the present invention.

The rectifier diode module is a three-phase bridge diode, which is a combination of six diodes for rectifying the three-phase power source. The capacitor used at this time is mainly an electrolytic capacitor. Electrolytic capacitors can be thought of as batteries with polarity and capable of very small charging and discharging, and their function is to make an irregular alternating current into a direct current state. In addition, the input rectifying unit 121 performs a function of rectifying the commercial power of three-phase 220 [V] or 380 [V], 60 [Hz] to convert the DC power.

For example, when using 3-phase 220V as input AC power, the converted DC voltage is determined as follows.

The smoothing unit 122 uses a smoothing capacitor to smooth the current generated by the input rectifying unit 121 to a ripple-free DC voltage.

The smoothing capacitor determines the capacitance in consideration of the current of the DC link, the allowable DC ripple rate, and the like, and the element may be selected in consideration of the price and volume.

In addition, since the charge and discharge of the capacitor should be the same,

Becomes

here, Is the ripple voltage of DC link, Is the discharge time,

Becomes,

The capacitance of the smoothing capacitor

Is calculated.

In this way, a capacitor of about 2,000 [uF] is required when the ripple voltage is allowed to about 10 [V]. Therefore, as a preferred embodiment, the smoothing capacitor may use a 400 [V] capacitor of 2,200 [uF] in series.

The inverter 123 for converting the DC input power converted through the input rectifier 121 into a high frequency of AC 50 kHz uses an IGBT element.

This Insulated Gate Bipolar Transistor (IGBT) device is a monolithic BI-MOS transistor that connects a PNP transistor and a MOSFET and is very expensive.

At this time, if the MOSFET is connected by applying a positive voltage between the gate and the emitter, the resistance is connected between the base and collector of the PNP transistor, and the PNP transistor portion becomes conductive.

In turn off operation, when the voltage between Gate-Emitter is set to 0 [V], the MOSFET is first cut off, and the PNP transistor is cut off because the BASE current is cut off.

As described above, the IGBT can be usefully applied to the present invention because the IGBT can control the ON / OFF state only by the voltage signal of the gate like the power MOSFET.

Meanwhile, the DC voltage converted by the input rectifier 121 becomes the supply voltage of the inverter 123. If the DC voltage is 311 [V], the voltage rating of the IGBT element is about 600 [V] in consideration of the safety factor. Capacity is sufficient.

In addition, the rated current of the switching element used for the inverter 123 is determined to have a sufficient margin as follows.

Rated Current = Load Capacity ÷ Efficiency ÷ AC Voltage ÷ × X overload rate ripple rate

= Idc × overload rate × ripple rate [A]

Inverter 123 conversion method can be altered by switching the DC power supplied through the input rectifier 121 to the IGBT element to convert to the desired frequency.

That is, the switching method using the IGBT applies a full bridge method, which is mainly used in a large power circuit. The conversion principle to the fast pulse power is as shown in FIGS. 4 and 5.

4 is an exemplary view illustrating a conversion method of the inverter 123 of the power control unit 120 applied to the inverter CO ₂ welder 100 according to the present invention, and FIG. 5 is an inverter CO ₂ welder according to the present invention. It is an implementation waveform diagram which shows the switching operation of the IGBT element which becomes the structure of the inverter 123 applied to 100).

I1 shown in FIG. 4 is the turn-on time of the first to fourth transistors TR1 to TR4, and V1 is the output voltage of the transformer primary side.

By adjusting the turn-on time of each of the transistors TR1 to TR4, the magnitude of the output voltage can be changed as shown in Figs. 4 and 5, and this is the PWM (PULSE WIDTH MODULATION) method. Through this, the desired frequency, that is, it can be converted into AC 50 kHz.

The main transformer 124 for converting the high frequency of AC 50 kHz converted through the inverter 123 into a low voltage high current power source has a great influence on miniaturization and weight reduction of the inverter CO ₂ welder 100 of the present invention.

The main transformer 124 is to change the value of the AC voltage and current by the electromagnetic induction action to adjust the transformer ratio between the primary and secondary to obtain the desired welding current.

And, as shown in Figure 6 the main transformer 124 is composed of a ferrite core and primary, secondary windings to efficiently pass through the magnet.

6 is a schematic view showing the main transformer 124, the output rectifier 125 and the reactor 126 applied to the inverter CO ₂ welding machine 100 according to the present invention.

Here, an important factor for determining the weight of the main transformer 124 is the cross-sectional area of the ferrite core.

E: 1CK voltage F: Frequency N: Number of turns

Bm: Magnetic flux density S: Iron core area

In addition, since the difference between the ferrite core for 60 Hz and 50,000 Hz applied to the inverter 123 is 833 times as large as the frequency f, it can be seen that as f becomes larger in the above formula, the cross sectional area may be inversely reduced by 833 times.

In addition, the ferrite core applied to the present invention compared to the general core core (Ferrite Core) is also a factor to reduce the cross-sectional area (S) because the magnetic flux density (Bm) is very large to minimize the number of turns N to minimize the size It has a great effect on making it possible.

On the other hand, PWM (Pulse Width Modulation) for controlling the power control unit 120 to supply a uniform output current by generating a pulse wave after detecting the error of the voltage generated from the power control unit 120 to match the reference voltage already set The controller 130 performs a function of providing the output current uniformly by basically applying the principle of pulse width modulation.

In the present invention, it is possible to sufficiently protect the inverter 123 of the power control unit 120, i.e., IGBT, which frequently causes a failure in the conventional welding machine, and it is possible to simultaneously control the constant voltage / constant current which is the strength of the welding quality. The key point is to improve the PWM control unit 130 to enable forced control by the function of spatter reduction.

In general, the CO ₂ welding generates an electric arc with the welding material when the welding wire is continuously supplied from the electrode of the welding torch, and the welding is possible, where the arc repeats a short circuit and a disconnection.

However, as described above, when the arc repeats a short circuit and a disconnection, the power control unit 120 that controls power inevitably receives a significant stress, and in the case where accurate feedback sensing of current and voltage does not occur continuously, power is reversed. Inverter 123 of the control unit 120, that is, the IGBT element is fatally damaged by overcurrent.

In order to prevent this, the current and voltage must be simultaneously controlled by receiving a signal from a feedback sensor. If the circuit configuration is not accurate or the response speed is slow, the IGBT may be damaged. Due to the high cost of the IGBT device, which is a component, the economic loss is large.

The inverter CO ₂ welding machine 100 shows the output of the constant voltage method, but when the welding wire is shorted, the short circuit and the arc state are repeated by breaking the wire as a constant current of a constant output, thereby facilitating the easy implementation of the welding operation. In other words, when the short-circuit is switched to the constant current method, and in the arc state to be a constant voltage state.

This switching is controlled by allowing the PWM controller 130 to switch sensitively to the output load.

The spatter reduction function is made possible by reducing the amount of current in the short-circuit instant of the welding wire by forcibly lowering the output current at the time of short-circuit of the welding wire, thereby reducing the debris, that is, the spatter. In addition, the reduction of the spatter can be achieved by increasing the instantaneous voltage to quickly get out of the short circuit state in order to reduce the spatter generated when switching from the short state to the arc state.

Here, a summary of the key suggestions of the present invention.

First, the PWM control unit 130 and the peripheral circuit of the current mode is hybridized to be strong against noise and simplify assembly production.

Secondly, the current amplifier 138, which receives and amplifies the output current from the feedback current sensor S3, is hybridized to resist noise and simplify assembly production.

Third, after setting the input current sensor (S1) in the input power supply unit 110 by the current control method and the feedback current sensor (S3) and the feedback voltage sensor (S2) on the output side, the first comparison unit in the PWM control unit 130 131, the second comparator 132, and the third comparator 133 are further provided to further strengthen the safety device by comparison control.

Fourth, the IGBT device utilized as the inverter 123 is modularized separately to prevent damage to the IGBT due to a bad contact.

By this core proposal, the present invention enables sufficient protection against damage of the inverter 123 applied to the power control unit 120, that is, breakage of the IGBT, compared to the conventional inverter welding machine, and the inverter CO ₂ welding machine 100. It enables simultaneous control of constant voltage / constant current, which is a strength of welding quality, and enables hybridization of the PWM controller 130 to achieve assembly production by being more resistant to noise and making the structure simpler.

Overall, the present invention is a continuous short-circuit disconnection state of the output due to the improvement of the PWM control unit 130 of the inverter CO ₂ welder 100 inevitably generated in the conventional inverter welder (about 10 times per second 200 times) and double protection to overcome the IGBT damage (economic loss is large) of the power control unit 120, which is fatally damaged when the sensing error of the instantaneous feedback occurs. In addition, by enabling simultaneous control of the constant voltage / constant current for improving the welding quality of the inverter welding machine, a uniform output state can be realized. See FIG. 7 for a detailed description thereof.

7 is a block diagram showing the subdivided PWM control unit 130 applied to the inverter CO ₂ welding machine according to the present invention.

Inverter CO ₂ welding machine 100 according to the present invention by receiving the input power (3 ° or 1 °) from the input power source 110, as shown in Figure 7 to rectify the first through the input rectifier 121 to DC the AC After the smoothing unit 122 is smoothed under the control of the PWM control unit 130 to provide a low-voltage high current pulse wave to the inverter 123.

Inverter 123 is converted to a high frequency of 50KHz using the IGBT element, and converts the AC 50KHz PULSE generated by the main transformer 124 to the desired voltage or current magnitude.

Then, the output from the secondary side of the main transformer 124 is rectified again through the output rectifying unit 125 to smooth the DC current by the reactor 126 of the output stage.

Here, the magnitude of the output is determined by the amount of the pulse width corresponding to the turn-on time of the inverter 123 and the amount is the PWM control unit 130 according to the feedback amount by the feedback current sensor S3 and the feedback voltage sensor S2. In comparison with the set value (reference value) of the main controller unit 150 to reduce or increase the constant (REGULATION) output is possible.

In other words, the inverter CO ₂ welding machine 100 according to the present invention is due to the improved PWM control unit 130 to prevent the damage of the IGBT of the power control unit 120, which is pointed out as a weak point compared to the conventional inverter 123 welding machine. To prevent it.

PWM (PUSE WIDTH MODULATION) control unit 130 performs a double feedback control as shown in FIG. That is, the second comparator 132 receives the signal of the input current sensor S1 of the input power supply 110 as a DC current through the DC converter 135, and the amount of the current is the main controller 150. When the reference value is exceeded, the output waveform is reduced, and the first comparator 131 senses the output side voltage through the feedback voltage sensor S2 and compares it with the reference value set in the main controller 150. When it comes out, it is maximized again within the output value of the second comparator 132.

Here, the limit of the primary control is determined by the third comparator 133. In addition, when the input amount reaches a risk criterion of the IGBT regardless of the output amount, the overcurrent interruption unit 136 may first block the driving of the inverter 123, that is, the driving of the IGBT. Therefore, the reference of the primary control can be a constant current value and the reference of the secondary control can be a constant voltage value.

In other words, in the inverter CO ₂ welding machine 100 according to the present invention, the value of the current control is controlled first and then the value of the voltage control is controlled. In fact, when the welder output is short-circuited, the current flowing through the IGBT becomes maximum, and if the feedback control of the current is not made quickly, the IGBT is broken.

In the voltage control state, the welder output is in the arc state, so the arc has some resistance value, which is much less burdened by the IGBT than the short circuit state, and the risk of breakage is less at this time.

And, in addition to the above primary and secondary control, if the amount of input current sensor S1 on the input side of the welder exceeds a certain level regardless of the feedback voltage sensor S2 and the feedback current sensor S3 of the welder output, An overcurrent breaker 136 to shut down the output prior to control is included to ensure safe operation of the inverter 123 of the welder regardless of whether the welder output is short or arced.

In other words, the inverter CO ₂ welding machine 100 according to the present invention is capable of simultaneous control of constant voltage and constant current. More specifically, the inverter CO ₂ welding machine 100 exhibits a constant voltage output, but when the welding wire is shorted, the welding is possible by repeating the short circuit and the arc state by breaking the wire as a constant current of a constant output. That is, in the case of a short circuit, it becomes a constant current power supply device, and in an arc state, it becomes a constant voltage state. This is realized by switching sensitively to the output load in the PWM controller 130.

For example, when the reference value of the current and the value of the feedback current sensor S3 coincide with each other in FIG. 7, the output of the third comparator 133 is inverted and the amount of the input primary current supplied to the second comparator 132. By reducing the threshold of the pulse width control unit 137 to quickly reduce the amount, if the value of the feedback current sensor (S3) is insufficient, the third comparator 133 is inverted and irrespective of the threshold of the amount of the input primary current The third comparator 133 outputs the output current.

In addition, in FIG. 7, when the reference value of the voltage is smaller than the value of the feedback voltage sensor S2 compared in the first comparator 131, the output is inverted, and the second comparator 132 again returns the amount of the input primary current. The output of the pulse width controller 137 is rapidly reduced by comparing the output by comparing the output, and when the value of the feedback voltage sensor S2 is insufficient, the first comparator 131 is non-inverted and the input 1 is input from the second comparator 132. The output of the pulse width controller 137 is quickly increased by adjusting the output in comparison with the amount of the difference current. In this way, the values of the constant voltage and the constant current are always adjusted according to the state of the output to obtain a uniform welder output.

In addition, the inverter CO ₂ welding machine 100 according to the present invention hybridizes the PWM control unit 130 to be resistant to noise, to simplify the structure, and to facilitate assembly production.

More specifically, in FIG. 7, the first comparator 131 and the second comparator 132 are hybridized into a single module, and reference numeral 134 in the figure indicates an output current from the shunt SHUNT, which is a feedback current sensor S3. It is a hybridized output current amplifier with the function of detecting and amplifying the current flow to detect the operating state of the welding machine.

The third comparator 133 is provided from the shunt through the output current amplifier 134 which is the feedback current sensor S3 and compared with the current set value (reference value) of the main controller unit 150. Supply to the comparator 132.

In the drawing, reference numeral 180 denotes an overvoltage blocking unit for detecting an input voltage state, and an overvoltage protection circuit is designed. 138 denotes a current amplifier for driving an IGBT. T1, T2, T3, and T4 are IGBT drive pulse transformers.

The IGBT element, which is an inverter 123, can prevent IGBT damage due to a bad contact due to a separate modularization as an IGBT gate circuit, and is separately provided as an IGBT GATE circuit board, that is, an IGBT gate module as shown in FIG.

The IGBT gate module is a C-MOS voltage driving method. If power is applied to the collector and emitter of the IGBT while the gate is disconnected, the IGBT gate module is short-circuited due to an internal short circuit. In order to prevent this phenomenon, the gate module of the IGBT is separately provided to be set in the PWM controller 130 so as to prevent damage to the IGBT element due to a poor contact.

On the other hand, the output rectifier 125 for converting the power of the low voltage high current converted through the main transformer 124 to the power of the low voltage high current of DC uses a high-speed diode different from the diode used in the input rectifier 121.

This high speed diode uses ULTLA FAST RECOVERY or Schottky Barrier DIODE, among which FAST RECOVERY DIODE has high breakdown voltage, which is more suitable for inverter CO ₂ welding machine 100 of the present invention than Schottky Barrier Diode used for low breakdown voltage. It can apply suitably.

For example, the diode of 30,000Hz to 40,000Hz does not cause any problem when it is turned on in the forward direction, but the short-circuit current is generated during turn-off, which causes noise and decreases efficiency. It can be seen that a high speed diode is suitable because the shorter the TRR, the smaller the amount of short circuit current can be generated.

In addition, by smoothing the power of the low-voltage high current of the DC converted through the output rectifier 125 to mitigate the impact of the inverter 123 due to the load fluctuations and lower the effective current of the output rectifier 125 and the main transformer 124 Reactor 126, unlike the input rectifier 121, uses a reactor 126 for a large current without using a capacitor as a smoothing circuit.

The basic principle of the reactor 126 for such a large current simply serves to hinder the flow of alternating current and alternating the flow of alternating current, and to mitigate the impact of the inverter 123 due to load fluctuations in addition to the purpose of smoothing. And the effective current of the output rectifier 125 is also lowered.

Since this action is a major factor in determining the characteristics of the load, the large current reactor 126 may be usefully used in the power control unit 120 applied to the inverter CO ₂ welder 100 according to the present invention.

As described above, the inverter CO ₂ welding machine 100 according to the present invention can hybridize the PWM control unit 130 and the peripheral circuit in the current mode to be strong in noise and simplify assembly production, and also provide a feedback current sensor (S3). The current amplification unit 138, which receives and amplifies the output current from the hybridization, is resistant to noise and can simplify assembly production.The input current sensor S1 is set in the input power supply unit 110 by a current control method. After installing the feedback current sensor S3 and the feedback voltage sensor S2 on the output side, the first control unit 131, the second comparison unit 132, and the third comparison unit 133 are provided in the PWM control unit 130. It is effective to reinforce the safety device by comparison control.

In addition, the IGBT device utilized as the inverter 123 may be separately modularized to prevent damage to the IGBT due to a bad contact.

That is, the inverter CO ₂ welder 100 according to the present invention enables sufficient protection against damage of the inverter 123 applied to the power control unit 120, specifically, damage of the IGBT, compared to the conventional inverter welder, and the inverter CO 2. ₂ enables simultaneous control of constant voltage / constant current, which is a strength of welding quality of the welding machine 100, and is also resistant to noise and simple structure through hybridization of the PWM control unit 130, thus enabling assembly production, and PWM control unit ( 130) The conventional inverter welding machine is a double protection against the IGBT damage of the power control unit 120, which is fatally damaged when the stress of the short-circuit disconnection state of the output is inevitable due to the welding characteristics and a sensing error of the instantaneous feedback occurs. It enables the protection and enables the simultaneous control of constant voltage and constant current to improve the welding quality of inverter welding machine. So that it is highly effective.

Claims (3)

Power having an inverter 123 for smoothing the input power of AC input from the outside to a high voltage of direct current of low voltage and high current so as to output a stable arc over a wide range from low current to high current And a PWM controller 130 which detects an error of the voltage provided from the power controller 120 to generate a pulse wave, and then outputs a uniform output current by matching a preset reference value. In the inverter CO ₂ welder 100 made, An input current sensor S1 sensing an input side current of the power control unit 120; A DC converter 135 for converting the current sensed by the input current sensor S1 into direct current; A second comparator 132 which receives the signal of the input current sensor S1 as a DC current through the DC converter 135 and reduces the output waveform first if the amount of the current exceeds a reference value; A feedback voltage sensor S2 for sensing an output side voltage of the power control unit 120; When the output side voltage of the power control unit 120 is sensed through the feedback voltage sensor S2 and compared with the reference value of the voltage, and the predetermined value is obtained, the second side is maximized within the output value of the second comparator 132. A first comparator 131 for controlling; Feedback current sensor (S3) for detecting the output side current of the power control unit 120, When the value of the feedback current sensor S3 matches the reference value of the current, the output is inverted to decrease the amount of pulse control by reducing the threshold of the amount of the input primary current supplied to the second comparator 132, When the value of the feedback current sensor (S3) is insufficient, the inverter CO ₂ characterized in that it is non-inverted to control the output current irrespective of the limit of the amount of the input primary current. Welder 100. The method of claim 1, Inverter, characterized in that it further comprises an over-current cut-off unit 136 to cut off preferentially when the amount of current inputted through the DC converter 135 is an overcurrent regardless of the output amount of the power control unit 120 CO ₂ welder (100). The method of claim 1, Inverter 123 is an inverter CO ₂ welder (100), characterized in that the IGBT gate module that is manufactured separately and detachably connected to the PWM control unit (130).