Alternating-current argon arc welding power supply with sine-wave current output

Abstract

The utility model relates to an alternating current argon arc welding power supply with sine wave current output, which comprises a three-phase rectifier module, a primary inverter, a transformer, a bridge rectifier, a single chip microcomputer, a PWM (pulse-width modulation) modulator, a characteristic control panel, a secondary inverter and a driving module, and the three-phase rectifier module, the primary inverter, the transformer and the bridge rectifier are sequentially connected. A signal output pin of the single chip microcomputer is connected with a control end of the secondary inverter through the driving module, the driving module comprises a driving chip U1 and driving optocouplers PC1 and PC2, a pin 8 of the driving chip U1 is used for receiving a switching signal output by the single chip microcomputer, a pin 5 of the driving chip U1 is connected with an input end of the driving optocoupler PC1 after being sequentially connected in series with a light emitting diode LED1 and a resistor R2, and the driving optocoupler PC1 is connected with an output end of the secondary inverter. The output end of the driving optocoupler PC1 is connected with the grid electrode of the IGBT1 of the secondary inverter, and the seventh pin of the driving chip U1 is connected with the input end of the driving optocoupler PC2 after being sequentially connected with the LED 2 and the resistor R3 in series. And the sine wave current is output to reduce the electric arc noise and reduce the impact on the secondary inverter.

Description

Technical Field

[0001] The utility model relates to the technical field of welding power sources, in particular to an AC argon arc welding power source with sinusoidal current output. Background Technique

[0002] AC argon arc welding is a welding process that uses a current with an output polarity that alternates periodically, a tungsten electrode as the welding electrode, and high-purity argon gas as the shielding gas. It is commonly used for welding non-ferrous metals (such as aluminum, magnesium, copper, etc.) and ferrous metals (such as stainless steel, carbon steel, etc.). AC argon arc welders generally use a non-contact arc ignition method that uses high frequency and high voltage to break down air. They output constant current control and use IGBT for secondary inversion to form a square wave alternating current for welding operations.

[0003] For existing AC argon arc welding power sources, they generally adopt the method of forming an H-bridge inversion with a primary IGBT. The inversion frequency is 20Khz. The output current is collected by an analog control board and compared with the given value. The drive circuit adjusts its duty cycle to achieve the purpose of adjusting the output current magnitude. The analog control board outputs a square wave signal through a digital integrated circuit to control the secondary inversion IGBT. The secondary inversion IGBT half-bridge module inverses the positive and negative direct currents after rectification into a low-frequency alternating square wave current. Since the output current is a constant current, the polarity is switched through the secondary IGBT half-bridge module to form an alternating square wave current. During the switching process, the impact on the IGBT is relatively large. A large margin needs to be reserved when selecting the IGBT, and the upper and lower bridge arms are prone to direct short circuit. A large switching dead zone needs to be set, which is prone to arc interruption. In addition, when directly switching the output polarity under a large current state, the welding arc sound is relatively large and very harsh, posing a certain threat to the health of the welder who is performing welding operations. Therefore, it is necessary to further improve and research the existing situation of the current AC submerged arc welding power source. Content of the Utility Model

[0004] Based on this, in view of the above problems, it is necessary to provide an AC argon arc welding power source with sinusoidal current output.

[0005] An AC argon arc welding power source with sinusoidal current output, comprising a three-phase rectification module, a primary inverter, a transformer, a bridge rectifier, a single-chip microcomputer, a PWM modulator, a characteristic control board, a secondary inverter and a drive module. The three-phase rectification module, the primary inverter, the transformer and the bridge rectifier are connected in sequence to rectify and step down the high-voltage alternating current to output a low-voltage direct current voltage. The signal input pins of the single-chip microcomputer are connected to the control end of the primary inverter through the characteristic control board and the PWM modulator in sequence. The signal output pins of the single-chip microcomputer are connected to the control end of the secondary inverter through the drive module. The drive module includes a drive chip U1, drive optocouplers PC1 and PC2. The 8th pin of the drive chip U1 is used to receive the switching signal output by the single-chip microcomputer. After the 5th pin of the drive chip U1 is sequentially connected in series with a light-emitting diode LED1 and a resistor R2, it is connected to the input end of the drive optocoupler PC1. The output end of the drive optocoupler PC1 is connected to the gate of the IGBT1 of the secondary inverter. After the 7th pin of the drive chip U1 is sequentially connected in series with a light-emitting diode LED2 and a resistor R3, it is connected to the input end of the drive optocoupler PC2. The output end of the drive optocoupler PC2 is connected to the gate of the IGBT2 of the secondary inverter. A diode D1 is connected in series between the 4th pin of the drive optocoupler PC1 and the positive extreme of the light-emitting diode LED2. A diode D2 is connected in series between the 4th pin of the drive optocoupler PC2 and the positive extreme of the light-emitting diode LED1.

[0006] Preferably, the models of the drive optocouplers PC1 and PC2 are TLP350, the model of the single-chip microcomputer is AT32F435ZGT7, and the model of the drive chip U1 is EG27324.

[0007] Preferably, the single-chip microcomputer collects the AC signal output by the transformer through a Hall sensor TA1.

[0008] The beneficial effects of the present utility model are as follows: The control signal of the single-chip microcomputer is an SPWM wave with a sinusoidally varying duty cycle, so that its output is a sinusoidal current, effectively reducing arc noise, protecting the health of welders, reducing the impact on the IGBTs in the secondary inverter, and increasing the reliability of the equipment; and the drive optocouplers are connected in reverse parallel to avoid the direct short circuit of the IGBTs in the output secondary inverter. Description of the Drawings

[0009] Figure 1 It is a circuit module diagram of an AC argon arc welding power source with sinusoidal current output in one embodiment;

[0010] Figure 2 It is a circuit diagram of the drive module. Detailed Embodiments

[0011] In order to make the above objects, features and advantages of the present utility model more obvious and understandable, the following detailed description of the specific embodiments of the present utility model will be given in conjunction with the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present utility model. However, the present utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present utility model. Therefore, the present utility model is not limited by the specific embodiments disclosed below.

[0012] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation.

[0013] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present utility model belongs. The terms used herein in the description of the present utility model are only for the purpose of describing specific embodiments and are not intended to limit the present utility model. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0014] Such as Figures 1 - 2As shown in the figure, an AC argon arc welding power source with sine wave current output includes a three-phase rectification module 1, a primary inverter 2, a transformer 3, a bridge rectifier 4, a single-chip microcomputer 5, a PWM modulator 6, a characteristic control board 7, a secondary inverter 8 and a drive module 9. The three-phase rectification module 1, the primary inverter 2, the transformer 3 and the bridge rectifier 4 are connected in sequence to rectify and step down the high-voltage alternating current and output it as a low-voltage direct current voltage. The signal input pins of the single-chip microcomputer 5 are connected to the control terminal of the primary inverter 2 through the characteristic control board 7 and the PWM modulator 6 in sequence. The signal output pins of the single-chip microcomputer 5 are connected to the control terminal of the secondary inverter 8 through the drive module 9. The drive module 9 includes a drive chip U1, drive optocouplers PC1 and PC2. The 8th pin of the drive chip U1 is used to receive the switching signal output by the single-chip microcomputer 5. After the 5th pin of the drive chip U1 is connected in series with the light-emitting diode LED1 and the resistor R2 in sequence, it is connected to the input terminal of the drive optocoupler PC1. The output terminal of the drive optocoupler PC1 is connected to the gate of the IGBT1 of the secondary inverter 8. After the 7th pin of the drive chip U1 is connected in series with the light-emitting diode LED2 and the resistor R3 in sequence, it is connected to the input terminal of the drive optocoupler PC2. The output terminal of the drive optocoupler PC2 is connected to the gate of the IGBT2 of the secondary inverter 8. A diode D1 is connected in series between the 4th pin of the drive optocoupler PC1 and the positive terminal of the light-emitting diode LED2. A diode D2 is connected in series between the 4th pin of the drive optocoupler PC2 and the positive terminal of the light-emitting diode LED1. Specifically, in this embodiment, the three-phase rectification module 1 is used to rectify the industrial high-voltage alternating current into direct current. A capacitor is added between the output terminal of the three-phase rectification module 1 and the primary inverter 2 for filtering. After rectification and filtering, a high-voltage direct current of 540V is formed and applied to the primary inverter 2. It is composed of IGBT components to form an H inverter bridge and is inverted into high-frequency alternating current with a frequency of up to 20KHz. Then it enters the transformer 3 for step-down. The transformer 3 is a high-frequency amorphous transformer. The stepped-down high-frequency alternating current is rectified by the bridge rectifier 4 into a low-voltage positive and negative direct current voltage of ±75V. The bridge rectifier 4 is specifically composed of fast-recovery diodes D1, D2, D3 and D4. It is supplied to the secondary inverter 8. The single-chip microcomputer 5 outputs a set frequency to control the secondary inverter 8, and the output passes through the load and the inductor L for filtering to form a sine wave current. In order to prevent the IGBT in the secondary inverter 8 from being directly short-circuited, we integrated the drive module 9 between the control output pin of the single-chip microcomputer 5 and the control terminal of the secondary inverter 8. The switching signal of the single-chip microcomputer 5 is input to the drive chip U1. The drive chip U1 amplifies and outputs the switching signal to the drive optocouplers PC1 and PC2. The drive optocouplers PC1 and PC2 are connected in reverse parallel. When the drive optocoupler PC1 is triggered, PC2 is in the reverse cut-off state, so the output is turned off. When the drive optocoupler PC2 is triggered, PC1 is in the reverse cut-off state. In this way, the direct short-circuit of the IGBT module in the output secondary inverter is avoided.Meanwhile, for the primary inverter 2 in this design, the control signal is an SPWM wave with a sinusoidally varying duty cycle, enabling its output to be a sinusoidal current. This can effectively reduce arc noise, protect the welder's health, reduce the impact on the secondary IGBT, and increase the reliability of the equipment. Specifically, the single-chip microcomputer 5 obtains a set of given current values that vary sinusoidally through sine calculation based on a preset output frequency. According to the cycle time of the set output frequency through the digital-to-analog conversion DA of the single-chip microcomputer 5, it outputs a control signal with a sinusoidally varying frequency to the characteristic control board 7, controls the duty cycle of the drive circuit when outputting the control signal, and at this time, the duty cycle is already an SPWM wave with a sinusoidally varying duty cycle. Moreover, the output reactor is changed to an autotransformer type, effectively reducing the current switching time; and the optocoupler drivers in the drive module 9 are connected in reverse parallel to prevent the output IGBT from being directly short-circuited.

[0015] Specifically, the models of the drive optocouplers PC1 and PC2 are TLP350, the model of the single-chip microcomputer 5 is AT32F435ZGT7, and the model of the drive chip U1 is EG27324.

[0016] As Figure 1 shown, the single-chip microcomputer 5 collects the AC signal output by the transformer 3 through the Hall sensor TA1. The specific model of the Hall sensor TA1 is TKC-600N, which is used to collect the AC signal output by the transformer 3. After the output current becomes a sinusoidal wave, it switches the output polarity at a small current, which can effectively reduce arc noise and reduce the current impact on the IGBT in the secondary inverter 8.

[0017] The above embodiments only represent several implementation modes of the present utility model. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the utility model patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several modifications and improvements can still be made, and these all belong to the protection scope of the present utility model. Therefore, the protection scope of the present utility model patent shall be subject to the appended claims.

Claims

1. An AC argon arc welding power supply with sinusoidal current output, characterized in that: The invention comprises a three-phase rectifier module, a primary inverter, a transformer, a bridge rectifier, a single-chip microcomputer, a PWM modulator, a characteristic control board, a secondary inverter and a drive module. The three-phase rectifier module, the primary inverter, the transformer and the bridge rectifier are connected in sequence to rectify and step down the high-voltage AC power and output it as a low-voltage DC voltage. The signal input pin of the single-chip microcomputer is connected to the control end of the primary inverter through the characteristic control board and the PWM modulator in sequence. The signal output pin of the single-chip microcomputer is connected to the control end of the secondary inverter through the drive module. The drive module comprises a drive chip U1, drive optical couplers PC1 and PC2. The 8 pins of the drive chip U1 are used to receive the output of the single-chip microcomputer. Switching signal, the 5th pin of the driving chip U1 is connected in series with the light-emitting diode LED1 and the resistor R2, and then connected to the input end of the driving optocoupler PC1, the output end of the driving optocoupler PC1 is connected to the gate of the IGBT1 of the secondary inverter, the 7th pin of the driving chip U1 is connected in series with the light-emitting diode LED2 and the resistor R3, and then connected to the input end of the driving optocoupler PC2, the output end of the driving optocoupler PC2 is connected to the gate of the IGBT2 of the secondary inverter, a diode D1 is connected in series between the 4th pin of the driving optocoupler PC1 and the positive terminal of the light-emitting diode LED2, and a diode D2 is connected in series between the 4th pin of the driving optocoupler PC2 and the positive terminal of the light-emitting diode LED1.

2. The AC argon arc welding power supply with a sinusoidal current output as claimed in claim 1, characterized in that: The model of the driving optical couplers PC1 and PC2 is TLP350, the model of the single chip microcomputer is AT32F435ZGT7, and the model of the driving chip U1 is EG27324.

3. The AC argon arc welding power supply with a sinusoidal current output as claimed in claim 1, characterized in that: The single chip microcomputer collects the AC signal output by the transformer through the Hall sensor TA1.

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