CN201371304Y - Portable IGBT inverter arc welding machine - Google Patents

Abstract

A portable IGBT inverter arc welding machine with high reliability, small size and low cost, which includes a main circuit and a control circuit connected to it and an auxiliary power supply circuit. The main circuit sequentially includes an input rectifying and filtering circuit, an inverter circuit, and a high Frequency main transformer, secondary output rectification circuit; control circuit includes PWM regulation circuit, IGBT drive circuit, current feedback circuit, current given circuit; the characteristic is that the inverter circuit adopts a full bridge hard switch structure, in which the insulated gate bipolar transistor IGBT G1, G3, G2, and G4 form bridge arms that are sequentially conducted. They are alternately conducted to convert DC into high-frequency square-wave AC. After passing through the high-frequency main transformer, it is rectified to output low-voltage DC. The resistors and capacitors connected in parallel at both ends of the IGBT are Spike voltage absorption network; the high-frequency main transformer uses a microcrystalline alloy iron core, and a high-voltage and high-temperature-resistant insulating layer is provided between the primary and secondary coils; the PWM regulation circuit uses a double-terminal output current control pulse width modulator chip.

Description

Portable IGBT inverter arc welding machine

technical field

The utility model relates to an inverter arc welding machine, in particular to a portable IGBT inverter arc welding machine.

Background technique

Existing small arc welding machines generally use power field effect transistors (hereinafter referred to as field transistors) as the main switching device, so the inverter arc welding machine has the following disadvantages. One is limited by the inability of a single field tube to generate a large current, the welding machine needs to be connected in parallel with multiple field tubes, thus increasing the possibility of failure of the welding machine. The second is that due to the high inverter frequency, the field tube and the fast recovery diode generate high heat, and the heat cannot be dissipated quickly due to the structure of the main transformer. Although the inverter frequency is high, the same current and the same duty cycle Welders, radiators, and fans are large, making it difficult to miniaturize. The third is that due to the large number of field tubes and the large volume of radiators and fans, the cost is relatively high under the same parameters.

Utility model content

The purpose of the utility model is to provide a portable IGBT inverter arc welding machine with high reliability, small volume and low cost.

In order to achieve the above object, the technical solution adopted by the utility model is a portable IGBT inverter arc welding machine, which includes:

The main circuit and its connected control circuit and auxiliary power circuit,

The sequence of the main circuit includes input rectification filter circuit, inverter circuit, high-frequency main transformer, and secondary output rectification circuit. The main circuit rectifies 50Hz mains electricity into DC, then converts it into high-frequency AC, and then rectifies it twice to become DC for welding,

The control circuit includes a PWM regulation circuit, an IGBT drive circuit, a current feedback circuit, and a current setting circuit. The welding current value set by the user is the current setting, and the current setting and the current feedback signal obtained by the shunt sample enter the current regulator together The error voltage is obtained by comparison, and the error voltage controls the PWM regulating circuit to generate a pulse signal with a certain width. The pulse drives the insulated gate bipolar transistor IGBT of the main circuit through the IGBT drive circuit, and then obtains the welding current through the main circuit. It is characterized in that,

The inverter circuit adopts a full-bridge hard switching structure, in which the insulated gate bipolar transistors IGBT G1, G3, G2, and G4 form bridge arms that are sequentially conducted, and they are alternately conducted to convert DC into high-frequency square-wave AC. The frequency main transformer rectifies and outputs low-voltage DC, and the resistance and capacitance connected in parallel at both ends of the IGBT are peak voltage absorption networks.

The high-frequency main transformer plays the role of power transmission and electrical isolation in the circuit. The high-frequency main transformer uses a microcrystalline alloy core, and a high-voltage and high-temperature-resistant insulating layer is provided between the primary and secondary pole coils.

The PWM regulation circuit adopts the dual-terminal output current control type pulse width modulator chip U2.

Preferably, the PWM regulating chip is a double-terminal output current control type pulse width modulator chip U2, the model of which is KA3846, and the KA3846 adopts a peak current control mode to realize pulse-by-pulse control.

Preferably, the IGBT drive circuit is an interface between the IGBT in the inverter circuit and the control circuit, so as to realize the isolation, amplification and protection of the PWM signal.

Because the inverter circuit adopts the commonly used full-bridge hard switch structure, the utility model is composed of insulated gate bipolar transistors IGBT G1, G3 and G2, G4 to form bridge arms that are sequentially conducted. The advantages of field effect tube and high-power triode GTR have the advantages of large single capacity, small switching loss, high withstand voltage, good thermal stability, easy driving, etc., benefiting from the advantages of IGBT, the utility model does not need to connect multiple tubes in parallel, and then The reliability of the welding machine is improved, and the volume of the whole machine is greatly reduced due to the low calorific value without the need for a large radiator and fan. Because the high-frequency main transformer of the present invention uses a microcrystalline alloy iron core, the primary pole adopts high-voltage-resistant and high-temperature-resistant insulating materials, which has the advantages of high power density, easy heat dissipation, and easy installation. The frequency of AC in this process is very high, generally tens of kilohertz. Due to the high frequency, the number of turns of the main transformer is small and the iron core is small, which makes the welding machine small in size and light in weight, and the loss of the transformer is also very small. Can improve the overall efficiency. The utility model adopts the peak current mode control method because the current control type pulse width modulator chip KA3846 with double-terminal output has the advantages of one by one pulse control, fast dynamic response, high output precision and stability Good; second, it has transient protection capability, which can effectively prevent IGBT overcurrent; third, it can prevent the occurrence of high-frequency main transformer bias, if severe bias will damage the IGBT or even the main transformer. The utility model is precisely due to the adoption of KA3846, so that the working reliability of the complete machine can be improved. In summary, the utility model is reliable in operation, small in size and low in cost.

Description of drawings

The utility model is described in further detail below in conjunction with accompanying drawing and specific embodiment.

Fig. 1 is the complete machine circuit principle diagram of the present utility model, comprises main circuit and relevant circuit block thereof;

Fig. 2 is a circuit diagram of the main circuit shown in Fig. 1;

Fig. 3 is a schematic diagram of PWM regulation in the control circuit shown in Fig. 1;

Fig. 4 is a schematic diagram of the IGBT drive circuit in the control circuit shown in Fig. 1;

Fig. 5 is a schematic diagram of the current feedback and current given circuit in the control circuit shown in Fig. 1;

FIG. 6 is a schematic diagram of the auxiliary power supply circuit shown in FIG. 1 .

Detailed ways

As shown in Figure 1, the utility model portable IGBT inverter arc welding machine includes a main circuit and a control circuit and an auxiliary power circuit connected thereto. In Figure 1, the main circuit refers to the control circuit, the drive module and the auxiliary power circuit block Other than the circuit, the drive module is the IGBT drive circuit.

As shown in Figure 2, the main circuit sequentially includes an input rectification and filtering circuit, an inverter circuit, a high-frequency main transformer, and a secondary output rectification circuit. The main circuit is the most basic and important part of the welding machine, and its main function is to convert the alternating current of the mains into the direct current used for welding. The main circuit is the main body to realize the inverter. The inverter process is to convert the 50Hz city power into DC through rectification, and then into high-frequency AC through inversion, and then into DC through secondary rectification. Among them, DC is transformed into AC into instant inverter. In this process, The frequency of AC is very high, generally tens of kilohertz. Due to the high frequency, the number of turns of the main transformer is very small and the iron core is small, which makes the welding machine small in size and light in weight. At the same time, the loss of the transformer is also very small, which can improve the overall performance machine efficiency.

As shown in Figure 2, the input rectification filter circuit consists of a power switch, a rectifier bridge, a closing surge limiting circuit, and a filter circuit connection. Its main function is to provide a relatively stable DC voltage for the inverter circuit.

As shown in Figure 2, the inverter circuit adopts the commonly used full bridge hard switch structure. IGBT G1, G3, G2, and G4 form bridge arms that are sequentially conducted. They are alternately conducted to convert DC into high-frequency square-wave AC, and then rectify and output low-voltage DC after passing through the high-frequency main transformer. The resistors and capacitors connected in parallel at both ends of the IGBT are peak voltage absorption networks, which absorb the peak voltage caused by the leakage inductance of the main transformer when the switch tube is turned off, and can prevent the IGBT from being damaged by overvoltage. The main switching device used in the utility model is IGBT, and the insulated gate bipolar transistor IGBT is the third generation power device, which combines the advantages of field effect transistor and high-power triode GTR, and has large single capacity, small switching loss and low calorific value , high pressure resistance, good thermal stability, easy driving and other advantages. Thanks to its advantages, the utility model does not need multi-pipe parallel connection, thereby improving the reliability of the welding machine, and because of the low calorific value, no large radiator and fan are needed, which greatly reduces the volume of the whole machine.

As shown in Figure 2, the high-frequency main transformer plays the role of power transmission and electrical isolation in the circuit. In the welding machine, it has high transmission power, high heat generation, and high insulation. It is a very important and cost-proportioned component. The high-frequency main transformer of the utility model uses a microcrystalline alloy iron core, and the primary pole adopts high-voltage and high-temperature-resistant insulating materials, which has the advantages of high power density, easy heat dissipation, and easy installation.

As shown in Figure 2, the secondary output rectification circuit rectifies the low-voltage high-frequency alternating current into direct current, and then it can be used for welding. Fast recovery diodes are used due to the high AC frequency.

The control circuit realizes the control of the welding process, and the control circuit includes a PWM regulation, an IGBT drive circuit, a current feedback circuit, and a current setting circuit. The current reference is the welding current value set by the user. It enters the current regulator together with the current feedback signal obtained by the shunt for comparison to obtain an error voltage. The error voltage controls the PWM regulation circuit to generate a pulse signal of a certain width, and the pulse passes through the IGBT The driving circuit drives the IGBT of the main circuit, and then obtains the welding current through the main circuit. The utility model control circuit is described as follows according to the contained content:

As shown in Figure 3, the PWM regulation circuit uses the PWM regulation chip U2, whose model is KA3846. This is a dual-terminal output current-controlled pulse width modulator chip. KA3846 adopts the peak current mode control method. The current mode control method has the following advantages: First, pulse-by-pulse control, fast dynamic response, high output accuracy, and good stability. Second, it has transient protection capability, which can effectively prevent IGBT from overcurrent. The third is to prevent the occurrence of high-frequency main transformer bias. If the bias is severe, the IGBT and even the main transformer will be damaged. Because the utility model adopts KA3846, the working reliability of the complete machine is improved.

As shown in Figure 4, the IGBT drive circuit is the interface between the IGBT and the control circuit (see Figure 1, the drive module is the IGBT drive circuit), which realizes the isolation, amplification and protection of the PWM signal, and the drive circuit plays a role in the normal operation of the IGBT. very important role. The utility model uses the driving transformer T1, which can effectively prevent IGBT through damage, and is cheap, thereby improving reliability and reducing cost.

As shown in Figure 5, the current feedback and current setting circuit, the utility model is a manual welding machine, the external characteristic is a constant current that needs feedback current, the current sampling device of this welding machine is a shunt, and its cost is low and its response speed is fast.

As shown in Figure 6, the auxiliary power supply circuit provides the low-voltage DC power required by the control circuit. The auxiliary power supply of the utility model adopts a single-ended flyback switching power supply.

Claims (3)

1. portable type IGBT invert arc welding machine, this portable type IGBT invert arc welding machine comprise,

Main circuit and connected control circuit and auxiliary power circuit,

The main circuit order comprises the input rectifying filter circuit successively, inverter circuit, and high frequency main transformer, the secondary output rectification circuit, main circuit becomes direct current with the 50Hz civil power by rectification, becomes high-frequency ac by inversion again, and it is used that the secondary rectification becomes direct current confession welding again,

Control circuit comprises the PWM regulating circuit, the IGBT drive circuit, current feedback circuit, the electric current given circuit, the welding current value that the user sets is that electric current is given, the given current feedback signal that obtains with current divider sampling of electric current enters current regulator and compares and obtain error voltage, error voltage control PWM regulating circuit produces the pulse signal of certain width, this pulse drives the insulation gate pole bipolar transistor IGBT of main circuit by the IGBT drive circuit, obtain welding current by main circuit again, it is characterized in that

This inverter circuit adopts full-bridge hard switching structure, the brachium pontis of gate pole bipolar transistor IGBT G1, G3 and G2, the G4 formation sequential turn-on that wherein insulate, their alternate conduction become direct current into high frequency square wave and exchange, by rectification output low-voltage direct after the high frequency main transformer, IGBT two ends institute parallel resistor electric capacity is that peak voltage absorbs network

This high frequency main transformer plays the effect of power transmission and electrical isolation in circuit, this high frequency main transformer is used microcrystallizing alloy iron core, just, be provided with high pressure resistant, temperature-resistant insulation layer between the secondary coil,

The PWM regulating circuit adopts both-end output current control type pulse width modulator chip U2.

2. portable type IGBT invert arc welding machine as claimed in claim 1, it is characterized in that it is both-end output current control type pulse width modulator chip U2 that described PWM regulates chip, its model is KA3846, this KA3846 adopts the peak point current control mode, realizes the control of pulse one by one.

3. portable type IGBT invert arc welding machine as claimed in claim 1 is characterized in that, the IGBT drive circuit is insulation gate pole bipolar transistor IGBT in the inverter circuit and the interface between the control circuit, to realize isolation, amplification and the protection to pwm signal.

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