Welding inverter for 5 do it yourself. Homemade inverter welding machine from parts of old TVs

Inverter welding machines have been widely used in the construction sphere due to their high performance and low weight. However, N. everyone can afford yourself such a tool. The only way out is to make a welding inverter with your own hands. On the Internet there are many schemes such devices. Many of them are distinguished by complexity and high costs, but there are also budget models.

General information about the welding inverter

Traditional welding machines have a fairly low price, easy working capacity, but a very significant drawback is not only their weight, but also dependence on the voltage. Entering an electronic counter is limited with a capacity of 4 to 5 kW. For thick metal welding, the machine consumes significant power and often work becomes impossible. Inverter welding machines came to replace them.

Appointment and features of functioning

It is used for welding work at home, as well as in enterprises, it is boring a stable burning and maintaining a welding arc using a high frequency current (different from 50 Hz).

Welding inverter It is an ordinary impulse power supply, whose work is based on the following principles:

1. Input voltage (network power supply of the welding inverter unit 220 V alternating current) is converted to constant.
2. Permanent current is transformed into a high-frequency variable.
3. There is a voltage conversion process by reducing it.
4. Stopping current and conversion for welding with frequency saving.

Due to these moments, the mass and dimensions of the device occurs. In order to collect inverter welding with their own hands, it is necessary to know the principle of operation of this device.

Principle of operation of equipment

In previous models, the main element was a huge powerful power transformer, which allows to obtain powerful currents in the secondary winding required for welding. To obtain this strength of the current, it is necessary to use a large diameter wire, which affects the weight of the welding machine.

In the invention of the pulsed power supply, solve the problem with mass and dimensions was simpler, because the size and weight of the transformer itself decreases in several tens or hundreds of times. For example, with an increase in frequency, 6 times can be reduced dimensions transformerand 3 times. This leads to a significant savings of the material.

Due to the powerful key transistors used in the inverter scheme, switching with a frequency of 50 to 80 kHz. These transistors operate only from constant voltage.

As is known from the course of physics, the simplest semiconductor device is used to obtain a constant voltage - a diode. The diode passes the current in one direction, cutting off the negative values \u200b\u200bof the sinusoidal voltage. But the use of one diode leads to great losses, therefore a group consisting of powerful diodes is used, which is called a diode bridge.

At the outlet of the diode bridge, a constant pulsating voltage is obtained. A condenser filter is applied to obtain a normal constant voltage. After these transformations at the output of the filter, a DC voltage of Over 220 V. appears

A block consisting of a rectifier bridge and filtering elements is called a power supply (BP).

BP serves as a power source of the inverter scheme. Transistors are connected to a decrease in transformer, which is a pulse and operates at frequencies in the range from 50 to 90 kHz. The power of such a transformer is approximately the same as its huge fellow - welding power transformer.

Modernization of such an appliance It becomes easier, because due to its size and mass, additional possibilities appear to increase the stability of the welding machine.

There is a huge amount of manufacture of self-made welding inverters, the schemes of which are varied by functionality and installation methods. We will analyze each of the homemade models in detail.

Making a resonant inverter

As a basis, you must use the power supply of the AT form-factor computer, from which the cooler and radiators will be required. Details are taken from the elementary base of monitors and televisions, in otherwiseIf they are not, then bought on the market. All components have a low cost.

After that, it is necessary to determine the parameters of inverter welding with your own hands. And it is also possible to use such characteristics:

Equipment scheme

The main part is the specifying generator assembled on the SG3524 chip, which is used in all uninterruptible power sources. The inverter has a low power consumption of about 2.5 kW, due to which it is possible to use in the apartment.

Transformer must collect nand E42 type cores, which is used in old lamp monitors. For the manufacture, approximately 5 pieces of such transformers are necessary.

Another transformer should be used for choke. The remaining elements of inductance are collected from the 2000 NM core. Diodes and transistors must be installed on radiators with a thermal pump CTP 8 or another type. The idling voltage is approximately 36 V with a long arc from 4 to 5 mm, which allows you to work with it novice builders. The output cables should be put in ferrite tubes or rings from the Ferrite Power Block.

A constructive feature of the scheme is the occurrence of maximum current in the I winding during the resonance.

Scheme 1 - Scheme of the welding resonance inverter

Thanks to low weight and dimensions, it is possible to upgrade the device.

Preventing the ships of the electrode

For this incident, the IRF510 transistor is used, which are field. In addition, it provides another smooth start and interruption of the entrance to the SG3524 chip:

1. At high temperature, the thermal sensor is triggered.
2. Disconnection using a toggle.
3. Blocking with KZ (short circuit).

Simple welding device

This model is designed for voltage 220 V and a current of 32a, after conversion, its value will reach 280a. Such a value is quite enough for a solid seam at a distance of 1.5 centimeters.

Scheme and components

The main element is a transformer, which is hard enough to do, but quite real.

Basic data:

1. It consists of a ferrite core (7 × 7 or 8 × 8).
2. The primary winding is approximately 100 turns and its diameter of 0.3 mm.
3. Secondary windings - 3 pieces: 15 turns and wire diameter 1 mm; 15 turns - 0.2 mm; 20 turns - 0.35 mm.
4. Materials for the transformer: Copper wires of the appropriate diameter, fiberglass, textolite, electrical steel (for Zheleznyak), cotton material.

For a clear understanding of the principle of operation, it is necessary to carefully examine the scheme of the main nodes.

Figure 1 - Structural diagram of inverter welding machine

Explanation to the scheme:

Power supply and power unit

A block consisting of a transformer, rectifier and filter (or filter systems) is performed separately from the power part.

Scheme 2 - principal scheme BP

Conductors (no more than 15 cm long) To control transistors, it is necessary to be soldered closer to the latter, and the conductors are connected in pairs to each other, the cross section does not play them.

The basis of the power unit is a lowering transformer with a core sh20 × 208 2000 nm, and the II winding is wound in several layers of the wire, which is not damaged. On the secondary, it is necessary to wind as follows, insulating layers: 3 layers, and then laying-fluoroplastic, then again 3 layers and again gasket-fluoroplastic. This is done to increase rescue overloads. After that, on the II winding, put the condenser at least 1000 V.

To ensure air circulation between the windings layers, a current transformer connected to a plus on the ferrite core is necessary, and its core should be copied to the thermal paper (cash register). Rectifying diodes to attach to the radiator.

Scheme 3 - power part of the inverter

Inverter block and cooling

The main purpose of the inverter block is the process of converting a constant to variable high-frequency current. Used for this powerful transistors, although in some cases it is possible to replace more powerful on 2 or more medium power transistors.

An important element of the entire device is quite good cooling. To do this, use a cooler with computer equipment, but one should not be limited to one, because it is necessary to ensure sufficient cooling for the power scheme, the radiators of which serve to remove heat, but this heat must be dispelled. To complete protection, you need to build a thermal sensor (installed on the heating element), thanks to which power will be opened.

Soldering, configuration and performance testing

The key factor is soldering, because with the proper placement of parts depends the size of the entire product and the possibility of optimal cooling. Diodes and transistors are installed in the oncoming direction to each other. The input circuit is calculated with a reserve, about 300 V.

Need to configure operation Connect the pulse modulator to 15 V for the cooler. The relay turns on together with the R11 resistor and should produce 150mA.

After the manipulations performed, it is necessary to proceed directly to check the performance of the device:

If this scheme seemed very difficult, then consider the scheme of a simple device.

The simplest inverter welding device

The model of this unit is very simple and budget. It is easy to assemble it thanks to a simple concept.

The process of all assembly can be divided into steps, in addition, it is necessary to collect all the details, materials:

Scheme 4 - diagram of the simplest welding inverter with their own hands

After assembling the device, you must configure and diagnose when you first start to identify work errors.

Setting inverter:

Thus, you can collect an inverter for welding and with your own hands. Optionally use complex schemes, because radio amateurs found the optimal solution in budget variant. And the level of complexity of the schemes varies from sufficiently complex to simple. To assemble the welding inverter with their own hands, it is not necessary to buy expensive parts, and you can use the remedies.

Make a homemade welding inverter is easy, especially if you are brought with electronics. The main thing is that you have free time (5-6 hours) and the desire to fulfill this work. This unit is useful to all owners. Welding inverters are new modern welding machines that go to the fore.

On the market you can find a lot different species Inverters. But the device made independently can get better and will cost cheaper than buying a new apparatus.

Some information about welding machines

It is now very difficult to imagine some kind of construction for which welding would not need. Different voltages are used for this work. Depending on it, welding machines are divided into two groups: DC apparatus and variable. On constant current is allowed to be allowed to cook electrically operated coating and electrodes. To make a burning arc on small currents, it is necessary to have an increased stroke voltage on the winding up to 70 V. The DC welding machine is better in use, it is used for thin-leaf metals, especially for automotive and roofing steel. The welding arc is stable at this stage, therefore welding goes on the line, and on the reverse polarity of the voltage, which is served.

What is the welding machine? The main composition of the welding device includes:

• transformer - Main Detail;
• primary and secondary coil;
• case for welding machine;
• fans;
• stationery or metro station from the cash register;
• copper strip;
• copper tape.

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How to make a homemade welding machine

The most important part in the work on the inverter is the scheme. The manufacture of a welding device is beginning with a selection of a transformer, which is wound up the copper strip of the tin (length 40 mm, thickness is 0.3 mm). You still need a thermal stroke, which is suitable for stationery or motok from the cash register. It should be durable and when winding does not break. Thick wire do not wake up, because This device will operate at high frequencies, which will lead to overheating of the transformer.

So that this does not happen, take a copper tape - it will be the second winding of three copper strips. They will be separated by fluoroplastic layer. For the second winding, take the paper, as at first. True, the paper will darken, but it will not lose properties from the color. Do not forget to put the fan in the transformer so that the winding is not heated and cooled. You can take a cooler from your computer to 220 V and 0.15 A. The scheme will help you understand the essence.

Next, continue the manufacture of the inverter based on your scheme. The next step should be a cooling system that protects the welding machine from overheating. Get it better from a computer processor. A total of 6 such fans will be required, 3 of them should be directed towards the engine winding. Do not forget to establish air fences opposite the coolers.

After that you need to install a power oblique bridge. It will be on two radiators. The top edge of the bridge will be on one side, and the bottom should be attached through the gasket to another bridge. Diodes need to withdraw and place towards transistors. To reduce emissions, capacitors should be soldered on the fee (14 pieces of 0.15 MK and 630 V), you need to distribute them to the entire supply line.

In order for the splashes to be intensified, and the loss of IGBT became the smallest, in the chain it is worth inserting supply supplies, which contains C15 capacitors, C16. IGBT opens rather, and the opposite process is longer in time. And at this point, C15 and C16 will start getting a charge through a diode that was installed. All this is done so that Snabber takes over and reduced heat consumption of 4-5 times.

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How to connect a welding inverter with your own hands

Make this device is not as hard as it is how to configure it. It will take longer. A serial connection scheme will help:

1. You should connect the welding inverter to the power grid. You will hear loud sounds, this unit will start passing the current. Electricity is fed to the fan, so that the welding machine works quieter and the heating decreases.
2. Next should be closed the resistor. To do this, after charging capacitors you need to connect the relay. Racing current when turned on decrease.
3. Please note that the transformer cannot be connected without resistor items, as an explosion may occur. To find out the level of the welding machine, you need to turn on the device on the ammeter mode, the incoming pulses must be equal to 44%.
4. Using an amplifier and optter, which transmit a signal to block, you can check the welding itself. The amplitude should be equal to 15 V.
5. With the help of an oscilloscope, you can check the operation of the welding machine. If the impulses that will come from different windings will be the same, then the operation of the inverter is performed correctly.
6. In the end, you need to check the inverter transformer running capacitors. To do this, increase the pass level up to 200 W, connect the oscilloscope and watch the sound signals that will be published by the emitter collector.

Inverter welding quickly entered the working sphere of mobile brigades and individual professionals that perform call orders. The presence of such a welding machine is useful and to each owner in the garage or private house. Compact sizes of the device, low weight and high weld quality indicators, it is beneficial to highlight it against the background of large transformers. Unfortunately, the store price allows not to all become the owner of this equipment. But for those who know how to work with their own hands, there is a homemade welding inverter. What instruments and materials will be needed to create it? How to collect basic nodes? What is included in the maintenance and repair of the self-made device?

Solving the Create Machine from handling parts, affordable, and suitable for welding at home or on small orders, you should recognize the reality of the result. Homemade inverter welding machine significantly loses in appearance Before store analogues. For a solid private entrepreneur specializing in the wiring of heating, installation of fences, metal doors and other services, such an aggregate will not look authoritative.

But a simple welding inverter is perfect for personal needs in a private house, or work in the garage. Such an apparatus will be able to consume 220V from the network, transform them in 30V, and increase strength to 200a. This is enough for operation with electrodes with a diameter of 3 and 4 mm. The quality of the seam will be better than the cumbersome transformer, since the alternating current is converted to a constant one, and then back to the variable, but with a high frequency.

Such inverters will rise to welding the fence, gates, their own heating, doors. It is convenient to transfer it, and even cook with him, hanging on the shoulder. If the newcomer will be hard to train, watch the video and try in practice to put the seams, then the welding of fine steel sheets will be possible. Subsequently, it is possible to improve the schemes of welding inverters, with their own hands adding a wire feed mechanism in them, drum mounting and gas valve to turn out to be semi-automatic. Alteration is possible under argon welding.

Required details and tools

To create an inverter welding machine, do not do without a hike to the store or market. Collect it absolutely free of charge, from items in the garage, it is impossible. But the final cost will be three times cheaper than buying finished products. In welders and their creation apply:

• screwdriver Set;
• passatia;
• soldering iron, for the manufacture of electric boards;
• drill, for holes for switches and ventilation;
• hacksaw;
• sheet metal under the case;
• bolts and screws;
• devices and buttons on the panel;
• capacitors, transistors and diodes;
• copper tire for winding;
• wires for connecting all nodes;
• elements for the core;
• insulating paper and tape;
• power and working cables.

Before you begin to create a welding inverter with your own hands, the diagram of which should already be printed on paper, it is worth a few videos from specialists about step-by-step assembly. This will help see clearly with what will have to face, and compare the result. The following is a phased instruction on how to make a welding inverter with your own hands. Some deviations and variations are allowed, depending on which power the device is necessary at the output, and which technicians are available.

Transformer

The electrical component of the inverter begins with a transformer. It is responsible for lowering the voltage to the working level, safe for life, and increasing the strength of the current, up to magnitude capable of melting the metal. First of all, you need to choose the material for the core. It can be factory standard plates or homemade carcass from sheet iron. The video in the network helps to see the main principle of this design, regardless of the options used.

Welding transformers are better to wind from the copper tire, since optimal characteristics are a sufficient width and a small cross section. Such parameters will allow you to use all physical resources of the material. But if there is no such bus, you can use the wire of another section. All this affects the degree of heat heating during operation.

The transformer wines manually and consists of two parts: primary and secondary windings. For the inverter with your own hands:

• Ferrite 7 x 7. The primary winding is created from the wires of the PEV 0.3 mm, which wound smoothly, the turn to the turn, 100 revolutions.
• The next layer is an insulating paper. Suitable ribbon from the cash register or fiberglass. The first very darkens when heated, but retains its properties.
• The secondary winding is applied to several levels. The first is the PEV 1.0 mm in 15 revolutions. Since there are few turns, they should be distributed across the entire width uniformly. They are covered with varnish and paper layer.
• The second level consists of 0.2 mm PEV in 15 revolutions, followed by insulation similar to the previous layers.
• The final level is made of PEV 0.35 in 20 revolutions. Isolate layers can also be a masterpiest ribbon.

Housing

When the chief element of the inverter is created with their own hands, you can make the manufacture of the case. You can navigate on the transformer width so that it is freely placed inside. From its size it is worth calculating another 70% of the required space for the rest of the details. The protective cover can be collected from the sheet of steel 0.5 - 1.0 mm. Corners can be combined with welding, bolts, or make one-piece side on a bending machine (which will require additional expenses). It will take to provide a handle or mount under the belt to transfer the inverter.

Creating a case should provide easy disassembly and access to the main elements in case of repair. It is necessary to make holes on the front side:

• current strength switches;
• power button;
• light diodes that signal on the inclusion;
• connectors under the cable.

Store welding inverters are painted with powder coating. In the home industry is suitable for ordinary paint. Traditional colors for welding machines are red, orange and blue.

Cooling

In the housing you need to drill enough holes for ventilation. It is desirable that they are in opposite sides opposite each other. You need a fan. They can be a cooler from the old computer. It is necessary to install it with the work on the hood of hot air. The influx of cold is made through the holes. Place the cooler is as close as possible to the transformer - the hottest element of the device.

TCA transformation

The scheme of the welding inverter necessarily includes a diode bridge. It is responsible for changing the voltage into constant. Soldering of diodes is carried out according to the scheme of "oblique bridge". These elements are also susceptible to heating, so they should be attached to radiators that are available in old system blocks. For their search, you can contact the repair shops on computers.

Two radiator are placed at the edges of the diode bridge. Between them and diodes it is necessary to install gaskets from thermoplastic or other insulator. Conclusions are sent to the contact wires of transistors, which are responsible for returning the current to the variable, but with an increased frequency. The wires connected together must have a length of 150 mm. The transformer and the diode bridge is recommended to divide the inner partition.

In the inverter scheme necessarily the presence of capacitors, with a serial connection. They are responsible for reducing the transformer resonance and minimizing the losses in the transistors. The latter open quickly, and close slowly. At the same time, current losses appear that condensers compensate.

Assembly and manual

After creating all components, you can go to the assembly. The base is attached to the transformer, the diode bridge, the electronic control circuit. There is a connection of all wires. On the outer panel are fixed:

• resistor switches;
• power button;
• light indicators;
• Shim controller;
• connectors under the cable.

Holder and clamp for mass is better to buy ready, because they are safer and comfortable. But it is possible to make a holder and independently, from steel wire with a diameter of 6 mm. When all the items are installed and connected, you can proceed to check the machine. The initial voltage is measured. At 15V it should not show above 100a. The oscilloscope is tested by a diode bridge. After, there is a temporary suitability for work, by tracking heating radiators.

Repair with your own hands

For long and uninterrupted operation, the inverter is important to maintain correctly. To do this, once every two months perform purge from dust, after removing the casing. If the device stopped working, you can independently repair, looking at the video in the network of the main breakdowns and removal methods.

What is checked first:

• Inlet voltage. If it is missing or not enough, then the device will not work.
• Circuit breakers. When jumping, protective elements are burned or shutdown with automatt.
• Temperature sensor. When damaged, blocks the operation of subsequent nodes.
• Contact terminals and soldering connections. The chain rupture stops the flow of current and workflows.

After studying the schemes of ordinary inverters, and acquiring the necessary parts, as well as viewing the training video, you can collect a high-quality welding machine, which is very useful to a good owner.

Make an inverter independently, even in the absence of deep knowledge in the field of electrical engineering, electronics. For this, just need to disassemble the principle of operation of a similar device, to clearly adhere to the finished scheme. If you do the manufacture of a self-made welding machine, which almost will not give up technical characteristics Factory analogue, you can save very well.

It should not be doubted that the welding unit made independently will work effectively. The device collected by the simplest scheme will allow the cooler with electrodes 3.0-5.0 mm, with a length of an arc - 1 cm.

1. An unnecessary computer unit can be the installation housing.
2. The equipment of the welding inverter is neoriginal, with their own hands, resembles most of the other homemade structures. Many elements can be replaced with analogs. In the presence of basic design details, you can calculate the optimal parameters of the case and start its manufacture.
3. Finished radiators from old devices, for example, PC power units are suitable. But they can be made independently, if there is an aluminum tire at hand, the thickness of which is from 2 to 4 mm, and the width is more than 3 cm. You can use a fan from a old device.
4. All parts of large sizes are advised to initially decompose on the plane so that it can be clearly defined to determine the capabilities of the connection according to the scheme.
5. Next you need to decide on the place under the fan. It should not drive a hot air flow from some elements of the device to another. If there are difficulties in this situation, then you can use multiple fans at the same time that will work on the hood. The price of coolers, their mass is insignificant, but the reliability of the unit will generally increase significantly.

https://youtu.be/mwk1co6dela

6. The main elements of the design of the self-made welding semi-automatic agent, which differ in large dimensions and mass is a throttle and a transformer. It is recommended to place them along the edges (symmetrically each other) or in the center. That is, their mass should not drag the device into one of the sides. For example, working with the installation suspended on the belt over the shoulder of the welder is quite uncomfortable when it will constantly slide in one direction.
7. After all the details from the welding inverter are placed in its place, it is necessary to determine the bottom parameters for the unit, cut out of the girlfriend, which must be non-electrically conductive. Most often for these purposes, glass is a glassist, getinax. If this material is not, then the usual wood is suitable, previously treated with moisture-resistant, fire solutions. The extreme option is even distinguished by some advantages.
8. Comprehensive fasteners are usually screws, which simplifies, hesitate to assemble the product.

Homemade welding: Materials for the manufacture, main characteristics

After assembling a semi-automatic welding inverter according to a standard simple electrical circuit, you will become the owner of an effective installation with the following operational characteristics:

• voltage - 220V;
• the current at the entrance is 32A, at the output - 250a.

The scheme of welding equipment with such technical indicators includes the following details:

• power Supply;
• power unit;
• drivers of power keys.

Before collecting the homemade welding machine, it is recommended to prepare all components according to the scheme, the tool for the assembly. For such a homemade, you will need:

• screwdriver kit;
• hoven for metal;
• wire, copper strips;
• soldering iron for connecting electronic circuit parts;
• metal sheet of small thickness:
• threaded components of fasteners;
• components for the formation of electronic circuits;
• textolite;
• thermobum;
• mica;
• fiberglass.

For use at home, inverters are more often manufactured, which function from standard power grid (220V). If there is a need, you can also assemble the device that will function from the three-phase power grid (380V). Inverters of this type are characterized by their own advantages, one of which can be denoted a rather high efficiency in contrast to single-phase products.

Winding transformer

To wind the transformer, you need a strip of copper: thickness - 0.3 mm, width - 40 mm. Copper wire is suitable for high heating. The thermal population can be made of paper used for cash registers, or a photocopy. But the second option is worse, the paper is not strong enough, it can break.

Lacoccal - optimal available insulation material, it is advisable to use a minimum layer. For electrical safety, the device can be placed in the winding of the plate from the textolite. Voltage depending on the quality of the insulation between the windings. The length of the paper strips should be enough for the full overlap of the perimeter of the winding and should still be a reserve - minimum 2 cm.

It is forbidden to use thick wire, since the operation of the inverter welding machine is based on high-frequency currents. If you take such a wire, then its core will not be used when working. As a result, transformer overheating can occur.

In order to prevent such an effect, it is recommended to take the conductor of the minimum thickness, larger area. The surface of this type does not overheat, is an effective conductor.

When performing the secondary winding, it is recommended to use 3 copper strips separated by a fluoroplastic plate. And the thermal layer from the paper cash register is performed again. The lack of this paper - darkens after heating, but remains strong on the gap.

Instead of copper strips, it is also possible to use a wire PEV - a diameter of not more than 0.7 mm. Such a wire has a large number of lived - this is its main advantage. But a similar winding option is much worse than copper, the wires of this type have significant air buses, which is why they are blocked.

When using the PEV, the semi-automatic design of the inverter has four windings (used by a diameter with a diameter - 0.3 mm):

• primary winding - 100 turns;
• 1st secondary winding - 15 turns;
• 2nd secondary winding - 15 turns;
• 3rd secondary winding - 20 turns.

Be sure to require a fan cooling of the transformer and the entire structure. For these purposes, the cooler of the system unit (220V, 0.15a) is perfect.

Cooling

The power components of the self-made welding inverter scheme made by their own, are significantly heated. This can promote fast breakdown. To prevent their overheating, except for cooling radiators for blocks, you need to additionally install fans.

If there is a high power fan, you can only do it. In this case, the flow of cold air needs to be directed to the power transformer. When using low power fans, for example, from old PCs, they need about six, three of which will cool the transformer.


Also, in order to prevent overheating of the welding machine with your own hands, it is recommended to install a temperature sensor on the most heated radiator, which, when the maximum allowable temperature is reached, will give a signal to automatic shutdown.

For the effective operation of the ventilation system in the welding unit housing, it is necessary to properly install air intakes, the lattices of which should not be blocked.

Setting

The homemade welding inverter is easy to assemble, and there are no significant investments for this. But to configure it without attracting a specialist is problematic. How to make and configure homemade inverter yourself?

Instruction

1. It is necessary to submit voltage before the welding unit fee. The block will publish a characteristic squeak. The network voltage also needs to be applied to the cooling fan, which will not allow the overheating of the parts, and the unit will be more stable.
2. When the power capacitors received sufficient charge, it is necessary to close the current-limiting resistor (the operation of the relay is checked, there must be zero voltage on the resistor).

It is important - if the welding is connected without a current-limiting resistor, an explosion is possible!

1. The use of a similar type of resistor significantly reduces current jumps at the time of welding to the 220V network.
2. Our tool produces current more than 100A. This parameter depends on the specifically used scheme, and it is possible to calculate it using an oscilloscope.
3. Check the welding mode on the control unit of the homemade plasma view. To do this, be connected to the output of the voltmeter optter. For minor power devices, the average amplitude voltage should be about 15V.
4. Next, you need to check the output bridge on the correctness of its assembly. For this, it is fed from a suitable power supply unit 16V to the input of the unit. The block at idle consumes the current of the order of 100 mA, which is worth considering when performing control measurements.
5. The work of its homemade inverter can be compared with the work of industrial. On both windings, the oscilloscope is measured by compliance with each other pulses.
6. Next you need to check the work. It is necessary to change the voltage from 16V to 220V, connecting the inverter directly to the power grid. With the oscilloscope, connected to the output transistors, we observe the signal form, its compliance with the minimum voltage.

Inverter for welding is a fairly popular unit in any field of activity: at work, at home. And thanks to the use of the built-in regulator, the current rectifier welding unit of an inverter type will make it possible to achieve the most effective welding results if compared with the results of similar works using standard welding units on which transformers made of electrotechnical steel are installed.

Output

Build homemade does not represent a special complexity. If there is no sufficient experience for this, you can always contact the specialists for additional advice. But as a result, you can collect an aggregate with additional features that are deprived of factory analogues, and significantly save money.

The characteristics of most budget inverters cannot be called outstanding, at the same time few people refuse to enjoy using equipment with a significant margin of reliability. Meanwhile, there are many ways to improve inexpensive welding inverter.

Typical scheme and principle of inverter

The more expensive the welding inverter, the greater its scheme of auxiliary nodes involved in the implementation of special functions. But the diagram of the power converter itself remains almost unchanged even in expensive equipment. The stages of the transformation of the power current into the welding fairly easy to trace - on each of the main nodes of the circuit, a certain part of the general process occurs.

From a network cable through a protective switch, the voltage is supplied to the rectifier diode bridge, conjugate with high tank filters. In the diagram, this site is easy to see, there are impressive electrolytic capacitors in the size of "banks". At the rectifier, the task is one - "deploy" a negative part of the sinusoids symmetrically up, the capacitors are smoothed the pulsation, leading the direction of current to almost clean "constant".

Welding Inverter Scheme

Further, according to the scheme, the inverter is directly located. This part is also easily identified, here is the largest aluminum radiator. The inverter is built on several high-frequency field transistors or IGBT transistors. Quite often, several power elements are combined in a common case. The inverter again converts a constant current into a variable, but its frequency is significantly higher - about 50 kHz. Such a chain of transformations allows the use of a high-frequency transformer, which is several times less and easier than usual.

With a downstream transformer, the voltage removes the output rectifier, because we want to welding at a constant current. Thanks to the output filter, the nature of the current changes with a high-frequency pulsating to a practically straight line. Naturally, in the considered circuit of transformations there are many intermediate links: sensors, control and control circuits, but their consideration is far beyond the framework of amateur radio electronics.

Design of the welding inverter: 1 - filter condensers; 2 - rectifier (diode assembly); 3 - IGBT transistors; 4 - fan; 5 - lowering transformer; 6 - control board; 7 - radiators; 8 - choke

Modernization nodes

The most important parameter of any welding machine is a volt-ampere characteristic (WA), due to it and the stable burning of the arc is ensured at different lengths. The correct WAY is created by microprocessor control: a small "brain" of the inverter on the go changes the mode of operation of power keys and instantly adjusts the parameters of the welding current. Unfortunately, it is impossible to reprogram the budget inverter in any way - control chips in it are analog, and the replacement for digital electronics requires an outstanding knowledge of circuitry.

However, the "skills" of the control circuit is enough to level the "crucial" of the novice welder, who has not yet learned steadily to keep the arc. It is much more correct to focus on eliminating some "children's" diseases, the first of which is a strong overheating of electronic components leading to degradation and destruction of power keys.

The second problem is the use of radio elements of doubtful reliability. The elimination of this shortcoming strongly reduces the likelihood of damage after 2-3 years of operation of the device. Finally, even a novice radio engineering will be fully able to implement the indication of the actual welding current to be able to work with special brands of the electrodes, as well as to hold a number of other small modifications.

Improved heat sink

The first disadvantage that the overwhelming majority of inexpensive inverter devices are sinned - a bad heat removal scheme with strength keys and rectifier diodes. Start refinement in this direction is better with an increase in the intensity of forced blowing. As a rule, in the welding machines, body fans are installed with a service chain of 12 V. in "Compact" models, forced air cooling may not be available that for electrical engineering of this class is definitely nonsense.

It is enough to simply increase the air flow by installing several such fans sequentially. The problem is that the "native" cooler is most likely to take off. To work effectively in consistent assembly, the fans must have an identical shape and the number of blades, as well as the speed of rotation. It is extremely simple to collect the same coolers in the "stack", it is enough to pull their pair of long bolts along diametrically opposing angular holes. It is also not necessary to worry about the power of the service source, as a rule, it is enough to install 3-4 fans.

If inside the inverter case is not enough to install the fans, you can adjust one high-performance "duct" outside. Its installation is easier for the reason that no connection to the internal circuits is required, the power is removed from the power button terminals. The fan, of course, should be installed opposite the ventilation luses, part of which can be cut to reduce aerodynamic resistance. The optimal direction of air flow - on the housing exhaust.

The second way to improve the heat sink is the replacement of regular aluminum radiators to more productive. New radiator need to choose from the greatest number As much thin ribers as possible, that is, with the largest contact area with air. Optimally, for this purpose, use radiators cooling computer CPUs. The process of replacing radiators is quite simple, it suffices to follow a few simple rules:

1. If the regular radiator is isolated from the flanges of radio-elements with mica or rubber gaskets, they need to be saved when replacing.
2. To improve thermal contact, you need to use a silicone thermal path.
3. If the radiator needs to be cut to fit into the housing, the cropped ribs must be carefully treated with supfil to remove all burrs, otherwise they will be abundantly tremendous dust.
4. The radiator should be tightly pressed to chips, so it is necessary to place and drill the fastening holes on it, it may be necessary to cut the thread in the body of the aluminum sole.

Additionally, we note that it makes no sense to change the piece radiators of separate keys, only heat sinks of integrated circuits or several high-power transistors installed in a row are subjected to replacement.

Indication of welding current

Even if the current setting indicator is installed on the inverter, it shows not a real value, but a certain service value scaled for visual display. The deviation from the actual current value can be up to 10%, which is unacceptable when using special brands of electrodes and working with thin parts. You can get the actual value of the welding current by installing an ammeter.

Within 1 thousand rubles, a digital ammeter of type SM3D will cost, it can even be safely embedded in the inverter body. The main problem is that for measuring such high currents requires connecting through the shunt. Its value is within 500-700 rubles for currents in 200-300 A. Please note that the shunt type must comply with the recommendations of the ammeter manufacturer, as a rule, is an insertion to 75 mV with its own resistance of about 250 μC for the measurement limit of 300 A.

You can install the shunt either on the positive or per minute terminal from the inside of the case. Usually, the sizes of the connective tire are sufficient to connect a length of about 12-14 cm. Bending the shunt is impossible, therefore if the length of the connective bus is not enough, it must be replaced with a copper plate, a pigtail of a purified single-rocker cable or a segment of welding core.

The ammeter is connected by measuring outputs to the opposite clips of the shunt. Also, a power supply voltage is required to operate the digital instrument in the range of 5-20 V. It can be removed from the wires of connecting the fans or to find on the point of the point with the potential for powering control microcircuits. The own consumption of the ammeter is negligible.

Increasing the duration of inclusion

The duration of inclusion in the context of welding inverters is more reasonable to call the load duration. This is the one of the ten-minute interval in which the inverter directly performs the work, the remaining time it should be idling and cool.

For most inexpensive inverters, the actual PN is 40-45% at 20 ° C. Replacing radiators and an intensive blowing device allow you to increase this indicator to 50-60%, but this is not a ceiling. To achieve Mon of the order of 70-75%, it is possible by replacing some radio elements:

1. Inverter keystrap capacitors need to be changed to the elements of the same capacity and type, but calculated under a higher voltage (600-700 V);
2. Diodes and resistors from the keys should be replaced with elements with a greater dispersion capacity.
3. Rectifiable diodes (valves), as well as MOSFET or IGBT transistors can be replaced by similar, but more reliable.

On the replacement of the power keys themselves should be told separately. To begin with, rewrite the markings on the element housing and find a detailed datential to a specific element. According to the passport information, select an element for replacement simply, the key parameters are the limits of the frequency range, the operating voltage, the presence of a built-in diode, the type of body and the limit current at 100 ° C. The latter is better to calculate itself (for high-voltage side, taking into account the losses on the transformer) and purchase radio elements with a limit reserve of about 20%. From manufacturers of this kind of electronics, International Rectifier (IR) or Stmicroelectronics is most reliable. Despite the fairly high price, it is extremely recommended to acquire details of these brands.

Winding output choke

One of the simplest and at the same time of the most useful additions for the welding inverter will be winding an inductive coil smoothing the DC pulsation, which inevitably remain when the pulse transformer is operational. The main specificity of such a venture is that the choke is manufactured individually for each individual apparatus, and can also be corrected with the degradation of electronic components or when the power threshold changes.

It will take all anything for the manufacture of choke: an isolated copper conductor with a cross section of up to 20 mm 2 and a core, preferably from ferrite. As a magnetic pipeline, it is optimally suitable or a ferrite ring or an armor transformer core. If the magnetic circuit is dialed from sheet steel, it must be drilled in two places with an indent of about 20-25 mm and pull the ripples to be able to unwarlier the clearance.

The choke begins to work, ranging from one full turn, but the real result is visible, starting with 4-5 turns. When testing, the turns should be added until the arc starts significantly stretching hard, interfere with the separation. When cooking with a margin will become difficult, you need to throw one round from the coil and connect parallel to the incandescent bulb in 24 V.

Thin adjustment of the throttle is performed using a plumbing screw clamp, which can be reduced clearance in the core, or a wooden wedge that this gap can be increased. It must be achieved that the burning of the lamp during the ignition of the arc was as bright as possible. It is recommended to make several chokes to work in the ranges up to 100 A, from 100 to 200 A and more than 200 A.

Conclusion

All "hinged" add-ons, such as choke or ammeter, is better to mount a separate console, which is included in the gap of any of the welding veins by means of a bayonet type plug. Thus, inside the inverter housing, there is enough space for ventilation, and additional devices can be easily disconnected as unnecessary.

It must be remembered that the cardinal, deep modernization will not work, in other words, the "rentant" in Kemppi is reasonable forces and means not to turn. However, the manufacture of devices and small refinement of equipment is a great way to better explore the technology of arc welding and penetrate professional subtleties.