Today, welding work is in demand both in assembly and in repair work. A job well done is always highly appreciated! Therefore, every home master simply needs welding equipment. And what is typical, it is not at all necessary to go to the nearest store to buy the installation. Almost every one of us is capable of implementing a circuit of a welding inverter machine with our own hands.
What is an inverter?
Welding inverter equipment is one of the types of modern devices that has almost completely replaced all other devices based on transformers, including various rectifiers, generators. Therefore, many people are starting to switch to a new type of equipment.
Typically, the first inverter models appeared in the late 70s, but they no longer have anything in common with modern devices. The only thing that has remained unchanged iscompact size and normal mains supply voltage (sometimes three-phase power can be used).
It is desirable to have such equipment for anyone who has a garage, or in his private household. And without welding in our time it is difficult to solve any problems in terms of repair, construction and other types of work. In addition, the inverter can be useful in some matters of car maintenance. Moreover, it is not necessary to have professional skills to work with it.
For clarity, below is a photo of the circuit of the Resanta 220 inverter welding machine.
But what is the actual principle of operation of such welding equipment? More on that later.
How an inverter works
Like any other welding device, the principle of operation here is based on the generation of a large current to initiate and maintain the welding arc. It occurs between the parts to be joined and the electrode, and the molten metal fills the cavity of the seam, due to which a strong connection is formed. And in the end it turns out to be monolithic.
Conventional electricity (220 Volt, 50 Hz) is not enough to create the necessary arc - both current and voltage must be converted. The source current enters the rectifier unit, where it is converted from alternating current to direct current and then sent to the inverter unit. This information is important, as it will allow you to repair the inverter welding machine with your own hands with skill.
Here's howonce in this place the most interesting begins - the current is again transformed into a variable form, but with a much higher frequency (tens of kilohertz). In devices created on industrial conditions, this is achieved thanks to high-frequency transistors and thyristors.
Then the current is supplied to the transformer to lower the voltage, by directly increasing the current strength. Next, a secondary rectifier is connected, which again makes the current constant. It is he who is fed to the welding electrode through a special cable. In addition, such devices have the ability to change polarity, due to which aluminum can be easily welded.
Technical equipment
Knowing how this invaluable piece of equipment works, we can now move on to consider the implementation of its scheme in practice. To understand how to repair an inverter welding machine with your own hands, familiarization with its technical parameters will help.
It should be noted that they will not be inferior to purchased devices:
- input voltage - 220 V;
- input current - 32 A;
- output current - 250 A;
- for work it is allowed to use electrodes with a diameter of 3-5 mm, a length of 10 mm;
- as for the efficiency of a homemade device, it will be no lower than that of professional devices.
The design of the device consists of the main components:
- power supply;
- power unit;
- power key drivers.
Required equipmentmay be of the following kind:
- screwdriver set;
- knife;
- hacksaw;
- sheet of metal of small thickness (to create a case);
- soldering iron;
- elements for the microcircuit, including copper wires and strips;
- threaded fasteners.
In addition, fiberglass, cash register thermal paper, textolite sheet, mica can be useful in repairing inverter welding machines with your own hands. For domestic needs, in most cases, single-phase welding equipment is used, which is capable of being powered by a 220 V network.
Power supply
When creating a power supply, it is important to pay attention to the transformer, because the stability of the supplied voltage will depend on this element. This element is wound on a ferrite with dimensions of 7 x 7 with the formation of 4 windings (primary - I and secondary - II):
- I (the number of turns is 100) - a PEV wire with a diameter of 0.3 mm is used.
- II first (number of turns 15) - the same wire is used, but a slightly larger diameter: 1 mm.
- II the second (number of turns 15) - and here the diameter is much smaller: already 0.2 mm.
- II third (the number of turns is 20) - the parameters are the same as when creating the primary winding.
Now regarding the implementation of the circuit of a simple inverter welding machine with your own hands. The primary winding must be done evenly over the entire width of the frame. As a result, voltage drops will not have a strong effect. After the formation of the primary winding is completed, it is necessary to carry outsurface insulation with fiberglass.
After that, a shield should be formed from the same wire as the creation of the primary winding. At the same time, its coils should cover the whole of it completely. These conditions must be observed when creating all other windings, and each layer must be insulated with fiberglass or masking tape.
As for the diodes, they must be installed according to the “oblique bridge” scheme. And since these elements will get very hot during the operation of home-made equipment, you should take care of their cooling. Cooling radiators from old computers are suitable for this.
In a pinch, you can find cheap options for the electrical circuit of the inverter welding machine at the computer parts store. The optimal and simple solution is the parts of a Pentium 4 or Athlon 64. Moreover, two heatsinks should be attached to the diode bridge: one to its upper part (through a mica gasket), and the other to its lower part (using thermal paste).
The diode leads must face the same direction as the transistor contacts, with the help of which the direct current is transformed into alternating current. The length of the wiring for connecting the terminals should not exceed 15 cm. In this case, both blocks (power supply and inverter) must be separated by a metal sheet, which in turn is welded to the device case.
Power block
Solving the problem of how to make a welding inverter machine with your own hands also consists of creatingthis node. And its main part is also a transformer, but already a step-down one. Its functional duties are to reduce the potential difference and at the same time increase the current strength. To create it, you will need a core W20 x 208 2000 nm in the amount of two pieces. The transformer is wrapped using a copper strip. Her dimensions:
- width - 40 mm;
- thickness 1/4 mm.
For thermal insulation, each layer must be covered with wear-resistant thermal paper. The secondary winding is created by three copper strips, which are insulated with PTFE tape.
The use of thick wire here is inappropriate and even erroneous. After all, the transformer will work with a high-frequency current, and therefore only the use of wide wiring is relevant.
Inverter
And, of course, how can this block be bypassed in the implementation of the circuit diagram of the inverter welding machine? Its task is to inversely convert the current of a constant nature into a variable form, while increasing its frequency.
The best option for assembling such a block would be to use transistors of medium and low power. In this case, you can simultaneously stabilize the frequency of the current and reduce the noise of the welding home-made equipment.
The circuit is complicated by capacitors connected in series. Such a measure will avoid resonant surges of the transformer and reduce the losses of the transistor unit.
Features of choosing transistors
To the choice of transistors (namely, soare called power keys) should be approached as competently as possible. The performance of the welding device will depend precisely on the fulfillment of this condition. To do this, the first step is to calculate the approximate power of the resulting inverter. Without this, it is unlikely that you will be able to understand how to assemble an inverter welding machine with your own hands.
For example, let it be a voltage of 24 V (the average value when the electric arc burns steadily) and you need to get an arc of 160 A. By multiplying these values by each other, we get the useful power that the inverter device will produce. In our case, this is 3.48 kW. With an efficiency of 85%, the transistors must pass through themselves this calculated power, multiplied by the efficiency. Ultimately, the value will be approximately 4.5 kW - this will be the desired value of the keys.
Since the welding equipment will use a regular household electrical network of 220 V, the current will be 20 A (4500 watts divided by 220). In this case, you should choose transistors that are able to withstand the current of this strength and not less than an ampere!
Cooling organization
As we know, the home-made inverter machine will get very hot during welding. And so much so that only cooling radiators will obviously not be enough, in this regard, you should take care of organizing a good cooling system. Otherwise, frequent repair of the inverter welding machine cannot be avoided. DIY Strat.
Overheating in itself is terrible because not only various electrical components fail - the device itself can become unusable. For this reason, in addition to heatsinks, fans should also be used.
There should be at least six low-power options from a computer (processor cooling). But to blow the step-down transformer, a powerful fan should be installed, which is also capable of cooling the entire system. The power transformer should also have several fans (at least 3 pieces).
To protect the welding equipment itself from overheating and in order to avoid its early failure, a temperature sensor should be fixed on the radiator (which heats up the most). Its main function is to turn off the power of the device when the maximum allowable temperature is exceeded.
Case
At the final stage of assembling an inverter-type welding machine with your own hands, you will need a good case, in which the equipment circuit itself will be located. For such a purpose, a system unit from an old computer is quite suitable, and the older it is, the better (the metal is thicker in it). Better than ATX. To do this, you can search in your own garage (shed) or visit computer disassembly points, they can probably offer some option there.
In a pinch, the body can easily be made from sheet metal. At the same time, a canister will do. Just make holes for ventilation and put additional fasteners. In this case, the circuit diagram of the inverter welding machine will be additionally protected from overheating.
Assembling the apparatus
Now the actual assembly procedure of welding equipment. Electronic boards are created using textolite 1 mm thick. To reduce the load on them, several small cuts are made. Finished windings of transformers are fixed on the basis of the unit using several brackets. In its quality, you can just take a getinax plate 5 mm thick or a little more. It should have a slot for a fan.
When installing magnetic circuits, they should be placed at a short distance so that gaps are formed (for air circulation). To ensure the stabilization of the current strength and potential difference, you should assemble an inverter welding machine with your own hands on tl494.
There can be many types of home-made structures, but regardless of this, they all have a common feature - the control of the operation of welding equipment. To do this, there is a switch, a knob that regulates the current strength, wire leads, and control LEDs on the front panel.
Setting step
When the inverter is assembled, you need to start setting it up. Do not underestimate the importance of this procedure, since this is a prerequisite and you should never use the device without it! To do this, you must perform certain operations.
First of all, it is worth submittinga small current value (15 V) to the PWM controller and fans. This will allow you to evaluate the he alth of the node. After the capacitors are charged, it is worth applying voltage to the relay that controls the operation of the resistor. But you can’t give current directly, otherwise the simplest inverter welding machine with your own hands can be simply ruined, and right away! But if everything is normal, you can start setting up the modulator, making sure that rectangular pulses appear when the relay is triggered.
The next step in the setup is to check the functionality of the board itself. For this, idling is set and a current of up to 100 mA is applied to the bridge. Such a seemingly trifling stage is actually very important, because it allows you to judge the performance of the diode bridge.
It is imperative to adjust the noise level of the transformer device noted on the phases. It is better that there are no extraneous sounds in the operation of the inverter on the phases. Otherwise, most likely, the polarity was violated - just change it. A similar noise test can be performed using any electrical household appliance. That is, a kettle with a power of at least 2.2 kW is suitable.
But it's not enough to make the simplest inverter welding machine with your own hands, you need to regularly diagnose the device, not forgetting about its maintenance. Because only with proper care and attitude, it can faithfully serve for many years.
Rulesusing the machine
Despite some simplicity, the inverter apparatus needs a responsible attitude towards its own person. Therefore, in order to avoid serious damage, as well as the failure of the device, you should follow simple rules during operation:
- Before work, you need to prepare free space - ideally, when there is a lot of it.
- It is worth considering that the inverter welding machine does not tolerate temperature extremes and weather conditions.
- Avoid dust accumulation as it is a good conductor. Industrial facilities deal with this with compressed air equipment.
- The choice of wires for the welding cable largely depends on the thickness of the electrode used. As a rule, for domestic use, their diameter is 3 mm, for which thin and light cables are suitable. At the same time, their length should be no more than 1.5 meters.
- Having put into practice the scheme of the inverter welding machine with your own hands, do not allow it to overheat! Intensive processes lead to strong heating of the electrical circuit parts. Burnt out elements are a fairly common problem. On average, it is worth spending 5 to 6 minutes on continuous work, which is quite enough.
- Immediately before work it is necessary to check all wire connections in order to avoid interruption of the current supply.
At the same time, one should not forget about basic safety precautions! That is, you need to work in special, non-flammable clothing and gloves, including the use of a shield.
And if trouble does occur, the main thing is to fix the problem in time. About what main breakdowns can occur and how to fix them - in the next section.
Main malfunctions of inverter equipment
After a homemade device has been tested, one should not forget that it can break down, as well as any electrical device. The determination of the causes of the breakdown should begin with an external examination. If a bad contact is found, they should be disconnected, cleaned well, and then reconnected.
Now it's worth considering how to repair an inverter welding machine with your own hands with the most common malfunctions:
- Too much power consumption when there is no load at all. Most likely there was a short circuit. In this case, it is necessary to rewind and improve the insulation of the layers.
- The welding arc falls, and often. With a greater degree of probability, this indicates a breakdown of the winding, due to which an overvoltage is observed in the circuit.
- Wrong adjustment of the welding current. There may be a short circuit of the clamps, a choke coil, or a failure of the screw that regulates the current.
- Lack of current. This means that the voltage has dropped in the network - it is necessary to check the he alth of the regulator.
- The transformer makes a lot of noise. Often this is a sign of overheating of the unit. In this case, you should check the fasteners that tighten the parts of the magnetic circuit, including the movement mechanisms and the corecoils. A short circuit in the welding wires cannot be ruled out.
- The device turns itself off. Most likely, the reason lies in the short circuit of the electrical circuit, which led to the auto-shutdown.
In addition, after creating a do-it-yourself inverter welding machine circuit, one nuance should be taken into account. Even such a homemade model has a weak point. And this is the terminal block that connects the welding cable.
As a conclusion
In conclusion, I would like to note a number of positive and negative sides of home-made inverter-type devices. And the most important advantage is the ability to use welding equipment not only at home, but also in small-scale production.
At first glance, it seems that the design is filled with many different details, and the circuit itself is quite difficult to implement. However, if you follow the instructions, use only high-quality materials, then everything becomes not so painful. In addition, you can achieve long-term performance at low cost.
As for the disadvantages, there is only one main one - a short service life with large amounts of work. Then you have to make a three-phase welder, only the power source for this type is difficult to find.
Ultimately, almost any home craftsman can implement a do-it-yourself inverter welding machine circuit. There would be a desire and free time. And the benefits of suchappliance will be essential!
