Certain repairs may require a welder. If you wish, you can do it yourself, and the quality of the work will be in no way inferior to a ready-made factory one. Of course, you can assemble a welding inverter yourself only if you have experience working with such equipment. If you do not have such experience, then it is not recommended to experiment; it is better to rent the device or hire a specialist.
When organizing welding work, it is imperative to observe caution and safety rules, since the welding process is potentially dangerous, as is the use of the welding equipment itself.
Winding the transformer
When a welding inverter is assembled, the transformer is wound first. In this case, the characteristics of the equipment will be:
- current consumption - 32 A;
- welding current - 250 A (may vary slightly);
- It is possible to weld with an arc length of 1 cm using electrodes 5.
The transformer is wound on ferrite, its type is Ш8*8 or 7*7. The primary winding is equal to 100 turns with a wire of 0.3 mm, the secondary winding is 15 screws, the wire has a cross-section of 1 mm.
- secondary from 0.2 mm wire - 15 turns;
- secondary winding with 0.35 mm wire - 20 turns (two windings).
It is necessary to wind the wire over the entire width of the future frame so that the voltage is stable.. The winding is made only of copper tin wire; it is usually used for cash registers; it is not difficult to obtain such tin. An ordinary thick wire cannot be used, as it will heat up, and the inverter cannot be used under such conditions. It must be remembered that during operation it is the wire that heats up, not the core, so you must choose it carefully. The transformer must be cooled by a fan; it is mounted inside the case (you can take a unit from an old computer).
Installation of the block: instructions
You can make a welding inverter if you have the necessary skills or experience. To cool the system, you can take old fan units from computers that are no longer working (they can be easily purchased, the cost of such units is low). HFA30 and HFA25 diodes are installed on radiators. If you have heat-conducting paste, you can treat the contacts with it. The terminals of installed diodes and transistors should be screwed in a position opposite each other. The board is mounted between two radiators and these terminals, a 300 V circuit and bridge elements are used for the connection.
Capacitors in the amount of 12 pieces of 630 V are soldered onto the board. They serve to ensure that emissions during operation of the transformer go to the supply circuit, while all resonant current emissions are completely eliminated.
The remaining elements must be firmly connected with conductors. The installation of so-called snubbers with capacitors of type C15/16 is used, which perform the following tasks:
- suppression of resonant current surges;
- Reduced IGBT loss during shutdown.
Setting up a welding inverter
It is quite possible to assemble, but this work is not for a beginner. After assembly, it is imperative to check the functionality of the structure. To do this, it is necessary to supply power equal to 15 V to the PWM. This voltage must be supplied to the fan so that the C6 discharge can be provided. This capacitance controls the response time of the relay installed on the inverter.
The relay is necessary to close resistor R11 (relay K1 is used for this) after the capacitors are fully charged. Charging is carried out through the resistor itself, while it reduces the likelihood of a current surge that occurs when the welding machine is connected to a 220 V electrical network. Starting current is characteristic of any equipment, so protection against it should be provided. If you do not use a resistor, then during switching on the inverter may simply burn out, all the work done before will be in vain.
Next you need to check how the relays operate. This occurs approximately 2-10 seconds after the PWM is initially powered up. The board itself is also checked; it should contain rectangular pulses that go to the HCPL3120 optocouplers after relays K1, K2 operate. In this case, the width of the pulses relative to the zero pause must be 44-66%.
On optocouplers, you should check the drivers to make sure that the IGBT voltage is 16 V, but not more. A voltage of 15 V is applied to the bridge to ensure that the bridge is operational. During the test, the current should not exceed 100 A, provided that the engine is idling. The next step is to check the phrasing of the power transformer. This is done using an oscilloscope.
If noise is observed during operation, then it is necessary to position the PWM board and drivers further from the source that is causing the interference.
All IGBT connections should be kept short, and the semiconductors that come from the PWM board should not be located far from sources of interference. To reduce their level, you also need to twist all the signal wires and make them shorter.
Next, you need to increase the welding current; for this, resistor R3 is used, located next to resistor R4. The welding output must be closed with the key of the lower IGBT. The operation of the PWM board will be indicated by an increase in the pulse width. The smaller the current, the smaller the pulse width will be.
Finishing work
If the welding inverter is ready, you need to check it in action. There should be no noise under any circumstances, otherwise the IGBTs may simply fail. It is necessary to monitor the oscilloscope as current is added so that the voltage does not exceed the lower specified key. The current should not be higher than 500 V; in the surge, the maximum value can be 550 V. Usually, with proper assembly, the readings fluctuate at 340 V. When the maximum “talking” width is reached, you need to stop.
Welding work can begin immediately after inspection. You can cook for the first 10 seconds, after which you check the radiators, the work continues. To test the equipment, it is better to use 2 long 4 mm welding electrodes at once. If the quality of work is normal and the seam meets the requirements, then the equipment can be used further, while observing safety precautions. Care must be taken to ensure that the transformer does not heat up too much. If this happens, then you need to wait until it cools down.
Making a welding inverter with your own hands is not so difficult, but to perform such work you must have the appropriate experience and skills. Before starting work, you should study the diagram, and then begin assembly. After installation, the device should be configured, operability and safety checked.
There are no Russian instructions. Under her guise, viruses and other evil spirits are downloaded from file hosting services.
There is a lot of information on this inverter on the Internet, but it is scattered and incomplete. I will describe the connection and setup process in detail.
IF marking.
Unscrew the two screws at the bottom of the front panel and remove the front cover. The inverter connection blocks are located there.
Connection blocks.
Lower power block.
R, S, T - inverter power connection. With three-phase power, phases are connected to all three contacts. Single-phase power is connected to any two of the listed three contacts.
P+, PR - a braking resistor is connected to these contacts. It is necessary to quickly stop the spindle. Its value can be found in the instructions for the inverter. For almost all inverters, the parameters of the braking resistors are the same. It is possible to deviate by 10-15% in the resistor parameters, but it is not recommended. In general, even without a resistor, the spindle stops perfectly with dynamic braking. You can wait a few seconds before stopping.
| Class voltage |
Power engine, kW |
Moment at full load, kg*m |
Characteristics resistors |
Brake moment at 10%ED |
| 220 V | 0.2 | 0.110 | 80W, 200 Ohm | 400 |
| 0.4 | 0.216 | 80W, 200 Ohm | 220 | |
| 0.75 | 0.427 | 80W, 200 Ohm | 125 | |
| 1.5 | 0.849 | 300W, 100 Ohm | 125 | |
| 2.2 | 1.265 | 300W, 70 Ohm | 125 | |
| 380 V | 0.4 | 0.216 | 80W, 750 Ohm | 230 |
| 0.75 | 0.427 | 80W, 750 Ohm | 125 | |
| 1.5 | 0.849 | 300W, 400 Ohm | 125 | |
| 2.2 | 1.265 | 300W, 250 Ohm | 125 | |
| 3.7 | 2.080 | 400W, 150 Ohm | 125 | |
| 5.5 | 3.111 | 500W, 100 Ohm | 125 | |
| 7.5 | 4.148 | 1000W, 75 Ohm | 125 | |
| 11 | 6.186 | 1000W, 50 Ohm | 125 | |
| 15 | 8.248 | 1500W, 40 Ohm | 125 | |
| 18.5 | 10.281 | 4800W, 32 Ohm | 125 | |
| 22 | 12.338 | 4800W, 27.2 Ohm | 125 | |
| 30 | 16.497 | 6000W, 20 Ohm | 125 | |
| 37 | 20.6 | 9600W, 16 Ohm | 125 | |
| 45 | 24.745 | 9600W, 13.6 Ohm | 125 | |
| 55 | 31.11 | 12000W, 10 Ohm | 100 | |
| 75 | 42.7 | 19200W, 6.8 Ohm | 110 | |
| 90 | 52.5 | 19200W, 6.8 Ohm | 100 |
U, V, W - the spindle is connected to these contacts. If the rotor rotates in the wrong direction, swap any two phases going to the spindle.
The shield of the spindle power cable is connected to pin 9.
We won't touch the top 2 pads for now.
Inclusion.
The power cable and spindle are connected. ATTENTION! If the inverter is not configured, the engine cannot be started. The engine will fail very quickly. On the Internet I saw data about 15-30 seconds.
To change the settings, press PRGM. Use the up and down keys to select the parameter number. Using the >> key you can select the digit of the parameter number to change. Then press the SET button and set the required value. Next, press SET to save the settings. End will appear on the screen. We check and, if necessary, set the following parameters.
PD001 - Source of start and stop commands. Value 0 - front panel of the inverter, 1 - control via the terminals of the multi-input block, 2 - RS485 port.
PD002 - Rotation speed source. Value 0 - front panel of the inverter, 1 - control via an external resistor or a resistor on the panel (if available), 2 - RS485 port.
PD003 - Current set frequency of the inverter. For the first run, set the value to 100.
PD004 - Base frequency - 400.
PD005 - Maximum permissible frequency - 400.
PD006 - Intermediate output frequency - 2.5
PD007 - Minimum frequency - 0.5.
PD009 - intermediate voltage - 15.
PD010 - minimum voltage limitation - 7.
PD011 - minimum frequency limitation - 100.
PD014 - engine acceleration time. To check, set it to 20 seconds. Setting a very short acceleration time is not recommended. The optimal time is 5-10 seconds.
PD015 - engine braking time. To check, set it to 20 seconds. It is not recommended to set a very short braking time, since during braking energy is recovered and the spindle begins to work as a generator. The instructions for a state of emergency of the same power, but from a different company, indicate that the generated voltage can reach 450 volts. Sharp braking can damage the drive. The optimal time depends on the load on the spindle and for light cutters is 4-7 seconds.
PD026 - braking mode. Value 0 - frequency reduction braking. 1 - freewheel braking. To check the spindle, I recommend setting the value to 1. When you press the STOP button, the voltage supply to the motor windings will immediately stop. It will start to stop on the coast and the operation of the bearings will be very clearly audible. When braking by reducing the frequency, the sound of the PWM carrier frequency is heard very strongly, which makes it difficult to hear the operation of the bearings.
PD041 - setting the PWM carrier frequency. A very interesting parameter, about which nothing is said on the forums. Can take values from 0 to 15.
| Meaning | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| Frequency kHz | 0,1 | 1 | 1,5 | 2 | 3 | 4 | 5 | 7 | 8 | 9 | 10 | 11 | 13 | 15 | 17 | 20 |
To correctly indicate speed on the front panel indicator, set:
PD143 - Number of motor poles - 2.
PD144 - Gear ratio - 3000.
Engine starting.
If you are sure that all the settings are correct, you can press the RUN button. You will hear the relay operating and the rotor will begin to accelerate to 6000 rpm. Listen for any extraneous sounds. If everything is fine, let the engine run for 3-5 minutes, monitor the engine heating and the presence of foreign odors (smoke, melted plastic), check the operating parameters by pressing the >> button. A00х.х - current in the motor windings, ххххх - number of revolutions, Uххх.х - voltage in the motor windings (more details are written in the inverter operating instructions on pages 15-16). Press the STOP button. If everything is good, press the up button and increase the frequency with the up and down buttons. The >> button changes the digit of the indicator that will be changed. Set the frequency to 200 Hz and press RUN. If everything is in order, without stopping the spindle, change the frequency to 400 Hz. Control sound and heat. Let the spindle run for about 10 minutes; it should not get very hot from the central part to the edges. If the heating is significantly higher at one of the edges than in the center, then the bearings are heating up. Do not increase the frequency and if there are no extraneous sounds, let the engine run for some time. There are known cases when bearings were broken in, although spindles in production must work for a day, and only after inspection they are sent for sale. Therefore, there may be slight traces of rust on the water spindle fittings.
If everything is good, then everything is good. Adjust the inverter to suit your needs, experiment, and most importantly, understand what you are doing. Search and download instructions in Russian for an inverter of similar power from another manufacturer. Carefully. The parameter numbers will most likely not be the same, but the set of parameters is 80% similar between different manufacturers. Read the description of the parameters.
The inverter also has a removable front panel connected by a 10-wire cable. The connectors are standard. I read that the cable can be extended by 1-2 meters and the panel can be installed in a convenient place.
Removable front panel.
I will discuss how to start the inverter from a computer and regulate its frequency in another article.
Welding equipment today comes in many varieties. But inverter devices have gained the greatest popularity among home DIYers due to their compactness and versatility. A welding inverter is equipment that allows a master to perform various types of welding work. But to carry them out efficiently, it is not enough to have an expensive unit; you also need to learn how to use a welding machine.
To use an inverter efficiently and safely, you first need to properly prepare it for operation. This process is carried out in several stages. The first task is to install and connect the unit. Inverter installation must be carried out according to certain rules:
- the unit must be placed so that it is at a distance of at least 2 m from walls or any objects;
- the device must be grounded;
- the welding location must be chosen so that it is away from flammable objects;
- It is recommended to cook either on a free area or on a metal table.
The inverter can be connected both to a household network (220 V) and to a network with a voltage of 380 V, which is usually used in production. If you plan to use the unit away from electrical networks, then it can be connected to a generator, diesel or gasoline.
Electrical connection
Connecting a welding machine to a household electrical outlet often causes problems. The reason for their occurrence may be old wiring or insufficient diameter of its wires. Typically, wiring is designed for current up to 16 A. And since all switched on devices in the house can exceed this value, circuit breakers (automatic circuit breakers) are installed for safety reasons. Therefore, when connecting, you need to know the power of the welding machine so that it does not trigger the machine.
Connecting the inverter to a household network
You should also pay attention to network drawdown. If, when you turn on the inverter, you notice a decrease in voltage in the electrical network, this indicates an insufficient cross-section of the wires. In this case, it is necessary to measure to what values the voltage drops. If it drops to values below the minimum values with which the inverter can operate (indicated in the instructions), then the device cannot be connected to such a network.
Using an extension cord
The network cable connected to the inverter meets all power requirements and does not cause connection problems. But if its length is not enough, then you should select an extension cord with a wire cross-section of at least 2.5 mm 2 and a length of no more than 20 meters. Such parameters of the extension cord will be enough for the inverter to operate with a current of up to 150 A.
It should be remembered that when connecting the device to the network through a carrying case, the remaining part should not be kept wound up, since when the unit is turned on, it will turn into an inductor. As a result, the conductors will overheat and the extension cord will fail.
Connection to generator
In cases where it is not possible to connect the device to the mains, you can connect it to a generator that runs on either gasoline or diesel fuel. Gasoline power plants are the most widespread. But not all of them are suitable for connecting welding machines. In order for the inverter to operate effectively, the generator must have a power of at least 5 kilowatts and produce a stable output voltage. Voltage fluctuations can damage the welder.
It should also be taken into account how electrode diameter you will work. For example, if the electrode has a diameter of 3 mm, then an operating current of about 120 A with an arc voltage of 40 V will be required. If we calculate the power of the welding inverter (120 x 40 = 4800), we get a value of 4.8 kW. Since this will be the power consumed, a power plant capable of producing only 5 kW will operate at the limit of its capabilities, which will significantly reduce its service life. Therefore, the generator must be selected with some power reserve, approximately 20-30% higher than that consumed by the inverter.
Connecting welding cables
There are 2 terminals on the front panel of the inverter, next to which there are markings in the form of “+” and “-” signs. Welding cables are connected to these terminals, one of which has a metal clip (clothespin) at the end, and the second has a holder for the electrode. Both cables can be connected to both terminals, depending on the welding method, which will be discussed later. After connecting the cables to the device, one of them, which has a clothespin, is connected to the welding table or to the workpiece.
In some cases, standard cable lengths may not be sufficient, for example when working at heights. In such situations, the question arises: is it possible to extend the welding cable? Professionals do not advise doing this, especially if it concerns an inverter device. This fact can be explained by the fact that each cable has certain resistance characteristics. Therefore, “leaks” of voltage and current along its entire length are inevitable. Therefore, the longer the cable length, the stronger tension sags.
If you try to compensate for the loss of voltage and current by adding values on the unit panel, then this measure will most likely damage the inverter electronics. It turns out that it is easier to bring the device closer to the welder’s workplace than to spend a considerable amount on repairing the unit after lengthening the cables.
Setting up the device
The quality of welding work depends on whether the welding inverter is adjusted correctly, especially with regard to the correct choice of electrodes. You should also consider:
- weld depth;
- location of the seam in space (vertical or horizontal);
- brand or type of metal being welded;
- metal thickness, etc.
You should know that corresponding electrodes are produced for each type of metal. Electrodes with a diameter of up to 5 mm can be used with inverters. But for each thickness of the equipment it is necessary to select the corresponding welding current strength. To properly set up the welding machine, you can use the table below.
For example, if you have to weld mild steel 5 mm thick with an inverter, then you should select a 3 mm electrode, and set the current on the machine to 100 A. After test welding, the current can be adjusted, that is, reduced or increased.
Safety precautions when working
The established safety rules, one might say, were written in the “blood” of the victims, and therefore it is strictly forbidden to neglect them. The health and life of not only the welding equipment operator, but also the people around him depends on their compliance. So, the safety rules include the following.
If the safety rules have already been studied, then you can begin to familiarize yourself with how to properly work with electric welding.
Polarity selection
It is no secret that the process of metal melting occurs due to the high temperature of the electric arc that occurs between the material being welded and the electrode. In this case, the cable with the holder for the electrode and the ground cable (with a clothespin) are connected to different terminals of the device. To connect the cables correctly, you need to understand in what cases they are swapped.
When welding with an inverter or any other welding unit, direct and reverse polarity is used for connecting cables to the machine. Straight polarity It is commonly called a connection when the cable with the electrode is connected to the minus, and the metal being welded is connected to the plus.
This connection method allows the metal to warm up well, which results in a deep and high-quality seam. The direct polarity method is used when welding thick metal products.
It involves connecting the electrode cable to the positive, and the ground cable to the negative.
With this connection, the metal heats up less, and the seam becomes wider. Reverse polarity is usually used when welding thin metal products to prevent through burning of the part.
Welding current selection
The welding current is selected taking into account the thickness of the metal to be welded and the diameter of the filler. To simplify the calculations, you can use the table that was given above in the section that discussed setting up the unit. Also, when choosing the optimal current strength, you should remember the rule: the higher the current strength, the deeper the seam is, and the faster the electrode can be moved. Therefore, it is necessary to achieve an ideal ratio between the speed of movement of the additive and the current strength so that the seam has the required convexity and depth sufficient for good welding of the edges of the parts.
Methods of working with different metals
Since the welding process is impossible without igniting the arc, you should know that there are 2 methods to do this:
- you need to hit the metal with the electrode several times until the arc ignites.
- You need to strike the metal several times with an electrode, like a match.
Each master selects the most convenient and suitable method of igniting the arc. But you need to scratch not just anywhere, but along the line of the weld, so that no marks are left on the workpiece.
The place where metal melts under the influence of an electric arc is called weld pool. To move it along the seam line, use one of the methods shown in the following figure.
For normal bath movement, the electrode is tilted at an angle of 45-50°. By tilting the additive at different angles, you can control the width of the bath. Each master selects the optimal angle of inclination to obtain a seam of acceptable quality.
Advice! The movement of the bath is facilitated if the device has the “arc force” function, which prevents it from going out.
The electrode can take position angle back or angle forward. To obtain a wide seam, the equipment is tilted at an angle forward, since this method produces less heat. Thin metals are welded using this method. It is customary to weld thick metal at an angle backwards.
To weld non-ferrous metals you will have to connect an argon burner to the welding inverter and use a non-consumable electrode (tungsten). The additive in this case is metal rods, which are placed on the weld line and melted by an electric arc. During the welding process, the pool is blown with inert gas.
Rules for servicing the inverter device
Maintenance of an inverter-type welding machine includes the following items.
- Visual inspection. It must be carried out every time before and after starting work to detect possible damage to the insulation of welding cables and the power cord. Also, during an external inspection, the absence of damage to the housing and controls is checked (you need to check the current regulator).
- Carrying out internal cleaning of the unit. It is carried out after removing the casing from the device to remove dust and accumulated contaminants from all its components. Cleaning is carried out using a directed stream of compressed air onto dusty parts.
- Checking and cleaning the device terminals. The places where the power cables are connected should be checked periodically. If oxidation is found on the terminals, it should be removed using fine sandpaper.
You should also avoid contact with the inverter welding machine by drops of water, water vapor and other liquids that can penetrate inside the unit and cause electrical circuits to short out. If any liquid nevertheless penetrates into the device, then the casing should be removed from it and all moisture should be removed. Dry the inverter electronic board especially carefully using a regular hair dryer.