Schemes of all homemade converters 12 220V. High voltage and more. Hz? It's very simple

This inverter was developed just a month ago and has gained wide popularity since that day. The circuit is relatively simple, does not contain microcircuits or complex circuit solutions - a simple master oscillator tuned to 57Hz and power switches.

The power of the inverter depends directly on the number of pairs of output switches and on the overall dimensions of the transformer used. The transformer itself is taken from an old uninterruptible power supply. Output voltage 220-260 Volts. Power with 3 pairs of field switches is up to 400 watts, with a good battery up to 500 watts!

The output frequency allows you to connect the following to this inverter: Appliances like - TV, tape recorder, players, chargers from mobile phones, laptops and netbooks, computer, refrigerator, grinder, drill, vacuum cleaner and everything you can get your hands on.

The circuit can be implemented for just a couple of dollars if a transformer is available. A few words about the circuit itself. Field keys can be used IRFZ40/44/48, IRF3205, IRL3705 or the more powerful IRF3808 - with just two pairs of these keys you can remove power in the region of 800-900 watts! The generator transistors can be replaced with KT817/815/819/805

With one pair of irfz44 you can pull up to 150 watts of pure power (in some cases up to 200 watts). Film capacitors with a voltage of 65-400 volts are not particularly important. Gate resistors of keys can have a value from 2.2 to 22 Ohms.

>The inverter operates without additional adjustment - immediately after switching on, the no-load current consumption is 270-300 mA, while the transistors should not overheat at idle. The transistors are secured to a common heat sink through mica spacers. Power supply buses must have a diameter of at least 5mm; the power of the inverter is still not small.

The whole design fits perfectly into the case from the computer power supply and still helps out in some situations when there is no electricity in the house or you need to power the household load in field conditions, an excellent option for a motorist if you need to carry out renovation work above the car, far from the outlet (with 3 pairs of irf3205, the power will be around 1000 watts, so you can connect drills, grinders and other similar tools without any problems).

A 12V/220V inverter is a necessary thing on a household. Sometimes it’s simply necessary: the network, for example, has disappeared, and the phone is dead and there’s meat in the refrigerator. Demand determines supply: for ready-made models of 1 kW or more, from which you can power any electrical appliances, you will have to pay somewhere from $150. Possibly over $300. However, making a voltage converter with your own hands in our time is accessible to anyone who knows how to solder: assembling it from a ready-made set of components will cost three to four times less + a little work and metal from scrap trash. If there is one for car batteries, you can generally spend 300-500 rubles. And if you also have basic amateur radio skills, then, after rummaging through the stash, it is quite possible to make a 12V DC/220V AC 50Hz inverter for 500-1200 W for nothing. Let's consider the possible options.

Options: Global

A 12-220 V voltage converter to power a load up to 1000 W or more can generally be made independently in the following ways (in order of increasing costs):

Place a ready-made unit in a case with a heat sink from Avito, Ebay or AliExpress. Search for "inverter 220" or "inverter 12/220"; you can immediately add the required power. It will cost approx. half the price of the same factory one. No electrical skills required, but - see below;
Assemble the same one from the kit: printed circuit board + “scattered” components. It can be purchased there, but diy is added to the request, which means self-assembly. Price still approx. 1.5 times lower. You need basic skills in radio electronics: using a multimeter, knowledge of the wiring (pinouts) of the terminals of active elements or the ability to look for them, the rules for including polar components (diodes, electrolytic capacitors) in the circuit and the ability to determine what current and what cross-section wires are needed;
Adapt a computer source to the inverter uninterruptible power supply(UPS, UPS). A working used UPS without a standard battery can be found for 300-500 rubles. You don’t need any skills - you simply connect the car battery to the UPS. But you will have to charge it separately, also see below;
Choose a conversion method, a diagram (see below) in accordance with your needs and the availability of parts, calculate and assemble completely yourself. It may be completely free, but in addition to basic electronic skills, you will need the ability to use some special measuring instruments (also see below) and perform simple engineering calculations.

From a finished module

Assembly methods according to paragraphs. 1 and 2 are actually not that simple. The housings of ready-made factory inverters also serve as heat sinks for powerful transistor switches inside. If you take a “semi-finished product” or “loose”, then there will be no housing for them: given the current cost of electronics, manual labor and non-ferrous metals, the difference in prices is explained precisely by the absence of the second and, possibly, the third. That is, you will have to make a radiator for powerful keys yourself or look for a ready-made aluminum one. Its thickness at the location where the keys are installed should be at least 4 mm, and the area for each key should be at least 50 square meters. see for each kW of power output; with blowing from a 12 V computer fan-cooler 110-130 mA – from 30 sq. cm*kW*key.

For example, there are 2 keys in a set (module) (they can be seen, they stick out from the board, see on the left in the figure); modules with keys on the radiator (on the right in the figure) are more expensive and are designed for a certain, usually not very high power. There is no cooler, the power required is 1.5 kW. This means you need a radiator of 150 sq. see. In addition to this, there are also installation kits for keys: insulating heat-conducting gaskets and fittings for mounting screws - insulating cups and washers. If the module has thermal protection (there will be some other piece sticking out between the keys - a thermal sensor), then a little thermal paste to glue it to the radiator. Wires - of course, see below.

From UPS

The 12V DC/220V AC 50Hz inverter, to which you can connect any devices within the permissible power limit, is made from a computer UPS quite simply: the standard wires to “your” battery are replaced with long ones with clamps for the car battery terminals. The wire cross-section is calculated based on the permissible current density of 20-25 A/sq. mm, see also below. But because of a non-standard battery, problems can arise - with it, and it is more expensive and more necessary than a converter.

UPS also uses lead-acid batteries. This is today the only widely available secondary chemical power source capable of regularly delivering large currents (extra currents) without being completely “killed” in 10-15 charge-discharge cycles. In aviation, silver-zinc batteries are used, which are even more powerful, but they are monstrously expensive, are not widely available, and their service life is negligible by everyday standards - approx. 150 cycles.

The discharge of acid batteries is clearly monitored by the voltage on the bank, and the UPS controller will not allow the “foreign” battery to be discharged beyond measure. But in standard UPS batteries the electrolyte is gel, while in car batteries it is liquid. The charging modes in both cases are significantly different: the same currents cannot be passed through the gel as through a liquid, and in a liquid electrolyte, if the charge current is too low, the mobility of the ions will be low and not all of them will return to their places in the electrodes. As a result, the UPS will chronically undercharge the car battery; it will soon become sulfated and become completely unusable. Therefore, a battery charger is required for the inverter on the UPS. You can make it yourself, but that's another topic.

Battery and power

The suitability of the converter for a particular purpose also depends on the battery. A boost voltage inverter does not take energy for consumers from the “dark matter” of the Universe, black holes, the holy spirit, or anywhere else just like that. Only from the battery. And from it he will take the power supplied to consumers, divided by the efficiency of the converter itself.

If you see “6800W” or more on the body of a branded inverter, believe your eyes. Modern electronics make it possible to fit even more powerful devices into the volume of a cigarette pack. But let’s say we need a load power of 1000 W, and we have a regular 12 V 60 A/h car battery at our disposal. The typical value of inverter efficiency is 0.8. This means it will take approx. 100 A. For such a current, wires with a cross-section of 5 square meters are also needed. mm (see above), but that’s not the main thing here.

Car enthusiasts know: if you run the starter for 20 minutes, buy a new battery. True, new machines have time limiters for its operation, so perhaps they don’t know. And certainly not everyone knows that the starter of a car, once spun up, takes a current of approx. 75 A (within 0.1-0.2 s at startup - up to 600 A). The simplest calculation - and it turns out that if the inverter does not have automatic equipment that limits the battery discharge, then ours will run out completely in 15 minutes. So choose or design your converter taking into account the capabilities of the existing battery.

Note: This implies a huge advantage of 12/220 V converters based on computer UPSs - their controller will not allow the battery to drain completely.

The service life of acid batteries does not noticeably decrease if they are discharged with a 2-hour current (12 A for 60 A/h, 24 A for 120 A/h and 42 A for 210 A/h). Taking into account the conversion efficiency, this gives a permissible long-term load power of approx. 120 W, 230 W and 400 W respectively. For 10 min. load (for example, to power a power tool), it can be increased by 2.5 times, but after this the ABC must rest for at least 20 minutes.

Overall, the result is not entirely bad. Of the ordinary household power tools, only the grinder can take 1000-1300 W. The rest, as a rule, cost up to 400 W, and screwdrivers up to 250 W. A refrigerator from a 12 V 60 A/h battery will work through an inverter for 1.5-5 hours; quite enough to take the necessary measures. Therefore, making a 1 kW converter for a 60 A/h battery makes sense.

What will be the output?

In order to reduce the weight and size of the device, with rare exceptions (see below), voltage converters operate at increased frequencies from hundreds of Hz to units and tens of kHz. No consumer will accept a current of such frequency, and the loss of its energy in conventional wiring will be enormous. Therefore, inverters 12-200 are built for the following output voltage. types:

Constant rectified 220 V (220V AC). Suitable for powering telephone chargers, most power supplies (PS) for tablets, incandescent lamps, fluorescent housekeepers and LED lamps. With a power of 150-250 W, they are perfect for hand-held power tools: the DC power they consume is slightly reduced, and the torque increases. Not suitable for switching power supplies (UPS) of TVs, computers, laptops, microwave ovens, etc. with a power of more than 40-50 W: these necessarily have the so-called. a starting unit, for the normal operation of which the mains voltage must periodically pass through zero. Unsuitable and dangerous for devices with iron-based power transformers and electric motors alternating current: stationary power tools, refrigerators, air conditioners, most Hi-Fi audio, food processors, some vacuum cleaners, coffee makers, coffee grinders and microwave ovens (for the latter - due to the presence of a table rotation motor).
Modified sine wave (see below) - suitable for any consumers, except for Hi-Fi audio with a UPS, other devices with a UPS from 40-50 W (see above) and, often local security systems, home weather stations, etc. with sensitive analog sensors.
Pure sinusoidal - suitable without restrictions, except for power, for any electricity consumers.

Sine or pseudosine?

In order to increase efficiency, voltage conversion is carried out not only at higher frequencies, but also with heteropolar pulses. However, it is impossible to power very many consumer devices with a sequence of multi-polar rectangular pulses (the so-called meander): large surges at the meander fronts with even a slightly reactive load will lead to large energy losses and can cause a malfunction of the consumer. However, it is also impossible to design the converter for sinusodal current - the efficiency will not exceed approx. 0.6.

A quiet, but significant revolution in this industry occurred when microcircuits were developed specifically for voltage inverters, forming the so-called. a modified sinusoid (on the left in the figure), although it would be more correct to call it pseudo-, meta-, quasi-, etc. sinusoid. The current shape of the modified sinusoid is stepped, and the pulse fronts are prolonged (the meander fronts are often not visible at all on the screen of a cathode-ray oscilloscope). Thanks to this, consumers with transformers on iron or noticeable reactivity (asynchronous electric motors) “understand” the pseudosine wave “as real” and work as if nothing had happened; Hi-Fi audio with a network transformer on hardware can be powered with a modified sine wave. In addition, the modified sinusoid can be sufficiently in simple ways smooth out to “almost real”, the differences from the pure one on an oscilloscope are barely noticeable by eye; Converters of the “Pure Sine” type are not much more expensive than conventional ones, on the right in Fig.

However, it is not advisable to run devices with capricious analog components and UPS from a modified sine wave. The latter are extremely undesirable. The fact is that the middle platform of the modified sinusoid is not a pure zero voltage. The UPS starting unit from a modified sine wave does not operate clearly and the entire UPS may not exit the startup mode into operating mode. The user sees this at first as ugly glitches, and then smoke comes out of the device, as in the joke. Therefore, the devices in the UPS must be powered from Pure Sine type inverters.

We make the inverter ourselves

So, for now it is clear that it is best to make an inverter for an output of 220 V 50 Hz, although we will also remember about the AC output. In the first case, to control the frequency you will need a frequency meter: the norm for fluctuations in the frequency of the power supply network is 48-53 Hz. AC electric motors are especially sensitive to its deviations: when the frequency of the supply voltage reaches the tolerance limits, they heat up and “go away” from the rated speed. The latter is very dangerous for refrigerators and air conditioners; they can irreparably fail due to depressurization. But we don’t need to buy, rent, or beg for a loan an accurate and multifunctional electronic frequency meter - we don’t need its accuracy. Either an electromechanical resonant frequency meter (pos. 1 in the figure) or a pointer of any system, pos. 2:

Both are inexpensive, sold on the Internet, and in large cities in electrical specialty stores. An old resonant frequency meter can be found at the iron market, and one or the other, after setting up the inverter, is very suitable for monitoring the network frequency in the house - the meter does not respond to connecting them to the network.

50 Hz from computer

In most cases, 220 V 50 Hz power is required by consumers that are not particularly powerful, up to 250-350 W. Then the basis for a 12/220 V 50 Hz converter can be a UPS from an old computer - if, of course, one is lying around in the trash or someone is selling it cheap. The power delivered to the load will be approx. 0.7 from the rated UPS. For example, if “250W” is written on its body, then devices up to 150-170 W can be connected without fear. You need more - you must first test it on a load of incandescent lamps. It lasted 2 hours – it can deliver such power for a long time. How to make a 12V DC/220V AC 50Hz inverter from a computer power supply, see the video below.

Video: a simple 12-220 converter from a computer power supply

Keys

Let's say there is no computer UPS or you need more power. Then the choice of key elements becomes important: they must switch high currents with minimal switching losses, be reliable and affordable. In this regard, bipolar transistors and thyristors are confidently becoming a thing of the past in this area of application.

The second revolution in the inverter business is associated with the advent of powerful field-effect transistors (“field transistors”), the so-called. vertical structure. However, they have revolutionized the entire technology of power supply for low-power devices: it is becoming increasingly difficult to find a transformer on iron in household appliances.

The best of the high-power field devices for voltage converters are insulated gate induced channel (MOSFET), e.g. IFR3205, left in the figure:

Due to the negligible switching power, the efficiency of an inverter with a DC output on such transistors can reach 0.95, and with an AC 50 Hz output 0.85-0.87. Analogues of MOSFET with a built-in channel, e.g. IFRZ44, give lower efficiency, but are much cheaper. A pair of one or the other allows you to bring the power in the load to approx. 600 W; both can be paralleled without problems (on the right in the figure), which makes it possible to build inverters with a power of up to 3 kW.

Note: The power loss of switching switches with a built-in channel when operating on a significantly reactive load (for example, an asynchronous electric motor) can reach 1.5 W per switch. Keys with an induced channel are free from this drawback.

TL494

The third element that made it possible to bring voltage converters to their current state is the specialized TL494 microcircuit and its analogues. They all represent a controller pulse width modulation(PWM), which generates a modified sinusoid signal at the outputs. The outputs are multi-polar, which allows you to control pairs of keys. The reference conversion frequency is set by a single RC circuit, the parameters of which can be changed within wide limits.

When is a permanent job enough?

The circle of 220 V DC consumers is limited, but it is they who need an autonomous power supply not only in emergency situations. For example, when working with power tools on the road or in the far corner of your own site. Or is it always present, say, at the emergency lighting of the entrance to the house, hallway, corridor, local area from solar battery, during the day recharging the battery. The third typical case is charging your phone on the go from the cigarette lighter. Here the output power is needed very little, so the inverter can be made with just 1 transistor according to the relaxation generator circuit, see next. video clip.

Video: boost converter on one transistor

Already to power 2-3 LED light bulbs you need more power. When trying to “squeeze” it, the efficiency of blocking generators drops sharply, and you have to switch to circuits with separate timing elements or full internal inductive feedback; they are the most economical and contain the least number of components. In the first case, to switch one switch, the self-induction EMF of one of the transformer windings is used together with a timing circuit. In the second, the frequency-setting element is the step-up transformer itself due to its own time constant; its value is determined primarily by the phenomenon of self-induction. Therefore, both inverters are sometimes called self-induction converters. Their efficiency, as a rule, is no higher than 0.6-0.65, but, firstly, the circuit is simple and does not require adjustment. Secondly, the output voltage is more trapezoidal than square wave; “demanding” consumers “understand” it as a modified sine wave. Disadvantage: field switches in such converters are practically inapplicable, because often fail due to voltage surges on the primary winding during switching.

An example of a circuit with external timing elements is given in pos. 1 pic:

The author of the design was unable to squeeze more than 11 W out of it, but apparently, he confused ferrite with carbonyl iron. In any case, the armored (cup) magnetic circuit in his own photo (see figure on the right) is in no way ferrite. It looks more like an old carbonyl one, oxidized on the outside with time, see fig. on right. It is better to wind the transformer for this inverter on a ferrite ring with a ferrite cross-sectional area of 0.7-1.2 square meters. cm. The primary winding should then contain 7 turns of wire with a copper diameter of 0.6-0.8 mm, and the secondary winding should contain 57-58 turns of wire 0.3-0.32 mm. This is for straightening with doubling, see below. For “pure” 220 V - 230-235 turns of wire 0.2-0.25. In this case, when replacing KT814 with KT818, this inverter will deliver power up to 25-30 W, which is enough for 3-4 LED lamps. When replacing KT814 with KT626, the load power will be approx. 15 W, but the efficiency will increase. In both cases, the key radiator is from 50 square meters. cm.

At pos. 2 shows a diagram of the “antediluvian” converter 12-220 with separate windings feedback. It's not that archaic. First, the output voltage under load is trapezoidal with rounded fractures and no spikes. It's even better than a modified sine wave. Secondly, this converter can be designed without any modifications in the circuit for a power of up to 300-350 W and a frequency of 50 Hz, then a rectifier is not needed, you just need to install VT1 and VT2 on radiators from 250 kW. see each. Thirdly, it protects the battery: when overloaded, the conversion frequency drops, the output power decreases, and if you load it even more, the generation stops. That is, to avoid over-discharging the battery, no automation is required.

The procedure for calculating this inverter is given in the scan in Fig.:

The key quantities in it are the conversion frequency and the working induction in the magnetic circuit. The conversion frequency is selected based on the material of the available core and the required power:

Type Magnetic cores	Induction/conversion frequency
	Up to 50 W	50-100 W	100-200 W	200-350 W
“Power” iron from power transformers with a thickness of 0.35-0.6 mm	0.5 T/(50-1000)Hz	0.55 T/(50-400)Hz	0.6 T/(50-150)Hz	0.7 T/(50-60)Hz
“Sound” iron from UMZCH output transformers with a thickness of 0.2-0.25 mm	0.4 T/(1000-3000)Hz	0.35 T/(1000-2000)Hz	-	-
“Signal” iron from signal transformers with a thickness of 0.06-0.15 mm (not permalloy!)	0.3 T/(2000-8000)Hz	0.25 T/(2000-5000)Hz	-	-
Ferrite	0.15 T/(5-30) kHz	0.15 T/(5-30) kHz	0.15 T/(5-30) kHz	0.15 T/(5-30) kHz

This “omnivorousness” of ferrite is explained by the fact that its hysteresis loop is rectangular and the working induction is equal to the saturation induction. The decrease in the calculated values of induction in steel magnetic cores compared to typical values is caused by a sharp increase in switching losses of non-sinusoidal currents as it increases. Therefore, from the core of the power transformer of the old 270 W “coffin” TV in this 50 Hz converter it will be possible to remove no more than 100-120 W. But - without fish, there is cancer in fish.

Note: If you have a steel magnetic core with a deliberately oversized cross-section, do not squeeze the power out of it! Let the induction be better - the efficiency of the converter will increase, and the shape of the output voltage will improve.

Straightening

It is better to rectify the output voltage of these inverters using a circuit with parallel voltage doubling (item 3 in the figure with diagrams): the components for it will cost less, and the power losses on a non-sinusoidal current will be less than in a bridge. Capacitors should be taken “power”, designed for large reactive power(designated PE or W). If you put “sound” ones without these letters, they may simply explode.

50 Hz? It's very simple!

A simple 50 Hz inverter (item 4 in the figure above with diagrams) is an interesting design. For some types of standard power transformers, the intrinsic time constant is close to 10 ms, i.e. half a period of 50 Hz. By adjusting it with timing resistors, which will also act as limiters of the switch control current, you can immediately obtain a smoothed 50 Hz square wave at the output without complex formation circuits. Transformers TP, TPP, TN for 50-120 W are suitable, but not just any kind. You may have to change the resistor values and/or connect 1-22 nF capacitors in parallel with them. If the conversion frequency is still far from 50 Hz, it is useless to disassemble and rewind the transformer: the magnetic circuit glued with ferromagnetic glue will fluff up, and the parameters of the transformer will deteriorate sharply.

This inverter is a weekend dacha converter. It will not drain the car battery for the same reasons as the previous one. But it is enough to illuminate a house with a veranda with LED lamps and a TV or vibration pump in the well. The conversion frequency of the adjusted inverter when the load current changes from 0 to maximum does not go beyond the technical norms for power supply networks.

The windings of the original transformer are routed like this. In typical power transformers, there is an even number of secondary windings for 12 or 6 V. Two of them are “set aside”, and the rest are soldered in parallel into groups of an equal number of windings in each. Next, the groups are connected in series so that you get 2 half-windings of 12 V each, this will be a low-voltage (primary) winding with a midpoint. Of the remaining low-voltage windings, one is connected in series with the 220 V mains winding; this will be the step-up winding. An additive is needed because... The voltage drop across switches made of bipolar composite transistors, together with its losses in the transformer, can reach 2.5-3 V, and the output voltage will be underestimated. Additional winding will bring it up to normal.

DC from the chip

The efficiency of the described converters does not exceed 0.8, and the frequency varies noticeably depending on the load current. The maximum load power is less than 400 W, so it’s time to think about modern circuit solutions.

The circuit of a simple converter 12 V DC/220 V DC for 500-600 W is shown in the figure:

Its main purpose is to power hand-held power tools. Such a load is not demanding on the quality of the supplied voltage, so the keys are taken cheaper; IFRZ46, 48 are also suitable. The transformer is wound on ferrite with a cross-section of 2-2.5 square meters. cm; A power transformer core from a computer UPS is suitable. Primary winding - 2x5 turns of a bundle of 5-6 winding wires with a copper diameter of 0.7-0.8 mm (see below); secondary - 80 turns of the same wire. No adjustment is required, but there is no monitoring of battery discharge, so during operation you need to attach a multimeter to its terminals and do not forget to look at it (the same applies to all other homemade voltage inverters). If the voltage drops to 10.8 V (1.8 V per cell) - stop, turn off! It dropped to 1.75 V per cell (10.5 V for the entire battery) - this is already sulfation!

How to wind a transformer on a ring

The quality characteristics of the inverter, in particular its efficiency, are quite strongly influenced by the stray field of its transformer. The fundamental solution to reduce it has long been known: the primary winding, which “pumps” the magnetic circuit with energy, is placed close to it; secondary ones above it in descending order of their power. But technology is such a thing that theoretical principles in specific designs sometimes have to be turned inside out. One of Murphy's laws states approx. so: if the piece of hardware still doesn’t want to work as it should, try doing the opposite in it. This fully applies to the transformer increased frequency on a ferrite ring magnetic core with windings made of relatively thick rigid wire. Wind the voltage converter transformer on a ferrite ring like this:

The magnetic circuit is insulated and, using a winding shuttle, a secondary step-up winding is wound onto it, laying the turns as tightly as possible, pos. 1 in Fig.:

Tightly wrap the secondary part with tape, pos. 2.
Prepare 2 identical wire harnesses for the primary winding: wind the number of turns of half the low-voltage winding with a thin unusable wire, remove it, measure the length, cut off the required number of winding wire segments with a reserve and assemble them into bundles.
Additionally, the secondary winding is insulated until a relatively flat surface is obtained.
Wind the “primary” with 2 bundles at once, arranging the wires of the bundles with tape and evenly distributing the turns over the core, pos. 3.
Call the ends of the bundles and connect the beginning of one to the end of the other, this will be the middle point of the winding.

Note: on electric circuit diagrams the beginnings of the windings, if relevant, are indicated by a dot.

50 Hz smoothed

The modified sine wave from the PWM controller does not the only way get 50 Hz at the inverter output, suitable for connecting any household electricity consumers, and it wouldn’t hurt to “smooth” that one too. The simplest of them is the good old iron transformer; it “irons” well due to its electrical inertia. True, it is becoming increasingly difficult to find a magnetic core rated at more than 500 W. Such an isolation transformer is switched on to the low-voltage output of the inverter, and a load is connected to its step-up winding. By the way, most computer UPSs are built according to this scheme, so they are quite suitable for this purpose. If you wind the transformer yourself, then it is calculated similarly to the power one, but with a trace. features:

The initially determined value of the working induction is divided by 1.1 and applied in all further calculations. This is necessary in order to take into account the so-called. non-sinusoidal voltage shape factor Kf; for a sinusoid Kf=1.
The step-up winding is first calculated as a 220 V mains winding for a given power (or determined by the parameters of the magnetic circuit and the value of the working induction). Then the found number of turns is multiplied by 1.08 for powers up to 150 W, by 1.05 for powers of 150-400 W and by 1.02 for powers of 400-1300 W.
Half of the low-voltage winding is calculated as a secondary voltage of 14.5 V for bipolar switches or with a built-in channel and 13.2 V for switches with an induced channel.

Examples of circuit solutions for 12-200 V 50 Hz converters with an isolation transformer are shown in the figure:

On the one on the left, the keys are controlled by the so-called master oscillator. a “soft” multivibrator, it already generates a meander in blocked fronts and smoothed fractures, so no additional smoothing measures are required. The instability of the frequency of a soft multivibrator is higher than that of a regular one, so to adjust it you need a potentiometer P. With keys on the KT827, you can remove power up to 200 W (radiators from 200 sq. cm without blowing). Keys on KP904 from old junk or IRFZ44 allow you to increase it to 350 W; single ones on IRF3205 up to 600 W, and paired ones on them up to 1000 W.

An inverter 12-220 V 50 Hz with a master oscillator on TL494 (on the right in the figure) maintains the frequency firmly in all conceivable operating conditions. To more effectively smooth out a pseudosinusoid, the so-called phenomenon is used. indifferent resonance, in which the phase relationships of currents and voltages in the oscillatory circuit become the same as with acute resonance, but their amplitudes do not increase noticeably. Technically, this can be solved simply: a smoothing capacitor is connected to the boost winding, the capacitance value of which is selected according to the best shape of the current (not voltage!) under load. To control the shape of the current, a 0.1-0.5 Ohm resistor is connected to the load circuit at a power of 0.03-0.1 of the rated value, to which an oscilloscope with a closed input is connected. The smoothing capacitance does not reduce the efficiency of the inverter, but can be used for tuning computer programs It is not possible to simulate the low frequencies of an oscilloscope, because the input of the sound card they use is not designed for an amplitude of 220x1.4 = 310 V! The keys and powers are the same as before. case.

A more advanced 12-200 V 50 Hz converter circuit is shown in Fig.:

It uses complex compound keys. To improve the quality of the output voltage, it uses the fact that the emitter of planar epitaxial bipolar transistors is doped much more heavily than the base and collector. When TL494 applies a closing potential, for example, to the base of VT3, its collector current will stop, but due to the resorption of the emitter space charge, it will slow down the closing of T1 and voltage surges from the self-induction emf Tr will be absorbed by circuits L1 and R11C5; they will “tilt” the fronts more. The output power of the inverter is determined by the overall power Tr, but not more than 600 W, because It is impossible to use paired powerful switches in this circuit - the spread in the value of the gate charge of MOSFET transistors is quite significant and the switching of the switches will be unclear, which is why the shape of the output voltage may even worsen.

Choke L1 is 5-6 turns of wire with a diameter of 2.4 mm on copper, wound on a piece of ferrite rod with a diameter of 8-10 m and a length of 30-40 mm with a pitch of 3.5-4 mm. The throttle magnetic circuit must not be short-circuited! Setting up a circuit is quite a painstaking task and requires a lot of experience: you need to select L1, R11 and C5 according to the best shape of the output current under load, as in the previous one. case. But Hi-Fi, powered from this converter, remains “hi-fi” to the most demanding ears.

Is it possible without a transformer?

Already the winding wire for a powerful 50 Hz transformer will cost a pretty penny. Magnetic cores from “coffin” transformers up to 270 W overall are more or less available, but in an inverter you cannot squeeze more than 120-150 W out of this, and the efficiency will be 0.7 at best, because “coffin” magnetic cores are wound from a thick tape, the eddy current losses in which are large at non-sinusoidal voltage on the windings. Finding an SL magnetic core made of a thin strip capable of delivering more than 350 W at an induction of 0.7 Tesla is generally problematic, it will be expensive, and the entire converter will be huge and heavy-lifting. UPS transformers are not designed for frequent operation in long-term mode - they heat up and their magnetic circuits in inverters degrade quite quickly - the magnetic properties deteriorate greatly, the power of the converter drops. Is there a way out?

Yes, and this solution is often used in branded converters. This is an electrical bridge made of switches on high-voltage power field-effect transistors with a breakdown voltage of 400 V and a drain current of more than 5 A. Suitable from the primary circuits of computer UPSs, and from old trash - KP904, etc.

The bridge is powered by a constant 220 V DC from a simple 12-220 inverter with rectification. The arms of the bridge open in pairs, crosswise, alternately, and the current in the load included in the diagonal of the bridge changes direction; The control circuits of all keys are galvanically separated. In industrial designs, the keys are controlled by special devices. IC with optocoupler isolation, but in amateur conditions both can be replaced with an additional low-power inverter 12 V DC - 12 V 50 Hz, powered by a small transformer on hardware, see fig. The magnetic core for it can be taken from a Chinese market low-power power transformer. Due to its electrical inertia, the quality of the output voltage is even better than a modified sine wave.

To connect to the vehicle's on-board electrical system household devices an inverter is required that can increase the voltage from 12 V to 220 V. There are sufficient quantities of them on store shelves, but their price is not encouraging. For those who are a little familiar with electrical engineering, it is possible to assemble a 12-220 volt voltage converter with your own hands. Two simple circuits we'll figure it out.

Converters and their types

There are three types of 12-220 V converters. The first is from 12 V to 220 V. Such inverters are popular among motorists: through them you can connect standard devices - TVs, vacuum cleaners, etc. Reverse conversion - from 220 V to 12 - is required infrequently, usually in rooms with severe operating conditions (high humidity) to ensure electrical safety. For example, in steam rooms, swimming pools or baths. In order not to take risks, the standard voltage of 220 V is reduced to 12, using appropriate equipment.

The third option is, rather, a stabilizer based on two converters. First, the standard 220 V is converted to 12 V, then back to 220 V. This double conversion allows you to have an ideal sine wave at the output. Such devices are necessary for the normal operation of most electronically controlled household appliances. In any case, during installation it is strongly recommended to power it through just such a converter - its electronics are very sensitive to the quality of power, and replacing the control board costs about half the boiler.

Pulse converter 12-220V 300 W

This circuit is simple, the parts are available, most of them can be removed from a computer power supply or purchased at any radio store. The advantage of the circuit is its ease of implementation, the disadvantage is the non-ideal sine wave at the output and the frequency is higher than the standard 50 Hz. That is, devices that require power supply cannot be connected to this converter. You can directly connect not particularly sensitive devices to the output - incandescent lamps, iron, soldering iron, phone charger, etc.

The presented circuit in normal mode produces 1.5 A or pulls a load of 300 W, at a maximum of 2.5 A, but in this mode the transistors will noticeably heat up.

The circuit was built on the popular TLT494 PWM controller. Field-effect transistors Q1 Q2 should be placed on radiators, preferably separate ones. When installing on one radiator, place an insulating gasket under the transistors. Instead of the IRFZ244 indicated in the diagram, you can use IRFZ46 or RFZ48, which are similar in characteristics.

The frequency in this 12 V to 220 V converter is set by resistor R1 and capacitor C2. The values may differ slightly from those shown in the diagram. If you have an old non-working power supply for your computer, and it contains a working output transformer, you can put it in the circuit. If the transformer is not working, remove the ferrite ring from it and wind the windings with copper wire with a diameter of 0.6 mm. First, the primary winding is wound - 10 turns with the output from the middle, then, on top - 80 turns of the secondary.

As already said, such a 12-220 V voltage converter can only work with a load that is insensitive to power quality. To be able to connect more demanding devices, a rectifier is installed at the output, the output voltage of which is close to normal (diagram below).

The circuit shows high-frequency diodes of the HER307 type, but they can be replaced with the FR207 or FR107 series. It is advisable to select containers of the specified size.

Inverter on a chip

This 12-220 V voltage converter is assembled on the basis of a specialized KR1211EU1 microcircuit. This is a generator of pulses that are removed from outputs 6 and 4. The pulses are antiphase, with a short time interval between them to prevent the simultaneous opening of both keys. The microcircuit is powered by a voltage of 9.5 V, which is set by a parametric stabilizer on a D814V zener diode.

Also in the circuit there are two high-power field-effect transistors - IRL2505 (VT1 and VT2). They have a very low open resistance of the output channel - about 0.008 Ohms, which is comparable to the resistance of a mechanical key. Acceptable D.C.- up to 104 A, pulsed - up to 360 A. Such characteristics actually allow you to get 220 V with a load of up to 400 W. Transistors must be installed on radiators (with a power of up to 200 W it is possible without them).

The pulse frequency depends on the parameters of resistor R1 and capacitor C1; capacitor C6 is installed at the output to suppress high-frequency surges.

It is better to take a ready-made transformer. In the circuit, it is turned on in reverse - the low-voltage secondary winding serves as the primary, and the voltage is removed from the high-voltage secondary.

Possible replacements in the element base:

The D814V zener diode indicated in the circuit can be replaced with any one that produces 8-10 V. For example, KS 182, KS 191, KS 210.
If there are no capacitors C4 and C5 of type K50-35 at 1000 μF, you can take four 5000 μF or 4700 μF and connect them in parallel,
Instead of an imported capacitor C3 220m, you can supply a domestic one of any type with a capacity of 100-500 µF and a voltage of at least 10 V.
Transformer - any with a power from 10 W to 1000 W, but its power must be at least twice the planned load.

When installing circuits connecting a transformer, transistors and connecting to a 12 V source, you must use wires large section- the current here can reach high values (with a power of 400 W up to 40 A).

Inverter with pure sine wave output

The circuits of daytime converters are complex even for experienced radio amateurs, so making them yourself is not at all easy. An example of the simplest circuit is below.

IN in this case It’s easier to assemble such a converter from ready-made boards. How - watch the video.

The next video shows how to assemble a 220 volt converter with pure sine wave. Only the input voltage is not 12 V, but 24 V.

And this video just tells you how you can change the input voltage, but still get the required 220 V at the output.

The inverter consists of a master oscillator of 50 Hertz (up to 100 Hz), which is built on the basis of the most common multivibrator. Since the publication of the scheme, I have observed that many have successfully repeated the scheme, the reviews are quite good - the project was a success.

This circuit allows you to get almost mains 220 Volts with a frequency of 50 Hz at the output (depending on the frequency of the multivibrator. The output of our inverter is rectangular pulses, but please do not rush to conclusions - such an inverter is suitable for powering almost all household loads, with the exception of those loads that have built-in motor that is sensitive to the shape of the supplied signal.

TV, players, chargers for laptops, laptops, mobile devices, soldering irons, incandescent lamps, LED lamps, LDS, even a personal computer - all this can be powered without any problems from the proposed inverter.

A few words about the power of the inverter. If you use one pair of power switches of the IRFZ44 series with a power of about 150 watts, the output power is indicated below depending on the number of pairs of keys and their type

Transistor Number of pairs Power, W)
IRFZ44/46/48 1/2/3/4/5 250/400/600/800/1000
IRF3205/IRL3705/IRL 2505 1/2/3/4/5 300/500/700/900/1150
IRF1404 1/2/3/4/5 400/650/900/1200/1500Max

But that’s not all, one of those people who assembled this device wrote with pride that he managed to remove up to 2000 watts, of course, and this is real if you use, say, 6 pairs of IRF1404 - really killer keys with a current of 202 Amperes, but of course maximum current cannot reach such values, since the terminals would simply melt at such currents.

The inverter has a REMOTE function (remote control). The trick is that to start the inverter you need to apply a low-power plus from the battery to the line to which low-power multivibrator resistors are connected. A few words about the resistors themselves - take everything with a power of 0.25 watts - they will not overheat. The transistors in the multivibrator need to be quite powerful if you are going to pump several pairs of power switches. Of ours, KT815/17 or even better KT819 or imported analogues are suitable.

Capacitors are frequency-setting capacitors, their capacity is 4.7 μF; with this arrangement of multivibrator components, the inverter frequency will be around 60 Hz.
I took the transformer from an old uninterruptible power supply, the power of the trance is selected based on the required (calculated) power of the inverter, the primary windings are 2 to 9 Volts (7-12 Volts), the secondary winding is standard - network.
Film capacitors with a rated voltage of 63/160 volts or more, take what you have on hand.

Well, that’s all, I’ll only add that power switches at high power will heat up like a stove, they need a very good heat sink, plus active cooling. Do not forget to isolate the pairs of one arm from the heat sink to avoid short-circuiting of the transistors.

The inverter does not have any protection or stabilization; perhaps the voltage will deviate from 220 Volts.

Download printed circuit board from the server

Sincerely - AKA KASYAN

Such an inverter is designed to produce alternating current 220 V 50 Hz from car battery or any 12 V battery. The inverter power is about 150 W and can be increased to 300.

The circuit operates as a Push-Pull converter. The heart of the inverter is the CD4047 chip, which acts as a master oscillator and simultaneously controls field effect transistors. The latter operate in key mode. Only one of the transistors can be open. If both transistors open at the same time, a short circuit will occur and the transistors will burn out instantly. This can happen due to improper management.

The CD4047 chip, of course, is not designed for high-precision control of field workers, but it copes with this task quite well.

The transformer was taken from a non-working UPS. It is 250-300 W and has a primary winding with a middle point where the plus from the power source is connected.

There are many secondary windings, so you need to find a 220 V network winding. Using a multimeter, the resistance of all taps that are on the secondary circuit is measured. The required leads should have the highest resistance (in the example, about 17 Ohms). All other wires can be bitten off.

It is recommended to check all components before soldering. It is better to select transistors from the same batch with similar characteristics. The capacitor in the frequency-setting circuit must have low leakage and a narrow tolerance. These parameters can be checked with a transistor tester.

A few words about possible replacements in the scheme. Unfortunately, the CD4047 chip has no Soviet analogues, so you need to buy it. “Field switches” can be replaced with any n-channel transistors that have a voltage of 60 V and a current of 35 A. Suitable from the IRFZ line.

The circuit also works great with bipolar transistors at the output, although the power will be much lower than when using field-effect transistors.

Gate limiting resistors can have a resistance of 10 to 100 ohms. It is better to set from 22 to 47 Ohms with a power of 250 mW.

The frequency-setting circuit must be assembled only from those elements indicated in the diagram. It will be finely tuned to 50 Hz.

A correctly assembled device should work immediately. But the first launch must be done with insurance. That is, in place of the fuse according to the diagram, install a resistor with a nominal value of 5-10 Ohms, or a 12 V (5 W) lamp, so as not to blow up the transistors if problems arise.

If the converter is working normally, the transformer makes a sound, and the keys should not heat up at all. If this is the case, then the resistor can be removed and power supplied directly through the fuse.

The average current consumption of an inverter at idle can be between 150 and 300 mA, but this will depend on the power supply and the transformer used.

Next, the output voltage is measured. In the example, the values were from 210 to 260 V. This is within normal limits, since the inverter is not stabilized. Now you can turn on the load, for example, a 60 W lamp. You need to drive the inverter for about 10 seconds, the keys should heat up a little, since they do not yet have heat sinks. The heating on both keys should be uniform. If this is not the case, then look for jambs.

The inverter is equipped with a Remote Control function.

The main power plus is connected to the midpoint of the transformer. But for the inverter to work, it is necessary to apply a low-current plus to the board. This will start the pulse generator.

A few words about installation. As always, everything fits well in the computer's power supply case. The transistors are installed on separate radiators.

If a common heat sink is used, it is necessary to isolate the transistor housings from the radiator. The cooler was connected directly to the 12 V bus.

The biggest drawback of this inverter is the lack of short circuit protection. In this case, the transistors will burn out. To prevent this from happening, a 1 A fuse is needed at the output.

A low-power button supplies plus from the power source to the board, that is, it starts the inverter as a whole.

The power busbars from the transformer are attached directly to the radiators of the transistors.

By connecting a device called an energy meter to the output of the converter, you can make sure that the voltage and frequency are within normal limits. If the frequency differs from 50 Hz, then it must be adjusted using a multi-turn variable resistor, which is present on the board.

During operation, when no load is connected to the output, the transformer is quite noisy. When the load is connected, the noise is negligible. This is all normal, since rectangular pulses are supplied to the transformer.

The resulting inverter is unstabilized, but almost all household appliances are designed to operate in the voltage range from 90 to 280 V.

If the output voltage is higher than 300 V, then it is recommended to connect a 25-watt incandescent light bulb to the output in addition to the main load. This will reduce the output voltage to a small extent.

In principle, it is possible to power commutator motors from a converter, but they heat up 2 times more than when powered from a pure sine wave.

The same thing happens with consumers that have an iron transformer. But it is not recommended to connect asynchronous motors.

The weight of the device is about 2.7 kg. This is a lot when compared with pulse inverters.

Attached files:

How to make a simple Power Bank with your own hands: diagram of a homemade power bank