To power electrical appliances, it is necessary to ensure the nominal values of the power supply parameters stated in their documentation. Of course, most modern electrical appliances operate on 220 Volt AC, but it happens that you need to provide power to devices for other countries where the voltage is different or to power something from the car's on-board network. In this article, we will look at how to increase the voltage of DC and AC and what is needed for this.
AC voltage boost
There are two ways to increase the alternating voltage - use a transformer or an autotransformer. The main difference between them is that when using a transformer there is a galvanic isolation between the primary and secondary circuits, but when using an autotransformer it is not.
Interesting! Galvanic isolation is the absence of electrical contact between the primary (input) circuit and the secondary (output) circuit.
Consider frequently asked questions. If you are outside the borders of our vast country and the power grids there are different from our 220 V, for example, 110 V, then in order to raise the voltage from 110 to 220 Volts, you need to use a transformer, for example, such as shown in the figure below:
It should be said that such transformers can be used "in any direction". That is, if the technical documentation of your transformer says “the voltage of the primary winding is 220V, the secondary is 110V” - this does not mean that it cannot be connected to 110V. The transformers are reversible, and if the same 110V is applied to the secondary winding, 220V or another increased value proportional to the transformation ratio will appear on the primary.
The next problem that many people face is, this is especially often observed in private homes and garages. The problem is related to the poor condition and overload of power lines. To solve this problem - you can use LATR (laboratory autotransformer). Most modern models can both lower and smoothly increase network parameters.
Its diagram is shown on the front panel, and we will not dwell on explanations of the principle of operation. LATRs are sold in different capacities, the one in the figure is approximately 250-500 VA (volt-amperes). In practice, there are models up to several kilowatts. This method is suitable for supplying a nominal 220 volts to a specific electrical appliance.
If you need to cheaply boost the voltage throughout the house, your choice is a relay stabilizer. They are also sold in different capacities and the range is suitable for most typical applications (3-15 kW). The device is also based on an autotransformer. About that, we told in the article to which we referred.
DC circuits
Everyone knows that transformers do not work on direct current, while in such cases how to increase the voltage? In most cases, the constant is increased using a field-effect or bipolar transistor and a PWM controller. In other words, it is called a transformerless voltage converter. If these three main elements are connected as shown in the figure below and a PWM signal is applied to the base of the transistor, then its output voltage will increase by Ku times.
Ku=1/(1-D)
We will also consider typical situations.
Let's say you want to make the keyboard backlight using a small piece of LED strip. For this, the charger power from a smartphone (5-15 W) is quite enough, but the problem is that its output voltage is 5 Volts, and common types of LED strips operate from 12 V.
Then how to increase the voltage on the charger? The easiest way to boost is with a device such as a "dc-dc boost converter" or a "switching DC boost converter".
Such devices allow you to increase the voltage from 5 to 12 volts, and are sold both with a fixed value and adjustable, which in most cases will allow you to raise from 12 to 24 and even up to 36 volts. But keep in mind that the output current is limited by the weakest element of the circuit, in the situation under discussion - the current on the charger.
When using the specified board, the output current will be less than the input as many times as the output voltage has risen, without taking into account the efficiency of the converter (it is in the region of 80-95%).
Such devices are built on the basis of MT3608, LM2577, XL6009 microcircuits. With their help, you can make a device for checking the regulator relay not on the car's generator, but on the desktop, adjusting the values \u200b\u200bfrom 12 to 14 Volts. Below you can see a video test of such a device.
Interesting! Homemade lovers often ask the question “how to increase the voltage from 3.7 V to 5 V to make a Power bank on lithium batteries with your own hands?”. The answer is simple - use the FP6291 converter board.
On such boards, using silk-screen printing, the purpose of the pads for connection is indicated, so you do not need a diagram.
Also, a frequently occurring situation is the need to connect a device to a 220V car battery, and it happens that outside the city it is very necessary to get 220V. If you do not have a gasoline generator, use a car battery and an inverter to increase the voltage from 12 to 220 volts. A 1kW model can be bought for $35 and is an inexpensive and proven way to hook up a 220V drill, grinder, boiler, or refrigerator to a 12V battery.
If you are a truck driver, the above inverter will not suit you, due to the fact that your on-board network is most likely 24 volts. If you need to raise the voltage from 24V to 220V, then pay attention to this when buying an inverter.
Although it is worth noting that there are universal converters that can work from both 12 and 24 volts.
In cases where you need to get a high voltage, for example, to raise from 220 to 1000V, you can use a special multiplier. Its typical diagram is shown below. It consists of diodes and capacitors. You will get a constant current output, keep this in mind. This is the Latour-Delon-Grenachere doubler:
And this is how the circuit of an asymmetric multiplier (Cockcroft-Walton) looks like.
With it, you can increase the voltage as many times as you need. This device is built in cascades, the number of which determines how many volts you get at the output. The following video describes how the multiplier works.
In addition to these circuits, there are many others, below are the circuits of a quarter, 6- and 8-fold multipliers, which are used to increase the voltage:
In conclusion, I would like to remind you about safety precautions. When connecting transformers, autotransformers, as well as working with inverters and multipliers, be careful. Do not touch live parts with bare hands. Connections should be made with the device powered off and should not be operated in damp areas where water or splashing may occur. Also, do not exceed the current of the transformer, converter or power supply declared by the manufacturer, if you do not want it to burn out. We hope that the tips provided will help you increase the voltage to the desired value! If you have any questions, ask them in the comments below the article!
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The voltage drop in the primary network of 220 volts is sometimes a very serious problem in rural areas, and not only. The refrigerator does not start, the tile does not heat, you can’t stroke it with an iron, you can’t solder it with a soldering iron, but you never know .... If the voltage drop for heating devices that have active resistance for the network is not a lethal phenomenon, then for equipment in which engines are installed, in particular refrigerators, it can be the last in their life.
Let's start with a simple one, with heating equipment. Since the shape of the voltage for heaters does not matter, it is not a problem to raise the effective (rms or effective) value of the supply voltage for them. Let's look at the diagram.
This attachment first rectifies the mains voltage (fig. 1) (fig. 2), and then, due to the energy stored in the capacitors, increases the effective voltage, see figure 3.
The rectifier bridge can be used both ready-made and soldered from individual diodes. In rural areas, overhead power lines and high-voltage impulse voltage surges not uncommon, so when choosing rectifier elements, pay attention to the maximum operating voltage of the diodes. The higher the better, within reason of course. The operating current of the diodes must exceed the load current by 2 to 3 times. You will have to choose the capacitance of the capacitors yourself. It also depends on the magnitude of the voltage dip in the network and on the power of your heater. Be careful with this prefix, if the mains voltage is restored to normal, then at its output the voltage will be higher than the operating voltage of the load. The value of the overvoltage depends on the capacitance value of the currently connected capacitors. Hence the necessary current margin of the diodes. I have such an attachment for a large 100W soldering iron in the form of an ax, for its quick heating.
Now about, for example, a refrigerator. This friend needs a variable sine. Of course, you can buy both an autotransformer and a stabilizer. But you can get by with a simple transformer, the so-called booster transformer. Let's look at the diagram.
It can be seen from the diagram that an additional winding of the transformer is connected in series with the upper wire of the 220 volt network. If it is turned on in phase with the network, then the voltages will add up (when it is necessary to raise the voltage), if it is turned on out of phase, then the mains voltage and the voltage on the secondary winding of the transformer will be subtracted, this is the case when the voltage needs to be reduced.
How to increase the voltage of the network, calculations.
Now let's calculate a little, at least approximately. Let's say you have a voltage drop of thirty volts. The required load current is five amperes. It follows that we need a power of 150W. A transformer from an old tube TV is guaranteed to cope with such power. For example, TS-180.
Transformer TS-180, TS-180-2, TS180-2V parameters download
So, we downloaded the data, found the TS-180, Add up all the turns of the primary windings, 375+58+375+58=866 turns. We find the number of turns per volt 866/220 = approximately 4 turns per volt. To get the 30V we need, we multiply 30 by 4 = 120 turns. 60 turns per coil (TS-180 has two). The wire diameter for five amperes is 0.7 √I = 0.7√5 = 0.7∙2.236 ≈ 1.56 mm. Small explanations. After disassembling factory transformers, I always increase the number of turns of the primary winding, first of all, this is due to the fact that it will not be possible to assemble the core back, as is done in production conditions. Therefore, an increase in the no-load current (possibly several times due to the absence of a ferron filler in the gap, since the core is split) is guaranteed. Yes, and the armor core cannot be completely assembled, the plate 1,2,3 will still remain.
You have probably already noticed that through such a transformer it is possible to feed a motor with a power of one kilowatt. There is no toggle switch in the circuit to connect our transformer. It can switch like the primary winding of a transformer, but there will be losses due to the secondary winding constantly connected to the network, so it can switch the secondary winding itself, but there will be losses due to the permanently switched on primary winding. As I write this post, an idea popped into my head. Now I will add and draw a diagram. So, to switch the transformer, you need two switches or one with several directions. Everything is now about the idea, I drew a diagram. Let's look at the diagram.
And so, the switch is in the down position, the transformer adds voltage. The switch is in the upper position, the primary winding is short-circuited, which means that there is a short circuit in the secondary winding, and this is nothing more than that the transformer has disappeared, only the active resistance of the secondary winding remains.
Taaa ... k, another scheme was born. Now I'll draw. Why didn’t I think of this before, although on the Web, maybe someone has drawn this for a long time. We look.
If the switches are both at the bottom or both at the top, then there is no transformer in the circuit, there is a short circuit in the primary winding, the remaining active resistance is less than an ohm. Now left up, right down - the transformer, for example, adds voltage, and right up, left down - reduces. Well, that's all, maybe someone will find it useful. Good luck. K.V.Yu. Yes, a little more, a little more. And if instead of switches to apply FET H-bridge, and even a microcontroller that monitors the level of mains voltage, then you can probably make a relay-type AC voltage stabilizer with a small (relatively) transformer for a large (relatively) power. Who would have done all this. At least there is something to think about.
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The transformer owes its appearance to the English scientist Michael Faraday. In 1831, the physicist described the phenomenon, which he called "electromagnetic induction." It lies in the fact that in closely spaced coils (windings) a pronounced
electromagnetic relationship. That is, if an alternating current is created in the first coil (primary winding), then a voltage is excited in the second coil (secondary winding) with a similar frequency and power, depending on many parameters, which we will consider later.
Voltage transformers purpose and principle of operation
Voltage transformers are designed to convert the energy of a voltage source into voltage with the value (amplitude) we need. It should be noted that such transformers work only with alternating voltage and its frequency remains unchanged.
What is a voltage transformer for?
Voltage transformers, due to their versatility, are needed in power supplies, signal processing devices, transmission devices, power transmission devices and many other equipment.
According to the transformation ratio, these devices can be divided into 3 types:
- step down voltage transformer- at the output of the device, the voltage is lower than the input (n> 1), for example, it is used in power supplies;
- step-up transformer– at the output of the device, the voltage is higher than the voltage at the input (n<1), например, применяется в ламповых усилителях;
- matching transformer does not change the voltage parameters, only galvanic isolation of circuits (n ~ 1) occurs, for example, it is used in audio amplifiers.
The operation of the transformer is based on the principle of electromagnetic induction, and for the most complete transfer of energy, to reduce losses during transformation, the device is usually performed on a magnetic circuit.
As a rule, there is one primary coil, but there may be several secondary ones, it all depends on the purpose of the transformer.
After an alternating voltage U1 appears in the primary winding, an alternating magnetic flux Ф appears in the magnetic circuit, which excites a voltage in the secondary winding U2. This is the simplest and most concise description of the principle of operation of a voltage transformer.
The most important parameter of transformers is the "transformation ratio" and is denoted by the Latin "n". It is calculated by dividing the voltage in the primary winding by the voltage in the secondary winding, or the number of turns in the first coil by the number of turns in the second coil.
This factor allows you to calculate the required parameters of your transformer for the selected device. For example, if the primary has 2000 turns and the secondary has 100 turns, then n=20. With a mains voltage of 240 volts, the output of the device should be 12 volts. Also, you can determine the number of turns at a given input and output voltages.
What is the difference between a current transformer and a voltage transformer?
By definition, these devices are designed to work with different electrical quantities, as the main ones and, accordingly, the switching circuits will be different. For example, a current transformer is powered by a current source and does not work, it can even fail if its windings are not loaded and no electric current flows through them. The voltage transformer is powered by voltage sources and, conversely, cannot operate for a long time in a mode with large current loads.
Measuring voltage and current transformers
When operating equipment with high operating voltages and high consumption currents, the question of their measurement and control arises. This is where instrument transformers come to the rescue. They provide galvanic isolation of measuring equipment from circuits with increased danger and reduction of the measured value to the level required for measurements.
Additional Information
Before buying a voltage transformer, you need to analyze all the requirements for the device. It is necessary to take into account not only operating voltages, but also load currents when using a transformer in various devices.
You can make voltage transformers yourself, but if you need a simple household transformer with a voltage of 220 volts and a drop to 12 volts, then it is better to buy it. You can find out how much voltage transformers cost on any Internet site, as a rule, prices for household step-down voltage transformers are not very high.
N/A Vladimir Vasiliev
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The transformation of tension is present everywhere in any area of our life and activity. The voltage generated at the power plant is increased to several kilovolts in order to be transmitted with the least loss through power lines for many thousands of kilometers. And then it drops again at transformer substations to our usual values of 380/220 volts.
The simplest and most understandable examples for an ordinary person: a mains charger for a car battery, a power supply for computer and other equipment, an inverter for autonomous power supply of 220 volts from low-voltage power sources, step-down transformers 220-115, etc.
In general, there are many devices in which a voltage transformer is installed. Let's consider it in a little more detail, without plunging into unnecessary complexity.
Changes the voltage value up or down depending on the ratio of the number of its windings:
- primary, to which the initial voltage is applied;
- secondary, from which its converted value is taken.
All windings are wound on a common core (magnetic core). If the number of turns in the secondary winding is greater than that of the primary, then this is a step-up transformer, if less - a step-down.
The power of the voltage transformer depends on the section of the winding wires, and the dimensions and weight depend on the type of core and wire material (copper or technical aluminum). By execution, it can be single- and three-phase. The most compact and lightest is the autotransformer, in which there is only one winding.
The first thought that comes to mind when the voltage in the network is getting low more and more often is to put a step-up transformer. At first glance it seems that this is a simple and excellent solution, and now, finally, there will be normal voltage, bright lighting and stable electrical appliances.
But not everything is so simple in the fairy-tale kingdom, and before you buy a step-up voltage transformer, the price of which is already very attractive, think about one feature of its work: it has constant factor voltage increase (transformation ratio). Let's look at this with an example.
Suppose you have a mains voltage of about 170 volts. To increase it to 220, you need a transformer with a transformation ratio of 1.29 (220/170). It seems that everything turns out well and logically, with the exception of one thing: if the voltage in the network becomes normal 220 volts, then the output of the transformer will already have a very high voltage of 285 volts (220 * 1.29)! Not all electrical appliances are able to withstand such an overvoltage for even a short time. So close to the fire!
Alternatively, you can purchase an adjustable autotransformer, the so-called. LATR, which provides a manual output voltage regulator. But it will not be a reliable solution, either. you will have to constantly monitor the value of the output voltage on the indicator and adjust it manually, especially during the maximum load on the power grid from the neighbors. If this is not done in time, then at the first jump in the power grid, the voltage at the LATR output will also rise sharply, and the connected electrical appliances may well burn out.
Therefore, step-up voltage transformers are applicable only when the network is ALWAYS significantly less than 220 volts, and this almost never happens.
Conclusion
The task of automatically maintaining the voltage at a constant level is solved by
What and why raises the transformer? And at whose expense?
We have already looked at what a transformer is, now let's take a closer look at what a step-up transformer is and what it is used for. Let's start with a simple example that will help you understand why step-up transformers are needed.
Take a flashlight and make sure the batteries are not dead and the bulb is bright. And now unscrew the head of the flashlight, and power the light bulb through a cable 50 meters long. Do it yourself if you don't believe us the bulb won't light up. This happens due to too large losses in the line for this voltage. Notice the word stress.
Approximately the same thing will happen in a regular line between two cities if there is 220V in the line. If there is no transformer in such wiring that increases the voltage, electricity will not reach the second city, it will all go to losses. Due to these losses, power engineers use a scheme in which, after generating electricity, the voltage at the generation point increases significantly, electricity is transmitted through high voltage lines to the consumer, where it is then reduced to the desired value and distributed to consumers.
So, in very rough strokes, the scheme in this case looks like this:
- A generator that generates electricity;
- step-up transformer;
- Power transmission line;
- A step-down transformer;
- Local power grids;
- Consumer of electricity.
For clarity, here is a picture:
Why Energy? The fact is that this is the main scope of step-up transformers, if we talk about the specific contribution of transformers to the transformation of electricity. That is, it is in this area that they are most in demand, and without them it is impossible to imagine modern energy systems.
In order to understand how the voltage rises from 110V to 220V, or the currents change, you need to remember that no one has canceled the law of conservation of energy and the transformer does not produce any “free” electricity. By the way, it is based on manipulating the laws of physics, it is worth plugging them into a socket.
On the contrary, the step-up transformer perfectly illustrates the law of conservation of energy. Why? Yes, because if we consider the transformer as a closed system, then we get:
- Incoming energy (U1) on the primary winding (electricity), the number of turns of which is indicated by N1;
- Variable magnetic field induced in the magnetic circuit (core);
- Outgoing energy (U2) on the secondary winding, number of turns N2.
(The ratio of U2 to U1 gives the parameter k, called the transformation ratio.)
So, if in this system the number of turns is the same, then we will get the same voltage at the output, minus the losses in the transformer itself. This is the first illustration. The second is that if the number of turns differs, then we will get a voltage higher or lower at the output, but at the same time in a closed "transformer" system, the power will remain the same at the input and output(minus the losses in the transformer itself).
On a note. This is worth rethinking. Some effects in electrical engineering seem miraculous to non-specialists, but all these effects always correspond exactly to the law of conservation of energy. Therefore, before thinking about how to choose and where to install a device that “will definitely save a lot of money,” remember this example.
Thus, the step-up transformer works in strict accordance with the laws of conservation of energy and electromagnetic induction in AC networks, changing voltage and currents, but not changing power.
Can the transformer be replaced?
The types, types and scope of the step-up voltage transformer are not easy to find on the network, but very simple. Let's run so as not to search:
- By phase (one or three);
- By windings (two or three (varieties with a split winding)). There are also single-winding ones, these are autotransformers;
- Insulation (oil, dry and non-combustible filling);
- By type of cooling (oil - natural, with air blast and with forced circulation, air and with the help of a nitrogen cushion).
The marking of step-up transformers (more precisely, all transformers) looks like this:
All these devices are well described, widespread and have a variety of applications: from large energy to very small household appliances.
In fact, it is simply impossible to replace most transformers that increase voltage with other devices, but, nevertheless, as the classic said, “There are no irreplaceable people” (c).
It is possible to change the voltage or currents in the electrical network in other ways, and the losses will be comparable, and in some cases even lower. One example is the so-called T-shaped transformation scheme:
It may seem that this, in fact, is the circuit of a step-up or step-down transformer. But the real difference is this:
This is just a transformer circuit, from which it is perfectly clear that the windings are not connected to each other in any way, and the current in the secondary winding is induced without the participation of wires, so to speak. But in the T-shaped equivalent circuit of the transformer, it is clearly seen that there is no wire break.
At the same time, we, just like in a step-up transformer, will receive different voltages U1 and U2. Such methods are used where it is not possible to use a conventional transformer that increases the voltage. So, the transformer can be assembled with your own hands and connected where necessary, if necessary.
As a conclusion, a few words about the fate of transformers
Do not think that we have decided to hit science fiction, we are practical and realistic people. But, nevertheless, today, in terms of generation, the situation is such that it is quite possible that transformers in ten years will not have such a wide application. An example is a little higher, this is only one of the options, but this is not the main thing.
Of course, they will serve for decades more, but in the main field of use - energy, a step-up transformer is needed only as a secondary, auxiliary device. And it is needed only for the transmission of electricity over long distances. However, it is already clear today that over the past 30 years, the focus of this application has increasingly shifted towards large enterprises. If 30 years ago a private house not connected to the power grid was exotic, today there are already entire villages that do not use general-purpose networks in any way. Moreover, these settlements themselves are generating, feeding energy systems with excess energy.
This is progress and the process that he once launched will surely come to a logical conclusion. An incandescent lamp, perhaps, is one of the first devices that has become widespread, and even 50 years ago it seemed to many an eternal attribute of the lighting system. But the process is ongoing and in ten years it will be an anachronism. Do not consider this a lyrical digression, this applies without exception to all electrical appliances. It is for this reason that we are so wary of new products, some of which are outright swindle, and some are dead-end branches of evolution, such as, for example.
One of the tasks that our team of authors is trying to solve is just to try to predict, evaluate at the level of instinct, if you like, which of the new products will take their rightful place in our home electrical networks, and which ones will remain expensive toys and a waste of money. Of course, we can be wrong, but we will try to argue our understanding of these issues, especially in the short term.
