Converters. Views. How the pulse voltage transducers (27 schemes) work the voltage conversion device is called

Modern science explains the existence of electricity by the clusters of charges of opposite signs. In nature, an incredible amount of electricity is produced. Friction forces in the atmosphere create huge spaces from thunderstorm clouds. Between the clouds, with the surface of the earth there are voltages in millions of volts. And a few minutes of thunderstorms with lightning are equivalent to the electrical power to the long operation of a large power plant.

But lightning may not be. However, electricity still hovers in space between heaven and earth.

• Obviously, the voltage is the first and main parameter of electricity energy.

In nature, there are only slowly changing and almost instantly endangered stresses. Thunderstorm gradually gaining strength, charges from friction moving air layers is becoming more and more. The voltage between the clouds and the surface of the Earth increases.

If the movement of air masses at a certain point stops, the voltage will gradually decrease. If not, the discharge of the lightning instantly "reset" the voltage.

• It's obvious that electricitywhich has a type of lightning, is the second parameter of electrical energy.

As the science develops, people learned to model atmospheric electrical processes, inventing electrostatic, or as it is called otherwise electrophore machine:

This machine has become the first transducer of mechanical energy into electricity. However, the transformation it failed to make reversible. Although the car was the source of voltage and current, the problem was to make further transformations of electrical energy did not work. But over time, science revealed another cause of the occurrence electrical charges. Not only friction, but the magnetic field turned out to be able to create electricity.

This discovery turned out to be a completely defined development of technologies. When a metal wire and a permanent magnet appeared, the interaction of which in nature does not exist, it became possible to open electromagnetic induction. It turned out that the resulting electricity energy is directly related at the rate of mutual movement of the magnet and wires.

• Obviously, the frequency is the third parameter of electricity energy.

After the discovery of the phenomenon of electromagnetic induction, various electrical machines were invented, including electrical energy converters. The first of these were transformers, which made it possible to transmit electricity energy by wires for considerable distances. It turned out that alternating voltage at the ends of the coil winding is evenly distributed between its turns. On each turn, the same voltage is obtained.

Therefore, the number of turns of the winding will determine the voltage that can be used to power the new electrical circuit. It also turned out that the additional coil covered by the core of the coil outside the main winding has at its ends the same tension as the turn of the main winding. Such coils covering the general magnetic core began to be called transformers. If all coils are connected to a serial circuit at the same time, such a device was called the autotransformer.

The autotransformer with the same parameters of the transformation of electricity turns out to be more efficient than the transformer, since it exists an electrical connection between the windings. Therefore, it can pass a large electrical power to the consumer. In the transformer between the windings there is only an electromagnetic connection.

But this feature provides complete electrical insulation of windings from each other. For this reason, transformers are widely used in all electrical devicespowered by an electrical network to obtain secure power supply to these devices. Transformers allow you to change the voltage and current, leaving their frequency without any change. In this capacity they are still applied. And in distant power supply systems, transformers have achieved huge sizes. One of these aggregates is shown in the image below:

But after the appearance of transformers, another possibility of transformation of electricity was manifested.

Coils

It turned out that any coil reserves energy in an electromagnetic field. It exists some time after the winding of the coil ceases to flow electrotes. And at the ends of the winding of the coil during this time, the voltage continues to exist. Such a phenomenon began to be called as emf of self-induction. It also turned out that the magnitude of self-induction EMF depends on the speed of turning off the electric flow in the coil.

The faster the current is reduced, the greater the voltage at the ends of the winding. This electricity converter received its name by the surname of his inventor and became known as the "Rumkor's coil", the image of which is shown below the left. In the same principle, the classic ignition system of the automotive gasoline engine is working.

However, convert the voltage frequency and current for a long time could only be rotated. The synchronous motor, which rotated at the frequency determined by the feed voltage frequency, rotated the generator. To increase the frequency, it was possible to either use the reduction gear, or increase the number of generator poles, or both together. Similarly, the problem of obtaining rectified current was solved. Mechanical contacts, for example, the engine manifold passed only one half of the current period. These impulses came to the general electric chainand thus obtained the straightened current of both semi-dimensions.

Decisive contribution to the development of electricity transformation made electronic devices. They allowed to create rectifiers and frequency converters without moving parts, providing electricity parameters unattainable for devices created on mechanical principles. It became possible to create powerful high-frequency generators called inverters. An increase in frequency allowed several times to reduce the size of transformers.

Inverters

Inverters were further developed with the advent of powerful high-voltage semiconductor devices - transistors and thyristors. With their appearance, electricity transformation at high frequency swept almost all devices with sources of secondary power supply. Inverter schemes began to be widely used for electronic ballasts of gas-discharge lamps. At the same time, a higher quality of light was achieved with a significant economy of electricity.

Inverters and rectifiers for high-voltage power lines were the most powerful moment in the development of electricity transformation. Such long-range power supply schemes began to be applied quite a long time with the emergence of mercury valves - powerful specialized electrovacuum devices.

Then they were ousted by more efficient thyristors and transistors. Semiconductor electricity transducers make it possible to provide electrical power transmission in 3.15 gigavatt / hour per distance of 2400 km in modern system Power supply in Brazil. For such electricity transmission systems, the future. LED operating on constant current are deprived reactive resistance and electricity losses associated with alternating voltage and current.

They do not have other processes and phenomena, very distinguishing joint work of several electric generating and transmitting systems in a single power supply scheme. But friction and electromagnetism are not the only processes that are used to convert electricity. In about the same years, the opening of the phenomenon of electromagnetic induction was discovered a piezoelectric effect.

As a result, a group of minerals was found, and subsequently, materials with piezoelectric properties were artificially created. These properties are concluded in converting the mechanical effects applied to the sample of piezoelectric material into electrical pulses. But the inverse transformation of electrical pulses into the mechanical deformation of the sample is also possible. On the basis of such samples, you can make a transformer without windings and magnetic fields in the core and outside it.

Such a transformer will increase the applied voltage many times with minimal sizes and weight. It will be just a ceramic plate with soldered wiring.

In this case, the resulting power will not be large. But winnings in size and cost compared with the electromagnetic transformer will be significant. Such piezoelectric transformers are used in the sources of secondary power supply. All modern smokers also enjoy lighters, in which the spark is created by a miniature piezoelectric transformer.

Further development of electricity converters is a battle for increasing the frequency of voltage and current. This process is associated with the need to create new semiconductor devices and materials. In the writings of some fiction writers, the energy ray, used instead of LPP, is mentioned. Perhaps their prophecies will come true.

Voltage converter is a device that changes the voltage chain. In the literature of foreign implies: it concerns the chains of alternating voltage, otherwise the device is called the converter direct current. The latter are considered full-fledged members of the family.

Appointment of voltage converters

The need to use devices of this kind occurs when an electrical device is required to implement in the region, where the standards of industrial energy supply networks differ from the product stated by the developers. The frequencies and amplitude of the US voltage are opposed to Europe, Russia. We see a number of reasons. Tesla noted: With an increase in frequency, it is possible to dramatically reduce the weight of the copper winding of the transformer, when the value of the value of 700 Hz electricity becomes a large extent safe for the human body. In parallel, the loss of cores grow, the radiation of the electromagnetic wave begins into the space.

Voltage converter

Assessing the weight of the arguments, the United States under the influence of Nikol Tesla wealed the frequency of 60 Hz. In Russia (Europe), they took note of the arguments of the famous engineer of Dolivo Dobrovolsky (justified the profitability of the use of three-phase networks). Throughout Eurasia, the Etalon is the de facto 50 Hz. Voltage amplitudes chose comfortable. 220 volts are dangerous for a person, the consumer simultaneously spends smaller current. The cross section of copper conductors is permissible to significantly reduce. American 110 Volt. alternating current It is impossible to be safe completely. People are aware, sciences by militants, more than once the main character destroyed the enemy by the electric discharge of the local energy session.

The effect of parameters on the technique is described simply:

1. The frequency of engine speed is determined by the amplitude of the applied voltage. Vala rotation speed asynchronous engine A short-circuited rotor directly depends on the frequency of the supply network.
2. Heating devices are designed for a working current, proportional to the magnitude of the voltage. Resistance is predominantly active. Power changes fourwise (current is taken in square) with similar variation between networks 110/220 volts. The consumer expects from the product of nominal parameters, the device may not be designed for non-standard operation.
3. Household appliances in the composition often uses voltages different from networks with a strictly defined amplitude. Conditions of the power supply. For normal operation, a voltage converter is required.

Why is world practice different stresses

Electrification in mass order was carried out from the beginning of the 20th century. The great number of people participated, each pursued, in addition to objective, their own interests. Edison promoted constant pressure, Tesla called - variable. Dolvo-Dobrovolsky had the basis of the disadvantaged of the second scientist (conflict of interest in the field three-phase networks), perhaps, the frequency of 50 Hz introduced the USA, Europe listened to the opinion of the closer to the neighborhood of the engineer.

As for the USSR, there is no doubt: voltage at 220 volts is left only from the military, strategic considerations of confrontation in the Cold War. The diameter of the cigarette corresponded to the cartridge caliber for the speedy translation of the equipment to the production of specific products.

Location of voltage converters in general classification

• Direct current:

1. Voltage level converters (discussed above).
2. Voltage regulators.
3. Linear voltage stabilizer.

• Alternating current in permanent:

1. Rectifiers.
2. Power supplies.
3. Pulse voltage stabilizers.

• Permanent current in variable:

1. Inverters.

• AC voltage:

1. Transformers of various kinds.
2. Voltage converters.
3. Voltage regulators.
4. Form converters and voltage frequency.
5. Transformers variable frequency.

Voltage converters form two more classes. Power blocks first. Each contains in its composition the voltage converter. Transformer. Level converters are suitable for the domestic definition of the subject of the conversation, stand out in separate class. The question is set by the book M.A. Shustova on the topic under consideration.

Classification of voltage converters

Conduct the primary classification of voltage converters:

Using conventional transformers or autotransformers to convert the amplitude of the voltage, remember the frequency. Many engines designed to work at 60 Hz will overheat with networks of 50 Hz, let the voltage amplitude corresponds to the specified one. As for the built-in options for power supplies, it is not always possible to switch the settings. The product is able to be marked with a sticker (in addition to the factory nameplate), an explanatory device operating conditions, according to purpose. As for the discrepancies between Europe and Russia (230 - 220 \u003d 10 volts), the specified inconsistency does not greatly affect the work (there are negative moments). Noted in the previous topics, the effect of the parameter for the service life of the gas lights, electronic lamps.

In accordance with the design in electronics, voltage converters are divided as:

1. Bestrange condenser.
2. With switched capacitors.
3. Multiplexing.
4. Pulse converters.
5. Pulse power sources.
6. Transformer with pulsed excitation.
7. Autogeneral.
8. On piezoelectric transformers.

Stress converter design

With increasing frequency, losses caused by vortex currents in transformer cores are increasing. The phenomenon is trying to stop by elevating. The core is divided into plates, with a plane parallel lines magnetic field. Special electrical steel with high resistivity is used.

As the frequency grows, the magnetic flow is supplanted to the thickness of the core outward. Ferromagnetic materials are used to increase inductance. At high frequencies it becomes inappropriate by the above reason. Magnetic permeability ceases to grow, there is no point in making a similar core. Magnetodielectrics with extruded powder are widely used on HF. By eliminating the losses created by vortex currents. The power of the magnetic flux is greatly reduced. The frequency of the laws of change of current, voltage dictates the following rule ...

Energy stored by the converter for the period is proportional to the square of the tank or inductance of the system.

The devices use inductive or capacitive type drives. This explains the use of ferromagnetic materials with power supplies, explains why Tesla in experiments was different. A scientist for creating high frequency currents used oscillatory contours. Similarly, the technique of voltage converters is moving. For DC, the design looks like this:

1. The input voltage becomes simultaneously feeding.
2. The heart of the converter is the variable voltage generator. Famous multivibrator (trigger on two transistors), the image is available everywhere. Sometimes it is advantageous to use ready-made industrial series chips, inverters.
3. Resulting voltage variable, often rectangular shape. If necessary, it is amplified, multiplied or decreases (with the help of switched capacitors), it is rectified, the desired polarity is obtained (voltage polarity converter). Note: these cascades are sometimes performed on chips. Multiplexers are widely used for switching capacitors, stocking power.

Voltage converter is not built directly without a transformer. However, if deviate from strictly defined, it will be possible to solve a variety of tasks. Any multivibrator contains a RC chain, which applied Tesla. To obtain the voltage, polarity should be applied properly performed on diodes and filter capacitors. Rectifier is made by bridge (see).

Similar schemes in practice are found in electronics for a simple reason: it is difficult to get high power. Not created semiconductor keys, bypassing the limitation, the capacitance of the capacitors would need simply gigantic. Therefore, manufacturers are constantly fighting electricity saving.

PC system unit applies pulse transformersThe generation of stable purity is used quartz resonators. We indicate the difference. Work with high-frequency voltage, it allows you to significantly reduce the number of energy fluctuations stored for the period. Dimensions of transformers can be strongly reduced, harmful ferromagnetic cores to throw away at all, lowered weight. There are structural features and other kinds. According to an outstanding circuit engineer MA writes Shustov:

1. Inductive converters of smaller dimensions with other things being equal. Therefore, used for increased capacity. What we see on the example of transformers.
2. As for capacitive converters, it is profitable to use for small capacities. Recall the multivibrators with the RC chain.

They heard about the "transformers" of constant voltage. Permissible to attribute K. constructive features. The generator uses the link feedback - Crystal quartz. The sparkling capacitor controls the mode of operation of the transistor, the variable voltage in the form of an acoustic wave passes a piezoelectric element. By virtue of obvious circumstances, working frequencies lie in the field of MHz units, the power is small. It is clear that directly constant voltage system is incapable, the term transformer is applied allegorically.

Converter - This is an electrical device that converts electricity to one parameters or into electricity with other values \u200b\u200bof parameters or quality indicators. The parameters may be a gene and voltage, their frequency, phase number, voltage phase.

According to the degree of manageability, electrical energy converters are divided into unmanaged and managed. In the controlled converters, the output variables: voltage, current, frequency - can be adjusted.

In the element base, electricity transducers are divided into electromachines (rotating) and semiconductor (static). Electromachine transducers are implemented on the basis of the use of electrical machines and are currently relatively rare use in electric drives. Semiconductor transducers can be diode, thyristor and transistor.

By the nature of the electricity conversion, the power transducers are divided into rectifiers, inverters, frequency converters, AC voltage regulators and direct current transducers of the voltage phases of AC voltage.

In modern automated electric drives are used mainly semiconductor thyristor and transistor transistor transducers of constant and alternating current.

The advantages of semiconductor transducers are wide functionality Electricity transformation process control, high speed and efficiency, large service life, convenience and simplicity of maintenance during operation, wide opportunities By implementing protection, alarms, diagnostics and testing both the electric drive itself and technological equipment.

At the same time, certain disadvantages are characteristic of semiconductor transducers. These include: High sensitivity of semiconductor devices to current overloads, voltage and speed of their change, low noise immunity, distortion of the sinusoidal current and voltage of the network.

The rectifier is called an alternating current voltage converter into a constant (straightened) current voltage.

Unmanaged rectifiers Do not provide voltage regulation on the load and are performed on semiconductor unmanaged unilateral conductivity devices.

Controlled rectifiers Performed on controlled diodes - thyristors and allow you to adjust your output voltage due to the corresponding control.

Managed rectifier

Rectifiers can be non-obserted and reversible. Reversing rectifiers make it possible to change the polarity of the straightened voltage at its load, and non-obverse - no. In the number of phases of the supply input voltage of AC, rectifiers are divided into single-phase and three-phase, and according to the power part scheme - on the bridge and with zero output.

A DC voltage converter to AC voltage is called. These converters are used as part of the frequency converters in the case of the power of the electric drive from the AC network or as an independent converter when powering the drive from the direct voltage source.

In the mechanics of electric drives, the greatest use was found, implemented on thyristors or transistors.

Autonomous voltage inverters (AIN) have a rigid external characteristic, which represents the dependence of the output voltage from the load current, as a result of which, when the load current changes, their output voltage virtually does not change. Thus, the voltage inverter in relation to the load behaves like.

Autonomous current inverters (AIT) Have a "soft" external characteristic and possess the properties of the current source. Thus, the current inverter in relation to the load behaves like a current source.

Frequency converter (PC) An AC voltage converter is called standard frequency and voltage to the voltage of the alternating current of the adjustable frequency. Semiconductor frequency converters are divided into two groups: frequency converters with direct connections and frequency converters with intermediate DC link.

Frequency converters with direct links allow you to change the voltage frequency on the load only towards it decrease compared to the power supply voltage frequency. The frequency converters with the intermediate link of DC do not have a similar limitation and are widely used in the electric drive.

Industrial frequency converter for electric drive control

AC voltage regulator called the voltage converter of the AC standard frequency and voltage in adjustable voltage AC current of the same frequency. They may be single and three-phase and used in their power part, as a rule, single-separation thyristors.

DC voltage regulator A converter of an unregulated source voltage is constantly the current to the adjustable voltage on the load. In such converters, power semiconductor managed keys operating in a pulse mode are used, and the voltage control is due to the voltage modulation of the power supply voltage.

The greatest distribution was obtained at which the duration of voltage pulses with a constant frequency of their follows.

In general, the converter or voltage converter is an electrical device capable of converting one level or the view of this parameter to another. As a rule, speaking of voltage converters, they mean converters operating in AC circuits (AC / AC).

In other cases, these devices are called constant voltage converters (DC / DC) or inverters (DC / AC or AC / DC). The voltage conversion devices are found in practice everywhere. Differ and classified them on various features.

By destination, the converters are divided into:

Permanent voltage converters, namely:

• regulators;
• linear stabilizers.

Alternating voltage converters. This category includes:

• transformers different types;
• regulators;
• form converters and signal frequency.

Inverters to convert a constant voltage into a variable and vice versa. The group of inverters also includes:

• rectifiers;
• pulse stabilizers.

In addition, experts allocate in a separate category of power supplies, each of which contains any voltage converter. They are:

• built-in different species equipment;
• small-sized adapters (chargers) intended for power supply (charging) mobile phones, electronic gadgets and devices.

Pulse voltage converters

Pulse converters are applied in cases where you need to convert one voltage level to another. Most often, they are assembled on the basis of inductive or capacitive energy storage. From other sources of power, they are distinguished high level CPD, which achieves in some cases 95%.

The fundamental electrical circuits of pulse converters are performed using 4 x items:

• commuting element;
• energy storage (inductance coil, choke, condensers);
• blocking diode;
• condenser connected in parallel with load resistance.

Combinations of listed components can form any type of pulse converter.

The value of the outlet voltage is determined by the width of the pulses that control the switched element. At the same time, an energy supply is created in inductance coil. Stabilization is implemented due to feedback, that is, the width of the pulses varies depending on the value of the output voltage.

To create high frequency currents, converters collected using oscillatory contours are used. In this case, the DC voltage coming to the variable voltage generator (multivibrator, trigger) is simultaneously powered. The output impulses are usually rectangular.

The resulting variable voltage can be strengthened, lower, etc. It is also easy to straighten and get the necessary polarity. To do this, use the appropriate inclusion of diodes, and the rectifier is collected, for example, on a bridge circuit.

The voltage at the output of the pulse converters must be stabilized. For this, various kinds of stabilizers (pulse or linear) are used. True, due to the low efficiency, the latter are rarely used.

As for pulse stabilizers, they use a latitude or frequency modulation in their work. In the first case, the duration in the second is the frequency of pulses. There are devices with a combined method of stabilization.

Automotive voltage converters

With the increase in the number of cars, the need for use in the process of their operation of various household appliances, including 220V operating voltage operating from alternating voltage.

For this, automotive inverters were developed, with the help of which constant voltage from car battery +12 V (passenger cars) or +24 V (cargo vehicles) is converted to a variable 220 V. You can connect an electric shaler or an electric door, charge a laptop, etc.

The car inverter is a voltage generator, the form of which is approximate to the sinusoid. In this case, the current at the output of the device does not depend on the current value at the inlet and it can be adjusted almost from zero to the maximum. Similarly, theoretically, you can adjust the frequency and voltage.

Simplified electrical circuit the car converter can be represented as a transformer, on primary windows Which voltage is fed through thyristor keys. Alternately including thyristor windings create alternating current at the transformer output.

In this case, a modified (stepped) sinusoid is formed, but it does not affect the performance of most household appliances.

Converters for use in cars have a rather high efficiency, which reaches 90%, which indicates a sufficiently high quality of the resulting sinusoids.

The consumer during the operation of the device has the ability to choose one of the three modes of its operation:

1. Working mode that provides long-term operation of the inverter with a nominal power.
2. Overload mode, which allows you to get a significantly higher power from the device than when working in normal mode. However, in this mode, the inverter should not work for more than 30 minutes.
3. The starting mode is used if you need to obtain instantaneous power at high load (launch of the electric motor, etc.).

When choosing a converter for auto focus on its power. Its value must be obviously more power connected devices. In addition, the type of connected electrical appliances is also important. If the automotive inverter is supposed to connect devices that consume significant currents when started, it is necessary to acquire a device with an appropriate power (from 300 to 2000 W).

Voltage converters for home

Currently, the wide use of voltage converters are found in everyday life. They began to use at home as a backup or emergency power sources, the task of which to ensure household appliances In case of unauthorized disabling network of centralized power supply.

As a rule, the voltage converter for the house is a combination of an inverter with one or more batteries. In cottages and country houses (cottages) they are also complemented by devices capable of charging batteries.

In some cases, solar panels or wind generators can be used.

The inverters intended for use at home are most often connected by low-power household appliances:

• televisions;
• computers, etc.

At the same time, it is necessary to remember electrical appliances, for example, refrigerators, electrics, etc., which require power supply with a "clean sinusoid", which requires acquiring significantly more expensive devices.

In places where there is no centralized power grid, by calculating the necessary electrical power, organize a power supply system of an integer home. However, this will require the acquisition of sufficiently expensive equipment.

For example, the cost of an inverter with a capacity of 10 ... 60 kW is at least $ 20,000. The use of this kind of devices is advisable in the event of an organization of power supply systems based on alternative energy sources.

If you compare the classic uninterruptible power unit (UPS), working in Online mode, with a voltage conversion, then the combination of the "battery + inverter" components looks preferable for a number of reasons, including:

• sparing operation of batteries;
• big choice rechargeable batteries;
• the ability to parallel connecting multiple converters, etc.

In the domestic electric equipment market pulse converters Presented in a wide enough assortment. Especially popular, for example, products of the Taiwanese company Mean Well and the Dutch company VICTRON ENERGY.

Products of these manufacturers are distinguished by high quality and has large quantity Different functions. So DC / AC type converters provide deep discharge rechargeable batteriesBy controlling the magnitude of the minimum input voltage. They control the output parameters.

All models of these companies have a large power supply, which allows them to withstand large overloads arising from the start of electrical appliances. A number of devices provide a sinusoid at the output high QualityThat allows you to connect the most demanding electrical equipment.

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