Voltage transformer

Voltage converter is a device that changes the voltage of the circuit. In the literature of foreign means: it concerns the AC voltage circuits, otherwise the device is called a DC converter. The latter are considered full members of the family.

Purpose of

Voltage Converters The need to use devices of this kind arises when an electrical device is required to be implemented in a region where the standards of industrial power supply networks differ from those laid down by the product developers. The frequencies and amplitudes of the US voltage are opposed to Europe, Russia. We see a number of reasons. Tesla noted: with increasing frequency it is possible to dramatically reduce the weight of the copper winding of the transformer, when the parameter reaches the value of 700 Hz, electricity becomes much more safe for the human body. In parallel, the losses of cores grow, the emission of an electromagnetic wave into space begins.

Assessing the weight of the arguments, the United States, under the influence of Nikola Tesla, legalized the frequency of 60 Hz. In Russia( Europe), they took into account the arguments of the famous engineer Dolivo-Dobrovolsky( substantiated the benefits of using three-phase networks).Throughout Eurasia, they became the de facto benchmark of 50 Hz. The voltage amplitudes were chosen convenient.220 volts are dangerous to humans, the consumer simultaneously consumes less current. The cross section of copper conductors permissible significantly reduced. American 110 volts AC cannot be considered completely safe. People are aware, taught by the militants, more than once the protagonist destroyed the enemy by electrical discharge of the local grid.

The effect of the parameters on the technique is described simply:

1. The engine speed is determined by the amplitude of the applied voltage. The rotation speed of an asynchronous motor with a short-circuited rotor directly depends on the frequency of the mains supply.
2. Heating devices are rated for operating current proportional to voltage. Resistance is predominantly active. Power varies four times( the current is taken in a square) with a similar variation between 110/220 volt networks. The consumer expects from the product nominal parameters, the device may not be designed for non-standard operation.
3. Household appliances in the composition often use voltages different from the network with a strictly defined amplitude. Power supply conditions are provided. A voltage converter is required for normal operation.

Why world practice different voltage

Electrification has been carried out in large numbers since the beginning of the XX century. A great number of people participated, each pursuing, besides objective, own interests. Edison promoted constant tension, Tesla out of spite - variable. Dolivo-Dobrovolsky had reason to dislike the second scientist( conflict of interests in the field of three-phase networks), perhaps the frequency of 50 Hz was introduced in defiance of the United States, Europe listened to the opinion of the closer engineer around that neighborhood.

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

The location of voltage converters in the general classification of

With the permission of the authors of Wikipedia, we give a classification of various types of electrical power converters so that readers understand where the subject of today's talk is located:

• DC:

1. Voltage level converters( discussed above).
2. Voltage Regulators.
3. Linear voltage regulator.

• Alternating Current to DC:

1. Rectifiers.
2. Power Supplies.
3. Switching voltage regulators.

• DC to AC:

1. Inverters.

• AC Voltage:

1. Transformers of various kinds.
2. Voltage Converters.
3. Voltage Regulators.
4. Voltage shape and frequency converters.
5. Variable Frequency Transformers.

Voltage converters form two more classes. Power supplies first. Each contains in its composition voltage converter. Transformer. Level converters fit the domestic definition of the subject of conversation, stand out in a separate class. The question is put the book MA.Shustov on the subject.

Classification of voltage converters

Let's conduct the primary classification of voltage converters:

• First of all, power supply units of equipment. We are sure that the system blocks of personal computers will seem close to readers. Let's look inside. The switching power supply unit of a personal computer contains a transformer with a multitude of windings, each operating at the same rating. From an alternating voltage of 230( or 110) volts, a series of constants is obtained: +5, -5, +12, -12.But! The subsequent rectification of alternating current by Schottky diodes.
  

  A voltage switch is built into the

• power supply unit. Secondarily, adapters for localizing equipment. In most household appliances, the option is considered to be built into the power supply( see photo).It is enough to switch the toggle switch on the back of the system unit, changing the working conditions. Be vigilant, avoid incorrect voltage settings in order not to disable the equipment.
• Cell phone adapters, gadgets can not be fully called voltage converters. Rather, modules that include the subject of today's topic in its composition.

Using conventional transformers or autotransformers to convert the amplitude of the voltage, remember the frequency. Many engines designed to operate at 60 Hz will be overheated by networks of 50 Hz, let the voltage amplitude correspond to the given one. As for the built-in power supply options, it is not always possible to switch settings. The product is capable of being marked with a sticker( in addition to the nameplate), which is available explaining the operating conditions of the device, according to its intended purpose. As for the discrepancies between Europe and Russia( 230 - 220 = 10 volts), this discrepancy does not greatly affect the work( there are negative points).Noted in the previous topics the effect of the parameter on the service life of incandescent light bulbs.

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

1. Transformer-free capacitor.
2. With switched capacitors.
3. Multiplex.
4. Pulse Converters.
5. Switching power supplies.
6. Transformer with pulse excitation.
7. Oscillators.
8. On piezoelectric transformers.

Design of voltage converters

With increasing frequency, losses due to eddy currents in the cores of transformers increase. Phenomenon trying to stop by shchitovaniya. The core is divided into plates, with a plane parallel to the lines of the magnetic field. Special electrical steel with high resistivity is used.

As the frequency increases, the magnetic flux is forced out of the core to the outside. Ferromagnetic materials are used to increase inductance. At high frequencies it becomes impractical for the above reason. Magnetic permeability ceases to grow, it makes no sense to make such a core. At HF, magnetodielectrics by extruded powder are widely used. Eliminating losses created by eddy currents. Magnetic flux is greatly reduced. The frequency of the laws of current, voltage changes dictates the following rule. ..

The energy stored by the converter over a period is proportional to the square of the capacitance or inductance of the system.

Devices use inductive or capacitive type drives. This explains the use of ferromagnetic materials by power units, explains why Tesla in experiments went a different way. The scientist used oscillatory circuits to create high frequency currents. In a similar way, voltage transducer technology is moving today. For direct current design looks like this:

1. The input voltage becomes simultaneously energized.
2. The ac voltage generator is the heart of the converter. Known multivibrator( trigger on two transistors), the image is available everywhere. Sometimes it is beneficial to use ready-made industrial series chips, inverters.
3. The resulting voltage is variable, often rectangular. If necessary, it is amplified, multiplied or lowered( with the help of switched capacitors), straightened, the desired polarity is obtained( voltage polarity converter).Note: these cascades are sometimes performed on chips. Multiplexers are widely used for switching capacitors that store power.

The voltage converter is not built directly without a transformer. However, if one deviates strictly from the definition, it will be possible to solve various problems. Any multivibrator contains the RC chain, which Tesla applied. To obtain the voltage you need polarity, a properly made inclusion of diodes and filter capacitors is applied. The rectifier is made as a bridge( see Diode Bridge).

Similar schemes in practice are found in electronics for a simple reason: it is difficult to obtain high power. No semiconductor switches were created that bypassed the limitation; the capacitors would simply require giant capacitors. Therefore, manufacturers are constantly struggling to save electricity.

The PC system unit uses pulse transformers, generating stable purity using quartz resonators. We indicate the difference. Work with high-frequency voltage, can significantly reduce the amount stored during the period of energy fluctuations. Dimensions of transformers can be greatly reduced, harmful ferromagnetic cores to throw at all, lower weight. There are design features of another kind. As writes outstanding circuitry MAShustov:

1. Inductive converters of smaller dimensions, all other things being equal. Therefore, apply for high power. What we see on the example of transformers.
2. As for capacitive transducers, it is advantageous to use for low power. Recall the multivibrators with RC chain.

Heard about the "transformers" of constant voltage. Acceptable attributed to design features. The generator uses a feedback link - a quartz crystal. The storage capacitor controls the mode of operation of the transistor, the alternating voltage in the form of an acoustic wave passes the piezoelectric element. Due to obvious circumstances, the operating frequencies lie in the range of MHz units, the power is low. It is clear that the system is unable to transmit the direct voltage directly, the term transformer is used allegorically.