Any voltage converter is an electrical or electronic device capable of changing its value by the required value. This device is especially in demand in situations where it is necessary to connect a load with different voltage ratings to the network. Moreover, they can not only lower the value of this parameter, but also increase it.
Principle of operation
The main requirement that determines the principle of operation of voltage converters is the ability to transfer useful power to the output with minimal losses (to ensure maximum efficiency). To do this, they often use modules that are economical in terms of losses, for example, electronic inverters. An electrical voltage converter built according to a transformer circuit is the most convenient for considering the principle of operation. The essence of its functioning is as follows:
- at the input of the device, the potential comes from an alternating voltage generator or a similar current source;
- a signal similar in shape is taken from the output of the transformer (from its secondary winding);
- if necessary, the alternating output voltage is first rectified by a special diode unit, and then stabilized.
It is very difficult to achieve the desired efficiency from such a scheme, since part of the transmitted power is lost in the transformer windings (due to heat dissipation).
To get high efficiency from the device, key circuits operating in economical mode are installed at the output of the transformer. When they work, based on the high-speed switching of transistors from the closed state to the open state, the power losses in the windings are significantly reduced.
Self-induction is traditionally used in voltage converters designed to operate with high-voltage power supplies. It is realized in the output ferrite cores with a sharp interruption of the current in the primary winding. All the same transistors are used as such a chopper, and the pulse voltage obtained at the output is then rectified. Such circuits make it possible to obtain high potentials of the order of several tens of kV. They are used in power circuits of already obsolete cathode ray tubes, as well as in television picture tubes. In this case, it is possible to obtain a good efficiency (up to 80%).
Areas of use
The scope of application of multi-zone voltage converters is very extensive. They are traditionally used for the following purposes:
- in linear devices for the distribution and transmission of electricity;
- for carrying out such critical technological operations as welding, heat treatment and the like;
- when it is necessary to supply power to load circuits in various fields of technology.
In the first case, the EMF generated at power plants is increased with the help of these devices from 6-24 kV to 110-220 kV - in this form, it is easier to "drive" it along wires over long distances. At regional substations, already other transformer devices ensure its reduction, first to 10 (6.3) kV, and then to the usual 380 Volts.
When servicing technological equipment, voltage converters are used as electrothermal installations or welding transformers.
The most extensive area of application is the provision of quality food for the following industrial designs of consumers:
- equipment operating in automatic control and monitoring lines;
- telecommunication and communication devices;
- a wide range of electrical measuring instruments;
- special radio and television equipment and the like.
A special function is performed by the so-called "isolation" transformers used to isolate the load lines from the high-voltage input.
Since such converters "play an auxiliary role", they most often have low power and relatively small dimensions.
In everyday life, medicine and defense industry
Voltage converters are widely used in everyday life. Most of the power supplies used to charge household appliances, as well as more complex devices such as:
- Surge Protectors;
- redundant power supplies, etc.
These devices are most in demand in medicine, the military sphere, as well as in energy and science. In these industries, especially "stringent" requirements are imposed on them regarding the quality of the converted voltage ("purity" of the sinusoid, for example).
Advantages and disadvantages
The advantages of voltage converters include:
- the ability to control the parameters of the output signal - converting its variable value into a constant value using the principle of frequency conversion;
- availability of an option for switching input and output circuits (varying the voltage amplitude);
- admissibility of adjusting their nominal values for a specific load;
- the compactness and simplicity of the design of household converters, which are often manufactured in a modular or wall-mounted version;
- profitability (according to manufacturers' statements, their efficiency reaches 90%);
- ease of use and versatility;
- the possibility of transmitting electricity over long distances and ensuring the operation of particularly critical industries.
The disadvantages include high cost and low moisture resistance (with the exception of models designed specifically for work in high humidity conditions).
Varieties of converters
- special devices for the home;
- high voltage and high frequency equipment;
- transformerless and inverter pulse devices;
- DC voltage converters;
- adjustable devices.
This category of electronic devices includes current-to-voltage converters.
An ordinary user constantly comes across this type of converting devices, since most models of modern technology have a built-in power supply. Uninterruptible power supplies (UPS) with a built-in battery belong to the same class.
In some cases, household converters are made according to a double ring (inverter) scheme.
Due to such a conversion from a direct current source (battery, for example), it is possible to obtain an alternating voltage of a standard value of 220 volts at the output. A feature of electronic circuits is the possibility of obtaining a purely sinusoidal signal of constant amplitude at the output.
These units are capable of the value of the output voltage and increase it. In practice, there are more often devices that allow you to smoothly change the reduced value of the output potential.
The classic case is when 220 volts act at the input, and an adjustable constant voltage of 2 to 30 volts is obtained at the output.
Devices with fine adjustment of the output parameter are traditionally used to test dial and digital measuring instruments in modern research laboratories.
Transformerless (inverter) units are built on an electronic principle, involving the use of a separate control module. A frequency converter is used as an intermediate link in them, which brings the output signal to a form convenient for rectification. In modern samples of inverter equipment, programmable microcontrollers are often installed, which significantly increase the quality of conversion control.
High-voltage devices are represented by the station transformers already described, which increase and decrease the transmitted voltage in the desired ratios.
When transferring energy through high-voltage lines and subsequent transformation, they strive to reduce its losses in watts to a minimum.
This class also includes devices that generate a signal to control the beam in a television tube (kinescope).