In this article you will learn everything about converters, what role they play in the field of measurements, consider all types of converters, describe the advantages and disadvantages of individual types of converters, and also consider areas of application.
What is a converter
A transducer is a device that converts energy from one form to another to make it readable for measurement. So it converts the energy into a readable form, e.g. thermometer that converts thermal energy into the height of mercury. In a converter, the output is controlled by the input.
Role of the converter
They play a vital role in the measurement field. As we said earlier, a transducer converts a physical quantity into an electrical signal. Thus, without a transducer, it would be very difficult to measure a continuous physical quantity such as light intensity, speed, flux, temperature, radiation, electric flux, etc. The quantities are first converted into an electrical signal, then they are controlled by special equipment. Some could not imagine measuring these continuous physical quantities without sensors.
Types of converters
They are broadly divided into two categories;
- Active converter
- Passive converter
Active converter.
To operate this type of converter, an external power source is required. Energy is supplied through a separate voltage source. An example is potentiometer, which measures resistance by passing a minute current through itself. Most converters are now active.
Passive converter.
They convert one form of energy into another without using energy. Passive converters convert physical quantities such as temperature, pressure, speed, etc.
Sensors are divided into:
- Resistive converter
- Thermistors
- Inductive converter
- Capacitive converter
- Displacement sensors
- Speed converters
- Pressure transducers
Resistive converter
These converters operate on the principle of changing resistance. Resistance changes in several ways, including:
- Using physical stress;
- Change of light on the photosensitive element;
- Temperature change.
RTD - Abbreviated as Resistive Temperature Detector
The resistance of an RTD changes with temperature, and this resistance change is monitored in terms of current/voltage changes. Typically RTDs are made from materials such as platinum. Ni and Germanium are used to make resistance thermometers for special applications. When it comes to performance, Platinum RTD (PRDS) are the best. The thermometer uses resistance thermometers with a range between BP O2 and the melting point of antimony.
Application:
- Widely used for high temperature measurement.
Thermistors
It is temperature sensitive. Like RTS, their resistance changes with temperature. However, they are made from a material that has a negative temperature coefficient (that is, resistance decreases as temperature increases), unlike RTS, which have a positive temperature coefficient. Thermistors are encapsulated in a transition metal oxide-like material. These oxides exhibit a high change in resistance with a small change in temperature. Thus, they are more sensitive, almost 400 times more sensitive than IC thermocouple. They are ideal for measuring the temperature of animal body microcircuits.
Main advantages:
- Sensitive enough to sense temperatures down to 0.01C;
- Chemically stable;
- Fast response time;
- Small size.
Flaw:
- Limited temperature range from -50C to 300C.
Inductive converter
Inductive transduction occurs when the measured quantity changes the inductance (Self or mutual) of the coil. A simple way to change -L is to move the sensing element in a magnetic field. This movement causes collateral emf.
Main advantages:
- There is no wear due to the absence of a sliding contact, as is the case with a potentiometer.
Applications:
- Linear variable differential transformers (LPDT)
- A tachometer uses an inductive transducer to convert speed into an electrical signal to control speed.
Capacitive converters
In converters of this type, the measured quantity changes the capacitance of the circuit. This change is monitored in terms of some other physical quantity.
Applications:
- Automatic LCD touch system.
- A capacitive microphone that uses acoustic pressure to change the position of the plate. This change is monitored in terms of an audible signal.
Displacement sensors
This type of sensor is used to determine the position of an object. The physical variable being measured (i.e. motion) is intended to change resistance. This change in resistance is measured in terms of voltage.
Applications:
- Quite sensitive for monitoring cracks in walls and buildings.
Speed sensor
They work on the basic principle of a generator, according to which, when there is relative motion between the conductors and the magnet, an emf is generated. The generated voltage is speed controlled. Thus, the faster the relative motion, the greater the emf created will be.
Applications:
- They are widely used in speed monitoring devices such as car speed meter.
A device for converting direct current (for example 12 V) into alternating current (for example 220 V) with or without changing the voltage value. Usually it is a periodic voltage generator, similar in shape to a sinusoid. Moreover, it is theoretically possible to obtain any current at the output, with any necessary parameters. The current received at the output does not depend on the input - inverters allow you to obtain not static current parameters at the output, but to regulate it from zero to maximum, at any frequency and any voltage. Sources of 12 volt DC power are usually rechargeable batteries.
There are two groups of inverters that differ in cost:
The first group of more expensive inverters provides a sinusoidal output voltage.
The second group provides a simplified output voltage that replaces a sine wave. The most commonly used signal is the trapezoidal sine.
The principle of operation of the inverter, if we simplify the process itself, is as follows - it is a transformer, to the primary winding of which 2 thyristors are connected. They open one by one. As a result, either the left or right windings work. They are directed in agreement and counter. This means that in the secondary winding a current of both positive and negative appears alternately. Currents in the winding increase and decrease, in the secondary winding as well, but also changing the direction of the current, depending on which primary winding is currently active. True, at the output we get a modified sinusoid, stepped, not smooth, but this is not essential for the operation of the devices. The main problem in inverters is not the conversion circuit itself, but ensuring the coordinated operation of all conversion elements. There are essentially three processes: the forward current decreases to zero, then the application of the forward voltage is delayed until the blocking ability is restored, and the current in the second thyristor increases. These processes can be either simultaneous or sequential. But preventing failures in the sequence of processes is the most difficult task.
For the vast majority of household appliances, it is acceptable to use alternating voltage with a simplified waveform. The sine wave is important only for some telecommunications, measuring, laboratory instruments, medical equipment, as well as professional (HI-FI, HI-END, DJ) audio equipment.
The choice of inverter is made based on the peak power consumption of standard voltage 220V/50Hz.
There are three operating modes of the inverter:
- Continuous operation mode. This mode corresponds to the rated power of the inverter.
- Overload mode. In this mode, most inverter models can deliver power 1.2-1.5 times the rated value for several tens of minutes (up to 30).
- Starter mode. In this mode, the inverter is capable of delivering increased instantaneous power within a few milliseconds to ensure the start of electric motors and capacitive loads.
Within a few seconds, most inverter models can deliver 1.5-2 times the rated power. A strong short-term overload occurs, for example, when turning on a refrigerator.
Why do you need a voltage converter (inverter)?
The simplest and most common use of an inverter is to use it as a backup or emergency power source for household appliances that consume 220 Volt alternating current.
Using an inverter, you can connect almost any household appliance: kitchen or office equipment, power tools or TV.
For example: the electricity was turned off at your dacha, and you have no light, you won’t be able to watch your favorite TV series in the evening, and, what’s most unpleasant, the refrigerator is leaking. With an inverter and batteries, you can provide yourself with electricity for at least a few hours.
Another example. The inverter is useful for using power tools (drills, saws, planes, etc.) autonomously, from a car battery, during the construction or repair of objects where there is no 220 V network nearby. The inverter is also very convenient for fishermen and hunters.
An uninterruptible power supply system installed in your home, which includes batteries and an inverter, will allow you to become independent from interruptions in the 220 V power grid. In the event of a power outage, the lighting and appliances of your home will be powered by batteries through the inverter. Once the electricity supply is restored, the inverter will automatically charge the batteries.
A generator can also be used as a backup power source, but the inverter system has advantages, such as being silent, and also the fact that you do not need to buy gasoline/diesel fuel and do not need to change the oil and filters in the generator engine. The inverter system has no moving parts and is therefore more reliable and requires virtually no maintenance.
In some uninterruptible power supply systems for cottages, inverter power systems can be supplemented with a generator to recharge batteries and achieve longer battery life.
What are the main characteristics of inverters?
The main characteristic of an inverter is power (Watt), and also a characteristic of more expensive inverters is the presence of a sinusoidal voltage at the output.
How do inverters differ from each other?
As already mentioned, first of all, power. In addition, the input voltage (12, 24, 48, 96, 240 V), the type of output alternating current (pure or modified sine wave), the presence of a built-in charger, the presence of a load switching relay, the type of output connection (sockets on the body of the inverter itself or terminal connections for wires), as well as the presence of additional functions, such as, for example, the ability to program operating parameters, the presence of remote control or various control relays.
How to connect a voltage converter (inverter)?
Portable inverters up to 180 W have a plug that can be plugged into a car cigarette lighter. This is convenient, but the power of such a connection is extremely limited. Most portable car inverters up to 500 watts will give you 220 volts of power for 30-60 minutes from your car battery, even if the car is not running. This time depends on the condition and age of the battery, as well as on the power consumption of the 220 volt equipment being switched on. If you use the inverter with the car's engine off, keep in mind that your battery will drain and you will need to turn on the engine to charge it every hour for at least 10 minutes.
More powerful portable inverters (from 300 to 1200 W) have terminals with clamps that are rigidly connected to the battery or connected directly to the on-board power supply of a car, yacht, etc. to avoid sparking of the contacts.
The basic rule is to use thick wires of the shortest possible length to connect direct current. If it is necessary to install the inverter away from the battery, it is recommended to increase the length of the 220 volt AC wires (for example, use an extension cord). It is recommended to make the DC connection (from the batteries to the inverter) no more than 3 meters, since the DC attenuation increases and the battery discharge accelerates.
Which type of inverter is better - pure or modified sine?
Advantages of inverters with a pure sine wave output current of 220 volts:
1. The 220 volt AC waveform at the inverter output has extremely low harmonic distortion values, and is practically no different from the standard 220 volt household voltage.
2. Inductive motors in microwave swords, as well as other household appliances containing electric motors, operate faster and generate less heat.
3. Less noise in devices such as hair dryers, fluorescent lamps, audio amplifiers, faxes, game consoles, etc.
4. Less chance of computer freezing, printer printing errors, monitor interruptions and noise.
5. Reliable operation of the following devices that may not function with modified sine wave current:
Laser printer, copier, magneto-optical drive
Some laptops
Some fluorescent lamps
Transistorized, variable speed power tools
Some chargers for cordless power tools
Microprocessor controlled devices
Digital clock with radio
Sewing machines with variable motor speed and microprocessor control
Some medical devices (such as oxygen concentrators)
Modified sine wave inverters will work with most electrical appliances. If your task is to provide uninterrupted power for home lighting, TV, refrigerator, then an inverter with a modified sine wave will be the most economical solution. Pure sine inverters are designed to work with more sensitive equipment.
My voltmeter shows 190 volts when measuring voltage from a modified sine wave inverter. Do I have a faulty inverter?
No, there is nothing wrong with your inverter. A conventional tester can give an error of 20% to 40% when measuring the voltage of an inverter with a modified sine wave. For correct measurements, use an “effective value” tester, also called a “root mean square” or “TRUE RMS” tester. Such a device is much more expensive than ordinary cheap multimeters, but only it can show the correct voltage of an inverter with a modified sine wave.
What are the best batteries to use?
We recommend using stationary maintenance-free VRLA batteries made using AGM or gel technology, which have a number of advantages, among which the main ones are quality and durability, as well as the absence of problems with acidic and explosive fumes.
What battery capacity is needed for an uninterruptible power supply system at home?
This depends on several factors:
1. What battery life do you need for your devices?
2. What is the total consumption of your devices (Watts) that require autonomous power supply?
3. What is the input voltage of your inverter?
Based on this, the battery is selected.
Features of the operation of TV and audio equipment.
Although all inverters are shielded devices to reduce interference, some interference that affects the signal quality may still occur (especially with a weak signal).
Here are some tips:
First of all, make sure that the antenna produces a normal signal under normal conditions, without an inverter. Make sure the antenna cable is of good quality.
Try changing the location of the antenna, TV and inverter relative to each other. Make sure the DC wires are as far away from the TV as possible.
Twist the TV's power wires and the wires connecting the battery to the inverter.
Place the filter on the TV's power cord.
Some inexpensive audio equipment may produce a slight hum when running on an inverter. The solution to this problem is only to purchase better equipment.
To convert direct current into alternating current, special electronic power devices called inverters are used. Most often, an inverter converts DC voltage of one value into AC voltage of another value.
Thus, an inverter is a generator of periodically varying voltage, and the voltage shape can be sinusoidal, close to sinusoidal or pulsed. Inverters are used both as independent devices and as part of uninterruptible power supply (UPS) systems.
As part of uninterruptible power supplies (UPS), inverters allow, for example, to obtain continuous power supply to computer systems, and if the network voltage suddenly disappears, the inverter will instantly begin to power the computer with energy received from the backup battery. At least the user will have time to shut down correctly and turn off the computer.
Larger uninterruptible power supply devices use more powerful inverters with batteries of significant capacity, capable of autonomously powering consumers for hours, regardless of the network, and when the network returns to normal again, the UPS will automatically switch consumers directly to the network, and the batteries will begin to charge.
Technical side
In modern technologies for converting electricity, an inverter can only act as an intermediate link, where its function is to convert voltage by transforming at a high frequency (tens and hundreds of kilohertz). Fortunately, today this problem can be easily solved, because for the development and construction of inverters, both semiconductor switches are available that can withstand currents of hundreds of amperes, as well as magnetic circuits with the required parameters, and electronic microcontrollers specially designed for inverters (including resonant ones).
Requirements for inverters, as for other power devices, include: high efficiency, reliability, and the smallest possible dimensions and weight. It is also necessary that the inverter maintains the permissible level of higher harmonics in the input voltage, and does not create unacceptably strong impulse noise for consumers.
In systems with “green” electricity sources (solar panels, wind turbines), Grid-tie inverters are used to supply electricity directly to the general network - inverters that can operate synchronously with the industrial network.
During operation of the voltage inverter, a constant voltage source is periodically connected to the load circuit with alternating polarity, while the frequency of connections and their duration are formed by a control signal that comes from the controller.
The controller in the inverter usually performs several functions: adjusting the output voltage, synchronizing the operation of semiconductor switches, and protecting the circuit from overload. In principle, inverters are divided into: autonomous inverters (current inverters and voltage inverters) and dependent inverters (grid-driven, Grid-tie, etc.)
Inverter circuit design
The semiconductor switches of the inverter are controlled by a controller and have reverse shunt diodes. The voltage at the inverter output, depending on the current load power, is regulated by automatically changing the pulse width in the high-frequency converter unit, in the simplest case it is.
The half-waves of the output low-frequency voltage must be symmetrical so that the load circuits in no case receive a significant constant component (for transformers this is especially dangerous); for this, the pulse width of the low-frequency block (in the simplest case) is made constant.
In controlling the output switches of the inverter, an algorithm is used that ensures a sequential change in the power circuit structures: direct, short-circuited, inverse.
One way or another, the magnitude of the instantaneous load power at the inverter output has a pulsating character with double the frequency, so the primary source must allow such an operating mode when pulsating currents flow through it, and withstand the corresponding level of interference (at the inverter input).
If the first inverters were exclusively mechanical, today there are many options for semiconductor-based inverter circuits, and there are only three typical circuits: bridge without a transformer, push-pull with zero terminal of the transformer, bridge with a transformer.
A bridge circuit without a transformer is found in uninterruptible power supply devices with a power of 500 VA or more and in automotive inverters. A push-pull circuit with a zero transformer terminal is used in low-power UPSs (for computers) with a power of up to 500 VA, where the voltage on the backup battery is 12 or 24 volts. A bridge circuit with a transformer is used in powerful uninterruptible power supplies (for units and tens of kVA).
In voltage inverters with a rectangular output, a group of switches with freewheeling diodes is switched so as to obtain an alternating voltage across the load and provide a controlled circulation mode in the circuit.
The proportionality of the output voltage is determined by: the relative duration of control pulses or the phase shift between the control signals of groups of keys. In an uncontrolled reactive energy circulation mode, the consumer influences the shape and magnitude of the voltage at the inverter output.
In voltage inverters with a step output, the high-frequency pre-converter generates a unipolar step voltage curve, roughly approximating a sinusoid in shape, the period of which is equal to half the period of the output voltage. The LF bridge circuit then turns the unipolar step curve into two halves of a multipolar curve, roughly resembling a sine wave in shape.
In voltage inverters with a sinusoidal (or almost sinusoidal) output waveform, the high-frequency preliminary converter generates a constant voltage close in magnitude to the amplitude of the future sinusoidal output.
After this, the bridge circuit forms a low-frequency alternating voltage from a direct voltage, using multiple PWM, when each pair of transistors at each half-cycle of the output sinusoid is opened several times for a time varying according to a harmonic law. The low-pass filter then extracts a sine wave from the resulting shape.
The simplest circuits for preliminary high-frequency conversion in inverters are self-generating. They are quite simple in terms of technical implementation and are quite effective at low powers (up to 10-20 W) for powering loads that are not critical to the energy supply process. The frequency of self-oscillators is no more than 10 kHz.
Positive feedback in such devices is obtained from saturation of the transformer magnetic circuit. But for powerful inverters such schemes are not acceptable, since losses in the switches increase, and the efficiency ends up being low. Moreover, any short circuit at the output disrupts self-oscillations.
Better circuits for preliminary high-frequency converters are flyback (up to 150 W), push-pull (up to 500 W), half-bridge and bridge (more than 500 W) on PWM controllers, where the conversion frequency reaches hundreds of kilohertz.
Types of inverters, operating modes
Single-phase voltage inverters are divided into two groups: with pure sine wave output and with modified sine wave. Most modern devices allow a simplified form of the network signal (modified sine wave).
A pure sine wave is important for devices that have an electric motor or transformer at the input, or if it is a special device that works only with a pure sine wave at the input.
Three-phase inverters are typically used to create three-phase current for electric motors, such as power supply. In this case, the motor windings are directly connected to the inverter output. In terms of power, the inverter is selected based on its peak value for the consumer.
In general, there are three operating modes of the inverter: starting, continuous and overload mode. In the starting mode (charging the capacity, starting the refrigerator), the power can for a split second exceed twice the inverter rating; this is acceptable for most models. Long-term mode - corresponding to the inverter rating. Overload mode - when the consumer's power is 1.3 times higher than the nominal - in this mode, the average inverter can operate for about half an hour.
Basic information
The basis of any email. A device intended for measuring a non-electrical quantity (hereinafter referred to as INV) is a measuring transducer used to convert the measured non-electrical quantity into an electrical one, i.e. input to output. Ypres. There can be both converters for their intended purpose and other converters with a specific function
Classification of converters according to operating principle(i.e. according to the physical phenomenon that is used to convert quantities).
- parametric– converters in which the measured quantity (hereinafter referred to as IV) is converted into electrical parameters such as resistance R, inductance L, mutual inductance M, capacity C. When using, an auxiliary power source is required.
- generator- converters in which INV is converted into EMF. They themselves are a source of electricity, and an auxiliary source is needed only to enhance the converting quantity.
- 1) Rheostat - a rheostat, the engine of which moves under the influence of the measured non-electrical quantity X, creating a dependency:
R=f(x), where R is the resistance of the converter
Input value the transducer is the linear or angular movement of the engine; day off– change in its resistance.
The conversion device is shown in Fig. 12.1
It consists of a frame 1, on which a wire 2, made of a material with high resistivity, is wound, and a current removable motor 3, mounted on an axis 4. 5 - conclusions.
The winding frame can also have a variable cross-section (dashed line), then the transformation function R=f(x), (where x is the displacement) is nonlinear, or the frame can be circular, then R=f(α) (α is the angular displacement ).
When the motor moves along the frame by the winding pitch ∆x=λ, the resistance changes to ∆R=(dR/dx)λ, where dR/dx is the derivative of the required conversion function R=f(x) with respect to the movement of the motor. When the engine moves from one turn to another, the resistance changes by an amount equal to the resistance of one turn.
They are used in instruments for measuring linear and angular movements.
- 2) Inductive - designed to convert movement into an electrical signal. They are the most compact, noise-resistant, reliable and economical IPR.
The main elements of the inductive converter (Fig. 1) are coil with two or more windings and a movable one located inside the coil anchor.
Depending on the arrangement and connection of the windings, inductive converters are available in two main types:
- differential transformer
(Fig. 2) - have a primary winding and two secondary windings connected towards each other. When the armature is located symmetrically to the secondary windings, Va = Vb and the total voltage at the terminals of the secondary windings is zero. When the armature is displaced in any direction, for example, to the left (Fig. 3), the voltage on one of the secondary windings increases, and on the other it decreases. This leads to the appearance at the terminals of the secondary windings of a voltage (signal) equal to Va - Vb and proportional to the displacement of the armature from the symmetry position. This signal is perceived by a secondary device and converted into a form that is most convenient for perception by humans or computers.
When the armature is located symmetrically to the secondary windings, Va = Vb and the total voltage at the terminals of the secondary windings is zero. When the armature is displaced in any direction, for example, to the left, when an alternating voltage Ve is applied to the primary winding, voltages of the same frequency Va and Vb are induced in the secondary windings, directed at each instant towards each other.
- half bridge
(Fig. 4) - have two windings connected towards each other, forming half of the inductive bridge. Its second half is formed by the input divider of the secondary device. When the armature is positioned symmetrically to the windings, the bridge is balanced and the voltage in its diagonal is zero. The displacement of the armature causes a proportional imbalance of the bridge. The imbalance signal is converted in the same way as in the previous case.
The inductive transducer consists of a housing (Fig. 5), in which a spindle is placed on the rolling guides, at the front end of which there is a measuring tip, and at the rear end there is an armature. The guide is protected from external influences by a rubber cuff. The armature connected to the spindle is located inside the coil fixed in the body. In turn, the coil windings are electrically connected to a cable fixed in the housing and protected from kinks by a conical spring. At the free end of the cable there is a connector used to connect the converter to a secondary device. The body and spindle are made of hardened stainless steel. The adapter connecting the armature to the spindle consists of a titanium alloy. The spring that creates the measuring force is centered, which eliminates friction when the spindle moves.
Induction – a converter in which the measured non-electrical (mechanical) quantity is converted into an induced one “LC/ According to the law of electromagnetic induction, the induced emf E determined by the rate of change of magnetic flux F, coupled to a coil of w turns: w
They are used to measure rotation speed (in tachometers), vibration parameters - for measurements of time-varying linear and angular displacements and accelerations (in vibrometers and accelerometers).
- 3) Induction - are based on the use of the phenomenon of electromagnetic induction, according to which the EMF in the circuit is determined by the formula e= dФn/dt, where Ф is the magnetic flux, n is the number of turns of the circuit.
Thus, day off the quantity is the emf, and input– rate of change of flow.
In general, an induction converter is a coil with or without a core located in a magnetic field. When one of the parameters changes: coil, core, magnetic field; EMF is induced in the coil.
For reel without core conversion equations are simplified and divided into subtypes:
- for a stationary coil in an alternating magnetic field
В=В m cosωt e= ωnB m sinωt;
- for a coil rotating with a frequency Ω in a constant magnetic field with induction B O
e=Ω nSB o sinωt,
where S is the area of the coil;
- for a circuit whose individual parts move linearly in a magnetic field B, changing the flow area coupled to the coil,
e=-dФ∕dt=-nBв(dx/dt),
where in and x are the dimensions of the coil, x changes, because part of the coil comes out of the magnetic field. dx/dt is the linear speed of movement or dα/dt is the angular speed relative to the magnetic flux.
- for a segment of length L moving in a uniform magnetic field with speed V so that the directions of the vectors L, B and V are mutually perpendicular, e=VBL.
Induction converters are regenerative converters and convert mechanical energy into electrical energy.
The errors of induction converters largely depend on their operating conditions (temperature, external mechanical vibrations, external magnetic field) and on the operating mode. The greatest error occurs in a mode in which a significant current flows through the load, i.e. at finite values of load resistance. Lowest error - in idle mode or when the load is electronic devices with high input impedance
- 4) Capacitive - Converters in which the electric field is created by an applied voltage. The main element in these converters is a variable capacitor, which is changed by the input measuring signal. In the future, by capacitive we will mean a converter that uses a capacitor with two or more electrodes). For the case of a capacitor with flat electrodes of area s placed from each other at a distance d in a medium with dielectric constant e, the capacitance will be
The converter under consideration on the electrical side is characterized by the applied voltage and charge q=CU, current I=dq/dt and energy W=CU/2. On the non-electrical side, the converter is characterized by a change in the parameters included in the expression for capacitance, i.e. Dd, Ds, De, and force f = dW/dx, where x should be understood as any of the quantities Dd, Ds, De.
The capacitive converter is reversible: when a voltage U is applied to the electrical side, a force f appears on the non-electrical side, which is used in balancing conversion devices as a result of the inverse conversion, in ES voltmeters and in devices with contactless suspension. In this latter case, an element of mass m can be suspended in an electrostatic field if the condition f³ gm is satisfied, where g is the gravitational acceleration.
Voltage converters are widely used both in everyday life and in production. For production and industry, they are most often made to order, because they need a powerful converter and not always with a standard voltage. Standard values for output and input parameters are often used in everyday life. That is, a voltage converter is an electronic device that is designed to change the type of electricity, its magnitude or frequency.
According to their functionality they are divided into:
- Downgrades;
- Raising;
- Transformerless;
- Inverter;
- Adjustable with adjustable frequency and output AC voltage;
- Adjustable with adjustable constant output voltage.
Some of them can be made in a special sealed design; these types of devices are used for wet rooms, or, in general, for installation under water.
So, what is each type?
High voltage voltage converter
This is an electronic device that is designed to produce alternating or direct high voltage (up to several thousand volts). For example, such devices are used to generate high-voltage energy for television picture tubes, as well as for laboratory research and testing electrical equipment with voltages increased several times. Cables or power circuits of oil switches designed for a voltage of 6 kV are tested at a voltage of 30 kV and higher, however, this voltage value does not have high power, and in the event of a breakdown it is immediately switched off. These converters are quite compact because they have to be carried by personnel from one substation to another, most often manually. It should be noted that all laboratory power supplies and converters have almost standard, accurate voltage.
Simpler high-voltage converters are used to start fluorescent lamps. The impulse can be greatly increased to the desired level using the starter and throttle, which can have an electronic or electromechanical basis.
Industrial installations that convert lower voltage to high voltage have many protections and are performed using step-up transformers (STVs). Here is one of these circuits that gives an output from 8 to 16 thousand volts, while only about 50 V is needed for its operation.
Due to the fact that quite high voltage is generated and flows in the windings of transformers, high demands are placed on the insulation of these windings, as well as on its quality. In order to eliminate the possibility of corona discharges, the parts of the high-voltage rectifier must be soldered to the board carefully, without burrs and sharp corners, and then filled on both sides with epoxy resin or a layer of paraffin 2...3 mm thick, ensuring insulation from each other. Sometimes these electronic systems and devices are called step-up voltage converters.
The following circuit is a linear resonant voltage converter that operates in boost mode. It is based on the separation of functions for increasing U and its clear stabilization in completely different cascades. 
At the same time, some inverter units can be made to work with minimal losses on power switches, as well as on a rectified bridge, where high-voltage voltage appears.
Home voltage converter
The average person comes across voltage converters for the home very often, because many devices have a power supply. Most often these are step-down converters that have galvanic isolation. For example, chargers for mobile phones and laptops, personal desktop computers, radios, stereo systems, various media players, and this list can be continued for a very long time, since their variety and applications in everyday life have recently been very wide.
Uninterruptible power supplies are equipped with energy storage devices in the form of batteries. Such devices are also used to maintain the operation of the heating system during an unexpected power outage. Sometimes home converters can be made according to an inverter circuit, that is, by connecting it to a direct current source (battery) powered by a chemical reaction, you can obtain a normal alternating voltage at the output, the value of which will be 220 Volts. A feature of these circuits is the ability to obtain a pure sinusoidal signal at the output.
One of the very important characteristics of converters used in everyday life is the stable signal value at the output of the device, regardless of how many volts are supplied to its input. This functional feature of power supplies is due to the fact that for stable and long-term operation of microcircuits and other semiconductor devices, a clearly standardized voltage is required, and even without ripple.
The main criteria for choosing a converter for a house or apartment are:
- Power;
- The magnitude of the input and output voltage;
- Possibility of stabilization and its limits;
- Load current value;
- Minimizing heating, that is, it is better for the converter to operate in a mode with a power reserve;
- Ventilation of the device can be natural or forced;
- Good sound insulation;
- Availability of protection against overloads and overheating.
Choosing a voltage converter is not a simple matter, because the operation of the powered device depends on the correctly selected converter.
Transformerless voltage converters
Recently, they have become very popular, since their production, and in particular the production of transformers, requires a lot of money, because their winding is made of non-ferrous metal, the price of which is constantly growing. The main advantage of such converters is, of course, the price. Among the negative aspects, there is one thing that significantly distinguishes it from transformer power supplies and converters. As a result of a breakdown of one or more semiconductor devices, all the output energy can reach the terminals of the consumer, and this will certainly damage it. Here is the simplest AC to DC voltage converter. The role of the regulating element is played by the thyristor.
The situation is simpler with converters that do not have transformers, but operate on the basis and in the mode of a voltage-increasing device. Here, even if one or several elements fail, dangerous destructive energy will not appear on the load. 
DC-DC converters
The AC/DC converter is the most commonly used type of device of this type. In everyday life these are all kinds of power supplies, and in production and industry these are power supply devices:
- All semiconductor circuits;
- Excitation windings of synchronous motors and DC motors;
- Oil switch solenoid coils;
- Operating and tripping circuits where coils require constant current.
A thyristor voltage converter is the most commonly used device for these purposes. A feature of these devices is the complete, rather than partial, conversion of alternating voltage to direct voltage without any kind of ripple. A powerful voltage converter of this type must necessarily include radiators and fans for cooling, since all electronic parts can operate for a long time and trouble-free only at operating temperatures. 
Adjustable voltage converter
These devices are designed to operate in both voltage increase and decrease modes. Most often, these are still devices that smoothly adjust the value of the output signal, which is lower than the input signal. That is, 220 Volts are supplied to the input, and at the output we get an adjustable constant value, say, from 2 to 30 volts. Such devices with very fine adjustment are used to test pointer and digital instruments in laboratories. It is very convenient when they are equipped with a digital indicator. It must be admitted that every radio amateur took this type as the basis for his first work, since the power supply for certain equipment can be different in size, but this power source turned out to be very universal. How to make a high-quality converter that works for a long time is the main problem of young radio amateurs.
Inverter voltage converter
This type of converter forms the basis for innovative compact welding devices. Receiving an alternating voltage of 220 volts for power supply, the device rectifies it, after which it again makes it alternating, but with a frequency of several tens of thousands of Hz. This makes it possible to significantly reduce the dimensions of the welding transformer installed at the output.
The inverter method is also used to power heating boilers from batteries in the event of an unexpected power outage. Due to this, the system continues to operate and receives 220 volts of alternating voltage from 12 volts of direct voltage. A powerful booster device for this purpose must be operated from a large-capacity battery; this determines how long it will supply the boiler with electricity. That is, capacity plays a key role.
High frequency voltage converter
Due to the use of boost converters, it becomes possible to reduce the size of all electronic and electromagnetic elements that make up the circuits, which means the cost of transformers, coils, capacitors, etc. is reduced. However, this can cause high-frequency radio interference, which affects the operation of other electronic devices. systems, and even ordinary radio receivers, so their housings need to be reliably shielded. The calculation of the converter and its interference must be carried out by highly qualified personnel.
What is a resistance to voltage converter?
This is a special type that is used only in the production and manufacture of measuring instruments, in particular ohmmeters. After all, the basis of an ohmmeter, that is, a device that measures resistance, is made in measuring the drop in U and converting it into pointer or digital indicators. Typically measurements are made relative to direct current. A measuring transducer is a technical device used to convert a measured value into another value or a measuring signal, convenient for processing, storage, further transformations, indication, and transmission. It is part of any measuring device.
Current to voltage converter
In most cases, all electronic circuits are needed to process signals represented in the form of voltage. However, sometimes you have to deal with a signal in the form of current. Such signals arise, for example, at the output of a photoresistor or photodiode. Then it is advisable to convert the current signal into voltage at the first opportunity. Voltage-to-current converters are used when the current in the load must be proportional to the input U and independent of the R load. In particular, with a constant input U, the current in the load will also be constant, therefore such converters are sometimes conventionally called current stabilizers.
Voltage converter repair
Repair of these devices to convert one type of voltage to another is best done in service centers, where the personnel are highly qualified and will subsequently provide guarantees for the work performed. Most often, any modern high-quality converters consist of several hundred electronic parts, and if there are no obvious burnt elements, then it will be very difficult to find a breakdown and fix it. Some Chinese inexpensive devices of this type, in general, are in principle deprived of the possibility of repairing them, which cannot be said about domestic manufacturers. Yes, they may be a little bulky and not compact, but they can be repaired, since many of their parts can be replaced with similar ones.
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