Zinoviev G.S. Power Electronics Fundamentals

Power electronics is a field of science and technology that solves the problem of creating power electronic devices, as well as the problem of obtaining significant electrical energy, controlling powerful electrical processes and converting electrical energy into sufficiently large energy of another type when using these devices as the main tool.

Semiconductor-based power electronics devices are discussed below. These devices are the most widely used.

The solar cells discussed above have been used for a long time to generate electrical energy. Currently, the share of this energy in the total volume of electricity is small. However, many scientists, including Nobel Prize winner Academician Zh.I. Alferov, consider solar cells to be very promising sources of electrical energy that do not disrupt the energy balance on Earth.

Control of high-power electrical processes is precisely the problem in which power semiconductor devices are already widely used, and the intensity of their use is rapidly increasing. This is explained by the advantages of power semiconductor devices, the main of which are high speed, low drop in the open state and low drop in the closed state (which ensures low power losses), high reliability, significant current and voltage load capacity, small size and weight, ease of use. control, organic unity with semiconductor devices of information electronics, which facilitates the combination of high-current and low-current elements.

Intensive research work on power electronics has been launched in many countries, and thanks to this, power semiconductor devices, as well as electronic devices based on them, are constantly being improved. This ensures the rapid expansion of power electronics applications, which in turn stimulates research. Here we can talk about positive feedback on the scale of an entire area of ​​human activity. The result is the rapid penetration of power electronics into a wide variety of technical fields.

A particularly rapid proliferation of power electronics devices began after the creation of power field-effect transistors and IGBTs.

This was preceded by a fairly long period when the main power semiconductor device was an unlatched thyristor, created in the 50s of the last century. Non-latching thyristors have played a prominent role in the development of power electronics and are widely used today. But the inability to turn off using control pulses often makes their use difficult. For decades, developers of power devices have had to come to terms with this drawback, in some cases using rather complex power circuit components to turn off thyristors.

The widespread use of thyristors led to the popularity of the term “thyristor technology,” which arose at that time, which was used in the same sense as the term “power electronics.”

The power bipolar transistors developed during this period found their field of application, but did not radically change the situation in power electronics.

Only with the advent of power field-effect transistors and 10 watts were fully controllable electronic switches in the hands of engineers, approaching ideal ones in their properties. This greatly facilitated the solution of a variety of problems related to the control of powerful electrical processes. The presence of fairly advanced electronic switches makes it possible not only to instantly connect a load to a constant or alternating source and disconnect it, but also to generate very large current signals or almost any required shape for it.

The most common typical power electronics devices are:

contactless switching devices alternating and direct current (breakers), designed to turn on or off a load in an alternating or direct current circuit and, sometimes, to regulate the power of the load;

rectifiers, transforming a variable in one polarity (unidirectional);

inverters, converting a constant into a variable;

frequency converters, converting a variable of one frequency into a variable of another frequency;

DC converters(converters) that convert a constant of one quantity into a constant of another quantity;

phase number converters, converting an alternating variable with one number of phases into an alternating one with a different number of phases (usually single-phase is converted to three-phase or three-phase to single-phase);

compensators(power factor correctors), designed to compensate for reactive power in the AC supply network and to compensate for distortions in the current and voltage waveforms.

Essentially, power electronics devices perform the conversion of high-power electrical signals. That's why power electronics is also called converter technology.

Power electronics devices, both standard and specialized, are used in all areas of technology and in almost any fairly complex scientific equipment.

As an illustration, we indicate some objects in which power electronics devices perform important functions:

Electric drive (control of speed and torque, etc.);

Installations for electrolysis (non-ferrous metallurgy, chemical industry);

Electrical equipment for transmitting electricity over long distances using direct current;

Electrometallurgical equipment (electromagnetic mixing of metal, etc.);

Electrothermal installations (induction heating, etc.);

Electrical equipment for charging batteries;

Computers;

Electrical equipment of cars and tractors;

Electrical equipment of aircraft and spacecraft;

Radio communication devices;

Equipment for television broadcasting;

Devices for electric lighting (power supply for fluorescent lamps, etc.);

Medical electrical equipment (ultrasound therapy and surgery, etc.);

Power tools;

Consumer electronics devices.

The development of power electronics is also changing the very approaches to solving technical problems. For example, the creation of power field-effect transistors and IGBTs significantly contributes to expanding the scope of application of inductor motors, which in a number of areas are replacing commutator motors.

A significant factor that has a beneficial effect on the spread of power electronics devices is the success of information electronics and, in particular, microprocessor technology. To control powerful electrical processes, increasingly complex algorithms are used, which can only be rationally implemented using sufficiently advanced information electronics devices.

Effective joint use of advances in power and data electronics produces truly outstanding results.

Existing devices for converting electrical energy into another type of energy when directly using semiconductor devices do not yet have high output power. However, encouraging results were obtained here as well.

Semiconductor lasers convert electrical energy into coherent radiation energy in the ultraviolet, visible and infrared ranges. These lasers were proposed in 1959 and first implemented using gallium arsenide (GaAs) in 1962. Semiconductor-based lasers are characterized by high efficiency (above 10%) and long service life. They are used, for example, in infrared spotlights.

Ultra-bright white LEDs, which appeared in the 90s of the last century, are already used in some cases for lighting instead of incandescent lamps. LEDs are significantly more economical and have a significantly longer service life. It is expected that the scope of LED lighting will expand rapidly.

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Textbook. – Novosibirsk: NSTU Publishing House, 1999.

Parts: 1.1, 1.2, 2.1, 2.2, 2.3, 2.4

This textbook is intended (with two levels of depth of presentation of the material) for students of the faculties of FES, EMF, who are not “specialists” in power electronics, but are studying courses of various titles on the use of power electronics devices in electrical power, electromechanical, and electrical systems. Sections of the textbook, highlighted in block font, are intended (also at two levels of depth of presentation) for an additional, deeper study of the course, which allows it to be used as a textbook for students of the specialty "Promelelectronics" REF, who are preparing "as specialists" in power electronics. Thus, the proposed edition implements the “four in one” principle. Reviews of scientific and technical literature on the relevant sections of the course added to individual sections make it possible to recommend the manual as an informational publication for both undergraduates and graduate students.

Preface.
Scientific, technical and methodological foundations for the study of power electronics devices.
Methodology of a systems approach to the analysis of power electronics devices.
Energy indicators of the quality of energy conversion in valve converters.
Energy indicators of the quality of electromagnetic processes.
Energy indicators of the quality of use of device elements and the device as a whole.
Element base of valve converters.
Power semiconductor devices.
Valves with incomplete control.
Valves with full control.
Lockable thyristors, transistors.
Transformers and reactors.
Capacitors.
Types of electrical energy converters.
Methods for calculating energy indicators.
Mathematical models of valve converters.
Methods for calculating the energy performance of converters.
Integral method.
Spectral method.
Direct method.
Adu method.
Adu method.
Adu method(1).
Methods AduM1, Adum2, Adum(1).
The theory of transformation of alternating current into direct current with ideal parameters of the converter.
Rectifier as a system. Basic definitions and notations.
Mechanism for converting alternating current into rectified current in the base cell Dt/Ot.
Two-phase single-phase current rectifier (m1 = 1, m2 = 2, q = 1).
Single-phase rectifier using a bridge circuit (m1 = m2 = 1, q = 2).
Three-phase current rectifier with trans winding connection diagram.
triangle-star formator with zero terminal (m1 = m2 = 3, q ​​= 1).
Three-phase current rectifier with a star-zigzag transformer winding connection diagram with zero (m1 = m2 = 3, q ​​= 1).
Six-phase three-phase current rectifier with a connection of the secondary windings of a star-reverse star transformer with an equalizing reactor (m1 = 3, m2 = 2 x 3, q ​​= 1).
Three-phase current rectifier using a bridge circuit (m1=m2=3, q=2).
Controlled rectifiers. Regulating characteristic theory of converting alternating current into direct current (with recuperation) taking into account the real parameters of the converter elements.
Switching process in a controlled rectifier with a real transformer. External characteristics.
The theory of rectifier operation on back-EMF at a finite value of inductance Ld.
Intermittent current mode (? 2?/qm2).
Extremely continuous current mode (? = 2?/qm2).
Continuous current mode (? 2?/qm2).
Operation of a rectifier with a capacitor smoothing filter.
Reversing the direction of active power flow in a valve converter with back EMF in the DC link - dependent inversion mode.
Dependent single-phase current inverter (m1=1, m2=2, q=1).
Dependent three-phase current inverter (m1=3, m2=3, q=1).
General dependence of the primary rectifier current on the anode and rectified currents (Chernyshev’s law).
Spectra of primary currents of transformers, rectifiers and dependent inverters.
Spectra of rectified and inverted voltages of the valve converter.
Optimization of the number of secondary phases of the rectifier transformer. Equivalent multiphase rectification circuits.
The influence of commutation on the effective values ​​of transformer currents and its typical power.
Efficiency and power factor of a valve converter in rectification and dependent inversion mode.
Efficiency.
Power factor.
Rectifiers with fully controlled valves.
Rectifier with advanced phase control.
Rectifier with pulse-width regulation of rectified voltage.
Rectifier with forced formation of a curve of current consumed from the supply network.
Reversible valve converter (reversible rectifier).
Electromagnetic compatibility of the valve converter with the power supply network.
Model example of electrical design of a rectifier.
Selecting a rectifier circuit (structural synthesis stage).
Calculation of parameters of controlled rectifier circuit elements (parametric synthesis stage).
Conclusion.
Literature.
Subject index.

see also

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Novosibirsk: NSTU, 1999. - 204 p. This textbook is intended (with two levels of depth of presentation of the material) for students of the faculties of FES, EMF, who are not “specialists” in power electronics, but are studying courses of various titles on the use of power electronics devices in electrical power, electromechanical, and electrical systems. Sections of the textbook, highlighted in block font, are intended (also at two levels of depth...

Zinovev G.S. Fundamentals of power electronics. Part 1

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Novosibirsk: NSTU, 1999. This textbook is intended (at two levels of depth of presentation of the material) for students of the faculties of FES, EMF, who are not “specialists” in power electronics, but are studying courses of various titles on the use of power electronics devices in electrical power, electromechanical, electrical systems . Sections of the textbook, highlighted in block font, are intended (also with two levels of inscription depth...

Zinoviev G.S. Power Electronics Fundamentals (1/2)

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Textbook. – Novosibirsk: NSTU Publishing House, Part One. 1999. – 199 p. This textbook is intended (with two levels of depth of presentation of the material) for students of the faculties of FES, EMF, who are not “specialists” in power electronics, but are studying courses of various titles on the use of power electronics devices in electrical power, electromechanical, and electrical systems. Sections of the textbook, highlighted in block font, are intended...

Zinoviev G.S. Fundamentals of power electronics. Volume 2,3,4

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Textbook. – Novosibirsk: NSTU Publishing House, Parts two, three and four. 2000. – 197 p. The second part of the textbook, a continuation of the first part, published in 1999, is devoted to the presentation of the basic circuits of converters of direct voltage to direct voltage, constant voltage to alternating voltage (autonomous inverters), alternating voltage to alternating voltage of constant or adjustable frequency. The material is also structured according to the principle “...

Zinoviev G.S. Fundamentals of power electronics. Volume 5

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Textbook. – Novosibirsk: NSTU Publishing House, Part Five. 2000. – 197 p. The second part of the textbook, a continuation of the first part, published in 1999, is devoted to the presentation of the basic circuits of converters of direct voltage to direct voltage, constant voltage to alternating voltage (autonomous inverters), alternating voltage to alternating voltage of constant or adjustable frequency. The material is also structured according to the four-in-one principle...

Zinoviev G.S. Fundamentals of power electronics. Part 2

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Novosibirsk: NSTU, 2000. This textbook is the second part of three planned for the course “Fundamentals of Power Electronics”. The first part of the textbook is accompanied by a methodological manual for laboratory work, implemented using the departmental software package for modeling power electronics devices PARUS-PARAGRAPH. The material in the second part of the textbook is supported by computerized laboratory courses.

Reviewer Doctor of Technical Sciences F. I. Kovalev

The principles of electrical energy conversion are outlined: rectification, inversion, frequency conversion, etc. The basic circuits of converter devices, methods of controlling them and regulating the main parameters are described, areas of rational use of various types of converters are shown. Features of design and operation are considered.

For engineers and technicians who develop and operate electrical systems containing converter devices, as well as those involved in testing and servicing converter equipment.

Rozanov Yu. K. Power Electronics Fundamentals. - Moscow, publishing house Energoatomizdat, 1992. - 296 p.

Preface
Introduction

Chapter first. Basic elements of power electronics
1.1. Power semiconductors
1.1.1. Power diodes
1.1.2. Power transistors
1.1.3. Thyristors
1.1.4. Applications of power semiconductor devices
1.2. Transformers and reactors
1.3. Capacitors

Chapter two. Rectifiers
2.1. General information
2.2. Basic rectification circuits
2.2.1. Single-phase full-wave circuit with midpoint
2.2.2. Single-phase bridge circuit
2.2.3. Three-phase circuit with midpoint
2.2.4. Three-phase bridge circuit
2.2.5. Multi-bridge circuits
2.2.6. Harmonic composition of rectified voltage and primary currents in rectification circuits
2.3. Switching and operating modes of rectifiers
2.3.1. Switching currents in rectification circuits
2.3.2. External characteristics of rectifiers
2.4. Energy characteristics of rectifiers and ways to improve them
2.4.1. Power factor and efficiency of rectifiers
2.4.2. Improving the power factor of controlled rectifiers
2.5. Features of the operation of rectifiers for capacitive load and back-EMF
2.6. Anti-aliasing filters
2.7. Operation of a rectifier from a source of comparable power

Chapter three. Inverters and frequency converters
3.1. Grid-Driven Inverters
3.1.1. Single Phase Mid Point Inverter
3.1.2. Three-phase bridge inverter
3.1.3. Power balance in a grid-driven inverter
3.1.4. Main characteristics and operating modes of grid-driven inverters
3.2. Autonomous inverters
3.2.1. Current inverters
3.2.2. Voltage inverters
3.2.3. Voltage inverters based on thyristors
3.2.4. Resonant inverters
3.3. Frequency converters
3.3.1. Frequency converters with intermediate DC link
3.3.2. Direct Coupled Frequency Converters
3.4. Regulation of the output voltage of autonomous inverters
3.4.1. General principles of regulation
3.4.2. Control devices for current inverters
3.4.3. Output voltage regulation via pulse width modulation (PWM)
3.4.4. Geometric addition of stresses
3.5. Methods for improving the output voltage waveform of inverters and frequency converters
3.5.1. The influence of non-sinusoidal voltage on electricity consumers
3.5.2. Inverter output filters
3.5.3. Reduction of higher harmonics in the output voltage without the use of filters

Chapter Four. Regulators-stabilizers and static contactors
4.1. AC voltage regulators
4.2. DC regulators-stabilizers
4.2.1. Parametric stabilizers
4.2.2. Continuous stabilizers
4.2.3. Switching regulators
4.2.4. Development of switching regulator structures
4.2.5. Thyristor-capacitor DC regulators with dosed energy transfer to the load
4.2.6. Combined converter-regulators
4.3. Static contactors
4.3.1. Thyristor AC contactors
4.3.2. Thyristor DC contactors

Chapter five. Converter control systems
5.1. General information
5.2. Block diagrams of control systems for converter devices
5.2.1. Control systems for rectifiers and dependent inverters
5.2.2. Direct Coupled Frequency Converter Control Systems
5.2.3. Control systems for autonomous inverters
5.2.4. Control systems for regulators and stabilizers
5.3. Microprocessor systems in converter technology
5.3.1. Typical generalized microprocessor structures
5.3.2. Examples of using microprocessor control systems

Chapter six. Applications of power electronic devices
6.1. Areas of rational application
6.2. General technical requirements
6.3. Protection in emergency modes
6.4. Operational monitoring and technical condition diagnostics
6.5. Ensuring parallel operation of converters
6.6. Electromagnetic interference
Bibliography

Bibliography
1. GOST 20859.1-89 (ST SEV 1135-88). Semiconductor power devices of a single unified series. General technical conditions.

2. Chebovsky O. G., Moiseev L. G., Nedoshivin R. P. Power semiconductor devices: Handbook. -2nd ed., revised. and additional M.: Energoatomizdat, 1985.

3 Iravis V. Discrete power semiconductors //EDN. 1984. Vol. 29, N 18. P. 106-127.

4. Nakagawa A.e.a. 1800V bipolar-mode MOSFET (IGBT) /A. Nakagawa, K. Imamure, K. Furukawa //Toshiba Review. 1987. N 161. P. 34-37.

5 Chen D. Semiconductors: fast, tough and compact // IEEE Spectrum. 1987. Vol. 24, N 9. P. 30-35.

6. Power semiconductor modules abroad / V. B. Zilbershtein, S. V. Mashin, V. A. Potapchuk, etc. // Electrical industry. Ser. 05. Power conversion technology. 1988. Vol. 18. P. 1-44.

7. Rischmiiller K. Smatries intelligente Ihstungshalbeitereine neue Halblieter-generation // Electronikpraxis. 1987. N6. S. 118-122.

8. Rusin Yu. S., Gorsky A. N., Rozanov Yu. K. Study of the dependence of the volumes of electromagnetic elements on frequency // Electrical industry. Conversion technology. 1983. No. 10. P. 3-6.

9. Electric capacitors and capacitor installations: Handbook / V. P. Berzan, B. Yu. Gelikman, M. N. Guraevsky and others. Ed. G. S. Kuchinsky. M.: Energoatomizdat, 1987.

10. Semiconductor rectifiers / Ed. F.I. Kovalev and G.P. Mostkova. M.: Energy, 1978.

11. Circuit configuration of the GTO converter for superconducting magnetic energy storage / Toshifumi JSE, James J. Skiles, Kohert L., K. V. Stom, J. Wang//IEEE 19th Power Electronics Specialists Conference (PESC"88), Kyoto, Japan, April 11 - 14, 1988. P. 108-115.

12. Rozanov Yu. K. Fundamentals of power converter technology. M.: Energy, 1979.

13. Chizhenko I. M., Rudenko V. S., Seyko V. I. Fundamentals of converter technology. M.: Higher School, 1974.

14. Ivanov V. A. Dynamics of autonomous inverters with direct switching. M.: Energy, 1979.

15. Kovalev F.I., Mustafa G.M., Baregemyan G.V. Control by calculated forecast of a pulse converter with a sinusoidal output voltage // Electrical industry. Conversion technology. 1981. No. 6(34).P. 10-14.

16. Middelbrook R. D. Isolation and multiple output extensions of a new optimum topology switching DC - tV - DC converter // IEEE Power Electronics Specialists Conference (PESC"78), 1978. P. 256-264.

17. Bulatov O. G., Tsarenko A. I. Thyristor-capacitor converters. M. Energoizdat, 1982.

18. Rozinov Yu. K. Semiconductor converters with a high-frequency link. M.: Energoatomizdat, 1987.

19. Kalabekov A. A. Microprocessors and their application in signal transmission and processing systems. M.: Radio and communication, 1988.

20. Stroganov R.P. Control machines and their application. M.: Higher School, 1986.

21. Obukhov S.T., Ramizevich T.V. Application of microcomputers for controlling valve converters // Electrical industry. Conversion technology. 1983. Vol. 3(151). P. 9

22. Control of valve converters based on microprocessors / Yu. M. Bykov, I. T. Par, L. Ya. Raskin, L. P. Detkin // Electrical industry. Conversion technology. 1985. Vol. 10. P. 117.

23. Matsui N., Takeshk T., Vura M. One-Chip Micro - Computer - Based controller for the MC Hurray Juneter // IEEE Transactions on industrial electronics, 1984. Vol. JE-31, N 3. P. 249-254.

24. Bulatov O. G., Ivanov V. S., Panfilov D. I. Semiconductor chargers for capacitive energy storage devices. M.: Radio and communication, 1986.

PREFACE

Power electronics is a constantly developing and promising field of electrical engineering. Advances in modern power electronics have a major impact on the pace of technological progress in all advanced industrial societies. In this regard, there is a need for a wide range of scientific and technical workers to have a clearer understanding of the fundamentals of modern power electronics.

Power electronics currently has fairly well-developed theoretical foundations, but the author did not set himself the task of even partially presenting them, since numerous monographs and textbooks are devoted to these issues. The contents of this book and the methodology for its presentation are intended primarily for engineering and technical workers who are not specialists in the field of power electronics, but are associated with the use and operation of electronic devices and apparatus and who want to gain an understanding of the basic principles of operation of electronic devices, their circuitry and general provisions for development and operation. In addition, most sections of the book can also be used by students of various technical educational institutions when studying disciplines whose curriculum includes issues of power electronics.

Published Date: 10/12/2017

Do you know the basics of power electronics?

We can trace the overwhelming progress in this matter to the development of commercial thyristors or silicon rectifiers (SCRs) by General Electric Co.

Power electronics concept

Power electronics is one of the modern topics in electrical engineering, which has recently achieved great success and has influenced human life in almost all areas. We ourselves use so many power electronic applications in our daily lives without even realizing it. Now the question arises: “What is power electronics?”

We can define power electronics as a subject that is a hybrid of power, analog electronics, semiconductor devices and control systems. We base the fundamentals of each entity and apply it in a combined form to produce a regulated form of electrical energy. Electrical energy itself is not usable until it is converted into a tangible form of energy such as motion, light, sound, heat, etc. To regulate these forms of energy, an effective way is to regulate the electrical energy itself, and these forms are the content of subjective power electronics.

We can trace the overwhelming progress in this matter to the development of commercial thyristors or silicon rectifiers (SCRs) by General Electric Co. in 1958. Previously, control of electrical energy was carried out mainly using thyratrons and mercury arc rectifiers, which work on the principle of physical phenomena in gases and vapors. After SCR, many high-power electronic devices appeared, such as GTO, IGBT, SIT, MCT, TRIAC, DIAC, IEGT, IGCT and so on. These devices are rated at several hundred volts and amps, as opposed to signal level devices that operate at a few volts and amps.

To achieve the purpose of power electronics, the devices act as nothing more than a switch. All power electronic devices act as a switch and have two modes i.e. ON and OFF. For example, the BJT (Bipolar Junction Transistor) has three areas of operation in the output characteristics disabled, active and saturated. In analog electronics, where the BJT must act as an amplifier, the circuit is designed to bias it into the active region of operation. However, in power electronics, a BJT will operate in the cutoff region when it is turned off and in the saturation region when it is turned on. Now when devices are to work as a switch, they must follow the basic characteristic of a switch, that is, when the switch is on, it has zero voltage drop across it and passes full current through it, and when it is OFF, it has full voltage drop across it. it and zero current flowing through it.

Now, since in both modes the value of V or I is zero, the power of the switch is also always zero. This characteristic is easily visualized in a mechanical switch and the same must be observed in a power electronic switch. However, there is almost always leakage current through the devices when it is in the OFF state, i.e. Ileakage ≠ 0 and there is always a voltage drop in the ON state, i.e. Von ≠ 0. However, the magnitude of Von or Ileakage is very less and hence the power through the device is also very small, in the order of a few millivolts. This power is dissipated in the device and therefore proper heat evacuation from the device is an important aspect. Apart from these state and OFF state losses, there are also switching losses in power electronic devices. This happens mainly when the switch switches from one mode to another and the V and I through the device change. In power electronics, both losses are important parameters of any device and are necessary to determine its voltage and current ratings.

Power electronic devices alone are not as useful in practical applications and therefore require design with a circuit along with other supporting components. These supporting components are similar to the decision making part that controls the power electronic switches to achieve the desired result. This includes the firing circuit and feedback circuit. The block diagram below shows a simple power electronic system.

The control unit receives the output signals from the sensors and compares them with the references and accordingly inputs the input signal into the firing circuit. The firing circuit is basically a pulse generating circuit that produces a pulse output in such a way as to control the power electronic switches in the main circuit block. The end result is that the load receives the required electrical power and therefore delivers the desired result. A typical example of the above system would be controlling the speed of motors.

There are mainly five types of power electronic circuits, each with a different purpose:

1. Rectifiers - Converts fixed AC current to AC DC
2. Choppers - Converts direct current to alternating DC
3. Inverters - convert direct current into alternating current with variable amplitude and variable frequency
4. AC Voltage Controllers - Convert fixed AC current to AC current at the same input frequency
5. Cycloconverters - converts fixed AC current to variable frequency AC current

There is a common misconception regarding the term converter. A converter is basically any circuit that converts electricity from one form to another. Therefore, all the listed five are types of converters.

In this article we will talk about power electronics. What is power electronics, what is it based on, what advantages does it provide, and what are its prospects? Let's dwell on the components of power electronics, consider briefly what they are, how they differ from each other, and for what applications certain types of semiconductor switches are suitable. Let us give examples of power electronics devices used in everyday life, in production and at home.

In recent years, power electronics devices have made it possible to make a serious technological breakthrough in energy saving. Power semiconductor devices, thanks to their flexible controllability, make it possible to efficiently convert electrical energy. The weight and size indicators and efficiency achieved today have already brought converter devices to a qualitatively new level.

Many industries use soft starters, speed controllers, and uninterruptible power supplies that operate on a modern semiconductor base and show high efficiency. These are all power electronics.

The flow of electrical energy in power electronics is controlled using semiconductor switches, which replace mechanical switches, and which can be controlled according to the required algorithm in order to obtain the required average power and precise action of the working element of a particular equipment.

Thus, power electronics are used in transport, in the mining industry, in the communications sector, in many industries, and not a single powerful household appliance today can do without power electronic units included in its design.

The main building blocks of power electronics are the semiconductor key components, which are capable of opening and closing a circuit at different speeds, up to megahertz. When turned on, the resistance of the key is units and fractions of an ohm, and when turned off, it is megaohms.

Key control does not require a lot of power, and losses on the switch that occur during the switching process, with a well-designed driver, do not exceed one percent. For this reason, the efficiency of power electronics turns out to be high compared to the declining positions of iron transformers and mechanical switches such as conventional relays.

Power electronic devices are devices in which the effective current is greater than or equal to 10 amperes. In this case, the key semiconductor elements can be: bipolar transistors, field-effect transistors, IGBT transistors, thyristors, triacs, turn-off thyristors, and turn-off thyristors with integrated control.

Low control power also makes it possible to create power microcircuits that combine several blocks at once: the switch itself, the control circuit and the monitoring circuit - these are the so-called intelligent circuits.

These electronic bricks are used both in powerful industrial installations and in household electrical appliances. An induction furnace for a couple of megawatts or a home steamer for a couple of kilowatts - both have semiconductor power switches that simply operate with different powers.

Thus, power thyristors operate in converters with a power of more than 1 MVA, in circuits of DC electric drives and high-voltage AC drives, and are used in reactive power compensation installations and in induction melting installations.

Turn-off thyristors are controlled more flexibly; they are used to control compressors, fans, pumps with a power of hundreds of KVA, and the potential switching power exceeds 3 MVA. make it possible to implement converters with a power of up to units of MVA for various purposes, both for controlling motors and for ensuring uninterruptible power supply and switching high currents in many static installations.

MOSFET field-effect transistors are characterized by excellent controllability at frequencies of hundreds of kilohertz, which significantly expands the scope of their applicability in comparison with IGBT transistors.

Triacs are optimal for starting and controlling AC motors; they are capable of operating at frequencies up to 50 kHz, and require less energy to control than IGBT transistors.

Today, IGBT transistors reach a maximum switching voltage of 3500 volts, and potentially 7000 volts. These components can replace bipolar transistors in the coming years, and they will be used on equipment up to MVA units. For low-power converters, MOSFET transistors will remain more acceptable, and for more than 3 MVA, turn-off thyristors will remain more acceptable.

According to analysts, most power semiconductors in the future will have a modular design, when one package houses from two to six key elements. The use of modules makes it possible to reduce weight, dimensions and cost of the equipment in which they will be used.

For IGBT transistors, progress will be an increase in currents to 2 kA at voltages up to 3.5 kV and an increase in operating frequencies to 70 kHz with simplified control circuits. One module can contain not only switches and a rectifier, but also a driver and active protection circuits.

Transistors, diodes, and thyristors produced in recent years have already significantly improved their parameters, such as current, voltage, speed, and progress does not stand still.

For better conversion of alternating current into direct current, controlled rectifiers are used, which allow smoothly changing the rectified voltage in the range from zero to nominal.

Today, thyristors are used mainly in the excitation systems of DC electric drives for synchronous motors. Dual thyristors - triacs, have only one control electrode for two thyristors connected back-to-back, which makes control even simpler.

To carry out the reverse process, converting direct voltage to alternating voltage is used. Independent inverters based on semiconductor switches produce an output frequency, shape and amplitude determined by the electronic circuit and not the network. Inverters are made on the basis of various types of key elements, but for high powers, more than 1 MVA, inverters based on IGBT transistors again come out on top.

Unlike thyristors, IGBT transistors make it possible to shape the output current and voltage more widely and more accurately. Low-power automotive inverters use field-effect transistors in their work, which, with powers up to 3 kW, do an excellent job of converting the direct current of the battery with a voltage of 12 volts, first into direct current, using a high-frequency pulse converter operating at a frequency from 50 kHz to hundreds of kilohertz, then - at variable 50 or 60 Hz.

To convert a current of one frequency to a current of another frequency, it is used. Previously, this was done exclusively on the basis of thyristors, which were not fully controllable; it was necessary to design complex circuits for forced locking of thyristors.

The use of switches such as field-effect MOSFETs and IGBT transistors facilitates the design and implementation of frequency converters, and it can be predicted that in the future, thyristors, especially in low-power devices, will be abandoned in favor of transistors.

To reverse electric drives, thyristors are still used; it is enough to have two sets of thyristor converters to provide two different directions of current without the need for switching. This is how modern non-contact reversing starters work.

We hope that our short article was useful to you, and now you know what power electronics is, what elements of power electronics are used in power electronic devices, and how great the potential of power electronics is for our future.