The Importance and Development Trends of Power Electronics_11zon

The Importance and Development Trends of Power Electronics

Power electronics, mainly studies various power electronic devices and the circuits or devices composed of these power electronic devices to accomplish the transformation and control of electrical energy.

It is both a branch of electronics in the field of strong electricity (high voltage, large current) or electrical engineering in the field of weak electricity (low voltage, small current), or a new science combining strong and weak electricity. Power electronics is an emerging engineering and technical discipline that spans the three fields of “electronics,” “electric power,” and “control.”

Electricity is divided into two categories: direct current (DC) and alternating current (AC). The former has different voltage amplitudes and polarities, while the latter, in addition to differences in voltage amplitude and polarity, also varies in frequency and phase.

In practical applications, it is often necessary to transform between these two types of electrical energy or to transform one or more parameters of the same type of electrical energy (such as voltage, current, frequency, and power factor).

The Importance and Development Trends of Power Electronics 2_11zon

1.There are four types of converters:

(1)AC-DC conversion: Converts AC power to DC power.

(2)DC-AC conversion: Converts DC power to AC power. This is the opposite of rectification and is also called inversion. When the output is connected to the grid, it is called active inversion; when the output is connected to the load, it is called passive inversion.

(3)AC-AC conversion: Changes the parameters of AC power (amplitude or frequency). Among them: changing the effective value of AC voltage is called AC voltage regulation; converting utility frequency AC directly into other frequencies of AC is called AC-AC frequency conversion.

(4)DC-DC conversion: Converts constant DC into intermittent pulse output to change its average value.

The Importance and Development Trends of Power Electronics 4_11zon

2.Development of Power Electronics Technology

Before the advent of power electronic devices, energy conversion relied on rotating machinery. Compared with these rotary AC generators, static energy converters composed of power electronic devices have the advantages of small size, light weight, no mechanical noise and wear, high efficiency, easy control, fast response, and convenient use.

Since the first thyristor—also known as a silicon-controlled rectifier (SCR)—appeared in 1957, the era of thyristors has begun since the 1960s.

After the 1970s, fully controllable power electronic devices (also known as self-commutating devices) that can both turn on and off, such as gate turn-off thyristors (GTOs), bipolar junction transistors (BJTs/GTRs), power field-effect transistors (P-MOSFETs), and insulated gate bipolar transistors (IGBTs), have emerged.

The control circuit has undergone a development stage from discrete components to integrated circuits. Now there are dedicated integrated circuits designed for various control functions, greatly simplifying the control circuit of the converter.

The introduction of microprocessors and microcomputers, especially their increasing bit numbers, continuously improving computing speed, and perfecting functions, has fundamentally changed control technology, making control not only rely on hardware circuits but also programmable using software, which is convenient and flexible.

Various novel and complex control strategies and schemes have been implemented, with self-diagnostic functions and intelligent capabilities. New control theories and methods are applied to converters.

In summary, microelectronics technology, power electronic devices, and control theory are the driving forces behind the development of modern power electronics technology.

The Importance and Development Trends of Power Electronics 1_11zon

3.The Important Role of Power Electronics Technology

(1) Optimization of electricity use. By processing electricity through power electronics technology, the use of electricity becomes rational, efficient, and economical, achieving optimal electricity use. For example, in terms of energy saving, investigations into 14 aspects such as wind turbine pumps, electric traction, rolling mill smelting, light industry papermaking, industrial kilns, induction heating, electric welding, and chemical electrolysis, the potential energy saving amount is equivalent to 16% of the national power generation in 1990. Therefore, the promotion and application of power electronics technology is a strategic measure for energy conservation, with general energy-saving effects ranging from 10% to 40%, and many devices in China have been included in the promotion and application projects for energy conservation.

(2) Transformation of traditional industries and development of electromechanical integration and other emerging industries. According to forecasts by developed countries, in the future, 95% of electricity will need to be processed by power electronics technology before use, that is, 95% of various electromechanical devices in industrial and civil use are related to the power electronics industry. In particular,

power electronics technology is the medium for weak electrical control of strong electricity and an important interface between electromechanical equipment and computers. It creates conditions for traditional industries and emerging industries to adopt microelectronics technology and becomes the guarantee and foundation for the role of computers.

(3) The development of high-frequency power electronics and frequency conversion technology will enable electromechanical equipment to break through the traditional frequency and develop towards high frequency. Achieving optimal efficiency will reduce the volume of electromechanical equipment by several times or tens of times, increase the response speed to high speed, and adapt to any reference signal, achieving noise-free operation and introducing new functions and applications.

(4) The advancement of intelligent power electronics will, to a certain extent, integrate information processing with power processing, integrate microelectronics technology with power electronics technology, and its development may cause a major reform in electronic technology. Some even propose that the next revolution in electronics will occur in the application of electronic technology to industrial equipment and power grids, and power electronics technology will edge people towards the second electronic revolution.

The Importance and Development Trends of Power Electronics 3_11zon

DRIVE CIRCUIT FOR GATE TURN-OFF THYRISTOR AND POWER MOSFET

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OVERVIEW OF DRIVE CIRCUIT AND TRIGGER CIRCUIT OF THYRISTOR