The development of power electronics technology

The development of power electronics technology

The development of power electronic devices plays a decisive role in the development of power electronic technology. Therefore, the development of power electronic technology is based on the development of power electronic devices. The development history of power electronics technology is shown in Figure 1.

The development of power electronics technology
Figure 1 – The history of power electronics

It is generally believed that the beginning of power electronics technology was marked by the birth of the first thyristor in 1957. But before the advent of thyristors, power electronics technology has been used for power conversion. Therefore, the period before the appearance of the thyristor is called the prehistoric period or dawn period of power electronic technology.

The electron tube appeared in 1904, which can control the flow of electrons in a vacuum and be used in communications and radio, thus opening the first electronic technology to be used in the field of electric power. From the 1930s to the 1950s, mercury rectifiers were widely used in the electrochemical industry, electric railway DC substations, and DC motors for steel rolling, and even DC transmission. During this period, the theories of various rectifier circuits, inverter circuits, and frequency converter circuits have matured and been widely used. At the same time, DC generator sets were also used to achieve current conversion during this period.

In 1947, the famous American Bell Labs invented the transistor, which triggered a revolution in electronic technology. The first semiconductor device used in the power field was a silicon diode. After the appearance of the thyristor, due to its superior electrical performance and control performance, it soon replaced the mercury rectifier and the rotary converter unit, and its application range was also rapidly expanded. The concept and foundation of power electronics technology are established due to the development of thyristor and thyristor converter technology. In the 20 years after the birth of the thyristor, with the continuous improvement of the performance of the thyristor, the thyristor has formed a series of products from low voltage and small current to high voltage and large current. At the same time, a series of thyristor derivatives have been developed, such as fast thyristor (FST), reverse conducting thyristor (RCT), bidirectional thyristor (TRIAC), light-controlled thyristor (LTT) and other devices. It has greatly promoted the application of various power converters in metallurgy, electrochemistry, power industry, transportation and mining industries, promoted the progress of industrial technology, and formed the first generation of power electronic devices with thyristors as the core. Also known as the traditional power electronic technology stage.

A thyristor is a device that can be turned on but not turned off by controlling its gate, and it is a semi-controlled device. The main control mode of the thyristor circuit is the phase control mode, referred to as the phase control mode. The turn-off of the thyristor is usually realized by external conditions such as the grid voltage, which limits the application of the thyristor.

In the late 1970s, the second-generation fully-controlled devices represented by gate turn-off thyristors (GTO), power bipolar transistors (BJT) and power field effect transistors (Power-MOSFET) developed rapidly. The feature of the fully-controlled device is that it can be turned on and off by controlling the gate (base, gate). In addition, the switching speed of these devices is generally higher than that of thyristors and can be used in circuits with higher switching frequencies. The superior characteristics of the fully-controlled device gradually replace the thyristor in the converter device, and promote the power electronic technology to a new stage of development. Corresponding to the phase control mode of the thyristor circuit, the main control mode of the circuit using the fully-controlled device is the pulse width modulation (PWM) mode, which is the chopping control mode, referred to as the chopping control mode. The PWM modulation technology occupies a very important position in the power electronic converter technology. It greatly improves the control performance of the circuit, enables the previously difficult to achieve functions to be realized, and has a profound impact on the development of power electronic technology.

In the 1980s, the third generation of compound field control semiconductor devices represented by insulated gate bipolar transistors (IGBT) appeared. ICBT is a combination of MOSFET and BJT, which combines the advantages of both. There are also static induction transistors (SIT), static induction thyristors (SITH), MOS thyristors (MCT) and so on. These devices not only have a very high switching frequency, generally tens to hundreds of kilohertz, but also have higher voltage resistance, large current capacity, and can form high-power, high-frequency power electronic circuits.

In the late 1980s, the development trend of power semiconductor devices was modularization and integration. According to various topological structures of power electronic circuits, multiple identical power semiconductor devices or different power semiconductor devices are packaged in one module, which can reduce the volume of the device, reduce costs, and improve reliability. Now there has been a fourth generation of power electronic devices-integrated power semiconductor devices (PIC), which integrates power electronic devices with drive circuits, control circuits and protection circuits on a single chip, opening up the direction of intelligent power electronic devices, and has broad application prospects. The Intelligent Power Module (IPM) that is often used at present, in addition to integrated power devices and drive circuits, it also integrates fault detection circuits such as overvoltage, overcurrent, and overheating, and can transmit monitoring signals to the CPU to ensure that the IPM itself is not damaged.

New power electronic devices present many advantages, which have caused a sudden change in power electronic technology and entered the stage of modern power electronic technology. The main characteristics of modern power electronic technology are: full control, integration, high frequency, high efficiency, miniaturization of converters, green power conversion, the power supply quality of the power supply grid, and the capacity and performance of power electronic devices have been significantly improved.