With the development of power electronic devices and the pursuit of efficiency, AC speed regulation has been rapidly developed. In addition, new technologies and new theories have continuously infiltrated into AC speed regulation to make it constantly appear new. This article mainly introduces the development status and trends of AC speed control system. First, it introduces the development of modern AC speed control technology. Secondly, it introduces the types of modern AC speed control system and the development of AC speed control system at home and abroad. Finally, it describes the AC speed regulation. The development trend of the system, specifically follow the Xiao Bian together to find out. Modern AC speed regulation can be divided into several stages. In the mid-1960s, Germany's ASchonung et al. took the lead in proposing the idea of ​​pulse width modulation frequency conversion. They applied the modulation technology in the communication system to frequency control. It has opened up a new path for the development and practical application of modern AC speed control technology. Since then, AC speed regulation theory and application technology have generally developed along the following four aspects. (1) The vigorous development of power electronic devices Power electronic devices are the backbone of modern AC speed control devices, and their development directly determines and influences the development of AC speed control technologies. To date, the development of power electronic devices has experienced discrete commutation shutdown devices (first generation) → self shutdown devices (second generation) → power integrated circuits PIC (third generation) → intelligent modules IPM (fourth generation) four stages. Before the mid-1980s, the thyristor components were mainly used in the power circuit of the frequency conversion device. The efficiency, reliability, cost, and volume of the device cannot be compared with a DC variable speed device of the same capacity. After the mid-1980s, frequency conversion devices such as GTR (Gant Transistor), GTO (Gate TurnOff thyristor), and VDMOS-IGBT (Insulated Gate Bipolar Transistor 2 tor), which are manufactured by the second-generation power electronic devices, can perform DC-to-DC conversion in terms of performance and price ratio. Speed ​​devices are comparable to each other. With the continuous development of large current, high voltage, high frequency, integration, and modularization, the third generation of power electronic devices is the mainstream product of frequency converter manufacturing in the 1990s, with medium and small power frequency converters ( 1-100kw) The main use of IGBT, medium and high power frequency converter (1000-10000kw) using GTO devices. From the 90s of the 20th century to the present, the development of power electronic devices has entered the fourth generation. The main practical fourth-generation devices are: (1) High-voltage IGBT devices (2) IGCT (Insulated Gate Controlled.) Due to insurmountable defects in the GTR and GTO devices, the GTR devices have been eliminated from use since the third generation of power devices. After entering the fourth generation, GTO devices will also be phased out. The fourth generation of power electronic devices is more modular. Such as intelligent module IPM, dedicated power device module ASPM. Modular power devices will dominate the device in the 21st century. It should be pointed out that the above-mentioned fully-controlled switching power devices are mainly used in asynchronous motor variable frequency speed control systems, and the reasons are well known. However, thyristors are still used in synchronous motor variable-frequency speed control systems. The reason is also well-known. A generation of power electronic devices brings a new generation of variable frequency speed control devices that cost more than one generation at a time. After the human society entered the age of information, the power electronics technology, together with electric drive control and computer technology, remained the two most important technologies in the 21st century. Harmonic components in voltage or current, thereby reducing or eliminating the torque ripple of the motor during frequency conversion, improving the efficiency of the motor, and expanding the speed range of the speed control system. (2) Pulse width modulation (PWM) technology Pulse-width modulation (PWM) technology is a variety of technologies and is constantly evolving. Basically, it can be divided into four categories: equal width PWM method, sinusoidal PWM method (SPWM), flux tracking PWM method, and current tracking PWM method. The application of PWM technology overcomes all the drawbacks of the phase control principle, so that the AC motor stator gets a voltage and current close to a sinusoidal waveform, which increases the power factor and output power of the motor. Modern PWM generation circuits mostly use a microcontroller (such as 80196) with a high output HSO and a digital signal processor (DSP) to generate PWM through software programming. In recent years, the new all-digital special-purpose PWM generation chip HEF4752 SLE4520 MA818 has been put to practical use and has been put to practical use. (3) Vector transformation control technology and direct torque control technology As we all know, the double closed-loop speed control system for DC motors has excellent static and dynamic speed regulation characteristics. The fundamental reason is that the electromagnetic torque of a self-excited DC motor as a control object can be easily and flexibly controlled. The AC motor is a multivariable, non-linear, strong coupling control object, as the control object of the variable frequency system, whether it can imitate the DC motor torque control law to control it. In 1975, the German scholar F Blaschke proposed the principle of vector transformation control, successfully solved the effective control of the electromagnetic torque of the AC motor, based on the rotor flux, using the modern control theory concept of parameter reconstruction and state reconstruction. The solution between the excitation component and the torque component of the stator current of the AC motor is realized, the control process of the AC motor is equivalent to the control process of the DC motor, and a major breakthrough is theoretically achieved, thereby enabling the AC speed regulation. Dynamic and static performance is entirely comparable to DC drive systems. The key to vector control is the coordinate control between the stationary and rotary coordinate systems. Torque control is also a promising control technique. At present, the variable frequency speed control device using the IG2 BT, IGCT direct torque control method has been widely used in industrial production and transportation departments. (4) Microcomputer Control Technology With the rapid development of microcomputer control technology, especially the microcomputer control technology with a single-chip microcomputer and a digital signal processor DSP as the control core, the control loop of the modern AC speed control system rapidly moves from analog control to digital control. Today's analog controllers have been eliminated and all-digital AC speed control systems have been widely applied. Digitization makes the controller greatly improve the ability of information processing, and many difficult to achieve complex control, such as complex coordinate transformation operations in vector control, untwist control, sliding mode variable structure control, adaptive control of parameter identification, etc., using microcomputer control After the device is resolved. A high-performance vector control system cannot be realized without the support of a microcomputer. In addition, the microcomputer control technology has added a variety of functions to the AC speed control system, especially the fault diagnosis technology has been fully realized. The application of microcomputer control technology has improved the reliability and operation of the AC speed control system, the diversity and flexibility of the installation, and reduced the cost and volume of the frequency conversion speed control device. Digital control based on microprocessors has become one of the main features of modern AC speed control systems. The development of microprocessors for AC speed control systems has gone through three stages: a single-chip computer (MCS), a digital signal processor (DSP), and a reduced instruction set computer (Reduced Instruction Set Computer RISC). The modern AC speed control system consists of four parts: AC motor, power electronic power exchanger, controller and detector. Power electronic power converters, controllers, and power detectors are integrated into one unit, called an inverter (inverter). Different AC motors produce different AC speed control systems. Therefore, modern AC speed control system can be divided into asynchronous motor speed control system and synchronous motor speed control system. Currently three commonly used programs, they are asynchronous motor AC speed control system: (1) Asynchronous motor AC speed control system. (2) AC reluctance system of switched reluctance motor (3) Synchronous motor speed control system. For a long time, China's drive technology, especially AC speed regulation technology, has a big gap with foreign developed countries. However, since the reform and development, this technology has developed rapidly and it has rushed up at an extremely fast pace. Although China's application of variable frequency speed control technology is currently still in its infancy, its growth rate has been growing rapidly year by year. The country has listed this technology as a key technology research and promotion project during the "Eighth Five-Year Plan" period. This will accelerate the popularization of AC speed regulation in China. At present, the status of the domestic frequency conversion speed control technology industry is as follows: (1) The basic research on the control strategy of the frequency converter is not far from the foreign countries; (2) The overall technology of the inverter is backward. Although many units in China have invested a certain amount of manpower and material resources, they have not formed a certain scale of technology and production scale due to the dispersed power. (3) The manufacturing of semiconductor power devices used in inverter products is almost a blank; (4) The related supporting industries and industries are backward; (5) Low production and sales volume, low reliability and process level. AC frequency conversion speed regulation technology has been widely used in industrial developed countries. In the United States, 60% - 65% of the electricity generation is used for motor drive. Due to the effective use of variable frequency speed control technology, only industrial drive power consumption can save 15% - 20% of the electricity. The foreign research and application of high-performance high-capacity AC motor drive technology is far ahead of us. There are already a number of higher-level high-voltage inverter products put into the market, and applied to electric locomotives, ships and ships electric propulsion, rolling, In systems such as papermaking and water supply, AC motor speed control technology and its products have become the leading industries in some industrialized countries. At present, the foreign advanced industrial countries produce a DC drive device basically showed a downward trend, while the production of AC variable frequency speed control device increased significantly. Take Japan as an example. In the field of speed regulation in 1975, DC accounted for 80%, and AC accounted for 20%. In 1985, AC accounted for 80%, and DC accounted for 20%. Until now, Japan has adopted DC motor drives in addition to individual locations. Almost all speed control systems use AC inverters. Developed countries rely on their strong scientific and technological strength to push frequency conversion technology to small-scale, high-reliability, anti-pollution, multi-functional, and high-performance. 1. High performance. The product will generally adopt vector control technology to improve the speed control performance and reach and exceed the level of DC speed control system. Vector change control is a new control theory and control technology. His idea is to try to simulate the control characteristics of the DC motor to control the AC motor. 2. The development of fully-controlled, high-power and fast power electronic devices provides material assurance for modern frequency converters. The development of AC motor speed control technology is inseparable from the development of power electronics technology. In 1957, thyristors of power semiconductor devices appeared in the world, which opened the way for the development of AC motor speed control systems. 3. The development and application of pulse width modulation technology optimize the performance of frequency conversion devices and can be applied to various types of AC motors. In 1964, Germany's A. Schonung and others took the lead in proposing the idea of ​​pulse width modulation frequency conversion, that is, applying pulse width modulation (PWM) technology of communication systems to AC electric drives. PWM type inverters have high input power factor and output. Good waveform characteristics. Positive flicker pulse width modulation (SPWM) is the most commonly used modulation method. The characteristics of a common modulation pulse are equal intervals, equal amplitudes, and unequal widths in a half cycle, and are narrow in the middle width and width of each pulse. It is proportional to the area under the sine wave. The new pulse width modulation (CNPWM) divides the half cycle into three equal parts. The first 60 pulses P and the last 60 pulses determine the modulation method is the same as the SPWM, but the middle 60 pulses equals the sum of the front and back pulses, ie, Pz=P1+P. This increases the switching frequency, and the composition also decreases. 4, the control system hardware from analog technology to digital technology, micro-computer performance, speed, degraded, volume and other aspects of the development of AC motor speed regulation theory provides the most important guarantee. The development process of AC speed regulation technology shows that the needs of modern industrial production and social development have promoted the rapid development of AC speed regulation. The development and application of modern control theory, the development and application of power electronics technology, the development and application of computer control technology and neural network technology have created technical and material conditions for the rapid development of AC speed regulation. The AC speed regulation system will play an increasingly important role in human pursuit of energy conservation. Diesel Generator Power Range,Single Phase Diesel Generator,Mobile Type Diesel Generator,Standby Power Diesel Generator Shanghai Kosta Electric Co., Ltd. , https://www.ksdgenerator.com
