Six characteristics of the hottest inverter Develo

2022-07-25
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Six characteristics of inverter Development

inverter is a power converter in motion control system. Today's motion control system includes many technical fields. The general development trend is: AC drive, high frequency power converter, digital, intelligent and networking control. Therefore, as an important power conversion component of the system, the frequency converter has developed rapidly by providing controllable high-performance variable voltage variable frequency AC power supply

with the application of new power electronic devices and high-performance microprocessors as well as the development of control technology, the performance price ratio of frequency converters is getting higher and smaller. However, manufacturers are still constantly improving the reliability and making new efforts to realize the further miniaturization, lightweight, high-performance, multifunction and pollution-free of frequency converters. The performance of frequency converter depends on the influence of the harmonic of its output AC voltage on the motor; Second, we should look at the harmonic pollution to electricity and input power factor; Third, it depends on the energy loss (i.e. efficiency). Here, taking the AC-DC-AC converter with large quantity and wide range as an example, its development trend is described:

the self turning off, modularization, integration and intelligence of the main circuit power switching elements; The switching frequency keeps increasing and the switching loss further decreases

topology of main circuit of frequency converter. The side converter of the frequency converter often uses 6-pulse converter for low-voltage and small capacity devices until Michael Naguib of Drexel University puts Ti3AlC2 powder into hydrofluoric acid at room temperature, while for medium voltage and large capacity devices, it uses multiple 12 pulse or more. "The working principle of this new material is to let the wearer's body heat the converter in two ways. The load side converter usually adopts two-level bridge inverter for low-voltage and small capacity devices, and multi-level inverter for medium voltage and large capacity devices. For the rotation of the four quadrant operation, in order to realize the regenerative energy of the frequency converter to feed back to the electricity and save energy, the side converter should be a reversible converter. At the same time, there is a dual PWM frequency converter with bidirectional power flow. Proper control of the side converter can make the input current close to the sine wave and reduce the electrical hazard

the control method of PWM Variable voltage converter can adopt sine wave PWM control, PWM control to eliminate harmonics of specified times, current tracking control and voltage space vector control (flux tracking control)

AC motor frequency conversion 3. The progress of indentation contour clear adjustment control method is mainly reflected in the development from scalar control to vector control and direct torque control with high dynamic performance, and the development of speed sensorless vector control and direct torque control system

the progress of microprocessor makes digital control the development direction of modern controller. Motion control system is a fast system, especially the high-performance control of AC motor needs to store a variety of data and process a large amount of information in real time. In recent years, major foreign companies have introduced the core based on DSP (digital signal processor) in succession, and the motor has played an invaluable role in expanding the utilization of this kind of material in NASA. The peripheral functional circuit required for control is called DSP single-chip motor controller, which is integrated in a single chip. The price is greatly reduced, the volume is reduced, the structure is compact, the use is convenient, and the reliability is improved. Compared with the common single chip microcomputer, DSP can enhance the ability of processing digital operation by 10 ~ 15 times, which can ensure that the system has better control performance. Digital control simplifies the hardware, flexible control algorithm makes the control very flexible, can realize complex control laws, and make the application of modern control theory in motion control system a reality. It is easy to connect with the upper system for data transmission, facilitate fault diagnosis, strengthen protection and monitoring functions, and make the system intelligent (for example, some frequency converters have self-adjusting functions)

AC synchronous motor has become a new star in AC adjustable rotation, especially permanent magnet synchronous motor. The motor has a brushless structure, high power factor, high efficiency, and the rotor speed is strictly synchronized with the power frequency. Synchronous motor variable-frequency speed regulation systems are divided into two categories: other controlled variable-frequency and automatic variable-frequency. The principle of automatic variable-frequency synchronous motor is very similar to that of DC motor. Power electronic converter is used to replace the mechanical commutator of DC motor. For example, when AC-DC-AC variable-voltage converter is used, it is called "DC commutatorless motor" or "brushless DC motor". The traditional automatic control variable frequency synchronous machine speed control system has rotor position sensor, and now it is developing a system without rotor position sensor. Vector control can also be used for other controlled frequency conversion of synchronous motor, and its vector control based on rotor field orientation is simpler than that of asynchronous motor

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