1, frequency control
AC motors, especially cage-type asynchronous motors, have a series of advantages such as small size, light weight, simple structure, convenient maintenance, low manufacturing cost and low operating cost, and reliable operation in harsh environments. However, in the past, due to the difficulty of speed regulation or the inefficiency of some speed control methods, it has long been occupied by DC speed regulation in the field of speed regulation. The advantages of AC motors have not been realized in the speed control transmission. Until the early 1970s, with the rapid development of power electronics, microelectronics (integrated circuits) and microcomputer technology, the long-awaited inverters achieved industrial production.
1.1 The so-called frequency converter - it converts three-phase power frequency (50Hz) AC power (or any power supply) into three-phase voltage adjustable, frequency adjustable AC power, and sometimes the inverter is called transformer Frequency conversion device VVVF. Mainly used for the adjustment of the speed of the AC motor (asynchronous machine or synchronous machine).
1.2 An AC motor variable frequency speed control system consists of three parts: the inverter motor driver AC motor and controller. The key core equipment is the inverter, which is used to achieve a smooth change in motor voltage and frequency.
1.3 Frequency control In the aspects of frequency modulation range, static accuracy, dynamic quality, system efficiency, perfect protection function, easy to realize automatic control and process control, etc., it is the previous voltage regulation, variable pole speed regulation, cascade speed regulation, Slip speed regulation and hydraulic coupler speed regulation are unmatched. It is recognized as the most ideal and most promising speed control solution for AC motors, representing the future development direction of electric drives.
1.4 In the past 30 years, frequency conversion speed regulation has been widely used in steel, metallurgy, petroleum, chemical, textile, chemical fiber, light industry, paper, rubber, plastic, electric power, water and other industries. The application of low-voltage motor frequency conversion speed regulation has been very popular and mature. The high-frequency motor frequency conversion speed regulation is also being paid attention to and gradually applied. In addition to excellent speed regulation performance, AC motor frequency conversion speed regulation also has significant functions of saving energy and protecting the environment. It is an ideal speed control device for technological transformation and product upgrading.
2, frequency control and fan pump energy saving
2.1 The contradiction between power supply and demand (supply in short supply) has a large power gap and needs to save electricity.