Functions of frequency converter:
1.AC-DC-AC frequency converter "rectifies" fixed frequency alternating current into DC, and then "inverts" DC into three-phase alternating current with arbitrary adjustable frequency (complex structure, expensive price, mostly used in large-scale industries).
2. The AC-AC converter directly converts AC power with fixed frequency into AC power with adjustable frequency and the same number of phases before and after conversion (simple structure, wide application, suitable for large, medium and small power).
3. Three-in and three-out frequency converter The input side and output side of the frequency converter are all three-phase alternating current. Most industrial frequency converters fall into this category.
4. Single-input three-output inverter The input side of the inverter is single-phase alternating current, and the output side is three-phase alternating current. Frequency converters in household appliances all belong to this category, and their capacity is usually small.
Frequency conversion drive is a power control device that uses frequency conversion technology and microelectronics technology to control AC motor by changing the frequency mode of motor working power supply. The frequency converter is mainly composed of rectifier (AC to DC), filter, inverter (DC to AC), braking unit, driving unit, detection unit and microprocessor unit. The inverter can adjust the voltage and frequency of the output power supply by switching the internal IGBT, and provide the required power supply voltage according to the actual needs of the motor, so as to achieve the purpose of energy saving and speed regulation. In addition, the inverter also has over-current, over-voltage, overload protection and other protection functions. With the continuous improvement of industrial automation, frequency converters have been widely used.
Three-phase alternating current is a transmission form of electric energy, which is called three-phase electricity for short. Three-phase AC power supply consists of three AC potentials with the same frequency, equal amplitude and phase difference of120. Three-phase alternating current has many uses, and most industrial alternating current electrical equipment, such as motors, adopts three-phase alternating current, which is commonly called three-phase four-wire system. In daily life, single-phase power supply is often used, which is also called lighting power consumption. When lighting is powered by electricity, one of the three-phase electricity is used to supply power to electrical equipment, such as household appliances, and the other is the fourth line of three-phase four wires, that is, the zero line, which leads out from the neutral point of three-phase electricity.