frequency converter (Variable-frequency Drive, abbreviation: VFD), also known as Variable frequency Drive or Drive controller, can be translated as Inverter (the same as Inverter in English). Frequency converter is a kind of adjustable speed drive system. It uses frequency conversion drive technology to change the frequency and amplitude of AC motor working voltage to smoothly control AC motor speed and torque, the most common is the AC/AC converter whose input and output are alternating current.

Before the frequency converter appears, the application of adjusting the motor speed needs to be completed through the DC motor, otherwise it needs to be completed through the VS motor using the built-in coupling machine, in operation, the coupling machine is used to reduce the actual rotation speed of the motor. The frequency converter simplifies the above work, reduces the equipment volume and greatly reduces the maintenance rate. However, there are high frequency switching signals on the power line and motor line of the frequency converter, which will cause electromagnetic interference. However, the power factor on the input side of the frequency converter is generally poor, which will produce harmonics on the power terminal. Frequency converter

Frequency converter has a wide range of applications, from small household appliances to large mine grinding machines and compressors. About 1/3 of the energy in the world is consumed on the motors that drive constant speed centrifugal pumps, fans and compressors, while the market penetration rate of frequency converters is still not high. The significant improvement of energy efficiency is one of the main reasons for using frequency converter.

Inverter technology is closely related to power electronics, including semiconductor switching components, inverter topology, control and simulation technology, as well as the progress of control hardware and firmware, etc.