What is the frequency converter? Frequency converter outputs the AC power to pure sine wave after the transformation of AC→DC→AC, the output frequency and voltage can be adjusted within a certain range. It is different from the variable frequency drive (VFD) used for motor speed regulation, and also different from the common AC regulated power supply. An ideal AC power supply is characterized by stable frequency, stable voltage, zero internal resistance and pure sinusoidal voltage waveform (without distortion). Frequency converter is quite close to the ideal AC power supply, so more and more countries use it as standard power supply to provide the best power supply environment for electrical appliances, so as to assess the technical performance of electrical appliances.