Fan frequency converter is a special frequency converter tailored for all kinds of fans. The frequency conversion speed regulation control device is used to change the fan speed, so as to change the fan air volume to meet the needs of the production process. Moreover, the operation energy consumption is the lowest and the comprehensive benefit is the highest. Therefore, frequency conversion speed regulation is the best speed regulation scheme with high efficiency. It can realize the stepless speed regulation of fans, and can easily form a closed-loop control system to achieve constant pressure or constant flow control.