Variable-frequency Drive, VFD is a power control device that uses frequency conversion technology and microelectronics technology to control the AC motor by changing the frequency of the motor's working power supply. The inverter is mainly composed of rectification (AC to DC), filtering, inverter (DC to AC), braking unit, drive unit, a detection unit, and micro-processing unit. The inverter adjusts the voltage and frequency of the output power supply by switching on and off the internal IGBT, and provides the required power supply voltage according to the actual needs of the motor, thereby achieving the purpose of energy-saving and speed regulation. In addition, the inverter has many protection functions. , such as overcurrent, overvoltage, overload protection, etc. With the continuous improvement of industrial automation, frequency converters have also been widely used.