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