The variable-frequency drive (VFD) is a power control device that uses frequency conversion technology and microelectronics technology to control board AC motors by changing the frequency of the motor's working power supply.

The inverter is mainly composed of rectification (AC to DC), filtering, inversion (DC to AC), braking unit, drive unit, detection unit, microprocessor unit, etc. The inverter adjusts the voltage and frequency of the output power supply by the internal IGBT's disconnection, 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 the degree of industrial automation, inverters have also been widely used.

The use and parameter adjustment of the inverter involve multiple aspects:

· Start and stop control: start and stop the motor through external control signals or built-in control panels.

· Speed regulation: change the speed of the motor by adjusting the frequency of the output power supply.

· Protection function: including overcurrent, overvoltage, overload protection, etc., to protect the motor and inverter from damage.
· Used in conjunction with controllers such as PLC: realize automatic control and improve the level of production automation.

The functions of frequency converters are extensive, including:

· Energy saving: reduce energy waste by adjusting the motor speed, especially in equipment such as fans and water pumps.

· Improve product quality and labor productivity: improve product quality and production efficiency by accurately controlling the motor speed.

· Reduce the impact on the power grid: reduce interference to the power grid by smoothing the voltage and current waveforms.

· Extend the service life of equipment: extend the service life of motors and related equipment by reducing mechanical wear and electrical stress.