Drive VFD, Variable-frequency is the application of frequency conversion technology and microelectronics technology, through changing the motor power frequency mode to control AC motor power control equipment. Inverter is mainly composed of rectifier (AC inverter), filter, inverter (AC), braking unit, driving unit, detection unit, and so on.. Inverter by internal IGBT disconnected to adjust power output voltage and frequency, according to the actual needs of the motor to provide the power supply voltage, so as to achieve the purpose of energy-saving and speed. In addition, inverter and a lot of protection, such as over-current, over-voltage, overload protection and so on. With the increase of industrial automation, inverter has been widely used.