The frequency converter is a device that converts a commercial frequency power supply (50 Hz or 60 Hz) into an AC power source of various frequencies to realize variable speed operation of the motor, wherein the control circuit completes control of the main circuit, and the rectifier circuit converts the alternating current into direct current, and the middle of the direct current The circuit smoothes the output of the rectifier circuit, and the inverter circuit reverses the direct current into alternating current. For a frequency converter such as a vector control inverter that requires a large amount of calculations, sometimes a CPU for torque calculation and some corresponding circuits are required. The frequency conversion speed regulation achieves the purpose of speed regulation by changing the frequency of the power supply of the stator winding of the motor.
There are various classification methods of frequency converters. According to the main circuit working mode, they can be divided into voltage type inverters and current type inverters. According to the switch mode classification, they can be divided into PAM control inverters, PWM control inverters and high carrier frequencies. PWM control inverter; according to the working principle, it can be divided into V/f control inverter, slip frequency control inverter and vector control inverter; according to the purpose classification, it can be divided into general inverter, high performance special inverter, High frequency inverter, single phase inverter and