1. Classified according to input voltage level
Frequency converters can be divided into low-voltage frequency converters and high-voltage frequency converters according to the input voltage level, and low-voltage frequency converters are common in China such as single-phase 220 V frequency converters, three-phase 220 V frequency converters, and i-phase 380 V frequency converters. High-voltage inverters commonly have 6 kV, 10 kV transformers, and the control mode is generally converted according to the high-low-high inverter or high-high inverter.
2. Classification according to the method of changing frequency
Frequency converters are divided into AC-AC frequency converters and AC-AC AC inverters according to the method of frequency conversion. The AC-AC AC inverter can directly convert the power frequency alternating current into AC that can be controlled by frequency and voltage, so it is called a direct frequency converter. AC-AC AC frequency converter is to first convert the power frequency alternating current into direct current through the rectifier device, and then convert the direct current into alternating current that can be adjusted by frequency and voltage, so it is also called indirect frequency converter.
3. Classified according to the nature of DC power supply
In the AC-DC-AC inverter, according to the process of converting the main circuit power supply into DC power supply, the nature of DC power supply is divided into voltage type frequency converter and current type frequency converter.