The principle of the inverter is: input AC, rectify it into controllable DC, and then invert it into AC output, so the output is AC. There are many types of inverters, including 220 volt input, 380 volt two-phase input, and 380 volt three-phase input. 220 three-phase output, 220 volt two-phase output, 380 volt three-phase output. The general inverter output is AC, and there are also special DC output inverters. Rare and rarely used.