When you turn on the welding supply, it will use the rectifier to convert the AC to DC. The current switches on and off rapidly in the supply, which creates a high frequency direct current to use for welding. Many choose to use inverter welders rather than traditional power supplies because they offer a number of advantages. They are more efficient and need a smaller transformer. This means the overall size and weight of the unit tends to be less, which makes them easier to transport. The power consumption is lower as well.