The old welding machines used electromagnetic winding to step up the current for welding rods. What is the new principle inside the welding machines?
Answers
That's one type of machine. Like your average Lincoln Idealarc or maybe an old coil tap Welder.
These machines have big copper windings with a movable metal core or just tap into the circuit at different points to change the amperage.
They also have an electrical device called a rectifier to take AC current and make it DC, which is better to weld with (generally speaking).
Then you have machine driven welders. These ones use an engine to drive a DC generator or AC Alternator.
Now we have inverter welders.
Rather than having a big old coil… there is a circuit board with something like an old solid state amplifier, called an insulated gate bipolar transistor or IGBT.
It takes AC current and rectifies it to DC and turns our regular 60Hz current and jacks it up to 10kHz. This gives us much finer control over our weld parameters such as the rise and fall of voltage as arc length increases and decreases… and they're small enough to wear over your shoulder on a strap.