The invention provides a reliable rotor commutator welding method, including the steps: the coil end heads of the upper coil and the lower coil are welded through the argon-arc welding;

It also gets the left shoulder turning so the upper body starts to coil against a stable lower body.

When powder core is used to preparation of APFC inductor, lower core loss will be obtained as long as core sizes and coil turns are properly selected.