How is current controlled in an MFDC inverter type?

In the case of the MFDC inverter type, welding current is controlled by changing the pulse-width using a semi-conductor, called IGBT.This control is called PWM (Pulse Width Modulation) control.The output from the welding power source is an alternating current of about 600 – 2,000Hz, but a large current cannot flow to the secondary side when the frequency remains high. Therefore, a rectifier, called a diode-stack, is installed on the secondary side of the welding transformer and the secondary current is converted to direct current.
The feedback control to keep the weld current constant is called constant current control.