Digital control of double- pulsed gas metal arc welding machine

In this paper, a fully digitalized phase-shifted full-bridge PWM gating signals generation based on symmetrical carrier is proposed. To make wire feeder vary synchronously with the output current of DC/DC converter, double closed loop control is implemented by DSP. Besides, to improve the dynamic response of wire feeder, power stage for the motor is made up of a buck converter cascaded with a full-bridge inverter . A triple closed loop control model with full digital control is also presented to achieve double-pulsed GMAW process. The control model also contains stick-out length compensation, arc length regulation and instantaneous current control. Flexibility and reliability of the proposed control strategy for DP-GMAW implemented by two DSPs are validated by welding experimental results of 20 kW prototype.