Sliding Mode Control and PI control for arc welding/cutting inverter

According to the basic characteristics of arc welding and cutting, the arc welding/cutting inverter with SMC and PI control is researched and designed. There are two alternate loops: voltage loop on no-load and current loop on load. Through demonstrating the external characteristics demands of arc welding/cutting power source and analyzing the control algorithm, PI control is used on current loop and sliding mode control (SMC) is introduced on voltage loop, which has not only effectively solved the voltage overshoot, but also realized a faster current response. In this paper, phase-shift full-bridge (PSFB) indirect SMC is adopted, then the control algorithms based on the average state space model is deuced theoretically, and in addition, a direct phase-shift PWM wave generation method is applied which makes the control more practical and simpler, and finally a 20 kW arc welding/cutting power source is developed on which the experiment results prove the effectiveness of control algorithm.