A novel composite control strategy for plasma cutting power supply based on arc control

This paper analyzes static characteristics of plasma arc with the derivation of plasma arc mathematical model according to the application of low-frequency(LF) pilot arc technology in the plasma cutting power supply,and integrates with the control requirements in low-frequency (LF) pilot arc,arc transferring and arc energy transferring,and proposes a novel composite control strategy. In order to meet the power's control requirements of rapidity and stability with the load of low-frequency(LF) pilot arc,the inner loop of this strategy builds up voltage loop composite control with feed-forward arc voltage and feedback arc voltage,and the current outer loop controls the energy of plasma arc,forming a control method of feed-forward composite control of double closed-loop. Simulations and experiments were given to verify that the mentioned control strategy not only improved system's stability and robustness,but also had excellent dynamic responsibility. The power had well non-liner resilience, meeting requirements for plasma cutting power supply.