New Compound Control Strategy of Plasma Cutting Power Supply under Sudden Change of Transferred Arc

Abstract:
According to the application of non-high frequency arc strike technology in plasma cutting power supply, this paper analyzes the transferring characteristic of the voltaic arc of plasma cutting power supply, designs the control requirements under the condition of non-high frequency arc strike, arc transfer and sudden change of arc energy, and deduces the mathematical model of plasma arc, based on which a new compound control strategy has been put forward. The inner loop of the strategy is a voltage closed-loop compound control composed of feedforward compensated arc voltage and feedback arc voltage, and the outer loop controls the energy of plasma arc column with current closed-loop, forming a feedforward compensated double closed-loop compound control mode, so as to meet the control requirements of power supply for rapidity and stability under the condition of non-high frequency arc strike load. Simulation and experimental results show that the proposed control strategy in the paper can not only improve the rapidity and robustness of the system, but also has excellent dynamic response ability and strong nonlinear adaptability of the power supply, which effectively solves the control requirements of plasma cutting power supply.