The present paper proposes a plasma cutting power supply based on a four-switch Buck-Boost cascaded LLC resonant converter, with a view to overcoming the limitations of conventional topologies, including low efficiency, limited power density, and high electromagnetic interference (EMI). The proposed solution has been demonstrated to achieve wide-range current regulation, high efficiency, and stable power output. In addressing the nonlinear and time-varying nature of the plasma arc load, a decoupled control strategy has been developed using a double-integral sliding mode control (DISMC) framework. The DISMC employs a sliding surface that incorporates current error, its derivatives, integrals, and double integrals to enhance dynamic response and robustness. The present paper undertakes a systematic analysis of the characteristics of the converter and the controller design, thus providing a practical reference for high-performance power supply design in nonlinear load applications.

Plasma Cutting Power Supply,double-integral sliding mode control,Four-Switch Buck-Boost,LLC resonant converter