Control of free-piston Stirling generator system using SVPWM and advanced sliding mode techniques

This paper introduces a novel control framework for a Free-Piston Stirling Linear Generator (FPSLG) system. The primary contribution is the first application of advanced sliding mode controllers specifically Super-Twisting (ST-SMC) and Third-Order Sliding Mode Control (TO-SMC) to regulate the DC-link voltage in a Space Vector Pulse Width Modulation (SVPWM) based rectifier. These controllers are implemented in the power converter to condition the FPSLG’s inherently variable electrical output, improving system performance under fluctuating conditions. The proposed ST-SMC and TO-SMC demonstrate superior performance by achieving reduced voltage/current ripple, improved robustness, and better dynamic response. Additionally, the system combines a bidirectional DC-DC converter with dual-loop PI control to maintain stable voltage for battery storage. MATLAB/Simulink simulations validate the effectiveness of this control strategy in significantly improving power quality and system stability for FPSLG-based renewable energy systems.