Cascaded Terminal Super Twisting Sliding Mode Control for DC–DC SEPIC Converters

DC–DC converters, particularly the single-ended primary inductor converter (SEPIC), are crucial in modern energy systems, providing versatile voltage regulation for applications in smart grids, renewable energy, and electric vehicles. However, effective control of SEPIC converters is essential to handle a wide range of input voltages and to ensure stability under varying load conditions. Traditional control methods such as proportional-integral-derivative (PID) and model predictive control have limitations in terms of dynamic response, robustness, and sensitivity to parameter variations. Even though the sliding mode control (SMC) is robust, it suffers from high chattering. To overcome this, super twisting sliding mode control (ST-SMC) has emerged in literature which offers finite-time convergence and alleviates chattering. However, prevailing ST-SMC approach has poor dynamic response, particularly under rapidly changing currents. To tackle this issue, this article proposes a novel PWM-based cascaded super twisting sliding mode control (CST-SMC) architecture that, unlike existing ST-SMC approaches, decouples current and voltage regulation via a terminal sliding function, enables finite-time convergence and significantly improves dynamic response under high current transients. Simulation and experimental results demonstrate the effectiveness of the CST-SMC method in achieving finite-time voltage regulation with improved dynamic performance which makes it promising and novel solution that differs from traditional SMC designs by leveraging cascaded control architecture for enhanced dynamic performance in real-world applications.