The harmonic performance, control robustness, and thermal characteristics of single-phase multilevel neutral-point-clamped (NPC) converters driving a single-phase reluctance motor (SPRM) are comprehensively analyzed in this study. Three converter topologies—a two-level single-phase NPC (2L-1P-NPC) converter, a three-level single-phase NPC (3L-1P-NPC) converter, and a four-level single-phase NPC (4L-1P-NPC) converter—are investigated under four modulation schemes: bipolar voltage pulsewidth modulation (BVPWM), unipolar voltage pulsewidth modulation (UVPWM), level-shifted pulsewidth modulation (LSPWM), and virtual-vector pulsewidth modulation (VVPWM), all operating at a fixed switching frequency of 10 kHz. High-fidelity simulations conducted in MATLAB-Simulink accurately replicate the coupled electromagnetic, mechanical, and thermal dynamics of the SPRM system, utilizing realistic motor and load parameters to ensure application-level relevance.

The results demonstrate that increasing the converter level substantially reduces total harmonic distortion (THD), with the 4L-1P-NPC topology under LSPWM achieving the lowest THD of 23.66%, thereby significantly improving voltage waveform quality and minimizing electromagnetic torque ripple. A proportional–integral (PI)-based feedback controller is implemented for velocity and position regulation, yielding precise trajectory tracking, a fast transient response, and negligible steady-state error. Additionally, thermal analysis quantifies power losses—conduction, switching, core, and copper—highlighting the trade-off between improved harmonic/dynamic performance and increased thermal stress. Notably, the junction temperature escalates from 121.8℃ in the 2L-1P-NPC converter to 188℃ in the 4L-1P-NPC converter, underscoring the necessity for advanced heat dissipation strategies in high-power applications.

By integrating harmonic distortion mitigation, closed-loop control design, and thermal evaluation, this work presents a unified framework for the optimal design and analysis of high-performance, thermally aware multilevel SPRM drives.

A comprehensive analysis of a two-level battery charger model is presented, focusing on its switched and averaged dynamics validated via MATLAB Simulink simulations. The system, powered by an 800 V DC source, is managed by a robust PI-compensated feedback loop, delivering minimal ripple, rapid transient response, and high stability under varying load conditions. Results demonstrate precise battery current control with a 4 ms settling time for step changes and ripple levels kept below 0.16% for current and 2.4% for capacitor voltage. Sensitivity analyses highlight the impact of non-ideal resistances—such as MOSFET on-resistance and inductor resistance—on efficiency and equilibrium voltage stability. Stability and loop gain studies confirm robust control performance, with all poles positioned in the stable region of the s-plane, ensuring reliable operation. This work provides key insights for designing high-efficiency, stable battery chargers and supports the use of advanced control techniques to further enhance converter performance.

This article presents an in-depth dynamic analysis and comparative evaluation of three distinct control strategies—proportional-integral (PI) compensator, linear quadratic regulator (LQR), and sliding mode control (SMC)—applied to a nonlinear process in two configurations: non-interactive system (NIS) and interactive system (IS). The primary objective was to optimize the regulation of fluid levels in a dual-tank system subject to external disturbances and varying operational conditions. The process dynamics were initially modeled using nonlinear differential equations, which were subsequently linearized to facilitate the design of the PI and LQR controllers. The PI compensator design was rooted in state-space representation and was tuned using the Ziegler-Nichols method to achieve the desired transient and steady-state performance. The LQR design employed optimal control theory, minimizing a quadratic cost function to derive the state feedback gain matrix, ensuring system stability by shifting the eigenvalues of the closed-loop system matrix into the left half of the complex plane. In contrast, the SMC leveraged the full nonlinear dynamics of the process, establishing a sliding surface to drive the system states toward a desired trajectory with robustness against model uncertainties and external disturbances. The SMC's performance was evaluated by analyzing the existence and stability of the sliding mode using the derived switching laws for the actuation signal. The comparative study was conducted through simulations in MATLAB/Simulink environments, where each controller's performance was assessed based on transient response, robustness to disturbances, and computational complexity. The results indicate that while the PI compensator and LQR provide satisfactory performance under linearized assumptions, the SMC demonstrates superior robustness and precision in managing the nonlinearities inherent in the IS configuration. This comprehensive analysis underscores the critical trade-offs between simplicity, computational overhead, and control efficacy when selecting appropriate control strategies for nonlinear, multi-variable processes.