Implementation of NLC-SHM based novel PWM scheme on packed U-cell multilevel inverter

Abstract

This article introduces a novel integrated nearest level controller (NLC) combined with selective harmonic mitigation (SHM) control approach aimed at efficiently suppressing lower-order harmonics has been introduced. The proposed methodology is implemented on the PUC-7 inverter topology, leveraging the combined benefits offered by both NLC and SHM controllers through a hybrid model. The proposed method demonstrates the capability to reduce lower-order harmonics up to the 49th harmonic from the load voltage. The particle swarm optimization algorithm is employed to determine optimal switching angles and their corresponding nearest levels, thereby reducing implementation time, computational complexity, and overall system intricacy. The performance analysis of the proposed control strategy across various scenarios, including fluctuations in modulation index and monitoring diverse parameters such as load dynamics has been performed. This approach yields a significant reduction in total harmonic distortion in both load voltage and current. A comparative analysis between NLC, selective harmonic mitigation (SHM), and the integrated NLC-SHM approach is carried out on the PUC-7 inverter. The integrated SHM-NLC control is implemented and validated using the MATLAB Simulink environment, complemented by hardware-based experimentation, to ascertain its effectiveness.