Title: An improved low switching frequency modulation scheme for a symmetric CCS-multilevel inverter

Authors: A. Rakesh Kumar; T. Deepa

Addresses: School of Electrical Engineering, Vellore Institute of Technology, Chennai, TN, India ' School of Electrical Engineering, Vellore Institute of Technology, Chennai, TN, India

Abstract: In this paper, a low switching frequency modulation scheme is proposed for the symmetrical configuration of cross-connected sources-based multilevel inverter (CCS-MLI). The proposed scheme, named modified nearest level modulation (mNLM), is an improvement over the conventional nearest level modulation (NLM) scheme for MLI. The implementation of mNLM, compared to the NLM, has shown a considerable reduction in total harmonic distortion (THD) at the ac output of MLI. The mNLM works through variations in the switching angles of the MLI. By suitably varying the switching angles, the THD content is brought to the minimum. An algorithm for the same is also proposed which enables the mNLM to be implemented on other MLI topologies. Simulation is carried out in MATLAB/Simulink environment and it is also extended to a hardware prototype. The effectiveness of the proposed modulation scheme is also seen in terms of improved inverter parameters such as rms voltage, rms current and generated power.

Keywords: multilevel inverter; MLI; pulse width modulation; inverter modulation scheme; total harmonic distortion; THD; nearest level modulation; NLM; cross-connected sources-based inverter.

DOI: 10.1504/IJPELEC.2021.116647

International Journal of Power Electronics, 2021 Vol.14 No.1, pp.56 - 69

Received: 17 Sep 2018
Accepted: 09 Jan 2019
Published online: 29 Jul 2021 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article