Review and re‐evaluation of modulation techniques for neutral‐point‐clamped inverters with high‐order filters

Abstract

The centred space vector modulation scheme is considered to be the best since it produces the least switching harmonics among the modulation techniques developed for neutral-point-clamped (NPC) inverters. However, this common belief was concluded in the condition when inverters interfaced to the grid with a simple inductor filter. Nevertheless, to achieve an excellent harmonic attenuation performance, higher-order filter is much preferred for NPC inverter. Consequently, the aforementioned common belief may lose its correctness due to the distinctive resonance characteristics accompanied by highorder filters. The objective is to review and re-evaluate the performances of the commonly used modulation techniques for NPC inverters when different high-order filters are applied. Furthermore, this study provides a guide to choose an appropriate modulation scheme when high-order filters are used. The sinusoidal pulse-width modulation with alternative phase opposition disposition shows the best performance since it always ensures high-quality current waveforms when high-order filters are used in NPC inverters. Apparently, this conclusion is against the common belief. Moreover, different conclusions in terms of the performances have also been found for other modulation techniques considered in this review. Finally, to validate the correctness of the analysis and the findings, simulated and experimental results are provided and discussed.

Modeling and Compensation for Dead-Time Effect in High Power IGBT/IGCT Converters with SHE-PWM Modulation

“…This paper establishes a detailed mathematical model and proposes both open-loop and closed-loop compensation methods for SHE-PWM modulation based on a 3-level NPC voltage source grid-connected inverter. This topology has been widely used in the field of medium-voltage high power grid-connected applications because it achieves good compromise between cost and harmonic performance [34][35][36]. It was noted that the proposed method and analysis are also applicable to other fields, such as medium-voltage variable-speed motor drives where the dead-time effect causes torque ripple [23].…”

Simplified hybrid space vector modulation for multilevel diode clamped converter

“…Multilevel converter (MLC) has been attracting considerable interest since it was discovered in 1981 [1]. It has great advantages over traditional two‐level converter, especially in the medium/high power applications [2–4]. Diode clamped converter (DCC), flying capacitor converter and cascaded H‐bridge are the main MLCs topologies [2–4].…”

“…Along with the evolution of MLC topologies, numerous research papers have grown up around the theme of modulation techniques dedicated to MLCs control [3, 5–7]. Among them, space vector modulation (SVM) has emerged as powerful modulation technique due to its significant advantages in terms of waveform quality improvement, full utilisation of DC‐bus and suitability for digital applications [3, 8]. However, despite its performance and efficiency, multilevel SVM technique suffers from a major drawback of the computational complexity especially when the number of DCC levels increases [3, 8].…”

“…Among them, space vector modulation (SVM) has emerged as powerful modulation technique due to its significant advantages in terms of waveform quality improvement, full utilisation of DC‐bus and suitability for digital applications [3, 8]. However, despite its performance and efficiency, multilevel SVM technique suffers from a major drawback of the computational complexity especially when the number of DCC levels increases [3, 8]. Therefore, the main challenge faced by researchers is to find a simplified and generalised SVM algorithm for any DCC level.…”