Modulation techniques applied to medium voltage modular multilevel converters for renewable energy integration: A review

Abstract

Modular multilevel converters (MMC) inherent features are gaining more attention for dc voltage transmission systems. One of the main research paths regarding the converter performance deals with its voltage modulation. Specifically, for medium voltage applications with relatively small number of submodules, the voltage modulation techniques impact on the MMC performance needs to be studied. This work provides an extensive review of the carrier-based pulse with modulation (CB-PWM) techniques proposed to be applied on previous multilevel inverter versions. The CB-PWM methods were adapted to be compatible with an additional cell ranking and selection algorithm to ensure equal energy distribution on the arm cells. The state-of-the-art of zero sequence signals (ZSS) applied on three-phase inverters is also reviewed. The alliance between the ZSS with the CB-PWM, as well as the nearest level modulation (NLM), has an important impact on the MMC harmonic content, efficiency and voltage ripple of its cells capacitors. A 15 MW 28-cell-based MMC is used to investigate each particular combination between the modulation method and the common mode ZSS.Postprint (author's final draft

An Overview of Carrier-based Modulation Methods for Z-Source Inverter

“…Several carrier modulation techniques are proposed and reviewed in the literature for MLIs (António-Ferreira et al, 2018). The basic Multi-Carrier PWM (M-C PWM) method provides an easy way to control the amplitude and frequency.…”

Recent contributions and future prospects of the modular multilevel converters: A comprehensive review

“…Mostly preferred of them are introduced in this paper. They can be categorized as carrier‐based PWM (CB‐PWM), nearest level modulation (NLM), and selective harmonic elimination (SHE), which is rarely preferred . CB‐PWM strategies are generally chosen due to the suitability in MMC‐based works, which contains PSC‐PWM and level‐shifted PWM (LS‐PWM) .…”

“…i ac (k), i dif,a (k), W ∑ a (k), and W Δa (k) are the measured variables at current step. i ac (k + 1), i dif,a (k + 1), W ∑ a (k + 1), and W Δa (k + 1) can be estimated by using (21) under various choices of V ∑ a and V Δa .…”

“…They can be categorized as carrier-based PWM (CB-PWM), 85,86 nearest level modulation (NLM), 87,88 and selective harmonic elimination (SHE), which is rarely preferred. 21 CB-PWM strategies are generally chosen due to the suitability in MMC-based works, which contains PSC-PWM [89][90][91] and level-shifted PWM (LS-PWM). 92,93 Besides, LS-PWM includes phase disposition PWM (PD-PWM) 94 and phase opposition disposition PWM (POD-PWM), 95…”

A Cost Effective Fault Diagnosis Technique for Cascaded H Bridge Multilevel Inverter

“…The ML inverter has three basic types of structures: Flying Capacitor (FC) [6], Cascaded H-Bridge (CHB) [7] Neutral Point Clamped (NPC) [5]. The other topologies are also derived from these basic topologies, which has ability to overcome some of the disadvantages of basic structures are: Active Neutral Point Clamped (ANPC) [8] [9], Hybrid multilevel inverter, Multilevel DC Link inverter (MLDCL) [10] and Modular Multilevel Converter (MMC) [11]. They can be chosen according to the different applications: grid [12].…”