Comparison of phase-shifted and level-shifted PWM in the modular multilevel converter

Abstract

This paper reports a comparison study of different carrier-based PWM techniques applied to the modular multilevel converter. Phase-disposition PWM (PD-PWM) and phase-shifted pulse-width modulation (PS-PWM) with non-interleaving and interleaving are considered in this study. In PS-PWM, two cases are evaluated. In the first case, the particular SMs that have to be activated/deactivated are defined by a voltage balancing algorithm, which is the same one implemented in PD-PWM. In addition, an algorithm to restrict the number of switching SMs is also implemented to reduce the switching frequency of the power devices. In the other case of PS-PWM, each sub-module (SM) has a carrier signal associated to it and capacitor voltage balance is achieved by individual control of its capacitor voltage. The circulating current is controlled to be a dc component in all the cases. Simulation and experimental results are presented to evaluate the quality of the line-to-line output voltages and SM capacitor voltage ripples for the different cases under study. © 2014 IEEE.Peer ReviewedPostprint (published version

Development of Nuclear Magnetic Resonance Downhole Logging Tool For Hydrocarbones Search

“…This is shown in Fig. 1.17 (Cendelchi, et al, 1998;Baker, et al, 1974;Bhagwat, et al, 1981;Tolbert, et al, 1999;Ilves, et al, 2011;Ilves, et al, 2015;Du, et al, 2004;Lai, et al, 1996;Kang, et al, 2012;Konstantinou, et al, 2010;Li, et al, 2015;Dahidah, et al, 2014;Darus, et al, 2014;Antunes, et al, 1999) The Phase Shift PWM method appears to be promising for this application as it is based on Multiple Module Converters (MMC), operates with the fundamental frequency and combines their output voltages using high frequency output transformers. In the frequency range 0.5 MHz to 1 MHz, these combining RF transformers are relatively small, fit the high pressure housings and are reliable for high temperature applications.…”

Analysis of strategies of modulation voltage of the active rectifier based on the modular multilevel converters

“…Определено, что в резул тате работы ММС согласно предложенным мет дикам, достигаются достаточно низкие значения коэффициента искажения синусоидальности кр вой выходного напряжения (THD). Сравнение трех различных способов модуляции показало, что и пользование ШИМ по принципу shifted с определенным чередованием подмодулей позволяет достичь минимального уровня THD 4,37 % при частоте переключений всего в 300 Гц, т. е. при шести переключениях за период [30].…”

“…3, данный способ модул ции является более предпочтител Преимуществом модульных многоуровневых конвертеров является возможность построения высоковольтных преобразователей частоты по бес б) Выходные линейные напряжения 11-уровневого ММС: формы кривых; б -спектр высших гармоник [30] напряжения активных выпрямителей на базе модульных многоуровневых конвертеров 33 является постоянным. Как следствие, возникают общие пульсации напряжения на импедансах верхних и нижних плеч, что увеличивает эффек-ичество уровней с (N + 1) до (2N + 1).…”

Double-Carrier Phase-Disposition Pulse Width Modulation Method for Modular Multilevel Converters

“…Many academic papers have focused on modeling [16][17][18][19], control [20][21][22][23][24], and modulation techniques [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] for MMCs. The multilevel converter pulse width modulation technique is one of the key technologies for MMCs as it affects the harmonic characteristics, voltage balancing and system efficiency.…”

“…Compared with PSCPWM, the phase-disposition pulse width modulation (PDPWM) method has superior harmonic characteristics by placing significant harmonic energy into the first carrier component in the phase voltage and relying upon the elimination of this component when the line-to-line voltages are created [25]. The main drawback of the PDPWM is the uneven loss distribution among the SMs, which can be solved by the voltage balancing method based on sorting [37][38][39][40]. In [41], an improved PDPWM method using a single carrier was proposed for MMCs, which reduces the control hardware requirement.…”