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The modular multilevel converter (MMC) is an emerging topology for high-power applications and is considered as the development trend of the high-voltage power converters. In this paper, general implementation of the phase-shifted carrier (PSC) modulation with a capacitor voltage balancing method for MMC is first introduced. Then, the mathematical analysis(More)
This letter respectively presents two closed-loop precharge control methods to fully charge the submodule (SM) capacitors of the modular multilevel converter (MMC) during dc-side and ac-side start-up processes. The proposed methods are aimed at regulating a constant charging current thus reducing the start-up time and eliminating the inrush current.(More)
The secretin GspD of the type II secretion system (T2SS) forms a channel across the outer membrane in Gram-negative bacteria to transport substrates from the periplasm to the extracellular milieu. The lack of an atomic-resolution structure of the GspD channel hinders the investigation of substrate translocation mechanism of T2SS. Here we report cryo-EM(More)
Modular multilevel converters (MMC) represent an interesting and emerging topology in medium-voltage motor drive applications. The main challenge of using such a topology in variable-speed drives is the large voltage ripple of submodule capacitors at low speed with constant torque. In this paper, an improved circulating current injection method is proposed,(More)
Maintaining a healthy ecosystem is essential for maximizing sustainable ecological services of the best quality to human beings. Ecological and conservation research has provided a strong scientific background on identifying ecological health indicators and correspondingly making effective conservation plans. At the same time, ecologists have asserted a(More)
The mixed grassland in Canada is characterized by low to medium green vegetation cover, with a large amount of canopy background, such as non-photosynthetic vegetation residuals (litter), bare soil, and ground level biological crust. It is a challenge to extract the canopy information from satellite images because of the influence of canopy background.(More)
The modular multilevel converter (MMC), eliminating the expensive and bulky multi-winding phase-shifting transformer compared with the cascaded H-bridge converter, is shown to be of great potential in the field of medium-voltage motor drive applications. However, special care needs to be taken for MMC driving motor at low speeds, since the voltage(More)
Person re-identification plays an important role in computer vision, aiming to identify the same person viewed by disjoint cameras at different time instants and locations. In this paper we present a novel appearance-based method by multi-resolution saliency-weighted color histograms and local structural sparse coding for re-identification work. The former(More)
This paper presents the design and control methods for a modular multilevel converter (MMC) based back-to-back (BTB) system. A 20kW, 50Hz three phase downscaled prototype is constructed to show the working principles, hardware design procedures, and control circuits implementation. In this prototype, there are two MMC stations, namely the inverter and the(More)