Solid-state transformer based on modular multilevel converters

A new highly compact topology for solid-state transformers is presented. It is based on modular multilevel converters and, therefore, has their usual advantages such as superior voltage shape, high reliability, and scalability. It utilises arm inductors for the isolated energy transfer between two converters and thereby allows for a more compact build compared to the design that uses separate transformers

GaN-Based Modular Multilevel Converter for Low-Voltage Grid Enables High Efficiency

Gallium Nitride (GaN) semiconductors with low inductance packages enable low switching losses and high efficiency. In this paper we present a compact arm PCB design with low loop inductance, allowing for fast and efficient switching. The PCB includes four full-bridge cells for a 7 kW Modular Multilevel Converter (MMC) for low-voltage grid applications

Control Strategy for Modular Multilevel Matrix Converters at High Output Frequencies

This paper presents a new control strategy for Modular Multilevel Matrix converters where the output frequency is higher then the input frequency. In operating points when ω$_{out}$ $\geq \$ ω$_{in}$ the energy pulsation in the converter cells are dominated by the second harmonic of the input frequency. These energy pulsations can be identified and compensated by inducing additional currents. The results are verified by simulation for a laboratory scaled prototype of the Modular Multilevel Matrix Converter

A generalized approach to the analysis and control of modular multilevel converters

A general method to derive the control strategy for arbitrary modular multilevel topologies is presented. The number of internal currents is derived from the topology. A strategy for arm symmetrization with arbitrarily controllable powers is given

Energy Pulsation Reduction in Modular Multilevel Converters Using Optimized Current Trajectories

In power electronics, the modular multilevel converter (MMC) is an easily scalable topology with an high output voltage quality. It is suitable for the transmission of large amounts of electrical power over long distances, which supports the realization of the ongoing energy transition. State-of-the-art methods require a comparatively large total cell capacitance in the system for energy pulsations during operation. In the present paper, in order to minimize this total capacitance, first a new method is developed to model the system, and second, by help of this model, optimal current trajectories are calculated. These currents are used for control to reduce the energy pulsation over the complete operating range, and thus, to better utilize the hardware. The new method independent on the Clarke transformations is implemented on a laboratory scale setup, and measurement results are presented which validate the new method. Furthermore, the new method is compared to the state-of-the-art method of the compensation of the 2nd harmonic and outperforms the latter significantly. This applies to the entire operating range for different power factors. A total reduction of up to 44% of the energy pulsations is achieved

Impact of Diabetes Mellitus and Chronic Kidney Disease on Cardiovascular Outcomes and Platelet P2Y(12) Receptor Antagonist Effects in Patients With Acute Coronary Syndromes : Insights From the PLATO Trial

Background-There are limited data on how the combination of diabetes mellitus (DM) and chronic kidney disease (CKD) affects cardiovascular outcomes as well as response to different P2Y(12) receptor antagonists, which represented the aim of the present investigation. Methods and Results-In this post hoc analysis of the PLATO (Platelet Inhibition and Patient Outcomes) trial, which randomized acute coronary syndrome patients to ticagrelor versus clopidogrel, patients (n=15 108) with available DM and CKD status were classified into 4 groups: DM+/CKD+ (n=1058), DM+/CKD- (n=2748), DM-/CKD+ (n=2160), and DM-/CKD- (n=9142). The primary efficacy end point was a composite of cardiovascular death, myocardial infarction, or stroke at 12 months. The primary safety end point was PLATO major bleeding. DM+/CKD+ patients had a higher incidence of the primary end point compared with DM-/CKD- patients (23.3% versus 7.1%; adjusted hazard ratio 2.22; 95% CI 1.88-2.63; P Conclusions-In acute coronary syndrome patients, a gradient of risk was observed according to the presence or absence of DM and CKD, with patients having both risk factors at the highest risk. Although the ischemic benefit of ticagrelor over clopidogrel was consistent in all subgroups, the absolute risk reduction was greatest in patients with both DM and CKD.Peer reviewe

Medium Voltage Power Electronic Building Block for Quasi-two-level Operation of a Flying Capacitor Converter

Today’s standard medium voltage converters are operated at low switching frequencies and contain bulky line filters. One concept to change this is the Quasi-Two-Level operation of multilevel converters with fast switching semiconductors to minimize passive components. This paper presents the hardware of a full-scale medium voltage SiC-based flying capacitor converter for quasi-two-level operation with up to 10kV DC voltage and 150A line current. This hardware enables studies on the influence of components, modulation principles and control algorithms on the needed filters and the operation of the converter

Modular Multilevel Converters as Active Filters to Mitigate Low Frequency Current Harmonics in Converter Fed Grid Applications

This paper describes a method to improve converter fed grid structures with Modular Multilevel Converters (MMC). In grids with decentralized energy production and bidirectional power flow, an increasing number of power electronic loads and sources make power quality an important issue to ensure grid stability. The MMC topology is highly suitable to meet the requirements of a low Total Harmonic Distortion (THD) and voltage stability due to its high quality output voltages. In combination with power line communication based on harmonic injection, MMCs compensate low frequency grid current harmonics and imbalances to improve the power quality. A standalone laboratoryscale converter-fed microgrid including low voltage MMCs shows the capability of the developed control algorithms