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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 ωout ≥ ωin 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...
Multi-port dc-ac and dc-dc converters are of great interest for applications where electricity is generated through a variety of energy sources and where energy storage systems are required. In this paper, a three-port, dc-dc-ac Solid State Transformer (SST) is presented that can control the magnitude and direction of power transfer between a battery, a dc bus and the ac grid. The proposed SST features...
This paper presents the first commercially available water-cooled MV motor drive based on the Modular Multilevel Topology (M2C). The motor drive specific features and HW are described. Measurement results from a 12 MW back-to-back test is included, e.g. operation at low motor frequencies down to zero speed at high torque.
At medium voltage level the three level NPC converter is commonly used. As generator side converter in wind energy applications the diodes are most stressed and limit operation. The BIGT combines the functionality of the IGBT and the free-wheeling diode in one chip. The larger usable chip area in both IGBT and diode mode decreases the maximum junction temperature as well as the junction temperature...
As process interruptions can be very expensive, reliability and availability values of a variable frequency drive (VFD) are often two of the most important requirements when selecting a drive. Reliability figures are hard to compare because methods and values depend on suppliers using different assumptions and definitions of failures. The main medium voltage VSI (voltage source inverter) topologies...
To overcome the drawbacks of diode rectifiers in applications without regenerative functionality active rectifiers can be used. Three level rectifiers are already known, but operating range is limited. A new four level rectifier topology that has an extended operating range and avoids all drawbacks of diode rectifiers is presented.
Background Severe middle cerebral artery stroke (MCA) is associated with a high rate of morbidity and mortality. We assessed the hypothesis that patient-specific variables may be associated with outcomes. We also sought to describe under-recognized patient-centered outcomes. Methods A consecutive, multi-institution, retrospective cohort of adult patients (≤70 years) was established from 2009 to...
Objective Identification of patients with posterior fossa infarction at risk for neurological deterioration remains a challenge. MRI-based assessments of MCA infarction can predict poor outcome. Similar quantitative imaging measures after cerebellar stroke have not been studied. We tested the hypothesis that MRI-based volumetric assessment of cerebellar infarcts can provide reliable information for...
The Modular Multilevel Converter (M2C) is an emerging multilevel converter for HVDC and FACTS as well as for future AC-fed traction vehicles or medium voltage drives (MVD). A suitable converter model of the Modular Multilevel Converter (M2C) is presented. A 7.2 kV, 7.5 MVA converter is taken as an example to analyze characteristic waveforms of the converter. The cause of the circulating currents -...
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