Due to wider band gap of Silicon Carbide (SiC) compared to Silicon (Si), MOSFET made in SiC has considerably lower drift region resistance, which is a significant resistive component in high-voltage power devices. With low on-state resistance and its inherently low switching loss, SiC MOSFETs can offer much improved efficiency and compact size for the converter compared to those using Si devices. In this paper, we report switching performance of a new 1700V, 50A SiC MOSFET designed and developed by Cree, Inc. Hard-switching losses of the SiC MOSFETs with different circuit parameters and operating conditions are measured and compared with the 1700V Si BiMOSFET and 1700 Si IGBTs, using same test setup. Based on switching and conduction losses, the operating boundary of output power and switching frequency of each device are found out in a DC-DC boost converter and compared. The switching / and / of SiC MOSFET are captured and discussed in perspective of converter design. To validate the continuous operation, three DC-DC boost converters using these devices, are designed and tested at 10kW of power with 1kV of output voltage and 10kHz of switching frequency. 1700V SiC Schottky diode is used as the blocking diode in each case. Corresponding converter efficiencies are evaluated and the junction temperature of each device is estimated. To demonstrate high switching frequency operation, the SiC MOSFET is switched upto 150kHz within permissible junction temperature rise. A switch combination of the 1700V SiC MOSFET and 1700V SiC Schottky diode connected in series is also evaluated for zero voltage switching (ZVS) turn-ON behavior and compared with those of bipolar Si devices. Results show substantial power loss saving with the use of SiC MOSFET. Index Terms-1700V SiC MOSFET, 1700V Si IGBT, 1700V Si BiMOSFET, switching characterization, switching losses, converter efficiency, zero voltage switching (ZVS) turn-ON.

Solid-State Transformers (SSTs) are a promising technology since they enable a reduction in weight and volume of transformers while integrating new functionalities and services in the grid. However, a new kind of electric stress for the insulation occurs in this type of power converter, given that low-frequency medium-voltage stresses are mixed with highfrequency stresses generated by the converter's switching actions. This paper analyzes, in time and frequency domains, the voltage stresses appearing in cascaded converters, employing converter cells based on two-level or three-level bridge legs. The highest electric fields occur in the medium-frequency transformers of the converter cells' DC-DC converters, which provide galvanic isolation within the SST. Numerical simulations of the electric field distributions in these transformers are presented for the different frequency components and the impact of the converter topology on the insulation stress is highlighted. Furthermore, it is shown that the dielectric losses of the transformer can be neglected despite the presence of high-frequency harmonics. Finally, a transformer insulation concept based on semiconducting tape is proposed.

Voltage Source Inverters (VSIs) are essential component for integration of renewable energy sources into utility grid or microgrid. Most of the utility grid regulation standards demand high quality sinusoidal current regulation by these inverters with renewable sources, which necessitates the use of LCL filters at the output of VSIs. Different load conditions and other factors influence grid conditions, such as voltage profile, harmonic distortion and frequency variation. The scope of this paper include comparison of effects on grid current of LCL filter based inverter while using PR controller and damped PR controller under distorted grid voltage and frequency variation conditions. The effects are analyzed through simulation studies in MATLAB/PLECS and real time simulation studies are carried out in Typhoon HIL environment.I.

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In this study, the comparative serum proteome profile of Day 5, 12 and 16 of gestation, representing three early embryonic events, namely formation, elongation and implantation of blastocysts, and non-pregnant control were explored by a label-free quantitation-based mass spectrometric approach to identify early pregnancy biomarkers in pigs. A total of 131 proteins were identified with respect to different groups, out of which 105 were found to be differentially expressed proteins (DEPs). Among the DEPs, 54 and 66 proteins were found to be up and downregulated respectively in early pregnancy groups (fold change >2) and the maximum number of upregulated proteins was observed in the Day 12 pregnancy stage. Functional classification and pathway analysis of the DEPs revealed involvement of most of the proteins in complement and coagulation cascades, metabolic processes and immune and inflammatory responses. Proteins such as glutathione peroxidise (GPX), pregnancy zone protein (PZP), thrombospondin-1 (THBS1), α-1-antitrypsin (AAT) and mannose-binding lectin C (MBLC) were differentially expressed during early pregnancy and actively involved in different pregnancy-related activities. To the best of our knowledge, this is the first report on comparative serum protein profiling of different early pregnancy stages in pigs and our results provide a set of proteins that can be used as potential biomarkers for early pregnancy diagnosis in pigs.