Impacts of the use of SIC semiconductors in actuations systems

Driven by customers’ demands to improve aircraft performance on one hand, while ensuring compliance to ACARE (Advisory Council for Aeronautics Research in Europe) environmental requirements for 2020 on the other, the aircraft industry has been pushing toward the concept of More Electric Aircraft (MEA) for the last ten years or so. One of the main challenges associated to the More Electric Aircraft is thus to increase drastically the power density of electrical power systems, such as electromechanical chains applied to actuation systems, without compromising on reliability. This paper explains the advantages of using Wide Bandgap (WBG) semiconductors made of Silicon Carbide (SiC) in the power converters that are used in an electromechanical chain as well as the associated drawbacks when it comes to EMI and partial discharge, which are mainly related to high dv/dt and overvoltage during commutation. It also shows the development of a generic electromechanical chain platform at the Institut de Recherche Technologique (IRT) Saint-Exupéry and all related research. This platform is being designed in order to test different technologies composing an electromechanical chain (SiC transistors, passive filters, cables, innovative motor) and to evaluate the impact of the use of such technologies

Trade-off between Losses and EMI Issues in Three-Phase SiC Inverters for Aircraft Applications

Power converters will only be effectively used in future aircrafts if they are compact, efficient and reliable. All these aspects can be improved by the use of disruptive technology such as the so-called Wide Bandgap (WBG) semiconductors made of Silicon Carbide (SiC) or Gallium Nitride (GaN). These components can switch much faster than their silicon counterpart, which can reduce converter losses and also decrease differential mode filter given the increase of switching frequency. However, such a fast commutation increases Electromagnetic Interference (EMI) issues in the converter and loads connected to it. This paper shows the approach developed at the French Institute of Technology (IRT) Saint-Exupery, in order to evaluate the trade-offs between losses and EMI issues of three-phase inverters used in future aircraft applications. Given the voltage DC bus of 540V, SiC MOSFETs are investigated and experimental results show the impact of these components on losses and EMI for different parameters

Unshielded Cable modeling for Conducted Emissions Issues in Electrical Power Drive Systems

In power electronics applications, high frequency models for cables are necessary to understand EMI issues in pulsewidth modulation drives. This paper shows the approach developed at the French Institute of Technology (IRT) Saint-Exupery, in order to take account of the frequency dependency of unshielded power cables per-unit-length parameters for EMC simulations. Fast, predictive models are compared to different shapes numerical models. The method was applied to unshielded two and three wires cables. Finally, common mode (CM) emissions modeling is proposed to predict the CM noise currents, which are the most disturbing in any variable-speed drive systems. The modeling principle is to consider the complete CM circuit as a chain of quadripolar matrices

Overvoltage at motor terminals in SiC-based PWM drives

Key points in the development of More Electrical Aircraft (MEA) are currently DC power distribution in higher voltage levels (540 V) and the use of disruptive technology such as Wide BandGap (WBG) semiconductors in power inverters. Using WBG components (SiC and GaN) increases the power converter mass density. However, fast switching of WBG components (tens of kV/s) induces voltage transient overshoots due to parasitic elements within the inverter. In addition, propagation and reflection phenomena along the harness connected to this inverter, even for small lengths, cause a significant voltage overshoot across the loads. Such overvoltage in Adjustable Speed Drives (ASD: association of inverter, harness and motor) supplied by the new HVDC 540 V aeronautical network could be fatal for the Electrical Insulation System (EIS). This paper proposes a fast and accurate modeling methodology to predict transient overvoltage; it allows us to analyze the impact of SiC inverter technology on overvoltage at motor terminals

Advanced analysis of transient overvoltage in electromechanical chain fed by SiC inverter

Key areas in the development of More Electrical Aircraft (MEA) are, currently, DC power distribution in higher voltage levels and the use of disruptive technology such as Wide BandGap (WBG) semiconductor. Using WBG components (SiC and GaN) increases the power converter mass density. However, fast switching of WBG components (tens of kV/µs) induces voltage transient overshoots due to parasitic coupling within the inverter. In addition, propagation and reflection phenomena along the harness, even for small lengths, cause voltage overshoots across the loads. Such overvoltage in an electromechanical chain (association of inverter, harness and motor) supplied by the new HVDC 540V aeronautical network could be fatal for the Electrical Insulation System (EIS). This paper proposes an accurate and fast model to predict overvoltage along a harness; it allows to analyze the impact of SiC inverter output voltage waveforms

Kinin B(1) receptor deficiency leads to leptin hypersensitivity and resistance to obesity

OBJECTIVE-Kinins mediate pathophysiological processes related to hypertension, pain, and inflammation through the activation of two G-protein-coupled receptors, named B(1) and B(2). Although these peptides have been related to glucose homeostasis, their effects on energy balance are still unknown.RESEARCH DESIGN and METHODS-Using genetic and pharmacological strategies to abrogate the kinin B(1) receptor in different animal models of obesity, here we present evidence of a novel role for kinins in the regulation of satiety and adiposity.RESULTS-Kinin B(1) receptor deficiency in mice (B(1)(-/-)) resulted in less fat content, hypoleptinemia, increased leptin sensitivity, and robust protection against high-fat diet-induced weight gain. Under high-fat diet, B(1)(-/-) also exhibited reduced food intake, improved lipid oxidation, and increased energy expenditure. Surprisingly, B(1) receptor deficiency was not able to decrease food intake and adiposity in obese mice lacking leptin (ob/ob-B(1)(-/-)). However, ob/ob-B(1)(-/-) mice were more responsive to the effects of exogenous leptin on body weight and food intake, suggesting that B(1) receptors may be dependent on leptin to display their metabolic roles. Finally, inhibition of weight gain and food intake by B(1) receptor ablation was pharmacologically confirmed by long-term administration of the kinin B(1) receptor antagonist SSR240612 to mice under high-fat diet.CONCLUSIONS-Our data suggest that kinin B(1) receptors participate in the regulation of the energy balance via a mechanism that could involve the modulation of leptin sensitivity.Universidade Federal de São Paulo, Dept Biophys, BR-04023062 São Paulo, BrazilUniv Mogi das Cruzes, Mogi Das Cruzes, BrazilUniversidade Federal de São Paulo, Dept Physiol, BR-04023062 São Paulo, BrazilSanofi Aventis, Montpellier, FranceUniversidade Federal de São Paulo, Dept Med, BR-04023062 São Paulo, BrazilInst Natl Sante & Rech Med, Dept Renal & Cardiac Remodeling, U858 I2MR, Toulouse, FranceUniv Toulouse 3, Inst Med Mol Rangueil, F-31062 Toulouse, FranceInst Natl Rech Agron AgroParisTech, UMR914 Nutr Physiol & Ingest Behav, Paris, FranceMax Delbruck Ctr Mol Med, Berlin, GermanyUniversidade Federal de São Paulo, Dept Biophys, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Physiol, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Med, BR-04023062 São Paulo, BrazilWeb of Scienc

Monoclonal anti-idiotypic antibodies to TSH receptor

info:eu-repo/semantics/nonPublishe

Modelling Process and Optimisation of EMC Filters for Power electronics Applications

International audiencePurpose - The frequency simulation and optimisation of electromagnetic compatibility (EMC) filter is often computation time consuming. Design/Methodology/approach -The paper proposes an approach for easy and fast modelling and optimization of power electronics structures. It focuses on the EMC filter design. To achieve this task time simulation, FFT and automatic frequency modelling are combined. Findings -An automatic frequency modelling is proposed and also gives automatically the model gradients. Therefore, the model can be used to optimize the EMC filter, but also can help in choosing its topology. Several optimization algorithms are used and compared. Research limitations/implications -The power electronics load is supposed to be a set of predefined harmonic sources, obtained by time simulation + FFT before the optimisation process. Practical implications -The aid to build the frequency model, and their automatic translation for sizing by optimisation allow to design and to compare rapidly several structures or modelling hypothesis on the parasitic elements and circuit imperfections. Originality/value - The frequency model is automatically generated, and sizing criteria on the component (e.g. inductors, capacitor) can be added in an analytical form, for example, to deal with volume or mass criteria

N-Glycans Modulate in Vivo and in Vitro Thyroid Hormone Synthesis

International audienceThyroglobulin (Tg) is the substrate for thyroid hormone biosynthesis, which requires tyrosine iodination and iodotyrosine coupling and occurs at the apical membrane of the thyrocytes. Tg glycoconjugates have been shown to play a major role in Tg routing through cellular compartments and recycling after endocytosis. Here we show that glycoconjugates also play a direct role in hormonosynthesis. The N-terminal domain (NTD; Asn1-Met171) of human Tg, which bears the preferential hormonogenic site, brings two N-glycans (Asn57 and Asn91). NTD preparations were purified from Tg with low and mild iodine content in vivo and from poorly iodinated Tg after in vitro iodination and coupling. NTD separated from poorly iodinated Tg was also submitted to iodination and coupling after desialylation and deglycosylation. The various NTD isoforms were analyzed for their N-glycan structures and hormone contents. Our results show that 1) in vivo as well as in vitro unglycosylated isoforms did not synthesize hormones, whereas fully or partially (at Asn91) glycosylated isoforms did; 2) high mannose type structures enhanced the hormone content; and 3) desialylation did not affect in vitro hormone synthesis. Evidence of a direct involvement in hormonosynthesis adds to the role of N-glycans in Tg function and opens the way to new mechanisms for regulation (e.g. TSH modulation of N-glycan) or alteration (e.g. Asn91 mutation) of thyroid hormone synthesis

MODELLING PROCESS AND OPTIMISATION OF EMC FILTERS FOR POWER ELECTRONICS APPLICATIONS

International audienceThe paper proposes an approach for easy and fast modelling and optimization of power electronics structures. It focuses on the EMC filter design. To achieve this task for electrical drives, a full EMC modelling of the application is defined by combining time simulation, FFT and automatic frequency modelling. The automatic modelling gives also automatically the model gradients. This process is very generic, fast and systematic, and can be used with any optimisation algorithm, using gradients or not. Therefore, the model can be used to optimize the EMC filter, but also can help in choosing its topology, according to the technological choices of the aircraft power electronics specifications