Tind Technologies (Norway)
Hes-so: ArODES Open Archive (University of Applied Sciences and Arts Western Switzerland / Haute école spécialisée de Suisse occidentale / FH Westschweiz)Not a member yet
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Double frame control and power compensation for power converters connected to weak networks with disturbances
No full textCERN is studying the implementation of high power active front ends, implying the operation of a voltage source inverters connected to a grid that can be considered as weak when compared to the converter nominal power. Proper synchronisation is a key point for current control stability. The handling of networks with asymmetric disturbances implies the accurate handling of the second harmonic component appearing under unbalanced networks by the proper decoupling of the positive and negative sequence of the network voltages and currents. The use of a double frame controller allow the full control of phase current symmetry or the compensation instantaneous active power oscillation
Operation of modular multilevel converters under grid asymmetries
No full textThe Modular Multilevel Converter is very likely to operate in a grid-connected mode under asymmetric conditions. Such a converter features several unique characteristics, which make its analysis different from other types of power converters in similar cases. The existence of three independent capacitive phase legs rather than a common DC-link capacitor requires special attention, in terms of stability and component dimensioning. This paper investigates the impact of unbalanced grid conditions on the operation of the Modular Multilevel Converter. The expressions for the branch energy variation are derived assuming that the grid-related quantities can be modeled by means of symmetrical components. Moreover, the effect of circulating current control for capacitive storage reduction as well as DC-link oscillation elimination is also studied. Finally, a control system is proposed and simulation results verify its discrete-time implementation
Solvent on granules 3D printing of shape memory alloys
No full textFe-based shape memory alloys are interesting alternatives to the performant but costly stoichiometric nickel-titanium alloys. Recently, the powder bed fusion additive manufacturing route has been explored for these systems, leading to interesting mechanical performance. However, the literature on sinter-based AM of these systems remains scarce. This work explores the use of pre-alloyed powders to print green parts, followed by debinding and sintering. A variant of binder jetting, which consists in dropping solvent on powder-polymer granule beds, is used to print Fe-Mn-Si test specimens and auxetic parts. The properties of the sintered parts are characterized by differential scanning calorimetry and thermo-mechanical analysis
A spatiotemporal analysis of photovoltaic electricity storage potential in electric vehicles
No full textDecarbonizing mobility and integrating more renewable sources in electricity production are necessary levers to meet the climate targets. Coupling electric vehicle (EV) charging with photovoltaic (PV) electricity generation could help to provide clean electricity for charging EVs and provide flexibility storage to PV installations. The batteries of the vehicles can then be discharged into the grid to support the electricity supply during periods of high demand. This study uses a GIS-based methodology to analyse the mobility needs of the European population and estimates the charging needs of an electrified vehicle fleet. Charging scenarios are then applied to distribute the charging needs between home, work, and point of interest to quantify the charging demand both in space by hectare and in time by hour. The charging load curves are then compared to a typical PV production to estimate the amount of PV electricity that can be stored locally in the EVs. Considering two charging scenarios (comfort and flexible charging) the spatio-temporal methodology was applied to three cities with varying solar irradiance and mobility patterns: Aalborg (Denmark), Bern (Switzerland), and Palermo (Italy). Results show that 10% of the building footprint covered with PV can cover from 53% (in Alborg) to 61% (in Bern) of the charging need over a year. EVs and PV electricity together can reduce the CO2 emission related to private cars of 17 to 28% by 2035 compared to the current fuel-based vehicle fleet
Une danse ancienne ::une œuvre chorégraphique située
No full textUne danse ancienne se compose d’une promenade commentée et d’un solo chorégraphique, d’une durée de 45 minutes environ. Programme : Lundi 29 avril 2024 14h : départ devant la Brasserie de Malley pour une balade commentée par le service de l'urbanisme de la ville de Prilly. 14h30 : Présentation de la danse sur la place Corminjo
The SnapShot project ::using vignettes to understand community mobility through the lens of intersectionality
No full textTranslating research findings into something that can be used for learning and teaching of complex concepts, can increase the impact of a research project and influence societal change. In this project, researchers from three countries collaborated to develop a series of vignettes that illustrated intersecting experiences of discrimination and participation restriction for people with disabilities and older people. Vignettes are short, first or third-person stories, that capture the meanings found in research conducted in these diverse contexts. We focussed specifically on community mobility as an everyday activity where intersectionality is experienced. This is an area in which the group have conducted research with diverse populations. In May and August 2024 we conducted World Café-style workshops with health and social care students and professionals from a range of disciplines, in Sweden and South Africa. This case study addresses the methodological and practical challenges we faced in creating vignettes based on our previous research, creating a World Café-style workshop to facilitate discussion on the vignettes, and collaborating within an international team that spans three countries, seven institutions, and includes 15 members speaking six different home languages. We found vignettes are a feasible way for participants to gain a more nuanced understanding of intersectionality, and to facilitate interprofessional discussion among students and healthcare professionals. Vignettes can be created using previous research findings mirroring international contexts. Vignettes are also useful in amplifying participants’ voices, increasing representation, and capturing the complexity of simultaneously oppressive situations
Active self-switching methods for emerging monolithic bidirectional switches applied to diode-less converters
No full textThis paper presents a recently introduced switching principle for emerging monolithic bidirectional devices. Based on the hypothesis that those switches may overcome conventional diode type solutions in power converters, an active self-switching process becomes compulsory. Its principle relies on the measurement of both voltage and current polarity, in order to allow a natural switching as commonly used in matrix conversion. A self-switching method, implemented close to the switch, allows the detection of both short-circuits and open circuits. The accuracy of the presented system is experimented and validated in a 1kVA buck converter where the free-wheeling path is performed by a synthesised diode. The results that are discussed in this paper open a new perspective by introducing the principle of a so-called bidirectional diode as well as the commutation of sources of a similar nature
The active self-controlled free-wheeling management principle applied to reverse recovery losses reduction
No full textSeveral works suggest the imminent appearance of bidirectional active devices. The promised performances go in the direction of a reverse recovery effects reduction and efficiency improvement. Our purpose is the study of an active management for switches that cannot be spontaneous in commutation as a diode. Based on zero-crossing detection and protection circuits, new mechanisms are introduced. As an application, a free-wheeling path is performed using a bidirectional active switch. The principles are verified in two basic converters. For experimental results, a bidirectional switch is implemented using a combination of MOSFETs in direct and reverse conduction
Impact of modularity and redundancy in optimising the reliability of power systems that include a large number of power converters
No full textCERN is working on a new particle accelerator that will require a very large number of power converters. In that view, the reliability of the whole powering will be a major issue. The use of a redundancy and modularity may help increasing the overall machine availability. However, the reliability of the redundancy system must be high enough to add a significant improvement when compared to simple module systems. This paper suggests a comparative study of several modular and redundant configurations for optimising power converters reliability and draws some conclusion from what has been achieved in the LHC previous experience