This paper presents novel bi-converter structure to supply the Doubly Fed Induction Machine (DFIM). Two Voltage Source Inverters (VSI) feed the stator and rotor windings. The outputs of two VSI are combined electro-mechanically in the machine and, as a result, novel features can be obtained. For example, for high power drive applications, this configuration use two inverters dimensioned for a half of the DFIM power. A new Dual-Direct Torque Control scheme is developed with flux model of DFIM. Two Switching Tables (ST) linked to VSI are defined for stator and rotor flux vector control. Experimental and simulation results confirm good dynamic behaviour in the four quadrants of the speed-torque plane. Moreover, experimental results show the correct flux vector control behaviour and speed tracking performances.
The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory. Athena is a versatile observatory designed to address the Hot and Energetic Universe science theme, as selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), X-IFU aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over a hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR (i.e. in the course of its preliminary definition phase, so-called B1), browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters, such as the instrument efficiency, spectral resolution, energy scale knowledge, count rate capability, non X-ray background and target of opportunity efficiency. Finally, we briefly discuss the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, touch on communication and outreach activities, the consortium organisation and the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship
This paper presents the studies made on the definition and design of a decentralized and modular electrical architecture of Power Conditioning Unit (PCU). The modular PCU is able to cover a large range of mission demands by adapting the number of power modules (PM) while the electrical interfaces remain the same. A decentralized architecture is proposed where each module is able to control the solar arrays and to manage the batteries. It appears that this kind of architecture becomes feasible thanks to digital circuits and using a communication bus [1]. Breadboards are being tested in order to validate the concept. Reliability and robustness aspects are studied and a redundant architecture is tested.
CONTEXTStudies made by CNES and TAS from 2008 to 2014, focused on a modular PCU based on BUCK solar array regulator with MPPT control [2]. This architecture is composed by N+1 power modules which control the solar array, manage the battery and use a reliable digital bus for communication. This solution is compatible with unregulated or regulated busses, and the MPPT can address very large needs in spacecraft power supplies. CNES decided to go on a second way by considering DET (Direct Energy Transfer) topologies for solar array regulator, unregulated bus and the possibility to implement remote power modules. For these reasons, this architecture is called Ultra Modular PCU. The trade-offs made for the architecture and the electronic design are more adapted for low cost applications or micro-satellites.
ARCHITECTURE
Architecture general considerationsThe architecture is based on remote power modules connected on the same primary Unregulated Power Bus (UPB). Each module controls one or several Solar Array sections and is connected to one or several battery modules (Figure 1 and 2). A digital bus interconnects all the modules via control circuits, and is directly connected to the On-board Computer (OBC). Lots of possibilities exist for the PM topology. In our objective to build a modular PCU, the elementary PM is sized for 8A to 10A which allows supplying a microsatellite and with 10 PM in parallel a big LEO spacecraft can be supplied. For example the figure 3 shows different topologies studied. The first one is composed of 8 SA sections with the possibilities to connect in parallel some or all of them for modularity and adaptability aspects. Each section is sized for the total PM current divided by 8. Second topology uses 3 SA sections, 2 DETs and one PWM. The third one is a DCDC converter which can operate at MPPT. We want to keep the possibility to have remote PMs and then solutions with PWM DCDC converters (second and third examples) were not chosen because of EMC
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