An efficiency-optimized modulation scheme and design method are developed for an existing hardware prototype of a bidirectional dual active bridge (DAB) dc/dc converter. The DAB being considered is ...used for an automotive application and is made up of a high-voltage port with port voltage V 1 , 240 V ≤ V 1 ≤ 450 V, and a low-voltage port with port voltage V 2 , 11 V ≤ V 2 ≤ 16 V; the rated output power is 2 kW. A much increased converter efficiency is achieved with the methods detailed in this paper: The average efficiency, calculated for different voltages V 1 and V 2 , different power levels, and both directions of power transfer, rises from 89.6% (conventional phase shift modulation) to 93.5% (proposed modulation scheme). Measured efficiency values, obtained from the DAB hardware prototype, are used to verify the theoretical results.
The differential diagnosis of parkinsonian syndromes is considered one of the most challenging in neurology and error rates in the clinical diagnosis can be high even at specialized centres. Despite ...several limitations, magnetic resonance imaging (MRI) has undoubtedly enhanced the diagnostic accuracy in the differential diagnosis of neurodegenerative parkinsonism over the last three decades. This review aims to summarize research findings regarding the value of the different MRI techniques, including advanced sequences at high- and ultra-high-field MRI and modern image analysis algorithms, in the diagnostic work-up of Parkinson’s disease. This includes not only the exclusion of alternative diagnoses for Parkinson’s disease such as symptomatic parkinsonism and atypical parkinsonism, but also the diagnosis of early, new onset, and even prodromal Parkinson’s disease.
The derivation of an accurate small-signal model for a galvanically isolated, bidirectional dc-dc converter and the implementation of a corresponding controller on a DSP as well as key methods and ...functions required for the digital implementation are detailed in this paper. The investigated dc-dc converter, an automotive dual active bridge (DAB) system, enables power transfer between a low-voltage port (ranging from 11 to 16 V) and an HV port (240 to 450 V). The nominal power rating is 2 kW. The developed small-signal model yields highly accurate results for the DAB system, but the proposed modeling procedure could also be applied to arbitrary resonant power converters with unidirectional or bidirectional power transfer.
A comprehensive procedure for the derivation of optimal, full-operating-range zero voltage switching (ZVS) modulation schemes for single-phase, single-stage, bidirectional and isolated dual active ...bridge (DAB) ac-dc converters is presented. The converter topology consists of a DAB dc-dc converter, receiving a rectified ac line voltage via a synchronous rectifier. The DAB comprises primary and secondary side full bridges, linked by a high-frequency isolation transformer and a series inductor. ZVS modulation schemes previously proposed in the literature are either based on current-based or energy-based ZVS analyses. The procedure outlined in this paper for the calculation of optimal DAB modulation schemes (i.e., combined phase-shift, duty-cycle, and switching frequency modulation) relies on a novel, more accurate, current-dependent charge-based ZVS analysis, taking into account the amount of charge that is required to charge the nonlinear parasitic output capacitances of the switches during commutation. Thereby, the concept of "commutation inductance(s)" is shown to be an essential element in achieving full-operating-range ZVS. The proposed methods are applied to a 3.7 kW, bidirectional, and unity power factor electric vehicle battery charger which interfaces a 400 V dc-bus with the 230 Vac, 50-Hz utility grid. Experimental results obtained from a high-power-density, high-efficiency converter prototype are given to validate the theoretical analysis and practical feasibility of the proposed strategy.
Gregor K. Wenning: a brilliant mind Fanciulli, Alessandra; Krismer, Florian; Struhal, Walter ...
Clinical autonomic research,
06/2024, Letnik:
34, Številka:
3
Journal Article
PDF
