No abstract

Investigation of active-clamped flyback (ACF) dc-dc converter 57 W used as the auxiliary power-supply (APS) of an inductive-charging system (ICS) is presented. The ACF was supplied from variable-dc-link 800 V which was challenge for its design. Anyway, some findings are applicable to any ACF. An overview of ACF control ICs is presented revealing that only two vendors have appropriate devices for ICS. The key-parts' choice and suggestion of new features targeting ACF in this emerging-application are given. Striving for high switching-frequency in ICS is not needed due to large safety-distances of transformer. Measured ''maximum-efficiency vs. magnetizing-inductance'' graph showed that extremes are reached for 400 µH. It was based on four transformers with manually-optimized resonant-tanks. Measurements of ''circulating-power losses vs. input-voltage'' are compared for several transformers. Those losses are in the range of few watts and increase with input-voltage. Measurements of ''bandwidth, phase-margin and gain-margin vs. input-power'', for different input-voltages, are discussed. Those quantities were changeable with load and input-voltage as expected. The short-circuit behavior is analyzed showing that usage of the hybrid-clamp with multi-mode control-ICs is mandatory. Finally, comparison with conventional flyback and quasi-resonant flyback converters showed that both are ≈23 % cheaper, occupy ≈11 % less board-space, and have similar or higher efficiencies. The reason for such efficiency is that ACF circulating-power losses were high as well as dc-voltage-conversion-ratio. Although this is a drawback, for an APS the efficiency is not the key-parameter as long as there are no thermal problems. Moreover, as ACF converter is known for having less EMI-problems that could be the key-advantage for this application. But problem is not-enough electronic components on the market that are suitable for ICS.INDEX TERMS Active-clamped flyback, auxiliary power-supply, control, dc-dc converter, inductive charging-system, quasi-resonant flyback. NOMENCLATURE ACF active-clamped flyback. ACM active-clamping mode. APS auxiliary power-supply. CCM continuous conduction-mode. DCM discontinuous conduction-mode. EMI electro-magnetic interference. EV electric vehicle. FET field-effect transistor.The associate editor coordinating the review of this manuscript and approving it for publication was Alfeu J. Sguarezi Filho .

Exited states in 134Pr were populated in the fusion-evaporation reaction 119Sn(19F,4n)134Pr. Recoil distance Doppler-shift and Doppler-shift attenuation measurements using the Euroball spectrometer, in conjunction with the inner Bismuth Germanate ball and the Cologne plunger, were performed at beam energies of 87 MeV and 83 MeV, respectively. Reduced transition probabilities in 134Pr are compared to the predictions of the two quasiparticle + triaxial rotor and interacting boson fermion-fermion models. The experimental results do not support the presence of static chirality in 134Pr underlying the importance of shape fluctuations. Only within a dynamical context the presence of intrinsic chirality in 134Pr can be supported.

No abstract