Simplified cascade multiphase DC-DC buck power converter for low voltage large current applications: part I --- steady-state analysis

This paper presents a new simplified cascade multiphase DC-DC buck power converter suitable for low voltage and large current applications. Cascade connection enables very low voltage ratio without using very small duty cycles nor transformers. Large current with very low ripple content is achieved by using the multiphase technique. The proposed converter needs smaller number of components compared to conventional cascade multiphase DC-DC buck power converters. This paper also presents useful analysis of the proposed DC-DC buck power converter with a method to optimize the phase and cascade number. Simulation and experimental results are included to verify the basic performance of the proposed DC-DC buck power converter.

Multi-band planar diplexers with sub-sets of frequency-contiguous transmission bands

A class of multi-band planar diplexer with sub-sets of frequency-contiguous transmission bands is reported. Such a radio frequency (RF) device is suitable for lightweight high-frequency receivers aimed at multi-band/multi-purpose mobile satellite communications systems. It consists of two channelizing filters, each of them being made up of the in-series cascade connection of replicas of a constituent multi-passband/multi-embedded-stopband filtering stage. This building filtering stage defines a multi-passband transfer function for each channel, in which each main transmission band is split into various sub-passbands by the multi-stopband part. In this manner, each split passband gives rise to several sub-passbands that are imbricated with their counterpart ones of the other channel. The theoretical RF operational principles of the proposed multi-band diplexer approach with sub-sets of imbricated passbands are detailed by means of a coupling–routing–diagram formalism. Besides, the generation of additional transmission zeros in each channelizing filter for higher-selectivity realizations by exploiting cross-coupling techniques into it is also detailed. Furthermore, for experimental demonstration purposes, a microstrip proof-of-concept prototype of second-order octo-band diplexer in the frequency range of 1.5–2.5 GHz that consists of two quad-band channelizing filters with pairs of imbricated passbands is developed and characterized.

Analysis of a High Step-Down DC/DC Converter Topology with a Single Inductor

This paper presents a novel high step-down dc/dc converter topology with a single inductor for 48V data center applications. Distinguished from conventional dc/dc converter topologies with a single inductor, the proposed converter topology is designed by series connecting a step-down cross-connected Fibonacci converter with a buck converter. By combination of these converter modules, the proposed converter topology offers a high voltage gain, viz. 1/48×, without cascade connection. Hence, high power efficiency is provided by the proposed single inductor topology. The characteristics of the proposed converter topology are investigated by theoretical analysis, computer simulations, and experiments. In the given theoretical analysis and the performed simulations, the proposed converter topology demonstrates higher power efficiency than the conventional converter topologies with a single inductor. Furthermore, the validity of the proposed topology is confirmed by the experiments.

A Method for Diagnosing Soft Short and Open Faults in Distributed Parameter Multiconductor Transmission Lines

This paper aims to develop a method for diagnosing soft short and open faults occurring in a distributed parameter multiconductor transmission line (DPMTL) terminated at both ends by linear circuits of very high frequency, including lumped elements, which can be passive and active. The diagnostic method proposed in this paper is based on a measurement test performed in the AC state. To write the diagnostic equations, the DPMTL is described by the chain equations in the frequency domain. For each considered fault, the line is divided into a cascade-connection of two lines, and a set of the diagnostic equations is written, taking into account basic circuit laws and the DPMTL description. This set includes nonlinear complex equations in two unknown real variables consisting of the distance from the beginning of the line to the point where it occurs and the fault value. To solve these equations, a numerical method has been developed. The procedure is applied to the possible soft shorts that can occur between all pairs of the line conductors, and the actual fault is selected. The method has also been adapted to the detection and location of open faults in DPMTL. Numerical examples, including three-conductor and five-conductor transmission lines, show that the diagnostic method is effective and very fast, and the CPU time does not exceed one second.

OPTIMIZATION OF ACTIVE CORRECTOR ELEMENTS OF CURRENT FORM IN COMPOSITION OF HYBRID FILTER BY ALGORITHM OF SWITCHING OF INVERTER TRANSISTORS

The algorithm for switching transistors of the inverter of the active corrector of current form is defined, which allow to reduce the maximum frequency of their switching or the inductance of the reactor of the active corrector of current form in a hybrid filter, which consists of a cascade connection of a parallel active filter and a series-parallel passive LMC-filter. References 10, figures 5.