Continuous input currents and high step-up ratios are desired from the dc-dc converters that work with renewable energy sources such as photovoltaic panels and fuel cells. Most dc-dc converters use transformers to have high step-up ratios. There is another type of converters that use coupled inductors, but they need to operate at high duty cycles to increase the gain. These converters suffer from low efficiency values because of the leakage inductance values and long reverse recovery times of the diodes. A new dc-dc converter based on Z-source topology is proposed in this study. It uses coupled inductors to increase the step-up ratio. Its main features are high step-up ratios, continuous input currents, high efficiency and galvanic isolation between input and output. Simulation and experimental results are given for a prototype converter that converts 25-400 V dc at 300 W with over 91% efficiency.

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Capacitive power transfer (CPT) technology is becoming increasingly popular in various application areas. Due to its limitations, such as low frequency, low coupling capacitance, and the high voltage stress on metal plates, the studies on high power CPT applications fell behind previously. Therefore, the wideband gap (WBG) semiconductor devices and the compensation topologies are further adopted to tackle these limitations. The main purpose of the paper is to review CPT applications in terms of performance parameters, advantages, disadvantages and also challenges. Initially, the basic principles of CPT technology are examined, which cover compensation topologies, coupler structures, transfer distance, power electronic components, and system control methods. Then, CPT applications are evaluated for performance parameters (i.e., power level, operation frequency, system efficiency, transfer distance) along with compensation types, inverter types, and coupler types. The applications are categorized into six main groups according to industrial topics as safety, consumer electronics, transport, electric machines, biomedical, and miscellaneous. Herein, power level changes from µW to kW ranges, the operation frequency varies from 100s of kHz to 10s of MHz ranges as well. The maximum system efficiency is recorded as 97.1 %. The transfer distance varies from µm range to 100s of mm ranges. The full-bridge inverter topology and four-plate coupler structure are noticeable in CPT applications. Finally, advantages, disadvantages, and challenges of CPT applications are evaluated in detail. This review is expected to serve as a reference for researchers who study on CPT systems and their applications.INDEX TERMS Capacitive power transfer, capacitive coupling, wireless power transfer.MEHMET ZAHID EREL was born in Sakarya, Turkey. He received the B.S. degree in electrical engineering from the Yildiz Technical University, Istanbul, Turkey, in 2013, and the M.S. degree in electronics and communication engineering from the Ankara Yildirim Beyazit University, Ankara, Turkey, in 2016. He is currently pursuing the Ph.D. degree with the department of electrical and electronics engineering,

Abstract-High-temperature superconducting (HTS) material in bulk form is used to design a linear synchronous motor for an electromagnetic aircraft launch system. The motor is designed without an iron core. Stator coils are placed in the air while the permanent magnets used in conventional design of linear permanent magnet synchronous motors are replaced by the HTS bulk magnets. The physical, operational, and equivalent circuit parameters of the linear motor with HTS bulk magnets are compared with those of a linear permanent magnet synchronous motor and linear induction motor designed for the same application. Results show that utilizing superconducting magnets is only superior at temperatures below 40 K.