In this paper, a comparative analysis has been presented on various topologies of isolated and non-isolated DC-DC converters. Here, the major focus remains on transformer-less (TL) DC-DC converters, based on the conventional basic boost converter. In addition, to attain high voltage gain, a classification of non-isolated converters based on extendable and non-extendable design has been presented. For comparative and theoretical analysis, the parameters chosen are the number of components utilized by each converter topology, high voltage gain offered, voltage stresses on each component involved and the efficiency of the high gain topologies. For the converters under discussion, operation under ideal and non-ideal conditions has also been highlighted. Based on this study, authors present a guide for the reader to identify various high voltage gain topologies for photovoltaic (PV) systems.

MVDC technology is a promising solution to avoid installation of new AC networks. MVDC can provide optimum integration of large-scale renewable energy sources, the interconnection of different voltage levels of DC and AC grids with the ancillary services. The development in MVDC depends significantly on the DC-DC converters. Such converters support the modern trends of utilising medium-frequency transformers in power networks. Research on isolated converters technology is in its infancy and limited by the conversion ratio and component ratings. Besides, there is no standards exist covering specific aspects of isolated converter product. Thus, a review of such converters is needed. This work presents, for the first time, a review of the DC-DC power converter families in MVDC grids including the leading families which are isolated and nonisolated converters, as well as other subfamilies comparing the specifications and characteristics. Also, the applications of these converters are provided by focusing on the essential requirements for each application. Index Terms-MVDC grids, DC-DC power converters, dual active bridge (DAB), multilevel converter. TABLE I RECOMMENDED CLASSES FOR MVDC VOLTAGE MVDC Class (kV) Nominal Rated Voltage (kV) Maximum Rated Voltage (kV)

The photovoltaic generation system (PGS) is considered a potential renewable energy harvesting system. However, the low conversion efficiency of PGS and maximum power point tracking (MPPT) technique are the main challenges that must be solved. In addition, the switching frequency of the converters employed also affects the MPPT system performance. A high gain voltage dc-dc converter is proposed to replace conventional power converter and Fuzzy Logic Control (FLC) is applied in the MPPT for optimizing solar energy harvesting system. Nevertheless, evaluation of suitable Fuzzy membership function is needed for optimal MPPT technique of photovoltaic system. In this paper, FLC of MPPT for photovoltaic application system was built using various membership functions in Matlab/Simulink environment. The switching frequency of the high gain voltage dc-dc converter is varied to test the robustness of the performance of each FLC membership function. The results showed that the FLC-based MPPT technique for high gain voltage dc-dc converter with GBell membership function type has capability to track the maximum power point (MPP) accurately and to achieve optimum power conversion. Furthermore, GBell membership showed having stable and consistent performance at various switching frequencies.

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This paper introduces a type-2 fuzzy logic controller (FLC) as a maximum power point tracker (MPPT), which can handle the uncertainties of the rules under high variations in weather conditions. The MPPT employed single-ended primary-inductor (SEPIC) converter. The new controller improves maximum power tracker search method by rules fuzzifying. An accurate and fast converging to maximum power point is offered by type-2 fuzzy tracker during both steady-state and varying weather conditions compared to conventional fuzzy MPPT methods. The performance of the proposed maximum power point tracker is demonstrated in MATLAB simulation at different operating conditions.

The extensive use of electric vehicles (EVs) needs ultra-fast-charging stations with high charging power greater than 22 kW (PCharging >22kW). Medium voltage direct current (MVDC) grids can provide the best solution for the high demand of EVs and fast-charging stations infrastructures with the existing distribution grids. The resonant bidirectional dual active bridge (DAB) DC-DC converter can be a promising technology in integrating an electric vehicle charging station (EVCS) with MVDC grid. This work focuses on the converter design with voltage control and stability by applying two different control strategies mainly: PI control and sliding mode control (SMC). All simulations will be performed in order to present the feasibility of the proposed solution and compare the results of each control methods. This comparison, for the first time, in the medium voltage level can open new insights for using nonlinear control methods such as SMC to ensure stability and obtain better dynamic performance

Abstract:The purpose of the presented flyback converter is to equalise the voltage between the cells in a series string within a battery pack providing an active cell-balancing system. This would be an important part of a battery management system (BMS) for charging li-ion batteries in electric vehicles. The converter is based on primary side current sensing, where the conventional feedback circuit is omitted. The purpose of this converter is to improve efficiency by decreasing losses and to increase battery power density by decreasing the number of elements which constitute the power electronics; these are important factors for the future development of electric vehicle battery packs. Analysis of the circuit and the design procedure of the DC-DC flyback converter with primary current sensing is presented in this paper. Finally, several experimental converters have been built and tested to validate the authors' approach.

This article classifies, describes, and critically compares different compensation schemes, converter topologies, control methods, and coil structures of wireless power transfer systems for electric vehicle battery charging, focusing on inductive power transfer. It outlines a path from the conception of the technology to the modern and cutting edge of the technology. First, the base principles of inductive coupling power transfer are supplied to give an appreciation for the operation and design of the systems. Then, compensation topologies and soft-switching techniques are introduced. Reimagined converter layouts that deviate from the typical power electronics topologies are introduced. Control methods are detailed alongside topologies, and the generalities of control are also included. The paper then addresses other essential aspects of wireless power transfer systems such as coil design, infrastructure, cost, and safety standards to give a broader context for the technology. Discussions and recommendations are also provided. This paper aims to explain the technology, its modern advancements, and its importance. With the need for electrification mounting and the automotive industry being at the forefront of concern, recent advances in wireless power transfer will inevitably play an essential role in the coming years to propel electric vehicles into the common mode of choice.