Transformerless inverters are being widely used in grid-connected photovoltaic (PV) generation systems. Transformer elimination, in grid-connected PV systems, has many advantages. This not only reduces cost, size, and weight, but also increases the whole system efficiency. However, once the transformer is removed, there is no galvanic isolation between grid and PV array; as a consequence, leakage current appears due to parasitic capacitance to the ground, resulting in prohibitive electromagnetic interference and security issues. This paper presents a novel topology in order to reduce this ground leakage current. It is established that the neutral line in the grid is the same as that of the negative terminal in a PV system, eliminating this way, any possibility of leakage current in this terminal. A sliding mode controller that controls the output current has been employed. The principle of operation of the transformerless inverter is analyzed, but also the topology has been simulated and experimentally tested.

In power electronics, magnetic components are fundamental, and, unfortunately, represent one of the greatest challenges for designers because they are some of the components that lead the opposition to miniaturization and the main source of losses (both electrical and thermal). The use of ferromagnetic materials as substitutes for ferrite, in the core of magnetic components, has been proposed as a solution to this problem, and with them, a new perspective and methodology in the calculation of power losses open the way to new design proposals and challenges to overcome. Achieving a core losses model that combines all the parameters (electric, magnetic, thermal) needed in power electronic applications is a challenge. The main objective of this work is to position the reader in state-of-the-art for core losses models. This last provides, in one source, tools and techniques to develop magnetic solutions towards miniaturization applications. Details about new proposals, materials used, design steps, software tools, and miniaturization examples are provided.

The use of an electric differential (ED) constitutes a technological advance in vehicle design along the concept of more electric vehicles (MEVs). EDs have the advantage of replacing loose and heavy mechanical differentials and transmissions with lighter and smaller electric motors directly coupled to the wheels via a single gear or an in-wheel motor. To date, EDs have been proposed for two- and four-wheeled vehicles. Despite its long reported success and possible advantages in terms of flexibility and direct torque control of the wheels during cornering and risky maneuvers, the ED has several problems that have limited its applicability, for instance, an increment of control loops and an increase of computational effort. Therefore, the main purpose of this paper is to present a simple and easy-to-implement ED that ensures both reliability and good path tracking. The proposed strategy has the advantage of being linear and, therefore, easy to implement. Furthermore, a rigorous proof of stability is presented, and connections with other controllers are discussed. Features and advantages of the proposed scheme are illustrated via numerical simulations in a 4-kW system, which is able to handle 500-kg mass and deliver peak power up to 10 kW during transit periods.

Magnetic cores for inductive wireless power transfer (WPT) have many applications and regularly uses E, U, pot and planar/circular shape coils. The systems for wireless energy transfer are not conveniently in the power levels required for some applications, as for the Electric Vehicle (EV) for instance, and there is a necessity to study different coil geometries to improve its efficiency and decrease its volume and weight. In this paper, is presented a new hexagonal-geometry coil design placed in the secondary of a WPT, and the tests demonstrate that a Type-II system compliance requirements (SAE J2954) can be accomplished with greater efficiency and lighter weight compared to circular coil. Finite element analyses accurately allow predicting the mutual inductance and achieving the optimal coil parameters and an experimental setup allows obtaining a rated power output of 7.7 kW operating at 85 kHz. The experimental testbed comprises a series-series resonance compensation circuit, a spiral coil used as primary, the proposed hexagonal pad for the secondary coil, and an AC-output, half-bridge inverter as source, achieving a lighter and efficient system in a realist scenario.

Currently, the design of power electronic converters (PECs) is in a stage which looks increasing its efficiency and reducing its dimensions from basic topologies through precise analysis of losses in each device that conforms. Although there have been important advances to improve the active components of PECs, passive components, particularly inductors, have changed very little since several decades ago, and those begin a limiting factor, when a high efficiency at very high power and switching frequency, are required. It is for the foregoing that this paper reviews new ferromagnetic materials to construct inductors and achieve a substantial increasing in efficiency through magnetic permeability and hysteresis improvements. Therefore, the main objective of this work is to position the reader in the state of the art of advanced ferromagnetic materials used in PECs. Details about how they are constructed and qualitative comparison of their dynamic behavior are provided. Also, estimation methods of energy losses, applications for different types of material, and its influence on the performance of some basic PECs are presented.