This paper presents a finite element-based dynamic modeling framework for magnetically controlled transformers. The model relies on pre-solving multiple static finite element simulations and storing the resulting windings flux linkages as functions of primary, secondary, and DC biasing currents in lookup-tables. Material non-linearities and geometry 3-D effects are inherently captured within the model. This flexible modeling approach allows to model transformers with different pre-magnetization methods. Additionally, a parameterized magnetic equivalent circuit model is developed. It is shown that the model of the control winding supply affects the simulation results. Both models are validated against the results from a dual active bridge converter, showing a good agreement with the experimental measurements.

Snubber circuits play a critical role in enhancing the reliability and performance of low voltage DC solid state protection devices. These circuits mitigate transient voltage spikes and oscillations, protecting sensitive semiconductor components from damage due to overvoltage and ensuring stable operation. This review provides a comprehensive overview of snubber circuits specifically designed for solid state protection applications. It explores various snubber configurations, highlighting their operational principles and protective capabilities. The differences between these snubber networks are discussed in detail, focusing on their effectiveness, complexity, and suitability for different protection scenarios. Additionally, the review delves into various aspects related to the application of snubber circuits in protection devices such as efficiency, and the impact on overall circuit performance. By examining these factors, the paper aims to guide the selection and design of a snubber circuit for application in bipolar bidirectional low voltage DC grids.

sponsorship: This work is part of the project 2020-EXT-007, "MIRA-ESTE: Specific, innovative microgrids solutions (accounting for environmental, social, technological and economic aspects) for isolated rural areas of Ecuador" from the Research Group of Propagation, Electronic Control, and Networking (PROCONET) of Universidad de las Fuerzas Armadas ESPE and KU Leuven. This work has been developed with the support of VLIR-UOS and the Belgian Development Cooperation (DGD) under the project EC2020SIN322A101. (Universidad de las Fuerzas Armadas ESPE|2020-EXT-007, KU Leuven, VLIR-UOS, Belgian Development Cooperation (DGD)|EC2020SIN322A101)

Several studies have been conducted on Hybrid Power Generation Systems (HPGS) to reduce the existing gap in access to electricity, especially in isolated and difficult access areas. The appropriate use of HPGS allows to power a community, reduces environmental pollution, and improves the performance of a system that only uses Fossil Fuel Generators (FFG). However, despite the efforts made in several countries, there are still isolated areas that remain without electricity due to several factors, such as the high cost of generation, transmission, and energy distribution. For this reason, this work seeks to generate new viable solutions to improve access to electricity especially in isolated areas of Ecuador, although the tool can be applied to any community without constant electricity access. For this purpose, the modeling of an HPGS is proposed, such system is composed of an FFG, a photovoltaic generator, and a hybrid energy storage system (i.e., electrical and thermal). A control algorithm for the FFG is used to adapt the motor rotational speed by using a minimum fuel consumption to supply the load profile. The results are obtained from simulations with real data of three case studies. A reduction in fuel consumption, greenhouse gas emissions, and loss power from renewable energy is demonstrated.

A fuzzy logic-based energy management system is proposed to allow the power exchange (PE) between the storage systems of multiple interconnected residential microgrids. The adjacent microgrids are connected to the utility network and comprise a solar roof-top photovoltaic system and an Energy Storage System (ESS). The proposed strategy for PE considers the battery state-of-charge and the rate of power change of each microgrid. The strategy's objective is to use the excess energy in the ESS of one microgrid to charge the ESS of another one that has a power shortage. Therefore, it is possible to optimize the energy generated by the renewable energy system and reduce the peaks and fluctuations in the power profile that each microgrid exchanges with the mains. Simulations and comparison results under different scenarios with and without PE using up to five interconnected microgrids, demonstrates the effectiveness of the proposed PE management while preserving the batteries' life.

This paper presents the comparison of two modulated model predictive control (M2PC) strategies (the classical M2PC approach, and the M2PC with optimized overmodulation) applied to a three-phase three-level voltage source inverter (3Ph-3L-VSI). The control strategies are tested under various scenarios: no-load, a linear load connection, and a nonlinear load connection. Although each algorithm has its advantages, simulations show that the overmodulated version presents a substantially better performance than the classical version since the classical M2PC creates gaps between switching regions, making rough transitions between them. In contrast, the overmodulation version can produce a continuous transition between those regions, resulting in lower THD and control effort.

Agricultural Robots are key and promising solutions for safe and sustainable food production. They can improve the quality of life of farmworkers, help reduce water and air pollution associated with traditional agricultural practices, enable bio and chemical-free crops. Finally, their deployment could bring us a better world. Agricultural Robots are essentially mobile platforms able to accomplish specific tasks in a field and work with an embedded electricity source with limited capacity. The accurate estimation of the available energy or the State of Charge (SoC) and the efficient management are primordial for their deployment. This paper provides a short review of SoC estimation methods implemented in mobile robots and highlights current challenges and limitations in this area. We also provide a study of model-based SoC estimation techniques and preliminary results of parameters and SoC estimation. We use a dataset of a Li-ion battery from Panasonic.

Capacitive Power Transfer (CPT) systems present some advantages when compared to its inductive counterparts, being cost and weight the main ones. CPT technology has been mostly used in low power and short distance applications. However, recent studies have shown highly efficient electric vehicle (EV) chargers in the kW level employing this approach. Unlike inductive power transfer (IPT) systems, CPT for high power levels and large distance ranges has been less explored, and phenomena such as frequency splitting still require more detailed analysis, especially for promising topologies like those based on full-bridge inverters with double-side compensation networks. This paper evaluates the relationship between coupling factor and frequency splitting load power phenomena in an LCLC-compensated CPT system. It was found that a load power split occurs at low coupling factors, contrary to characteristics shown by other topologies. Therefore, determining the critical coupling factor to avoid the aforementioned issue is important to define the maximum plate distance at the charger design stage.

This paper has the objective of presenting and discussing topologies and techniques that allow step-up and step-down conversion ratios in DC systems offering a DC front and back ends. This leads to applications of DC-DC converters. In this paper, different characteristics are discussed such as: (non)-isolation in converters, the combination of isolated and non-isolated converters and the impact on the step-up/down conversion ratio of these converters, coupled-inductor techniques, voltage/current multiplier/divider structures, among others. This brings to the reader a broad overview regarding the possible DC-DC converters that enable different voltage capabilities. The key outcome is to present a brief review of the techniques applied to converters to enable future full DC grid operation.

Aircraft's electrical systems operate at a fundamental frequency of 400 Hz, and it is important to test the compliance of power converters with the existing EMI standards. This paper investigates the application of three phase buck type rectifier in aircrafts and its compliance with the MIL-STD-461G. Due to control simplicity, high efficiency and high-power density, Swiss rectifier topology is chosen for this study. A complete simulation model of the rectifier including standard line impedance stabilization network (LISN) and high frequency filter is developed for evaluating the quality of input current. For high power density and high efficiency, a cascaded two-stage LC filter with parallel R-L damping is chosen to remove the high frequency ripple from input current. Harmonics in the current are calculated by following the regular procedure given by the standards. Simulation results under various operating conditions revealed that this rectifier comply with MIL-STD-461G subsection CE102 as it draws the input current with very low THD (<; 5%) and high frequency harmonics are reduced well below the standard limits by a LC filter. However, glitches in input current at phase crossings and impedance of LISN introduce high harmonics near 10 kHz, which exceeds the standard limit values. Hence, Swiss rectifier with standard operation does not comply with MIL-STD-461G subsection CE-101.

One of the main problems in autonomous electric vehicles is the energy storage, because a high autonomy and high power condition demand large mass, big volume and high cost of the storage unit. Consequently, in order to avoid power losses and to downsize the storage unit and the electric systems, the electric power train in the vehicle must be as efficient as possible. This paper proposes a methodology to optimize the efficiency of a DC-DC converter that interface the storage unit with the motor's drive. In this way, with the purpose of increasing the efficiency, this methodology combines three techniques: 1) The use of low-loss components such as Si CoolMos, GaN and SiC diodes and Mosfets, and Multilayer Ceramic Capacitors, 2) a complete power loss analysis as a function of the switching frequency and a calculation method of core losses based on the approximation of Fourier Series, and 3) the Area Product Analysis of magnetic components. With this methodology, it is possible to achieve high efficiency and high power density, which is suitable for automotive applications. The methodology has been verified with a set of tests on a 1kW prototype. As a result of the proposed methodology, a power efficiency of 99% was experimentally obtained.