This research focuses on simulating a transformer using electromagnetic field solver software: FEMM and COMSOL Multiphysics®. These tools are used to simulate and extract the model of a three-winding transformer. The primary objective of the extracted model is to predict key magnetic parameters, such as leakage and magnetizing inductances. These inductances play a critical role in switch-mode power converter topologies, ensuring proper operation and achieving high efficiency through zero-voltage or zero-current switching. In this study, the transformer, based on an ER28/14/11 core, is simulated using both FEMM and COMSOL, with the resulting models compared to each other and experimental measurements. FEMM is a free, 2D solver, while COMSOL is a commercial, 3D solver. This research aims to evaluate the feasibility of using the noncommercial FEMM tool to simulate complex transformer core shapes. Transformations of the E, ER, and ETD core types for simulation in both 2D axis-symmetric and planar problem types are also proposed.

This document presents a simple method that allows the use of time-domain simulation to extract an AC small signal model of the power stage of a power converter. Such extraction can be important for the simulation of feedback loop gain and the stability of complex power converter topologies, such as resonant converters or converters with complex switch control. With the presented approach, a single simulation run in the time domain is sufficient to extract a small signal model, resulting in a time-efficient extraction process. The method is based on the step response simulation, where the input control signal source (duty cycle, switching frequency, etc.) is applied as a step function. The output parameter of the converter (output voltage, current, etc.) is recorded during the time-domain simulation and then transformed into a SPICE netlist using Laplace transform statements. The Laplace transform in s-domain is supported by most SPICE simulators, such as LTspice, PSpice, etc. The presented algorithm and model are automatically generated using a developed open-source software tool. Thus, the free software LTspice, along with the presented open-source tool, can be used as a free alternative to commercial SPICE programs like PSpice, PADS, Simetrix, MATLAB, etc.

This article presents a description of the process of creating a model of the EZ-17 (Model 02) current probe by Rohde & Schwarz, which is extensively used in electromagnetic compatibility (EMC) research. A methodology for evaluating each component of the model is outlined step by step. However, the goal is not to physically disassemble an EZ-17 sensor, but to use only the parameters provided in the technical specifications of the device in creating the model. A comparison of the simulation results and the characteristics in the documentation shows a good fit between the model and the real device. An attempt was made to construct a doit-yourself (DIY) analog of the EZ-17 sensor using inexpensive parts and experimental comparisons were made between the analog and the actual device.

This paper presents a multi-channel phase-shift LLC resonant converter that was specially optimized for fuel-cell applications and has a wide input and output voltage range. The worst-case minimum stack voltage and the battery voltage range were used to find the optimal parameters of the LLC converter. The voltage gain of the converter operating at a constant power was considered, and the algorithm for such a calculation was proposed. Current balancing was implemented using channel temperature measurements instead of expensive current measurements. A natural self-balancing mechanism was investigated for converters operating at high frequencies above the series resonance of a resonant converter. Recommendations for the converter's transformer turn ratio were illustrated for efficiency optimization. The multi-object optimization is implemented to reach the optimized design so the minimum and maximum voltage gains can be reached and, at the same time, the transformer turn ratio is kept at the minimum to reach high efficiency. An experimental prototype of a four-channel converter was presented and tested at a 5 kW power level. Active content and C-language code files for converter calculations are provided as well with this work.

This study presents a method for extracting transformer parameters using simulations in the Finite Element Method Magnetics (FEMM) electromagnetic solver. The extracted parameters represent a full model of a linear transformer and can be used in Simulation Program with Integrated Circuit Emphasis (SPICE) simulations. A model of the two-winding transformer is presented in three variants, for which different approaches were used in the transformer simulation in the SPICE program, all yielding the same simulation results. A three-winding transformer T-model extraction is also developed in the study. A method for extracting transformer parameters from FEMM is proposed, along with an automated tool based on a scripting language built into the FEMM software.

Being able to predict radiated emissions before using an accredited laboratory can be both time-effective and cost-effective. This study presents a model for predicting radiated emissions from power converters by measuring the common mode current in the attached cable. When power converters are tested for radiated emissions, the attached cables tend to be thick because of the high currents they carry. Ideally, these cables leave the chamber through connectors in an opening positioned precisely at the middle of the bottom of the turntable in keeping with CISPR 32. However, these connectors are typically not intended for currents higher than 16 A. Consequently, such cables are usually inserted through the side wall of the chamber and are necessarily laid horizontally on the chamber floor. When the turntable is to be rotated with a device on it during a test, the length of the cable attached to the device can exceed 10 meters. The proposed model in this study is based on the transmission line model of a cable loaded with reactive impedance and the assumption that the current distribution along the cable follows a sinusoidal distribution law, much like in dipole antenna theory. The analytic equation of the radiation pattern is derived, and a simplified approximation equation has also been presented. The proposed model also works with short, attached cables and is thus universal. The Maxima software code for automated calculation of the radiated field from measurement data is supplied as supplemental material. The proposed model was experimentally validated by running the fuel cell converter module at 5 kW output power.

This paper presents a way to generate the correct SPICE sub- circuit using only parameters from the manufacturer's diode datasheet. Characterization tool software was created and tested and is now freely available to download and use.