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It is not a secret that the identification of the high-frequency ladder network model (LNM) parameters for the transformer winding is a crucial task. This paper aims to present the application of one of the latest swarm intelligence algorithms, namely, gray wolf optimizer (GWO) for the identification of the high-frequency LNM parameters for the transformer winding.

The physical realizability of a unique ladder network is ensured and it is based on the frequency response analysis and some terminal measurements of a transformer winding.

The test results on a real transformer winding indicated that the identified model, which is improved and detailed, is superior in terms of representing the physical behavior of the transformer winding in high frequency. The efficiency and the superior capabilities of the proposed GWO method are demonstrated by comparing the later with recent algorithms, such as particle swarm optimization-simulated annealing and crow search. Results show that the proposed GWO is better in terms of optimal solution and fast convergence.

The identified LNM model is mutually coupled and able to reflect the physical behavior of the transformer winding in high frequency; therefore, it is more reliable for the diagnosis and analysis.

Contribution has been offered for the identification and the diagnosis of the transformer winding, using robust algorithms for future research.

Significant achievements in ferrite material processing enable developments of many ferrite devices with a wide range of power levels and working frequencies, which make demands for new characterization and modelling methods for ferrite materials and components. The purpose of this paper is to introduce a modelling and measurement procedure, which can be used for the characterization of two‐port ferrite components in high frequency range.

This paper presents a commercially available ferrite component (transformer) modelling and determination of its electrical parameters using in‐house developed software. The components are measured and characterized using a vector network analyzer E5071B and adaptation test fixture on PCB board. The parameters of electrical equivalent circuit of the ferrite transformer parameters are compared with values extracted out of measured scattering parameters.

A good agreement between modelled and extracted electrical parameters of the ferrite transformer is found. The modelled inductance curves have the same dependence versus frequency as extracted ones. That confirms the model validity in the wide frequency range.

In‐house developed software based on proposed model provides inclusion of the ferrite material dispersive characteristics, which dominantly determines high‐frequency behaviour of two‐port ferrite components. Developed software enables fast and accurate calculation of the ferrite transformer electrical parameters and its redesign in order to achieve the best performance for required application.

The purpose of this paper is to propose a numerical procedure for the extraction of RL equivalent circuits of high frequency multi‐winding transformers with a low computational time.

Rigorous RL equivalent circuits of multi‐winding transformers can be obtained by performing open and short‐circuit tests. In this work, the finite element method (FEM) is employed as a virtual laboratory in order to derive such circuits. However, an accurate modeling of skin and proximity effects in the windings requires extremely dense meshes at high frequencies. Therefore, a 2D frequency‐domain homogenization of the windings, which conducts to coarser meshes, is applied in order to decrease the computational burden. The fine and homogenized models are compared in terms of simulation time as well as accuracy.

A significant decrease in simulation times is observed with the homogenized model (one order of magnitude at high frequencies for 2D models), while keeping acceptable relative error values (below 8 percent in the worst case, taking the fine model as reference). Furthermore, it is shown that the skin effect could contribute in a significant way to the total values of the circuit parameters, especially for high frequencies and for small fill factors. It should therefore not be neglected compared to the proximity effect when gathering such conditions, as commonly assumed in the literature.

Equivalent circuits which capture the skin and proximity effects are obtained at an acceptable computational cost, thanks to the use of homogenization techniques in FE simulations. To the best of the authors knowledge, such a procedure has not yet been published.

To derive an analytical model for a dc‐ac‐dc parallel resonant converter operating in lagging power factor mode based on the steady‐state operation conditions and considering the effects of a high‐frequency transformer.

A range of published works relevant to dc‐ac‐dc converters and their control methods based on pulse‐width‐modulation technique are evaluated and their limitations in output measurement of higher output voltage converters are indicated. The circuit diagram of the converter is described and the general mathematical model of the system is obtained by deriving and combining the mathematical models of the different converter blocks existing in the system. The derived mathematical model is used to study the steady‐state and transient performance of the converter. The deriving procedure of the analytical model for a parallel resonant converter is extensively given and the analytical model obtained is verified by simulation results achieved using MATLAB/SIMULINK and the program written by the authors.

The paper suggests an analytical model for dc‐ac‐dc parallel resonant converters. The model can be used in the output voltage estimation of a converter in terms of its phase‐shift angle and the dc‐link voltage.

The resources in the library of the authors' university and also the English resources relative to dc‐ac‐dc converters reachable through the internet were researched.

The analytical model suggested can be used in estimating the output voltage of the converters used in high‐voltage applications or where there are difficulties in employing sensors in measurement of the output voltage due to high price or implementation problems.

The originality of the paper is to present an analytical model for dc‐ac‐dc parallel resonant converters. Using this model makes it possible to estimate the output voltage of the converter using the dc‐link voltage and the phase‐shift angle. The proposed model provides researchers to regulate the output voltage of the converters using feed‐forward control technique.

The purpose of this paper is the attempt to model a variable speed permanent magnet synchronous generator (PMSG) for extracting a standalone power source to assuage the needs of a welding application. The emphasis orients to evolve a framework for the effective exploration of renewable energy resource and prevent the injection of grid harmonics.

The system involves the use of self-commutated dc-dc converter interfaces to extradite the current and voltage requirements of the welding attributes. The philosophy incites a pulse width formulation for reducing the voltage ripples in the dc output and improving the time response characteristics.

The proper selection of closed loop Fuzzy tuned PI control ensures the restriction on the magnitude of the current drawn from the source, enhances the dynamic response and betters steady state response.

PMSG-based welding power source with parallel-connected cascaded buck fed cuk converters. MATLAB-based simulation of the methodology offer interesting results in the sense it orchestrates the range of converter operation and the ability to provide a high-quality weld without polluting the ac mains. The experimental prototype further proliferates to validate the simulated performance and claims a space for its use in the real-world utilities.

This paper aims to describe a new concept of transformer based on the displacement current. The paper shows how this idea can be translated into reality and presents an example of a working design.

The authors replace the primary winding of the transformer with a capacitor. The displacement current between the capacitor plates induces a magnetic flux in the core. This flux in turn induces electromotive force in the classical secondary winding.

The basic mathematical aspects illustrated by results obtained from a simulation developed using a commercial software ANSYS-HFSS are given. The saturation of the magnetic core due to the applied high-frequency range is investigated and simulated using a finite difference time domain code implemented in MATLAB. A prototype transformer was built and tested; the obtained results confirm the previous ones from simulations.

A new concept of the single winding transformer was used as a pulse forming circuit.

The results of an empirical investigation into the design and fabrication of high frequency planar thick‐film transformers for use in resonant mode power supplies are reported. A 50 W planar transformer design which realises efficiencies in excess of 90% is presented. The findings are used in order to establish an understanding between winding topologies and dimensions and the physical planar transformer parameters.

To analyze the operating performance of an ac‐dc‐ac‐dc PWM parallel resonant converter operating at lagging power factor mode controlled based on fuzzy logic control method.

A range of published works relevant to dc‐ac‐dc converters and their control methods based on PWM technique are evaluated and their limitations in converter output voltage control are indicated in the first section of this paper. The Simulink model and different stages of the converter are described in the second section. In Section 3, the general mathematical model of the system is derived and the phase‐shift PWM switching technique is explained. The equivalent circuit of the high‐voltage high‐frequency transformer used in the converter and the effects of the transformer parameters on the converter operation are presented in Section 4. In Section 5, fuzzy logic control and the basic concepts of this method are described and its application to the proposed converter output voltage control is explained. In Section 6, the Simulink simulation results of the fuzzy logic control application are given for different operating conditions. In Section 7, an overview of the hardware used in this study is presented and the experimental results are given to show the performance of the controller. Finally, Section 8 gives the conclusions of the study.

The fuzzy logic control which is a suitable method for nonlinear systems such as the converter proposed in this paper, is successfully applied for output voltage control of the converter. The controller performance is satisfied. The phase‐shift angle of the converter is used as the control parameter. The paper also presents how the parasitic parameters of the transformer used in high‐voltage applications can be used as the circuit resonant elements.

In preparing this paper, the resources books and periodic journals existing in our university library and also the English resources relative to dc‐ac‐dc converters reachable through the internet were researched.

The suggested control method can be used in the control of linear and nonlinear systems. The study carried out in this paper is also a very good approach to be used in high‐voltage high‐frequency converters output voltage control.

Since, the control approach proposed in this paper does not require the information on converter and transformer parameters that affect the converter output voltage, so it can effectively be used in applications where there are parameter variation problems. The design of the transformer for the required load, finding an optimum operating frequency for the converter, and using the transformer parameters as resonant elements of the circuit to decrease the switching losses are the other contributions of this paper.

The purpose of this paper is to study the multi-objective optimization design method of high-power high-frequency magnetic-resonance air-core transformer (ACT).

First, this paper studies the interleaved winding technology, the process of modeling and simulation, the calculation method of high-frequency loss of Litz wire and the design of magnetic shielding in detail. Second, the multi-objective optimization design process of high-frequency magnetic-resonance ACT is established by parametric scanning method and orthogonal experiment method.

An ACT model of 2 kV/100 kW/81.34 kHz was designed. The efficiency, weight power density and volume power density are 99.61%, 21.6 kW/kg and 5.1 kW/kg, respectively. Finally, the multi-physical field coupling simulation method is used to calculate the port excitation voltages and currents and temperature field of ACT. The maximum temperature of the ACT is 95.5 °C, which meets the design requirements.

The above research provides guidance and basis for the optimization design of high-power high-frequency magnetic-resonance ACT.

The purpose of this paper is to study the insulation structure optimization method of multiwinding high-frequency transformer (HFT).

This paper takes 100 kW, 10 kHz multiwinding HFT as the research object. First, the distribution of electric field strength within the core window of multiwinding HFT with different winding configurations is simulated by the electrostatic field finite element method. The symmetrical hybrid winding structure with minimum electric field strength is selected as the insulation design. To reduce the electric field strength at the end region of the winding, the electrostatic ring and angle ring are designed based on the response surface method.

The optimal results show that the maximum electric field strength can be reduced by 15.4%, and the low voltage stress can be achieved.

The above research provides guidance and basis for the optimal design of insulation structure of multiwinding HFT.