<span>This paper introduces a 2-D FE model to analyze the electric field distribution to evaluate and improve the insulation structure of the 250kVA, 33/0.4kV wound core type distribution transformer using the ANSYS 17.2 by implementing APDL program. The dielectric lighting impulse test was simulated in order to test the presented transformer model according to the IEC67006-3 standard, the assessment process is based on determining the electric stresses and compare it with the maximum permissible value of electric field intensity. Three proposed FE model as an improvement to the insulation structure of the transformer included reducing the insulation distances, changing the materials type, and mix both of them. The results obtained from the FE solution were compared with those of the real test, and presented in form of contours, curves, and vectors. The results obtained from the presented model can be further treated as a reference data in the design process.</span>

This paper presents photovoltaic three-phase grid-connected inverter with an inductor-capacitor-inductor (LCL)-filter. For robustness against variation of filter parameters and external disturbance, the passivity-based control (PBC) method has been adopted. In this method, there are two interactively coupled feedforward terms and three damping gains in the control loops which are designed to limit the steady state error of grid current. Boost converter with P&amp;O maximum power point tracker (MPPT) is used for each photovoltaic (PV) string to extract maximum power and to raise the PV voltage to a value suitable for the grid-connected inverter. The outputs of all boost converters are connected in parallel and controlled to fixed reference voltage using proportional-integral (PI) controller to make the direct-current (DC) link voltage robust against variations in sun radiation intensity and system parameters change. The suggested system is analyzed, designed and simulated using PSIM program. 1 kW, 2kW, and 3kW PV systems connected to grid of 220V/50Hz are tested and the results show the validity of the suggested grid-connected PV systems and robustness against filter parameters variation.

<p>This paper deals with the design, simulation and implementation<br />of the high-frequency transformer for a push-pull converter. It<br />also includes transformer design and simulation for two switches,<br />two outputs forward converter. Design these transformers by<br />building a program, this program is designed in MATLAB<br />software using a graphical user interface (GUI). The program is<br />aimed to reduce the efforts and reduce the time compare with the<br />manual design which takes time and effort. This paper provided<br />the shape and geometry of the core that can influence the<br />efficiency of the converter by designing these transformers in two<br />types of core. The design results were validated by simulation in<br />power simulation software (PSIM), and compare the results of<br />simulation and design.</p>

This paper presents a 2-D &amp; 3-D FE model of 250kVA, 33/0.416 kV wound core type distribution transformer, simulated using ANSYS 17.2 software in order to evaluate the insulation system via dielectric strength under power frequency and induced withstand tests and using two types of analysis, time-harmonic analysis to simulate the dielectric tests, and electro-static analysis to calculate the capacitance matrix. The assessment is based on the maximum allowable electric field intensity. the obtained results were compared with those of the real test, and the values of electric stress were less than the maximum allowable values. also, improvements to the presented model were applied following the transformer assessment. The improvement to the transformer insulation structure was done using three suggested finite element models included reduction and changing the materials type. the results were reviewed in form of contour plots, vector plots, and curves.

<span>Permanent-magnet excitation machines (SPMMs) having mounted magnet on the outer surface of their rotor are preferred for high speed applications such as turbochargers, mechanical turbo-compounding systems, racing engines and fuel pumps, over other types of machines including induction and switched-reluctance machines, since the SPMMs integrate the features of high torque density, compact rotor structure, high reliability and simple structure. However, in the SPMMs, due to the need for a retaining sleeve for the rotor, a large magnetic airgap results and consequently a large magnet thickness is required, hence the magnetic end-effect is relatively high. On the other hand, the use of an overlapping distributed winding leads to a significantly large end-winding length. Hence, the end-effect and the end-winding influences on the performances of a high-speed SPMM is considered in this paper. With a view to get the impact of the end-effect, a comparison between three-dimensional (3D-FEA) results and counterparts two-dimensional finite element analyses (2D-FEA) have been conducted. Results show that, higher efficiency at low torque and low speed due to the low electromagnetic losses and at high speeds due to the high flux-weakening capability are seen when the influences of end-effect as well as end-winding are taken into account.</span>