An improved dual boost converter with zero voltage transition

This work proposes a soft switching approach for dual-boost converter using an auxiliary resonant circuit. The topology is composed of a general dual-boost converter and an auxiliary resonant circuit including one switch, inductor, capacitor and diode. The auxiliary resonant circuit helps the main switch to operate under ZVT and ZCS conditions. The auxiliary switch also operates at soft switching mode. Furthermore, the proposed circuit removes the voltage stress on the main and auxiliary switches. Under soft switching conditions the efficiency of the converter increases. The converter has various advantages compared with the conventional boost converters as higher boost rate with low duty cycle, lower voltage stress on components and higher efficiency

Analysis of a soft switched dual-boost converter

This paper proposes a soft switched dual-boost converter using an auxiliary resonant circuit. The topology is composed of a general dual-boost converter and an auxiliary resonant circuit including one switch, inductor, capacitor and two diodes. The auxiliary resonant circuit helps the main switch to operate under ZVT condition. The auxiliary switch is also operated at soft switching mode. Furthermore, the proposed circuit removes the voltage stress on the main and auxiliary switches. Under soft switching conditions the efficiency of the converter increases. The converter has various advantages compared with the conventional boost converters as higher boost rate with low duty cycle, lower voltage stress on components and higher efficiency

Steady-state modeling of a phase-shift PWM parallel resonant converter

Purpose - 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

Design Studies of VSC HVDC Converter According to AC Voltage Tests

Since high-voltage direct current (HVDC) systems are very expensive and operationally critical, these systems must be tested before they are put into service. Insulation and performance tests are the two main subjects of these tests. AC voltage tests, as part of the insulation tests, should be performed after system installation is complete and before commissioning. However, in this study, the objective was to perform these tests during the prototype phase of VSC HVDC. Unlike other studies, this study attempted to use COMSOL Multiphysics to determine in advance the problems that may occur in the real system. In this regard, the busbars connecting the submodules of the VSC HVDC system were first modeled in 3D, and the tests to be performed were simulated using COMSOL Multiphysics software. During the simulation, the finite element method (FEM) was used to identify critical points that could cause partial discharge. To validate the simulation results, partial discharge tests on a real system were conducted, and the design changes made in response to each test result were explained. After the improvement actions, the targeted partial discharge values were achieved

Design Studies of VSC HVDC Converter According to AC Voltage Tests

Since high-voltage direct current (HVDC) systems are very expensive and operationally critical, these systems must be tested before they are put into service. Insulation and performance tests are the two main subjects of these tests. AC voltage tests, as part of the insulation tests, should be performed after system installation is complete and before commissioning. However, in this study, the objective was to perform these tests during the prototype phase of VSC HVDC. Unlike other studies, this study attempted to use COMSOL Multiphysics to determine in advance the problems that may occur in the real system. In this regard, the busbars connecting the submodules of the VSC HVDC system were first modeled in 3D, and the tests to be performed were simulated using COMSOL Multiphysics software. During the simulation, the finite element method (FEM) was used to identify critical points that could cause partial discharge. To validate the simulation results, partial discharge tests on a real system were conducted, and the design changes made in response to each test result were explained. After the improvement actions, the targeted partial discharge values were achieved

A New Core Geometry for Wireless Power Transfer Based on Magnetic Resonance

The most important goal in Wireless Power Transfer (WPT) applications is to provide efficient energy transfer. WPT is applicable at mobile phone charging, electric vehicle charging, lighting, control etc. Due to its high efficiency and low environmental impact, magnetic resonance is the most preferred method for short-range distances. In WPT systems based on magnetic resonance, a high efficiency WPT transformer should be used to increase system efficiency. In this study, a WPT system based on magnetic resonance is designed. For this purpose, firstly, a transformer with air-ferrite hybrid core is designed. The transformer's circular-sliced segmented (C-SS) ferrite core structure was used for the first time in this study. The transformer windings are designed as litz conductors. In order to minimize leakage fluxes in the transformer, the magnetic field was forced to stay between the windings by using aluminum plates on the outer surfaces of the windings. Magnetic analysis of the designed transformer was made with finite element method and the results were confirmed by numerical calculations. Using the magnetic analysis results, the WPT transformer was loaded over the simulation circuit and power transfer was achieved in a 5 cm air gap with 97% efficiency. The results showed that C-SS ferrite core structure can be used successfully in WPT transformer applications

FEA simulation of the electromagnetic effects on the flux distribution of the joints in the transformer core structure

2nd International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT) -- OCT 19-21, 2018 -- Kizilcahamam, TURKEYWOS:000467794200015In the manufacturing of the transformer the occurrence of air gaps at the joints of the legs and yokes of the core lamination stacking of the transformers is inevitable. The air-gap in the core joints affects the magnetic flux density and the magnetic flux distribution in the core. The location, shape, length and number of air-gaps all are different from each other. The increase in air-gap of transformer core will increase the reluctance of the core causing a reduction in the total magnetic flux value. The effects of the air-gap in joints cannot be exactly analyzed mathematically. However, the electromagnetic modeling using the finite element method provides facility to simulate and analyze such a problem. In this study, the effects of air-gaps with different shapes and length in the transformer legs on the stray magnetic are compared with using Finite Element Analysis (FEA) software.IEEE Turkey Sect, Karabuk Univ, Kutahya Dumlupinar Uni

Finite Element Method-Based Optimisation of Magnetic Coupler Design for Safe Operation of Hybrid UAVs

The integration of compact concepts and advances in permanent-magnet technology improve the safety, usability, endurance, and simplicity of unmanned aerial vehicles (UAVs) while also providing long-term operation without maintenance and larger air gap use. These developments have revealed the demand for the use of magnetic couplers to magnetically isolate aircraft engines and starter-generator shafts, allowing contactless torque transmission. This paper explores the design aspects of an active cylindrical-type magnetic coupler based on finite element analyses to achieve an optimum model for hybrid UAVs using a piston engine. The novel model is parameterised in Ansys Maxwell for optimetric solutions, including magnetostatics and transients. The criteria of material selection, coupler types, and topologies are discussed. The Torque-Speed bench is set up for dynamic and static tests. The highest torque density is obtained in the 10-pole configuration with an embrace of 0.98. In addition, the loss of synchronisation caused by the piston engine shaft locking and misalignment in the case of bearing problems is also examined. The magnetic coupler efficiency is above 94% at the maximum speed. The error margin of the numerical simulations is 8% for the Maxwell 2D and 4.5% for 3D. Correction coefficients of 1.2 for the Maxwell 2D and 1.1 for 3D are proposed