Design of symmetrical half-bridge converter with a series coupling capacitor

Purpose With the advancement of technology, size, cost, and losses of the switched mode power supply (SMPS) have been decreasing. However, due to the high frequency switching, design of magnetic drives and isolation circuits are becoming a crucial factor in SMPS. This paper presents design criteria, procedure and implementation of AC-DC half bridge (HB) converter with lower cost, smaller size and lower voltage stress on the power switch. Design/Methodology/approach The HB converter is designed in a symmetrical mode with a series coupling capacitor. Isolated power supplies are used for the converter and control circuit. Further, a transformer based isolated gate driver is used to drive both MOSFETs. The control IC works in voltage control mode to regulate voltage by controlling the duty cycle of the MOSFETs. Findings Control characteristics and performance of the HB converter is simulated using the MATLAB software and prototype of 170 W HB converter is built to validate the analytical results under variable load current and source voltage. The power quality and variation of load voltage at 2 A, 5 A, 7 A are reported. Originality/value This paper presents the design of a low-cost HB converter in a symmetrical mode which saves the additional cost of symmetric correction circuit normally required in asymmetrical mode design. This paper also focuses on the selection of primary and secondary side switch, series coupling capacitor, commuting diode, isolated drive and charge equalizer resistor.

Investigation of High Lift Force Generation of Dragonfly Wing by a Novel Advanced Mode in Hover

In the paper, a novel flapping mode is presented that can generate high lift force by a dragonfly wing in hover. The new mode, named partial advanced mode (PAM), starts pitching earlier than symmetric rotation during the downstroke cycle of the hovering motion. As a result, high lift force can be generated due to rapid pitching coupling with high flapping velocity in the stroke plane. Aerodynamic performance of the new mode is investigated thoroughly using numerical simulation. The results obtained show that the period-averaged lift coefficient, CL, increases up to 16% compared with that of the traditional symmetrical mode when an earlier pitching time is set to 8% of the flapping period. The reason for the high lift force generation mechanism is explained in detail using not only force investigation, but also by analyzing vortices produced around the wing. The proposed PAM is believed to lengthen the dynamic stall mechanism and enhance the LEV generated during the downstroke. The improvement of lift force could be considered as a result of a combination of the dynamic stall mechanism and rapid pitch mechanism. Finally, the energy expenditure of the new mode is also analyzed.

Principles of electricity metering in networks with non-liner load

The existing approach to electricity metering, which underlies the formation of payment for consumed electricity, has a significant drawback. It can be correctly used in systems with a sinusoidal symmetrical mode, but needs to be improved in other network modes. The article defines indicators that numerically reflect the effect of distortions on the modes of distribution electric networks, as well as indicators that take into account consumed inactive power (by analogy with reactive power in a sinusoidal mode) when paying electricity bills to an electricity supplier. The proposed principles of electricity consumption metering includes the influence of such indicators as the spectral composition of voltage and current, the ratio of linear and nonlinear loads of consumers, as well as the influence of the topology of the electric network.

Potential Application in Energy Harvesting of Intermodal Energy Exchange in a Frame: FEM Analysis

This paper presents a Finite Element Analysis (FEA) of modal energy exchange and harvesting in a simple portal frame structure. We consider both horizontal and vertical support excitations resonant first with the first mode (sway mode) and latter with the second mode (the first symmetrical mode). As 2:1 internal resonance is present between these two modes, the phenomena of mode saturation and energy exchange (modal coupling) may occur. Thus, energy pumped into the system through one of the modes, is partially transferred to the other mode, not directly excited. An evaluation of the energy available for harvesting in each of the considered mode is computed.

The Impact of Gymnasium Form’s Tilting Side Interfaces on Natural Ventilation and Thermal Comfort of Exercise Site

To improve air change rate and exercise site’s thermal comfort of gymnasium under natural ventilation in hot and humid areas, taking Guangzhou as an example, symmetrical model, unsymmetrical model, and unsymmetrical model with corbel table were simulated and calculated with Fluent and other software. The result indicates that, compared with symmetrical mode, unsymmetrical model and unsymmetrical model with corbel table can improve exercise site’s wind velocity and integral air change rate, and the latter model improves more. Based on unsymmetrical model with corbel table, window-opening ventilation strategies for competition are further put forward. In the end, it discusses about the influence towards thermal comfort of exercise site by natural ventilation in different form models and different use modes.

Dynamic Propagation Problems Concerning Symmetrical Mode III Interface Crack of Aluminum Alloys

By application of the theory of complex variable functions, dynamic propagation problems concerning symmetrical mode III interface crack of Aluminum alloys were investigated. The problems dealt with can be very facilely translated into Riemann-Hilbert problem by the approaches of self-similar functions, and the universal representations of analytical solutions of the stresses, displacements and dynamic stress intensity factors for the surfaces of symmetrical mode III interface crack subjected to motive increasing loadings Pt5/x5 and Px6/t5 were attained, respectively. After those solutions were utilized by superposition principle, the solutions of discretionally complicated problems could be easily acquired.

Dynamic Propagation Problems of Symmetrical Mode III Crack

By the measures of the theory of complex variable functions, dynamic propagation problems of symmetrical mode III crack were researched. The problems considered can be very facilely translated into Riemann-Hilbert problem by means of self-similar functions, and the analytical solutions of the stress, the displacement and dynamic stress intensity factor under the conditions of motive variational loads Px/t and Pt3/x2 which were applied the surfaces of mode III crack, respectively, were acquired.

Symmetrical Dynamic Expansion Issues of Mode III Interface Crack

By means of complex variable functions, symmetrical dynamic extension issues of mode III interface crack were researched. The problems considered can be very facilely transformed into Riemann-Hilbert problem by the approaches of self-similar functions, and the general expressions of analytical solutions of the stresses, displacements and dynamic stress intensity factors for the edges of symmetrical mode III interface crack subjected to motive variable loadingsPt4/x4andPx5/t4were attained, respectively. After those solutions were utilized by superposition theorem, the solutions of arbitrary complex problems could be acquired.