This paper presents a novel ZVZCS full-bridge DC/DC converter, which is able to process and deliver power efficiently over very wide load variations. The proposed DC/DC converter is part of a plug-in AC/DC converter used to charge the traction battery (high voltage battery) in an electric vehicle. The key challenge in this application is operation of the full-bridge converter from absolutely no-load to full-load conditions. In order to confirm reliable operation of the full-bridge converter under such wide load variations, the converter should not only operate with soft-switching from full load to no-load condition with satisfactory efficiency for the full range of operation, but also the voltage across the output diode bridge needs to be clamped to avoid any adverse voltage overshoots arising during turn-OFF of the output diodes as commonly found in regular full bridge converters. In order to achieve such stringent requirements and high reliability, the converter employs a symmetric passive near lossless auxiliary circuit to provide the reactive current for the full-bridge semiconductor switches, which guarantees zero voltage switching at turn-ON times for all load conditions. Moreover the proposed topology is based on a current driven rectifier in order to clamp the voltage of the output diode bridge and also satisfy ZVZCS operation of the converter resulting in superior efficiency for all load conditions. In this paper operation of the converter is presented in detail followed by analytical design procedure. Experimental results provided from a 3KW prototype validate the feasibility and superior performance of the proposed converter.

A Novel ZVZCS Full-Bridge DC/DC Converter Used for Electric Vehicles

A method for calculating the reluctance of air gaps in magnetic circuits making use of a Schwarz-Christoffel transformation is described. The method is applied to the calculation of the inductance of example inductor and transformer configurations and its validity established through comparisons with calculations based on the finite-element method of numerical analysis. >

Air-gap reluctance and inductance calculations for magnetic circuits using a Schwarz-Christoffel transformation

A general model of the multiple-winding transformer and coupled inductor is presented, in which all parameters can be directly measured. The approach is suitable for all winding geometries, and simplifying approximations can be easily made. This model can be applied in the determination of cross-regulation, current ripple and small-signal dynamics of multiple-output DC-DC power converters. An experimental four-winding flyback transformer example is investigated. Observed leakage inductance parameter measurements are interpreted physically, and are related to observed flyback converter waveforms. It is also shown that the model correctly predicts small-signal dynamics.

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A multiple-winding magnetics model having directly measurable parameters

Performance Improvements of Multi-Channel Interleaving Voltage Regulator Modules with Integrated Coupling Inductors

A new modelling method for magnetic circuits is presented. The method can be used to model magnetic circuits with any number of windings. The models incorporate adequate information about the correct distribution of leakage energy, the presence of gaps throughout the core, the arrangement of the windings, and the type of core used. Several commonly used arrangements such as toroids with uniformly distributed turns, and bobbin core structures with multiple windings were modelled with the new technique. The measured electric circuit model values always compared favorably with the predicted physical values derived with the new method.

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Abraham Dauhajre

Papers

Modelling and estimation of leakage phenomena in magnetic circuits