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In this article, inductor loss models are developed based on the experimental characterization of off-the-shelf components. The modelling steps and techniques are described and validated. It is shown that the model exhibits fairly good accuracy over a large range of ripple current frequency and magnitude. Then, these models are used, as an illustration, in order to present the possible optimization process of the tradeoff between switching frequency-current ripple magnitude and output inductors value in the case of a Buck-derived converter. This optimization has shown that a large current ripple may lead to minimized losses in some cases. The developed modelling technique aims to represent Joules and iron losses, as well as DC and AC losses of inductors. It is not based on physical behaviour description but on mathematical equations based on a set of experimental characterizations. The modelling technique is not suitable for designing the component itself but is useful for selecting the best component value in the manufacturer's series of components. Since it remains difficult with the manufacturer datasheet to estimate AC losses accurately with respect to frequency and ripple current magnitude, a specific characterization is carried out to complement the available data. [ABSTRACT FROM AUTHOR]

This paper deals with the design and the implementation of an isolated and highly integrated low voltage, low power microconverter. A dual active-bridge topology is considered as a good candidate for reducing the number of passive elements. The design of a “power die” integrating power inverter legs and their driver circuits is carried out in order to benefit from the high level of integration and to reduce the amount of active components and the volume of the converter. Thus, a microconverter is built for 10 W power supply (5 V/2 A) and is operating at 1 MHz switching frequency. The measured efficiency of the converter is 88% for 6.5 W transferred power and 86% for 8.5 W transferred power without taking into account its control unit. The converter is operating in natural convection, and no cooling system is implemented. Therefore, a power density of 9.9 kW/L is achieved, which is beyond the state of the art of the conventional isolated converters whose power densities are around 1–2 kW/L at the same power level. [ABSTRACT FROM AUTHOR]

As a consequence of the increase of power needs in low-voltage applications, wiring several windings in parallel to sustain large currents has become common. This choice may have a serious impact on the transformer reliability. In practice, due to additional currents that we call "circulation currents," highly localized extra losses occur. Although hot points resulting from these currents can destroy the component, the related losses are generally not taken into account by analytical approaches. In planar transformers, windings are made of printed circuit board layers, and circulation currents lead to severe unbalance of current sharing between parallel layers. This paper presents an analytical method enabling the evaluation of the currents in every layer using only a circuit simulation software such as Pspice or PSIM. For a designer, this method is very intuitive and fast compared with the use of finite element method simulations. Several extensions of the modeling method used here are also presented. [ABSTRACT FROM AUTHOR]