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- Resumen es exacto "A DC-DC converter with half-bridge topology structure is presented which, by adopting an asymmetric duty cycle, allows for the soft switching characteristic to be incorporated. This reduces the switching losses in the power transistors, which, in addition to improving performance, allows better use of the devices, being able to extract higher powers than usual in a converter with this topology. However, the use of an asymmetric duty cycle introduces a DC magnetic bias in the transformer core that would make the transformer larger and with higher losses in the magnetic material of the core. This is mitigated considering in an application for battery chargers the power to be transferred when the batteries are charged is very small and therefore, the losses become very small as they are only a fraction of the power transferred. The converter is designed so that in full load the duty cycle is close to an optimum value so that the continuous magnetic polarization is very small and its adverse effects are negligible. On the other hand, when the battery to be recharged has been deeply discharged, charging is performed with a fallback feature that reduces the initial charging current so as not to damage the battery. This, in turn, reduces the power to be supplied by the converter, reducing the losses inherent to operating with a duty cycle far to the value corresponding to full load. In this way, for this particular application, the advantages of soft switching are used without introducing the drawbacks of operating with asymmetric duty cycles. The work presents the theoretical foundations of this type of converters, numerical simulations and an experimental realization to test the suitability of the proposal for applications in chargers with powers between 2 and 3 kW.
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