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Due to their exceptional performance in coping with large variations in output voltage and current, parallel resonant converters (PRC) are commonly used in high-voltage applications. The incorporation of step-up transformer parasitic components as part of a power topology, on the right duty and a suitable switching frequency, determines the high efficiency and wide variety of applications with PRC. Switching losses are reduced in the same topology by tracking and running on the optimum mode for each power and voltage by a set frequency and duty. The PRC's static model behaviors, under optimum operating circumstances, are illustrated. The equivalent polynomial model is used to quickly compute the switching frequency and duty cycle required to achieve the converter's desired output voltage and power. The polynomial model is simple and easy to implement in any form of a digital signal controller (DSC). Normalized parameters are used to widen the operational range and generalize the model. This also offers the essential protection against current and voltage spikes. The work in progress depicts the specific procedures involved in developing a polynomial model. The normalized equations provide a graphical description of the static model, from which the graphical representation of the polynomial are derived. Hence, polynomial equations are obtained. This paper describes the PRC static model, how to convert it to a polynomial model, how to validate it with MATLAB-Simulink, how to program F28335 using Simulink, and how to use it in practice. [ABSTRACT FROM AUTHOR]

One of the major drawbacks of high-ratio step-up transformers is the high value of their secondary-side capacitor. This value is reflected at the primary side, giving rise to a nondesirable one. There are some converters which include this capacitor in the topology and can cope with it, and even more, they need it. In particular, in high-voltage applications, we will find transformers with a large capacitance value since they use high-ratio step-up transformers. In this kind of applications, it is always interesting not to have inductors at the output filter, with single-capacitor filters being preferred instead. Thus, one of the simplest topologies is the parallel resonant converter (PRC) with a single-capacitor output filter. It can be controlled by the switching frequency and/or duty cycle, which makes zero voltage switching feasible in the power switches. In this paper, the PRC modeling and design and the experimental results are shown in a prototype delivering 3.5 kV and 260 W. [ABSTRACT FROM AUTHOR]

Nowadays, piezoelectric transformers (PT) are a good alternative to substitute magnetic materials in ac/dc and dc-dc converters. They have high isolation voltage and operate at higher frequencies than magnetics, with lower losses. However, their optimum operating frequency exhibits a strong dependence on different parameters, such as temperature, load, or even voltage level applied. This is usually an inconvenience, because this drift af- fects PT gain and efficiency, which can vary enormously within a few hundred of hertz. On the other hand, not only is it necessary to ensure the PT is driven at the proper frequency-in terms of gain and efficiency, including zero voltage switching in the power stage-output voltage must also be regulated. In this paper, two simple feedback loops are implemented in a PT.based dc-dc converter. One of them adjusts the switching frequency to obtain the best gain and efficiency. The other one performs the output voltage regulation. [ABSTRACT FROM AUTHOR]