Transcutaneous battery charger using a half bridge SRC controlled by resonant current phase

A transcutaneous battery charger based on a half-bridge series resonant converter (SRC) and controlled by resonant current phase is presented. One of the main problems of these kind of converters is the large (and variable) air gap in the transformer. On the other hand, the batteries used are mainly Li+, due their energy density; the main problem of this kind of battery is that they need to be charged carefully, in several steps. Things being so, the whole system is based on two stages: The power stage and charge controller. The first one sends the energy inside the human body; this energy transference is carried out in such a way that it will be independent of the distance between primary and secondary, even if the windings are not completely opposed. It would be desirable to perform this issue without any feedback from the secondary side. The second stage is based on an special circuit, which transform the energy sent by the first one, in order to perform the charge process in a perfect way, in terms of a Li+ battery.