Linear-assisted DC/DC converters (or linearswitching hybrid DC/DC converters) consist of a voltage linear regulator (classic NPN or nMOS topologies and LDO) connected in parallel with a switching DC/DC converter. They are a good candidate for energy processing in photovoltaic solar facilities. In order to control these hybrid structures, different strategies exist, allowing fixing the switching frequency as a function of some parameters of the linear regulator. This article compares two control strategies that, although can be applied to the same circuital structure of linear-assisted converter, are sensibly different. The first one, reported in previous literature, cancelscompletely the average current through the linear regulator in steady state to achieve a reduction of the losses. Thus, the efficiency of the whole system increases and almost equals the one of the standalone switching converter. The proposed approach, in spite of a slightly increment of linear regulator’s losses, reduces the output ripple due to the crossover distortion of linear regulator output stage.
CitacióMartinez, H. Capacitorless DC-DC regulator as a candidate topology for photovoltaic solar facilities. "Renewable Energy and Power Quality Journal", Març 2015, núm. 13, p. 1-6.