## 1 Introduction
At the beginning of the 21 st century, a systematic method (applicable to all conduction modes) to obtain circuit-oriented average models for multiple-output DC/DC converters is presented [27]. From here, it seems to be noted that there are no recent major developments over basic DC/DC converter modeling, probably because the current modeling approaches have been very well complemented with accurate simulations. Actually at the present time, it seems that interest is mostly focused on frequency analysis [28], and in the control-oriented models [29; 30], with emphasis on stability analysis [31; 32; 33]  
In any case and from our view, it is suitable and formal (for analytical studies and demonstrations and of course in higher education, where students learn DC/DC converter theory from the three basic topologies) to have accurate analytical models that match the DC/DC converters' actual behavior. With this aim, the authors of the present work have tried to develop a new realistic static model of concentrated parameters, which it is aimed to be intuitive and useful, and faithfully reflecting the actual operation of the three basic DC/DC converters. In order to contribute in this field, this work presents a new model of DC/DC converter, where losses are shaped as electrical components (they are the model parameters), which allows, based on the usual circuit theory, the obtaining of useful and easy-to-use mathematical relationships. The developed model allows accuracy in theoretical calculations and reliable simulations, as well as previous steps to successful experimental implementations, as their final results may be guaranteed in advance. Even more, the developed model is the result of an intuitive approach and very easy to understand and interpret, which can facilitate its use and understanding DC/DC converters' actual operation. The proposed model is based on the well-known transformer theory. Just as a transformer can be used for coupling impedances in AC (by controlling the ratio between the number of turns in its primary and secondary), a DC/DC converter can be used to match resistances in DC (controlling its duty cycle \(\delta\), i.e., the relationship between the time interval in which its switch is on, \(T_{ON}\), regarding the switching period \(T\)). This means that for the coupling DC generator \(\rightarrow\) DC/DC converter \(\rightarrow\) load, if \(\delta\) control is made adaptive (under generator and/or load demand), then the resistance of the generator and the load can be matched so that the DC/DC converter allows maximum power transfer from generator to load. Moreover, in the case of renewable power sources, which are subjected to constant fluctuations as a result of environmental changes, the DC/DC converter enables the generator to work at maximum power. Ideally speaking, the relationships that allow load adaptation by DC/DC converters according to their \(\delta\) are well-known [34; 35]. The problem lies in the fact that these expressions are approximate and in many operating conditions undergo deviations that can make them practically inapplicable, since DC/DC power converters are strongly non-ideal systems. Therefore, the theoretical results expected as a consequence of the application of the expressions commonly found in literature are usually very far from experimental reality. This requires that reliable experimental implementation demands a previous step: careful and exhaustive simulations. From here arises the challenge in finding a truly useful model, which provides close-to-experimentation results. It should also be simple, intuitive, easy to use and really general (i.e., valid for the three basic converter types: boost, buck and buck-boost). Figure 1 shows the proposed model, which is remarkably simple, as it comprises an ideal DC/DC converter formed by two voltage gain (\(A_{VI}\))-dependent sources: a current source in its input and a voltage source in its output.