**4. Discussion**

As the mathematical model developed herein for the full-bridge Buck inverter–DC motor system was differentially flat, all system variables were parameterized in terms of the flat output. Later, by proposing and replacing *ω*<sup>∗</sup> into the differential parametrization of the system, the reference variables (*i*∗*a* , *i*<sup>∗</sup>, *υ*<sup>∗</sup>) and the input signal (*u*<sup>∗</sup>*av*) were found offline. This was made to compare the results of the circuit simulation with the differential parametrization results, both shown in Figures 5–8. The same thing was done in order to compare the experimental results and the differential parametrization results, both shown in Figures 11–14. Regarding these latter, a tracking error between system variables *ω*, *ia*, *υ*, *i* and reference variables *<sup>ω</sup>*<sup>∗</sup>, *i*∗*a* , *<sup>υ</sup>*<sup>∗</sup>, *i*∗ can be observed. Such an error appears because some dynamics were not included into the mathematical model, i.e., energy losses associated with semiconductors and parasitic resistances related to capacitor and inductors. In this sense, note that, due to these omitted dynamics and the existence of the load *R*, the efficiency of the Buck converter is 89.14 %. On the other hand, if all the neglected dynamics were taken into account, then the mathematical model would be more complex and this is far beyond the scope of this paper. In brief, the obtained results depicted in Figures 5–8 and 11–14 validate the good accuracy of the proposed mathematical model.
