**4. Discussion**

In this paper, the effectiveness and viability of a fractional-order PID controller approximation to regulate voltage in a buck–boost converter were addressed. The importance of the converter rests in its variety of applications from which biomedicine ones take on special relevance, since the need for a stable and fast-response source of power is one of the main drawbacks of emerging cardiac technologies, which as in high-power systems, require an appropriate energy management/harvesting/storage strategy.

From the proposed approach, the controller design method considered both performance of closed-loop response and robustness. A biquadratic module that exhibits flat phase response was used to generate the controller structure. Fractional calculus is integrated due to its proven ability to describe systems with higher accuracy and robustness against parameter variations/uncertainties.

The proposed approach viability is investigated as an alternative for highly efficient converters such as Silicon-Carbide ones. Experimental results confirmed effectiveness of the controller to regulate output voltage in a buck–boost converter using a single control loop. These results open the possibility of applying this approach to a current control mode to determine if regulation velocity can be enhanced even more.

Although it could represent a disadvantage the required extra hardware for the implementation of the proposed controller, this could be dismissed considering the promising results of the proposed approach as well as the availability in commercial values of the extra components.
