@article {314,
	title = {A fast and robust closed-loop photovoltaic MPPT approach based on sliding mode techniques},
	journal = {Sustainable Energy Technologies and Assessments},
	volume = {47},
	year = {2021},
	pages = {101499},
	abstract = {<p>This article presents a closed-loop Maximum Power Point Tracking (MPPT) method for a photovoltaic (PV) system that includes a PV array, a DC-DC converter and a DC bus. The proposal consists of a controller and two observers developed into the sliding mode (SM) theoretical framework. The converter switching signal is driven by an Integral First-Order Sliding Mode (IFOSM) controller whose input corresponds to the PV power gradient estimation. This estimation is obtained through a pair of Second Order Sliding Mode Observers (SOSM). The first one corresponds to a Levant{\textquoteright}s differentiator which estimates the first-time derivative of the PV voltage and feds a specific SOSM which delivers the PV power gradient estimation. These kinds of observers converge in finite time even in the presence of unmodeled dynamics and external perturbations. The proposed structure permits to synthesise a whole MPPT closed-loop system with a fast-tracking dynamics, a moderate computational burden and a reduced hardware cost, requiring only two variable measurements. This approach, simplifies the controller design and the system start-up, which does not need any specific initial conditions to be started from. The system performance is evaluated using representative computer simulations with standardised radiation and temperature profiles and corroborated through experimental tests. Finally, the proposal capabilities to work under partial shading conditions are also evaluated.</p>
},
	keywords = {Maximum power extraction, MPPT, Photovoltaic energy, Sliding modes},
	issn = {2213-1388},
	doi = {https://doi.org/10.1016/j.seta.2021.101499},
	url = {https://www.sciencedirect.com/science/article/pii/S2213138821005105},
	author = {Inthamoussou, Fernando A. and Valenciaga, Fernando}
}
@article {321,
	title = {Robust exact differentiators with predefined convergence time},
	journal = {Automatica},
	volume = {134},
	year = {2021},
	pages = {109858},
	abstract = {<p>The problem of exactly differentiating a signal with bounded second derivative is considered. A class of differentiators is proposed, which converge to the derivative of such a signal within a fixed, i.e., a finite and uniformly bounded convergence time. A tuning procedure is derived that allows to assign an arbitrary, predefined upper bound for this convergence time. It is furthermore shown that this bound can be made arbitrarily tight by appropriate tuning. The usefulness of the procedure is demonstrated by applying it to the well-known uniform robust exact differentiator, which is included in the considered class of differentiators as a special case.</p>
},
	keywords = {Disturbance rejection, Finite-time convergence, Fixed-time convergence, Sliding modes, super-twisting algorithm},
	issn = {0005-1098},
	doi = {https://doi.org/10.1016/j.automatica.2021.109858},
	url = {https://www.sciencedirect.com/science/article/pii/S0005109821003782},
	author = {Seeber, Richard and Haimovich, Hernan and Horn, Martin and Fridman, Leonid M. and De Battista, Hern{\'a}n}
}
