Daniel Gonzalez Montoya

Improved Design of Sliding-Mode Controllers Based on the Requirements of MPPT Techniques

In many grid-connected applications, a dc/dc switching converter is usually connected between the PV modules and the inverter. This paper presents an improved procedure to design a sliding controller for the PV system, which drives the PV voltage to follow a reference provided by an external MPPT algorithm and mitigates the perturbations caused by the irradiance changes and oscillations in the bulk voltage. By considering that the switching surface is the linear combination of the input capacitor current and the PV voltage error, the proposed design exhibits advantages in comparison with existing solutions that rely in the linearization of inner current loop dynamics. The proposed integral procedure, by taking also into account the effects in the closed-loop system dynamics of a reference filter, ensures a stable sliding regime in all the desired operation range of the system, while the settling time and overshoot of the PV voltage required by an MPPT algorithm are provided. Differently from a previous similar but less rigorous approach, the switching function and reference filter parameters are obtained by numerically solving a set of nonlinear equations. Simulations and experiments were used to demonstrate the efficiency of the proposed solution in presence of environmental and load perturbations.

A new solution of maximum power point tracking based on sliding mode control

This paper presents a new solution to control the PV voltage following a reference provide by an external algorithm and to mitigate the oscillations in the bulk voltage. The implementation is compared with other techniques its advantages are demonstrated. The sliding mode control stability is validated for the chosen surface ensuring a good behavior in all operation range of the PV panel. Finally, simulations are used to show the effectiveness of the solution in presence of changes in the irradiance level and sinusoidal oscillations in the bulk voltage.

Maximum power point tracking based on the sliding mode control of the average PV admittance

TMs paper presents a new sliding surface to control the average photovoltaic admittance to follow a reference provided by an external algorithm, and at the same time, to mitigate the oscillations in the bulk voltage. The sliding mode control convergence and stability are validated for the designed surface to ensure the same performance in all operation range. Finally, simulations are used to demonstrate the efficiency of the proposed solution in presence of changes in the irradiance level and sinusoidal oscillations in the bulk voltage. This solution is useful to avoid the use of electrolytic capacitors that degrade the reliability of the system.

Design method of the perturb and observe controller parameters for photovoltaic applications

This paper presents an analysis of the Perturb and Observe Maximum Power Point Tracking controller, providing a useful tool to design an optimal MPPT controller for photovoltaic applications. The method uses the complete equation for the photovoltaic module to calculate exact values in the non-linear power-voltage profile. The amplitude of the duty cycle perturbation is designed from the maximum power losses restriction and the sampling time of the algorithm is designed to track a dynamic irradiance profile with three-point behavior. Finally, simulations are used to validate the proposed methodology and to demonstrate the effectiveness of the solution.

Reconfiguration of Photovoltaic Arrays Based on a GPU-Accelerated Exhaustive Search Algorithm

This paper proposes a parallel exhaustive search algorithm to find the best electrical configuration of PV arrays. This information is required to reconfigure, in real-time, the PV array in order to mitigate the power losses caused by partial shading and other mismatching conditions. The algorithm is based on a parameterized model of the PV system, and it is designed to run in commercial graphic processing units (GPU). This GPU-accelerated approach provides a significant reduction in the processing time compared with the classical CPU-only serial algorithm. Hence, the proposed GPU-based reconfiguration enables to reconfigure, in real-time, PV systems much larger contrasted with the CPU-only approach.