Photovoltaic (PV) systems are more efficient when operated in its maximum power point (MPP). Even with the existence of high number of MPP tracking (MPPT) techniques, it is possible to improve the MPPT efficiency. One way to achieve this improvement is to use model-based MPPT techniques, since they can estimate the MPP with reasonable accuracy, accelerating the MPP search process. Based on this motivation, the main objective of this article is to propose an efficient double-diode model-based + perturb and observe (P&O) heuristic-based hybrid MPPT technique. The proposition has the following three unique features: the double-diode model used in the MPPT technique has the capability of extrapolating the I–V curves of the PV modules for any environmental condition, even for temperature and irradiance values not used during the model building process; a parameter estimation technique that uses a combination of analytical equations and pattern search optimization algorithm is also presented for this unique model; and an irradiance estimation algorithm is also proposed, avoiding the irradiance sensor usually needed in model-based and hybrid MPPT techniques. Experimental results demonstrate that the integration of the model, the irradiance estimator, and reduced step P&O algorithm is an effective hybrid MPPT solution for PV systems.

The development of technologies to improve the performance of photovoltaic (PV) module integrated converters (MICs) is fundamental to increase the use of distributed generation systems with photovoltaic power source in large urban centers, mainly for complex residential roofs. For two-stage PV MICs, high step-up DC-DC converters are required to boost the low PV module voltage to a higher voltage, in order to suit the DC bus voltage requirements of grid-tied inverters. Thus, to support researchers interested in developing DC-DC power conversion for PV microinverters, this paper classifies the DC-DC converters according to their operational and constructive characteristics and presents some elementary voltage-boosting techniques to aid in analyzing and understanding more complex topologies. Finally, high step-up DC-DC converters based on magnetic coupling and switched capacitor widely cited by important works related to PV applications are presented, with their principles of operation analysed in a simple and objective way, but sufficient to understand their capability to provide high voltage gain. The approach presented by this paper leads to insight into how to place the energy storage elements to create new topologies of DC-DC converters, so that high voltage gain is achieved, and how to analise the high voltage gain capability of complex topologies

This article proposes a hybrid global maximum power point (MPP) tracking technique, named improved global fractional characteristic curve (IGFCC), which combines the advantages of both the model-based and heuristic techniques. The IGFCC technique aims to achieve high speed and accuracy in tracking the MPP of photovoltaic (PV) modules. The model-based technique employed in the IGFCC technique utilizes a precise single-diode model that considers the effects of irradiance and temperature to estimate the MPP voltage. This model-based approach ensures accurate tracking of the MPP and is particularly suitable for PV series applications with string inverters. One of the advantages of the IGFCC technique is its computational efficiency. It involves solving simple equations derived from the single-diode model, which reduces the computational effort required for MPP tracking. This makes the technique practical and feasible for real-time implementation.

This article proposes a current-fed high-gain high-efficiency dc–dc converter for renewable energy applications such as photovoltaic energy. The converter is based on the modified SEPIC, in which the secondary inductor is replaced with a built-in transformer with differentially connected windings (mSEPIC-DBT). The high voltage gain is achieved through a magnetic-coupling-based VMC, in which the built-in transformer is paired to diodes and capacitors. The capacitors, alongside the leakage inductances of the transformer, form a resonant tank, allowing for the zero-current switching of the diodes, while also blocking dc currents from circulating through the transformer windings, which, in turn, allows employing gapless cores for the transformer, reducing its size. The converter operational stages are discussed and steady-state analysis is performed, from which the design guidelines are derived. The theoretical analyses are validated by an experimental 300-W, 50-kHz laboratory prototype. The experimental results show a full-load efficiency of 96.6% and a maximum efficiency of 96.8% at 90% of the full load, which demonstrate that the proposed converter is a strong candidate for applications that require high voltage gains.

This paper proposes a high step-up high-efficiency converter, comprised of an active switched coupled-inductor cell. The secondary windings are integrated into a rectifier voltage multiplier cell in a boost-flyback configuration, allowing the operation with high voltage gain with low switches duty cycle and low turn-ratios on the coupled-inductors. Both coupled-inductors are integrated into a single core due to the parallel operation of the switches. The leakage inductances of the coupled-inductors are used to mitigate the reverse recovery currents of the diodes, while regenerative clamp circuits are used to protect the switches from the voltage spikes caused by the leakage inductances. The operation of the converter is analyzed both quantitatively and qualitatively, and the achieved results are validated through experimentation of a 400 W prototype. A 97.1% CEC efficiency is also reported.