Wesley Josias de Paula

Comparative Study of Maximum Power Point Tracking Techniques for Photovoltaic Systems

The generation of electricity from photovoltaic (PV) arrays has been increasingly considered as a prominent alternative to fossil fuels. However, the conversion efficiency is typically low and the initial cost is still appreciable. A required feature of a PV system is the ability to track the maximum power point (MPP) of the PV array. Besides, MPP tracking (MPPT) is desirable in both grid-connected and stand-alone photovoltaic systems because the solar irradiance and temperature change throughout the day, as well as along seasons and geographical conditions, also leading to the modification of the (current versus voltage) and (power versus voltage) curves of the PV module. MPPT is also justified by the relatively high cost of the energy generated by PV systems if compared with other sources. Since there are various MPPT approaches available in the literature, this work presents a comparative study among four popular techniques, which are the fixed duty cycle method, constant voltage (CV), perturb and observe (P&O), and incremental conductance (IC). It considers different operational climatic conditions (i.e., irradiance and temperature), since the MPP is nonlinear with the environment status. PSIM software is used to validate the assumptions, while relevant results are discussed in detail.

Comparison among mathematical models of the photovoltaic cell for computer simulation purposes

ABSTRACT This paper presents a comparison among mathematical models used in the simulation of solar photovoltaic modules that can be easily integrated with power electronic converters. In order to perform the analysis, three models available in literature and also the physical model of the module in software PSIM® are used. Some results regarding the respective I × V and P × V curves are presented, while some advantages and eventual limitations are discussed. Besides, a DC–DC buck converter performs maximum power point tracking by using perturb and observe method, while the performance of each one of the aforementioned models is investigated.

Comparative study of high power factor boost rectifiers in continuous conduction mode

This work presents a comparative study of single-phase boost-based ac-dc converters applied to power factor correction. Three structures are chosen for this purpose and analyzed in detail e.g. the classical boost converter, the bridgeless boost converter, and the boost converter based on the three-state switching cell (3SSC) operating in continuous conduction mode (CCM). The aforementioned topologies are briefly revised so that they can be properly designed and validated considering results obtained from simulation tests, where aspects such as the input current, regulated output voltage, harmonic content, and dynamic response are investigated.

An extensive review of nonisolated DC-DC boost-based converters

High voltage step-up is necessary in several applications, especially considering that dc-ac converters must be supplied by high dc voltages. The conventional boost converter is the most popular topology for this purpose, although the conversion efficiency is limited at high duty cycle values. In order to overcome such limitation and improve the conversion ratio, many converter topologies have been proposed so far. Within this context, this work intends to review some of the most important works regarding boost-based dc-dc converters. Some structures are covered and classified basically as converters with and without wide conversion ratio. Some of the main advantages and drawbacks regarding the existing approaches are also discussed. Finally, a proper comparison is established among the most significant converters regarding the voltage stress across the semiconductor elements, number of components, and static gain.

SPICE simulation and evaluation of a GaN-based synchronous full-bridge resonant converter

This paper presents a SPICE-based simulation for a full-bridge converter applying Gallium Nitride (GaN)-based switches. The evaluated converter is concerned to a resonant topology which achieves extra-high efficiency when using an LLC network. The studied GaN-based switch model considers resistances and capacitances which are equivalent to each terminal of the transistor. Otherwise, the current through the device is modeled by a voltage controlled current source. Furthermore, high-frequency parasitic inductances are included in the circuitry in order to achieve a suitable and relevant simulation, since these parameters are important to a proper modeling of the switch dynamic losses. A comparative analysis regarding silicon-based devices is carried out highlighting the GaN improved efficiency for this full-bridge topology.

Application of the commutated power concept to the classical isolated dc-dc converters

In order to define which power converter topology is the most adequate one for a given application, several aspects must be analyzed, such as cost, efficiency, size, and volume of the chosen structure. This paper extends the concept of the commutated power to classical dc-dc high-frequency isolated converters e.g. the one-switch and two-switch forward converters. It allows determining which topology has the best performance from the efficiency point of view considering the stresses in the semiconductor elements. Initially, it is necessary to obtain the expressions that provide the commutated power for each structure. By defining a given operating point and properly designing the converters, it is possible to estimate conduction and switching losses so that the concept is validated. Finally, the theoretical curves for the total commutated power are compared with the ones obtained in SPICE simulations, while relevant issues are discussed.