Marcos Antônio Severo Mendes

Comparison of MPPT approaches in autonomous photovoltaic energy supply system using DSP

This paper presents a methodology for choosing the most suitable Maximum Power Point Tracking - MPPT for charging the batteries of an autonomous photovoltaic energy supply system. Experimental results are provided.

Passivity-based control of PFC boost converter with high-level programming

This paper presents a procedure for high-level programming of a microcontroller using passivity-based control implemented in PFC (Power Factor Correction) boost converters. This is a non-conventional approach, where libraries are used to directly interface with the Texass DSP 2812. Initially, the block diagrams that contain the control equations are constructed. Then, the codes are generated automatically. The advantages provided by the proposed method are: economy of development cycle time, easy understanding of the control process and programming, standardization and concurrent simulation. The other contribution of the paper refers to the development of a regulated source with high power factor and low THD using a boost converter controlled via passivity-based method. The approach based on passivity has been studied recently due to clear advantages in view of disturbances in the operation conditions of the system. The purpose of this technique is to improve the converter efficiency in applications of low and medium power, and improve the quality of the energy in the grid. Finally, in a new and satisfactory way, this nonlinear control technique has been validated experimentally for boost converters.

Reconfigurable parallel interleaved three-phase inverter for aeronautical applications

This paper presents a reconfigurable parallel interleaved inverter connected through InterCell Transformers (ICT) and driving two separate and identical AC loads. The proposed system can be connected to both 270V and 540V bus DC available in aeronautical applications, without any difference in the system operation and with no need of oversizing switches, filters and passive components. This feature is achieved through the reconfiguration of the inverters, by connecting the DC link of each sub-system in parallel or in series. This paper also presents a study of the impact of differences between the two separate loads on the system behavior, especially with regard to the magnetic flux ripple in the ICTs and the capacitors voltage balance. Simulation and experimental results confirm the operation and effectiveness of the proposed system.

The role of photovoltaic generators in low voltage residential voltage regulation: A comparison between standards

This paper studies different standards for the role of photovoltaic (PV) generators in voltage regulation in low voltage residential grids, in the interest of mitigating the voltage rise caused by the PV power injected into the grid. The analysis was made applying each standard to PV inverters inserted on a network, modeled with 24 hours load profile. The main parameters present or not in all standards were listed, and the simulations were conducted in order to highlight how each one differs or resembles from one another. The default method of voltage regulation is by altering the inverter power factor, and most standards follow the same behavior curve, only differing by the value of some of the parameters, which causes most of them to behave similarly. The IEEE standard is the only one to diverge, having no power factor delimitation. The Brazilian standard proves to be the strictest one.

Methodology for the design of a stand-alone photovoltaic power supply

Resumen es: Este trabajo presenta una completa metodologia para el diseno de un sistema fotovoltaico autonomo que maximiza el uso de la energia solar. El metodo prop...

A New Modulation Method For Multilevel Converters With A Better Tradeoff Between Switching Losses And Thd

This paper presents a new modulation method for multilevel converters applied to high power applications with reduced switching frequency, switching losses and THD of the output voltage, when compared with carrier-based Sinusoidal Pulse Width Modulation and Space Vector Pulse Width Modulation methods. In addition, the new method has a low computational cost. Its advantages compared to the Space Vector PWM method were verified by digital simulation of a system composed by a 5 levels converter driving a 4.16 kV, 0.5 MW induction motor. Preliminary experimental results using a Digital Signal Processor verify some of the simulation results.

A multilevel wind power conversion system with an open winding squirrel cage induction generator

The growing use of wind energy conversion systems around the world is pushing the individual power of wind turbines to higher values. Especially in offshore farms, where installation and maintenance have higher costs, high power wind turbines and their reliability become critical issues to make investments economically viable. In this context, multilevel converters, widely used in high power drive systems, have been gaining attention also for variable frequency generation systems. Among the several topologies developed for multilevel converters, there is a structure that employs 2 conventional two-level converters connected to an open winding machine, resulting in a three-level behavior. This structure will be studied in this paper, applied to wind power conversion with a squirrel cage induction generator. The structure is interesting for its high number of redundant switching states, compared to the conventional system, and for the possibility to sustain operation if one of the converters fails. The squirrel cage induction machine is a cheap and robust solution, which is very important when dealing with high power and offshore exploration. The resulting switching states and an initial modulator design will be presented along with the machine modeling, leading to a dynamic simulation of the system.