V. Fernao Pires

Bio: V. Fernao Pires is an academic researcher from INESC-ID. The author has contributed to research in topics: Inverter & Fault (power engineering). The author has an hindex of 18, co-authored 154 publications receiving 1457 citations. Previous affiliations of V. Fernao Pires include Technical University of Lisbon & University of Lisbon.

A Grid-Connected PV Multilevel Cascaded Inverter System Based on Single and Three-Phase Two-Level Inverters

Abstract: In this paper it is presented a new multilevel-cascaded inverter (MCI) based grid connected photovoltaic system. To avoid a dispersed PV structure the proposed multilevel topology uses a combination of three and single-phase classical two-level inverters. The multilevel topology consists in a conventional three-phase VSI inverter, connected to the PV generator DC/DC converters, and three single-phase inverters connected to the AC grid. The DC side of the single-phase inverters will use floating capacitors. The output levels voltage are maximized through the asymmetry that will be used between the DC voltages of the single and three-phase bridge inverters. A control strategy for this three-phase MCI is also presented. This strategy is based on a sliding mode and proportional-integral (PI) linear controllers. Their design is made to obtain the SPWM modulator parameters. The algorithm of this controller also ensures the DC voltage balancing of the single phase inverters floating capacitors. Simulation results are presented in order to confirm the proposed topology and the control adopted.

Power Transistor Fault Diagnosis in SRM Drives Based on Indexes of Symmetry

Abstract: To reduce the negative impacts of power converters on a machine such as switched reluctance motor (SRM) a fast and accurate fault detection method is required. Several fault types could occur in SRM drives, such as, open and short-circuit transistor faults. Thus, this paper presents a new fault detection and diagnosis method for transistor faults in a SRM drive. The method is based on symmetry indexes that are created from the analysis of the currents patterns. The proposed approach results in a fast and robust method, presenting immunity to different mechanical conditions. The characteristics of the proposed method will be verified through several simulation tests.

Development of an off-grid micro-inverter for a scalable photovoltaic kit

Abstract: Taking into account the geographic location of some rural areas, it is not viable, due to technical or economical reasons, to connect certain villages to the electrical grid. Since access to energy is essential for human development, a DC-DC-AC micro-inverter topology for a photovoltaic kit able to address the previous scenario is proposed in this paper. This kit is capable of working in both isolated and parallel modes, with other kits. This solution is also adequate for a post-natural catastrophe scenario, given the power outages associated with these types of phenomena. Each kit consists of a photovoltaic module, an energy storage system and a DC-DC-AC micro-inverter. A control system for all the subsystems is also presented in this paper. Besides that, the management of the DC bus, taking into consideration the photovoltaic system and energy storage system is also proposed. All the theoretical analysis of this kit is detailed in the paper and confirmed through simulations.

Single-phase induction motor controller for photovoltaic powered water pump

Abstract: The objective of this paper is to present a centrifugal pump control system driven by a single-phase induction motor (SPIM) that is supplied by a photovoltaic generator. The study system consists of a PV array, a DC/DC converter, a DC/AC converter and a single-phase AC motor. The DC/DC converter is controlled in order to ensure the maximum power of the PV array. For the maximum power point tracking (MPPT) it is used the classical perturb and observe. In order to control the flow of the centrifugal pump a controller based on a diametrical inversion (DI) of the stator voltage is proposed. All the components of the system are implemented, modeled and simulated using the program Matlab/Simulink. The obtained results show the effectiveness and validity of the proposed control system.

Fault diagnosis method for three-phase high power factor rectifier based on a pattern recognition algorithm

Abstract: This paper proposes a new fault diagnosis methodology for of high power factor rectifiers. This method Is based on the combined with input line currents three dimensional space and the use of the on Principal Component Analysis (PCA). With the proposed method it is possible to detect and identify the power switch in which the fault has occurred. Such detection requires only the measurement the rectifier input currents. Simulation and experimental results are presented, considering for both healthy and faulty cases, to demonstrate the correctness of the proposed method.

Multi-level conversion : high voltage choppers and voltage-source inverters

Abstract: The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<>

Recent Advances in the Design, Modeling, and Control of Multiphase Machines—Part II

Abstract: The main objective of this two-part state-of-the-art paper called “Recent Advances in the Design, Modeling, and Control of Multiphase Machines” is to present latest contributions in the multiphase machines' field. The first part of this paper focuses on the recent progress in the design, modeling, and control, whereas the drive is in healthy operation. This second part presents relevant contributions in two not analyzed fields. The first is in relation with the use of the additional degrees of freedom of multiphase machines and the exploitation of their fault-tolerant capabilities without adding extra hardware. The second one analyzes multiphase generation, particularly in grid-connected wind energy conversion systems and stand-alone applications. Recent progresses are shown and open challenges and future research directions are discussed.

Overview of Control Systems for the Operation of DFIGs in Wind Energy Applications

Abstract: Doubly fed induction generators (DFIGs), often organized in wind parks, are the most important generators used for variable-speed wind energy generation. This paper reviews the control systems for the operation of DFIGs and brushless DFIGs in wind energy applications. Control systems for stand-alone operation, connection to balanced or unbalanced grids, sensorless control, and frequency support from DFIGs and low-voltage ride-through issues are discussed.