Percorrer por autor "Foito, Daniel José Medronho"
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- Bidirectional Boost/Buck Quadratic Converter for Distributed Generation Systems with Electrochemical Storage SystemsPublication . Foito, Daniel José Medronho; Cordeiro, A.The increasing number of distributed generation systems using renewable and non-conventional energy sources show the trend of future generation systems. Most of these systems require power electronic converters as an interface between the DC voltage buses and electrochemical storage systems. Such storage systems, like batteries or supercapacitors, usually need bidirectional DC-DC converters to allow their charge or discharge according with necessary operation conditions. In this paper, a non-isolated bidirectional Buck-Boost converter with high voltage gain for electrochemical storage devices used in distributed generation systems is presented. To achieve high voltage gain ratios, the proposed topology presents quadratic characteristics in both step-down (Buck) and step-up (Boost) operation modes. In addition to the wide conversion range, it presents continuous input and output current, reduced charging/discharging ripple and simple control circuitry. All these features allow the energy exchange smoothly and continuously resulting in a longer durability of storage devices. The principle of the operation of the proposed converter in both operation modes, as well as their theoretical analysis will be discussed. The performance of this bidirectional power converter is confirmed through simulation and experimental results.
- Bidirectional DC-DC Converter with High Voltage Gain for the Charge/Discharge Control of Storage SystemsPublication . Pires, Vítor Fernão; Foito, Daniel José Medronho; Martins, J. F.This paper presents a study of a bidirectional dc-dc converter with high voltage gain to regulate the charge and discharge of electrochemical storage systems. The converter is characterized by quadratic voltage gain characteristics in both directions. In this context it can be used to regulate a dc interface between the storage system and a dc/ac converter connected to the electrical grid. It will be analysed the converter in ideal and non-ideal conditions. A control system to regulate the output voltages and currents are also proposed. Simulation results are presented in order to validate the control system associated to the converter for the charge/discharge of the storage system.
- A DC-DC Converter with Capability to Support the Voltage Balance of DC Bipolar MicrogridsPublication . Pires, Vítor; Foito, Daniel José Medronho; Cordeiro, Armando; Silva, J. FernandoBipolar DC microgrids are now starting to become an interesting solution for power distribution. Although presenting several advantages over DC unipolar microgrids, bipolar DC has the intrinsic problem of voltage unbalance that may appear depending on the converter topology and load sharing. Therefore, this paper presents a new DC-DC converter topology that can be used with renewable energy sources and has the capability to simultaneously ensure the bipolar microgrid voltage balance. The operation of the proposed topology together with its characteristics is described. A theoretical study of this converter will also be presented, complemented by a set of results from computer simulations. To support these simulations, results from a laboratory prototype will also be displayed. The voltage balance capability of the converter will be checked experimentally.
- Dual Output and High Voltage Gain DC-DC Converter for PV and Fuel Cell Generators Connected to DC Bipolar MicrogridsPublication . Pires, Vitor Fernão; Cordeiro, Armando; Foito, Daniel José Medronho; Silva, J. Fernando A.This paper introduces a new topology for a DC-DC converter with bipolar output and high voltage gain. The topology was designed with the aim to use only one active power switch. Besides the bipolar multiport output and high voltage gain this converter has another important feature, namely, it has a continuous input current. Due to the self-balancing bipolar outputs, the proposed topology is suitable for bipolar DC microgrids. Indeed, the topology balancing capability can achieve the two symmetrical voltage poles of bipolar DC microgrids. Furthermore, it is possible to create a midpoint in the output of the converter that can be directly connected to the ground of the DC power supply, avoiding common-mode leakage currents in critical applications such as transformerless grid-connect PV systems. The operating principle of the proposed topology will be supported by mathematical analysis. To validate and verify the characteristics of the presented topology, several experimental results are shown.
- Fault detection and diagnosis technique for a SRM drive based on a multilevel converter using a machine learning approachPublication . Amaral, Tito G.; Pires, Vítor; Foito, Daniel José Medronho; Pires, A. J.; Martins, J. F.SRM drives based on multilevel converters is now a solution well accepted due to their interesting features like extended voltage range and capability to fault tolerance. However, one aspect that is fundamental to ensure fault tolerance or preventive maintenance is the fault detection and diagnosis of failures in power semiconductors. In this way, in this paper it is presented a new diagnostic method for the failure of those semiconductors in asymmetric neutral point clamped converters. The proposed method will be based on the development of specific patterns that are associated to each semiconductor and fault type. The procedures presented here are based on the image identification of the currents patterns in the multilevel converter that allow the identification of distinct fault type. The pattern recognition system uses visual-based efficient invariants features for continuous monitoring of multilevel converter The proposed method will be verified through several tests in which were used a simulation tool and an experimental prototype.
- A Fault Diagnosis Scheme Based on the Normalized Indexes of the Images eccentricity for a Multilevel Converter of a Switched Reluctance Motor DrivePublication . Amaral, Tito G.; Pires, Vitor; Foito, Daniel José Medronho; Cordeiro, Armando; Rocha, José Inácio Pinto Rosado; Pires, A. J.; Martins, J. F.This paper addresses the fault detection and diagnosis of a fault in the switches of the Switched Reluctance Machine (SRM) power electronic converter. Due to the advantages of using multilevel converters with these machines, a fault detection and diagnosis algorithm is proposed for this converter. The topology under consideration is the asymmetric Neutral Point Clamped (ANPC), and the algorithm was developed to detect open and short circuit faults. The proposed algorithm is based on an approach that discriminates eccentricity of the images formed by the converter voltages. This discrimination is realized through the development of normalized indexes based on the entropy theory. Besides the different fault type the algorithm is also able to detect the transistor under fault. The possibility to implement the proposed approach will be verified through simulation tests.
- Fault-Tolerant SRM Drive with a Diagnosis Method Based on the Entropy Feature ApproachPublication . Pires, Vitor Fernão; Amaral, Tito G.; Cordeiro, Armando; Foito, Daniel José Medronho; Pires, A. J.; Martins, João F.The power electronic converter design is essential for the operation of the switched reluctance motor (SRM). Thus, a fault-tolerant power converter is fundamental to ensure high reliability and extend the drive operation. To achieve fault tolerance, fault detection and diagnosis methods are critical in order to identify, as soon as possible, the failure mode of the drive. To provide such capability, it is proposed in this paper a new fault-tolerant power converter scheme combined with a fault detection method regarding the most common power semiconductors failures in SRM drives. The fast and reliable proposed diagnosis method is based on the entropy theory. Based on this theory, normalized indexes (diagnostic variables) are created, which are independent from the load and speed of the motor. Through this method, it is possible to identify the faulty leg, as well as the type of power semiconductor fault. To test and evaluate the proposed solution several laboratory experiments were carried out using a 2 kW four-phase 8 / 6 SRM.
- Industrial Automation Self-Learning Through the Develoment of Didactic Industrial ProcessesPublication . Cordeiro, A.; Abraços, M.; Monteiro, L.; Andrade, E.; Foito, Daniel José MedronhoTeaching industrial automation is a complex mission. The classical approach is based on lectures and laboratories assisted by teachers. Nevertheless, teaching industrial automation using the classical approach is not easy because this multidisciplinary area requires knowledge in control, energy, electronics, robotics and computer engineering, among others. In this way, this paper presents an approach to teach Industrial Automation based on a self learning strategy. Instead of using the classical approach, students must develop a research work and a didactic automation prototype. The results of this methodology indicate that students increase the interest about industrial automation and clarify important aspects of assembly, commissioning, parameterization and programming of electric and electronic devices. Additionally this methodology seems to increase self-confidence of students and give them the necessary background to face the challenge of working in the real world.
- A Multilevel Fault-Tolerant Power Converter for a Switched Reluctance Machine DrivePublication . Pires, Vítor Fernão; Cordeiro, Armando; Foito, Daniel José Medronho; Pires, A. J.; Martins, João; Chen, HaoReliability in the electrical drives is becoming an important issue in many applications. In this context, the reliability associated to the switched reluctance machine (SRM) is also an important area of research. One of the major problems, that strongly affect its operation, are drive power semiconductors faults. Typical power converter topologies used in SRM drives cannot handle faults in their power semiconductors. So, this paper presents a power converter topology that provides fault-tolerant capabilities to the drive under a switch fault. This power converter will be used considering that a change in the direction of the current that flows in the SRM windings does not affect the behavior of the machine. Besides that, the proposed power converter will allow to generate multilevel phase voltages in order to apply different voltage levels as function of the SRM speed. A laboratory power converter was developed to test the SRM drive in normal and faulty conditions. From the obtained results it was possible to verify the fault-tolerant capability of the drive under switch faults in different devices and failure modes. It was also possible to confirm the multilevel operation of the drive.
- PV Generator-Fed Water Pumping System Based on a SRM with a Multilevel Fault-Tolerant ConverterPublication . Pires, Vítor Fernão; Foito, Daniel José Medronho; Cordeiro, Armando; Chaves, Miguel; Pires, A. J.This paper presents a pumping system supplied by a PV generator that is based on a switched reluctance machine (SRM). Water pumping systems are fundamental in many applications. Most of them can be used only during the day; therefore, they are highly recommended for use with PV generators. For the interface between the PV panels and the motor, a new multilevel converter is proposed. This converter is designed in order to ensure fault-tolerant capability for open switch faults. The converter is based on two three-level inverters, with some extra switches. Moreover, to reduce the number of switches, the converter is designed to provide inverse currents in the motor windings. Due to the characteristics of this motor, the inverse currents do not change the torque direction. In this way, it was possible to obtain an SRM drive with fault-tolerant capability for transistor faults; it is also a low-cost solution, due to the reduced number of switches and drives. These characteristics of fault-tolerant capability and low cost are important in applications such as water pumping systems supplied by PV generators. The proposed system was verified by several tests that were carried out by a simulation program. The experimental results, obtained from a laboratory prototype, are also presented, with the purpose of validating the simulation tests.