Instituto de Engenharia de Sistemas e Computadores, Investigação e Desenvolvimento em Lisboa

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A Multilevel Fault-Tolerant Power Converter for a Switched Reluctance Machine Drive

Publication . Pires, Vítor Fernão; Cordeiro, Armando; Foito, Daniel José Medronho; Pires, A. J.; Martins, João; Chen, Hao

Reliability 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.

2020-01Journal article

Open access

Fault-Tolerant SRM Drive with a Diagnosis Method Based on the Entropy Feature Approach

Publication . 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.

2020-05Journal article

Open access

The BioVisualSpeech corpus of words with sibilants for speech therapy games development

Publication . Cavaco, Sofia; Guimarães, Isabel; Ascensão, Mariana; Abad, Alberto; Anjos, Ivo; Oliveira, Francisco; Martins, Sofia; Marques, Nuno; Eskenazi, Maxine; Magalhães, João; Grilo, Ana Margarida

Abstract: In order to develop computer tools for speech therapy that reliably classify speech productions, there is a need for speech production corpora that characterize the target population in terms of age, gender, and native language. Apart from including correct speech productions, in order to characterize the target population, the corpora should also include samples from people with speech sound disorders. In addition, the annotation of the data should include information on the correctness of the speech productions. Following these criteria, we collected a corpus that can be used to develop computer tools for speech and language therapy of Portuguese children with sigmatism. The proposed corpus contains European Portuguese children’s word productions in which the words have sibilant consonants. The corpus has productions from 356 children from 5 to 9 years of age. Some important characteristics of this corpus, that are relevant to speech and language therapy and computer science research, are that (1) the corpus includes data from children with speech sound disorders; and (2) the productions were annotated according to the criteria of speech and language pathologists, and have information about the speech production errors. These are relevant features for the development and assessment of speech processing tools for speech therapy of Portuguese children. In addition, as an illustration on how to use the corpus, we present three speech therapy games that use a convolutional neural network sibilants classifier trained with data from this corpus and a word recognition module trained on additional children data and calibrated and evaluated with the collected corpus.

2020-10-02Conference object

Open access

Standardization of Power-from-Shore Grid Connections for Offshore Oil & Gas Production

Publication . Antunes, Tiago A.; Castro, Rui; Santos, Paulo; J. Pires, A.

Offshore oil and gas (O&G) production is typically powered by local diesel engines or gas turbines. Power-from-shore (PFS) is an alternative that takes advantage of onshore renewable production and reduces greenhouse emissions but is limited to bespoke projects that are tailored to the characteristics of each site. This lack of repetition leads to an increase in the construction risk, delivery time, and lifecycle costs, therefore limiting their large-scale deployment. Furthermore, the absence of standardized designs is also notorious in mature applications such as offshore wind farms (OWF) despite their long-standing track record, with the negative consequences extensively covered in the literature. This research paper addresses offshore transmission standardization in two parts. First, by providing the scientific community with a review of the existing offshore O&G production and substations and secondly, by outlining a lean optioneering algorithm for the cost-optimized and technically feasible selection of the key design criteria. The exercise is centred on the main limiting component of the transmission systems—the cables. As such, it addresses their operational range and the cost to calculate the most effective configuration in terms of voltage and rated power. The end goal, based on the spread of connection proposals, is to cluster the candidates to a limited set of grid connection options, the achievement of which the model has been shown to be adequate.

2023Journal article

Open access

PV Generator-Fed Water Pumping System Based on a SRM with a Multilevel Fault-Tolerant Converter

Publication . 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.

2022-01Journal article

Open access