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- Hybrid Sepic-Ćuk DC-DC Converter Associated to a SRM Drive for a Solar PV Powered Water Pumping SystemPublication . Cordeiro, Armando; Chaves, Miguel; Canacsinh, Hiren; Luís, Ricardo; Fernao Pires, Vitor; Foito, Daniel; Pires, A. J.; Martins, JoaoThe present paper describes a solar photovoltaic (SPV) powered water pumping system employing a switched reluctance motor (SRM) and a merged Sepic-Ćuk DC-DC converter. The proposed solution was designed to use efficiently the available solar energy in order to supply water pumping systems. Solutions of this kind assume a special importance in the current scenario of natural and renewable resources optimization. The proposed DC-DC converter operates in continuous conduction mode (CCM), which combined with a maximum power point tracking (MPPT) controller, helps to optimize the power of the solar photovoltaic panel (SPV). The proposed DC-DC topology is characterized by high voltage static gain when compared with the classical boost topology and reduced voltage stress across the power switch and diodes. Several simulation and experimental results are presented in order to confirm the characteristics of the proposed solution for water pumping systems.
- A multilevel topology based on the T-Type converter for SRM drivesPublication . Fernao Pires, Vitor; Cordeiro, Armando; Pires, A. J.; Martins, João; Chen, HaoMultilevel power converters have been used in SRM drives to improve high speed operating characteristics and reduce switching frequency. Several topologies have been proposed to these drives but it requires an increased number of switches. In this paper it is presented a new multilevel topology for the SRM drives. This topology is based on the T-type structure and characterized by a reduced number of power semiconductors resulting in a low cost, size and weight system. With this topology it is possible to accelerate the magnetization and demagnetization process as well as the efficiency of the system through the reduction of the switching frequency at low speed operation. The characteristics and performance of the proposed topology will be verified through several numerical tests.
- Three-phase T-type qZ source inverter with control current associated to a vectorial modulator for photovoltaic applicationsPublication . Fernao Pires, Vitor; Foito, D.; Cordeiro, Armando; Martins, JoãoThis paper presents a fast and robust control system for a three-phase quasi-Z-source inverter (qZSI) connected to the grid. The topology combines two quasi-Z-source networks with a T-type inverter allowing to obtain AC voltages with multilevel characteristics and properties of the referred networks. To control this system a closed-loop current controller for the AC currents is proposed. The controller is based on a vectorial modulator associated to the shoot-through states. The DC-link voltage is maintained stable at the reference value by adjusting the shoot-through duty cycle. The controller is characterized by fast transient response and robustness to parameter and load variations. In order to confirm the desired characteristics and performance of the converter and control system several simulation tests were performed.
- PV generators combined with UPQC based on a dual converter structurePublication . Fernao Pires, Vitor; Foito, Daniel; Cordeiro, Armando; Martins, JoaoIn this paper a power converter topology where an Unified Power Quality Conditioner (UPQC) is combined with the photovoltaic generators is presented. This topology is based on a dual structure of the classical three-phase two level inverters. Thus, multilevel operation is achieved with the advantages of this type of inverters. Another feature of this structure is the higher reliability of the combined system. In fact, even with a fault in one of the inverters the system can still operate. Voltage and current controllers are also described. The current and voltage controllers are implemented in the synchronous rotating reference frame (dq0-axis). Several results are presented in order to verify the operation of the system under various conditions.