Browsing by Author "Martins, J. F."
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- An 8/6 SRM drive with a multilevel topology based on a cross-switched configurationPublication . Fernao Pires, Vitor; Foito, Daniel; Pires, Armando J.; Cordeiro, Armando; Martins, J. F.SRM drives based on multilevel power electronic converter presents several advantages, like reducing the switching frequency and improve the operation of the motor under high speed. In this way, several multilevel power converter topologies have been developed for the SRM drives. In line with this, this paper proposes a new multilevel power converter topology for the 8/6 SRM drive. The topology was developed with the purpose to reduce the number of power semiconductors, without reducing the performance of the motor. The proposed topology was designed in a way that uses crossover switches. The operation of the power converter topology in all of their modes is analyzed in a detailed way. The verification of the global system performance (drive and motor) is realized by the implementation of simulation studies. Indeed, through these studies it is verified that at low speed operation the switching frequency is reduced, but maintaining the application of the maximum voltage during the magnetization and demagnetization process.
- A DC-DC converter for bipolar DC microgrids with voltage balance capability to supply a multilevel SRM drivePublication . Fernão Pires, V.; Foito, Daniel; Pires, A. J.; Cordeiro, Armando; Martins, J. F.In this work it is proposed a DC-DC converter to supply a multilevel Switched Reluctance Machine (SRM) drive. The proposed converter was designed to be integrated in a bipolar DC microgrid. Usually, this kind of microgrid requires a support to avoid unbalances between the poles. Thus, the proposed converter also integrates voltage balance capabilities allowing the required support to the bipolar DC microgrid. Besides that, the converter can also supply the drive using only one of the poles. The behavior and operating modes of the converter will be described in detail. Several simulation tests will also be provided. From these tests, the behavior and the several operation modes of the DC-DC as well as the multilevel SRM drive supplied by this converter will also be presented and analyzed.
- Multilevel converter fed SRM Drive for Single stage PV array based water pumpingPublication . Fernao Pires, Vitor; Foito, Daniel; Pires, A. J.; Cordeiro, Armando; Martins, J. F.; Chen, HaoIn this work it is proposed a switched reluctance machine (SRM) drive supplied by a renewable source (PV array) to operate a water pumping system. To improve the speed of the commutation between phases it is proposed the use of a multilevel converter for the SRM drive. This converter was designed to reduce the number of controlled power semiconductors, reducing the cost of the system. To obtain the maximum power extraction of the PV system is proposed the use of an algorithm based on the product of the time derivative of power with the time derivative of voltage. A control system to ensure the balance between the power generated by the renewable source and the water pumping system is also proposed. The operation and characteristics of the system will be verified by several numerical tests.
- Three-level quadratic boost DC-DC converter associated to a SRM drive for water pumping photovoltaic powered systemsPublication . Cordeiro, Armando; Fernao Pires, Vitor; Foito, Daniel; Pires, A. J.; Martins, J. F.This paper presents a water pumping system powered by solar photovoltaic (PV) panels employing a switched reluctance motor (SRM) drive and a three-level quadratic Boost (3LQB) DC-DC converter for a dual output. The DC-DC topology is characterized by quadratic voltage static gain, capability to ensure voltage balance in the output capacitors and reduced voltage stress across power switches and diodes. The three-level voltage of the DC-DC converter allows to connect an asymmetrical half-bridge (AHB) converter integrated into the SRM drive. The DC-DC converter also operates in continuous conduction mode (CCM) which, combined with a proposed maximum power point tracking (MPPT) algorithm, helps to optimize the power supplied by the PV panels. A laboratory prototype was also developed and installed in a workbench to verify its practical implementation considering all devices involved. The tests were performed considering different loads and solar irradiations to verify the system performance under different situations. The PV panels were simulated using a remotely controlled DC power source to impose the typical characteristic I-V curves of the PV panels according to solar irradiation and the water pump behavior was emulated in the laboratory using a controlled torque load coupled to the SRM drive. The experimental results indicate that the proposed solution allows to fully exploit the solar energy to provide as much as possible a continuous water flow in isolated pumping solutions. The operating limits of this solution should be determined by the minimum water flow rate required, necessary head (elevation) and net positive suction head (NPSH).