Browsing by Author "Chen, Hao"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- 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.
- A multilevel fault-tolerant power converter for a switched reluctance machine drivePublication . Fernao Pires, Vitor; Cordeiro, Armando; Foito, Daniel; Pires, A. J.; Martins, Joao; 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.
- Multilevel inverter based on a dual two-level nine-switch converter for a dual three-phase or six-phase motor drive systemPublication . Pires, V. Fernão; Cordeiro, Armando; Foito, Daniel; Pires, A. J.; Silva, J. Fernando A.; Chen, HaoThe nine-switch inverter is considered as a very interesting solution for three-phase dual output applications, such as dual three-phase or six-phase motor drive systems. The main advantage of this approach is a converter topology with a reduced number of power semiconductors. However, the AC output voltages are limited to only two levels. This work proposes a new inverter topology for dual three-phase or six-phase motor drive systems with multilevel output characteristics. The proposed topology is based on two isolated inverters, but the number of legs is reduced from six to three. This structure creates a modular multilevel inverter with a high number of voltage levels while using a comparatively smaller number of power semiconductors. A modulation strategy, associated with the proposed topology, is presented to ensure multilevel operation. The proposed topology and modulation strategy will be tested first through a simulation in Matlab/Simulink and then by laboratory tests using an experimental prototype. The obtained results show a good agreement between simulations and experiments, both confirming the theoretical studies.
- 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.