No abstract

No abstract

There are various types of Multilevel Converters (MCs) in addition to various types of modulation techniques for these types of MCs; the challenges in selecting the best one of them with regard to the amount of the required of components, and its harmonics content. So, a comparison study among these types has been done in this paper. For comparison study, the simulation of seven level of two popular topologies of MCs: Neutral Point Clamped (NPC) converter, and Cascaded-MCs were carried out with Matlab/Simulink software program. These converters are used to drive a single phase capacitor start motor drive. Multicarrier modulation control techniques are used for controlling the MCs; these techniques involve two main type: Level Shifted Carrier (LSC), and Phase Shifted Carrier (PSC). The comparison is made with respect to the performance factors as, the amplitude of  the Total Harmonic Distortion (THD), and the DC-bus utilization performance which measured by Root Mean Square of the output voltage Vrms at variable modulation indices and variable carrier frequency. Based on simulation results it's found, that the cascaded-MC with PSC modulation method gives best results, in addition to the Alternative Phase Opposition Disposition APOD-LSC modulation technique (with even number of modulation frequency) generate the output voltage with a lower harmonic content compared with the other techniques.

No abstract

The Applications of a Fuel cell (FC) in the field of the electric vehicle has realized wide popularity since the past few years because of the problem of relative increases in fossil fuel prices in addition to depletion of this fuel. The objective of this study is to design DC drivers based on DC-DC buck converter for separately excited DC motor as a traction motor used for an electric vehicle. This motor is fed by Polymer Electrolyte Membrane (PEM) FC as a renewable energy source. Many control strategies are implemented to produce the suitable gating signal for the buck converter and get the best motor operation response which where Proportional Integral (PI) controller, Fuzzy Logic (FL) controller, and FL based self-tuning PI controller. The proposed FC power system is modeled and simulated using Matlab-Simulink and Fuzzy toolbox. The performance and accuracy of the proposed algorithm have been investigated in different situations. The simulation results showed that the speed response of the DC motor controlled by the FL based self-tuning PI controller had improved the performance (overshoot, rising time, settling time and steady-state error) when compared to the typical PI controller, and FL controller.