Mohamad Fathi Mohamad Elias

Transistor-Clamped H-Bridge Based Cascaded Multilevel Inverter With New Method of Capacitor Voltage Balancing

This paper presents a three-phase cascaded multilevel inverter that uses five-level transistor-clamped H-bridge power cells. Multicarrier phase-shifted pulse-width modulation method is used to achieve balanced power distribution among the power cells. A new method to balance the midpoint capacitor voltage in each cell is developed and tested. The analysis of the output voltage harmonics and the total power losses covering the conduction and the switching power losses are carried out and compared with the cascaded neutral-point-clamped and the conventional cascaded H-bridge inverters. For verifications, the proposed inverter is experimentally tested on an induction motor. From the results, the proposed inverter provides higher output quality with relatively lower power loss as compared to the other conventional inverters with the same output quality.

Asymmetrical Cascaded Multilevel Inverter Based on Transistor-Clamped H-Bridge Power Cell

This paper presents an asymmetrical cascaded multilevel inverter based on a five-level transistor-clamped H-bridge power cell. A two-cell configuration with a dc link voltage ratio of 4 : 1 is presented. The modulation method is based on the fundamental frequency switching. An analysis of the inverter output voltage and harmonics is presented. Injection of the third harmonic voltage as to maximize the output voltage and the issue of the inverse power flow or regeneration in the low-voltage cell are presented. The prototype of the proposed inverter was built, and its functionality was verified through experimental results.

Performance Investigation of a Plate Heat Exchanger Using Nanofluid with Different Chevron Angle

Plate heat exchanger with chevron angle has higher heat transfer area than flat type and increases the level of turbulent due to its corrugated channel. In this study, both water and nanofluid were used to determine the heat transfer coefficient and rate, pumping power, and pressure drop. A commercial plate heat exchanger with two different symmetric (300/300, 600/600) and one mixed (300/600) chevron angle plates were considered for analysis. Al2O3 and SiO2 nanoparticles with 0-1 vol. % concentration were used with water. From the analysis it was found that, convective heat transfer coefficient, heat transfer rate, pressure drop and pumping power increases with the increase of volume concentration. Moreover, the above parameters were found to be higher for 600/600 chevron angle plates. A correlation of Nusselt number as a function of Reynolds number and Prandtl number for different chevron angles needs to be obtained based on experimental and analytical work. Nomenclature

A three-phase five-level inverter for DTC drives application

This paper presents a new three-phase five-level inverter for direct torque control (DTC) drives application. The advantages of the inverter are reduced output harmonics, switching losses and number of power switches. The multilevel PWM modulation method as well as output voltage analysis based on symmetrical sampling are presented. The proposed inverter is compared with the conventional inverter in terms of its currents total harmonics distortion (THD). Experimental results of DTC drive of permanent magnet synchronous motor (PMSM) are also presented for verification of its proposed function.

Asymmetrical transistor-clamped H-bridge cascaded multilevel inverter

This paper presents an asymmetrical cascaded multilevel inverter based on five-level transistor-clamped H-bridge power cell. Two-cell configuration with dc link voltage ratio of 4:1 is presented. The modulation method is based on the fundamental frequency switching. Analysis of the inverter output voltage and harmonics is presented. Injection of the third harmonics as to maximize the output voltage and the issue of the inverse power flow in the low voltage cell are presented. The prototype of the proposed inverter is built and the experimental results are obtained to verify its functionality.

Analysis of Current Harmonics Compensation and the Effect of Frequency Variation for Single-Phase Stand-Alone PV Inverters using PR Controller

ABSTRACT This paper presents the analysis of current harmonics compensation using the proportional-resonant controller for single-phase stand-alone photovoltaic inverter applications. The effect of frequency variation in the reference signal to the controller performance was also analyzed. The controller parameters (Kp , Ki , and ωc ) and the inductor-capacitor (LC)-filter parameters are optimally selected to obtain a very low current total harmonic distortion . The control algorithm was implemented using a low-cost digital signal processor (DSP) TMS320F28335 eZdsp development board. Both simulation and experimental results validate the performance and the effectiveness of the control technique used.