Ayoob Alateeq

Study of the BER performance in RoF-OFDM system modulated by QAM and PSK

Orthogonal frequency division multiplexing (OFDM) is considered as a one of the essential components in most of recent telecommunication systems. To maintain a high bit rate and provide a high bandwidth, using the OFDM as a modulation format in RoF system is preferred over other modulation formats. In this paper, up-converting a 20 Gb/s and a 30 Gb/s OFDM signal on a 20-GHz microwave carrier over 40 km SMF was applied under a different modulation methods of OFDM such as QAM and PSK in order to study the BER performance in all proposal cases.

Modeling a multilevel boost converter using SiC components for PV application

This paper discusses a DC-DC multilevel boost with wide bandgap components for PV applications. In the PV system, the multilevel boost converter is advisable to be used over the conventional boost converter because of the high ratio conversion. The multilevel boost converter is designed with one inductor, 2N-1 silicon carbide (SiC) schottky diodes, 2N-1 capacitors and one SiC MOSFET where N is the number of levels. Inserting SiC components in the design helps to maintain the temperature effect that could cause a high power loss. Most function of using a multilevel boost converter is to produce a high output voltage without using either a power transformer or a coupled inductor. Achieving a high gain output in the multilevel boost converter depends on the level of the converter and the switching duty cycle. The demonstrated design is a multilevel boost converter supplies from 220 V to rate 2 KW power. The switching frequency is 100 KHz and the output voltage of 4-level is 3.5 KV. Several values of temperatures are applicable to the system and the effect of changing the temperature on efficiency is studied. The developed design is simulated by using a LTspice software and the results are discussed.

Silicon carbide DC-DC multilevel Cuk converter

In this paper, DC-DC multilevel cuk converter using silicon carbide (SiC) Components is presented. Cuk converter gives output voltage with negative polarity. This topology is useful for applications require high gain with limitation on duty cycle. The gain of the design can be enhanced by increasing the number of multiplier level (N). This relation between the gain and the number of levels is the major advantage of this multilevel cuk converter. In the proposed cuk converter, a single SiC MOSFET, 2N-1 SiC schottky diodes, 2N capacitors, 2 inductors, and single input voltage are used to supply a load with negative polarity. 300V input voltage, 50KHz switching frequency, and 75% duty cycle are the main parameters used in the design. The output parameters are 3KW power and -5.7 KV voltage. Because this design can be used in applications which temperature plays a critical role, the relation between increasing temperature and output voltage and power are tested. The design is simulated using LTspice software and the results are discussed.

A switched-inductor model for a non-isolated multilevel boost converter

This paper discusses a switched inductor design for a non-isolated multilevel boost converter. A Non-isolated proposed multilevel boost converter is suitable to provide a high conversion ratio which essentially benefits renewable energy systems. In addition to the voltage stress reduction, the proposed switched inductor MBC has shown an improvement in voltage gain. The new switched inductor model has been inserted as an input into the multilevel boost converter. The proposed converter consists of 2N-1 capacitors, 4N-1 diodes, three inductors and a single switch. The proposed model is a three-level boost converter which is supplied by 12 V to produce 280 V at a 50 KHz switching frequency. A MATLAB/SIMULINK simulator was used to evaluate and test the proposed switched inductor model.

Non-isolated high gain switched inductor DC-DC multilevel cuk converter for photovoltaic applications

In this paper, a non-isolated high gain switched inductor dc-dc multilevel cuk converter for photovoltaic applications is presented, which combines switched inductor with a voltage multiplier. By doing so, the conversion ratio is increased. High voltage gain cannot be possible if using traditional cuk converter. The output voltage can be boosted negatively by using a combination of capacitors and diodes without disturbing the main circuit is the key advantage of the proposed design. This switched inductor multilevel cuk converter topology is suitable for photovoltaic applications where the voltage is needed to be increased with negative polarity. 2N capacitors, 2N+2 diodes, three inductors, single switch, and single input supply are used to design Ν level switched inductor dc-dc multilevel cuk converter topology. The proposed converter is designed for three levels with rated power 300W, output voltage is −225V, input voltage is 12V, switching frequency is 50kHz, and 75% duty cycle. This design is simulated and tested by using Matlab/Simulink.

Molding and simulation of GaN step-up power switched capacitor converter

This paper discusses a proposed DC-DC switched capacitor converter for low voltage electronic products. The proposed converter is a two-level power switched capacitor (PSC) which is a boost converter. The suitability to convert a voltage into four times higher than its input is one of the converter’s objectives. Because of the proposed two-level PSC consist of eight switches and five capacitors, it occupies a small area of the electronic products. The eight switches were selected to be GaN transistors to maintain the efficiency at high rated power or high temperatures. The LTSpice simulator was used to test the proposed model. Since the design contains semiconductor elements such (GaN transistor), then 10% error is a reasonable variance between the mathematical and simulation results.

Simulation and performance comparison of Si and SiC-based interleaved boost converter

In this paper, simulation and performance comparison of Si and SiC based interleaved boost converter is presented. Wide bandgap devices such as silicon carbide and gallium nitride are desirable and recommended in high-power applications because of their capability of operating under high temperature, high switching frequency, and high voltage with reduced switching losses. The main advantage of using SiC materials is the ability to raise the switching frequency which will reduce the size. However, their cost is high compared to Si. In this paper, 60V input voltage is used to get 120V output voltage under 100 KHz switching frequency and 0.5 duty cycle. With the help of LTSpice software, an efficiency comparison between silicon and silicon carbide by considering interleaved boost converter are simulated and studied.

Using SiC MOSFET in switched-capacitor converter for high voltage applications

This paper addresses a study of output voltage of a switched capacitor step down converter for a high voltage application. The proposed design is 3:4 Series to parallel switched capacitor converter based on capacitors and switches only. The Slow Switching Limit Impedance was theoretically calculated and proven. The Slow Switching Limit Impedance has an inverse relation with switching frequency and the capacitors size. A minimum value of the Slow Switching Limit Impedance is desired; however, that requires a high switching frequency. Increasing the switching frequency might produce losses from switching devices. To maintain the output voltage by keeping switching losses low, a wide bandgap silicon carbide SiC MOSFET was used in this work. The output voltage and its ripple were tested and compared when ideal switches or SiC MOSFET was used. The comparison between ideal switches and SiC MOSFET was applied under several values of the switching frequency. When the fsw increases, a SiC MOSFET successfully shows its ability to keep the switching losses suitable. The LTspice software have been used to simulate the proposed switched capacitor, and the results have been analyzed and discussed.