Browsing by Author "Karakilic, Murat"

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Design of a 21-Level Multilevel Inverter With Minimum Number of Devices Count
(Wiley, 2023) Karakilic, Murat; Hatas, Hasan; Almali, M. Nuri
Multilevel inverters (MLIs) have attracted the attention of researchers for their needs in industrial applications, renewable energy systems, and electric vehicles. MLIs require a large number of power electronic components to synthesize higher levels at the output voltage. However, overuse of power electronic devices increases the complexity, losses, and cost of MLIs. In this study, a new MLI has been proposed with a reduced number of power switches. The basic unit of the proposed MLI comprises only three independent DC sources and 10 switches (eight unidirectional and two bidirectional) to produce 21 levels at the output voltage waveform. The nearest level control (NLC) modulation method has been used to produce gate pulses. Furthermore, three extension topologies have been proposed to generate a higher number of levels, and the extension parameters have been compared with recently introduced and conventional topologies. The comparative study shows that the proposed MLI topology requires fewer components in terms of power electronics parameters than the others. On the other hand, the presented first extension study that can be used for all non-extendable basic units is one of the prominent values of the study. Simulation studies showing modulation methods, switching patterns, and signal outputs were performed with Matlab/Simulink. A prototype of the proposed main module has been realized and tested in the laboratory with an FPGA processing board. Experimental results have been verified with simulation results, and the performance of the proposed topology has been proven.
Design of Hybrid Switched Diode Multilevel Inverter Using Single Dc Source
(Springer Singapore Pte Ltd, 2024) Karakilic, Murat; Almali, M. Nuri
This paper presents a novel design of a 21-level switched diode multilevel inverter using a High-Frequency Link (HFL) and a single DC source. The inverter structure consists of 10 power switches and 2 diodes, which significantly reduces the number of components compared to existing topologies. Despite the utilization of HFL for generating multiple voltages, the analysis reveals that the majority (65%) of the power is directly drawn from the single DC source, while only a small portion (35%) passes through the HFL. This reduces the size of the high-frequency transformer and the need for a large DC-DC converter. The proposed topology achieves 21 levels with a low output total harmonic distortion (THD) of 3.99% without the use of additional filters. These features make it suitable for various applications, including electric vehicles and motor systems.
Low-Cost Single-Source 17 Level Multilevel Inverter With Reduced Switch Count
(Iop Publishing Ltd, 2025) Karakilic, Murat; Zeynalov, Javanshir; Hatas, Hasan
This paper introduces an innovative multi-level inverter (MLI) topology operating with a single DC source. The proposed structure consists of a DC-DC rectifier (HFL), a switched capacitor (SC) unit and a Packaged U-Cell (PUC) module. The topology synthesizes 17 voltage levels at the output with only 10 power switches, offering low control complexity and high power efficiency. The high number of levels at the output voltage provides a high quality output voltage wave. A soft charging cell (SCC) is used to suppress impulsive charging currents in the switched capacitors. Experimental results show that SCC effectively suppresses impulsive currents in switched capacitors. The high frequency link (HFL) used to provide high voltage gain improves the cost efficiency of the system by reducing transformer sizes and costs. Simulation and experimental results show that the proposed topology achieves 96.92% efficiency, near sinusoidal current output and total harmonic distortion (THD) values between 4.99% and 1.23%. Moreover, with a low cost function (CF) value of 1.60, it is proven to offer a viable alternative for applications such as Renewable Energy Systems (RES) and Electric Vehicles (EVs). These findings demonstrate the applicability of the proposed MLI topology in these areas with low cost, high efficiency and quality power output.
Seven-Level Soft Charging Switched-Capacitor Multilevel Inverter
(IEEE-Inst Electrical Electronics Engineers inc, 2025) Memis, Mehmet; Karakilic, Murat
This paper proposes a novel 7-level switched capacitor multilevel inverter (SC-MLI) topology with soft charging capability and analyzes the performance in terms of efficiency and component optimization. The proposed structure achieves high efficiency up to 97.32% while producing the same output level with fewer components compared to existing SC-MLI designs in the literature. Moreover, the total cost function (CF) value of 3.26 is among the lowest values, indicating that the system offers an economically advantageous solution. Simulation and experimental studies confirm that the system generates stable output waveforms under resistive and inductive loads and operates stably over a wide frequency and modulation index (MI) range. In particular, the effect of the soft charging technique on capacitor currents has been investigated and it has been found that this technique minimizes switching losses by reducing inrush current transients. The Sinusoidal Puls Width Modulation (SPWM) method using high switching frequency produces a natural soft charging effect on the capacitor currents, producing lower peak currents compared to Nearest Level Control (NLC) method and improving the overall efficiency of the system. The study shows that SC-MLI is optimized as a function of low component count, high efficiency and low cost. The results reveal that this structure is suitable for high-performance applications such as renewable energy systems, electric vehicle power conversion systems, uninterruptible power supplies (UPS), microgrids, and motor drives. These findings provide an important reference for the future development of SC-MLI designs.