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- ArticleYalnız künye2026A Cost-Effective Ultra-High-Gain Single-Switch DC–DC Converter with Direct Power Transfer for Low-Voltage PV Applications
Sahin, Yakup; Ozgenel, Mehmet Cihat; Ting, Naim Suleyman
This paper presents a novel cost-effective, nonisolated ultra-high-gain single-switch DC–DC converter (UHGS2C) employing a voltage lift (VL) cell and a direct power transfer (DPT) mechanism, specifically designed for low-voltage photovoltaic (PV) applications. The proposed topology achieves an 8× voltage gain at a duty cycle of 0.5 using only a single active switch, three inductors, three capacitors, and five diodes, thereby reducing component count and control complexity compared with conventional high-gain converters. Through the DPT mechanism, a portion of the input energy is transferred directly to the load during the switch-on interval, thereby reducing the energy processed by the magnetic elements and lowering both switch current stress and capacitor voltage ratings. The steady-state analysis confirms that the maximum capacitor voltage is limited to half of the output voltage (VCmax = VO/2), enabling the use of compact, low–voltage-rated capacitors that improve power density and reduce cost. Both continuous and discontinuous conduction modes (CCM/DCM) are analyzed in detail, and a systematic design procedure, along with a comprehensive power loss model, is provided. To validate the theoretical analysis, a 200-W experimental prototype operating at 25-V input, 200-V output, and 50-kHz switching frequency was implemented. The prototype achieves a peak efficiency of 96.4%, while the closed-loop PI control verifies stable line- and load-regulation performance. Comparative results demonstrate that the proposed UHGS2C provides a favorable trade-off among voltage gain, efficiency, component stress, and compactness, making it a strong candidate for renewable energy applications such as PV systems.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2026Torque ripple reduction in brushless DC motors by employing three-phase conduction mode drive
Ozgenel, Mehmet Cihat
In this article, this study aims to reduce torque ripple in a brushless direct current motor by employing a three-phase active mode voltage source inverter, and the torque ripple caused by commutation has been studied in detail. In this study, brushless direct current motors with two different pole numbers and central phase windings, which are frequently used in printing machines, were used. Nowadays, six-step two-phase winding active drives are used as brushless direct current motor (BLDC) drives. In conventional two-phase active mode drives, two phases are connected in series at any time, and the voltage at the ends of the phase windings is half that of the direct current source. In this proposed drive, the phase windings are connected in three different ways, creating a stepped-sinusoidal voltage across the phase windings. This voltage across the phase windings ensures that the current flowing through the phase windings is very close to a sinusoidal current. The closer the current flowing through the phase windings is to a sinusoidal current, the lower the torque ripple. Although the phase windings of the BLDC motors used in the study were centered type phase windings, phase currents were close to sinusoidal. The results from this experimental study showed that the torque ripple of the three-phase active mode drive was significantly reduced. In this work, the torque ripple was found to be 12% in two-phase conduction mode, while it was found to be 7% in three-phase conduction mode.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2025Enhanced soft-switched T-type neutral-point clamped (T-NPC) inverter with reduced component number
Ozgenel, Mehmet Cihat; Ting, Naim Suleyman; Sahin, Yakup
This paper presents an enhanced soft-switched T-type neutral-point clamped inverter featuring a compact active snubber cell that delivers zero-voltage transition turn-on and zero-voltage switching (ZVS) turn-off for the main switches, while auxiliary switches operate with zero-current switching turn-on and ZVS turn-off. Unlike prior designs, four auxiliary-path diodes are eliminated, reducing component count, conduction path length, and reverse-recovery losses, which in turn lowers cost, eases thermal management, and boosts power density. The proposed topology maintains full soft switching (SS) for all active devices without introducing additional voltage or current stress. The theoretical analysis of the inverter is clarified, and the operating modes for steady-state analysis are presented in detail. Experimental validation on a 400 V, 1 kW, and 100 kHz prototype demonstrates consistent SS across load conditions and a peak efficiency of 97.2%. The combination of higher efficiency, structural simplicity, and cost-effectiveness makes the proposed inverter a strong candidate for high-performance, compact T-type applications in renewable energy, and electric drive systems.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2023Design and Implementation of a Flyback-Assisted Wide-Range Fully Soft-Switched T-Type Inverter
Ting, Naim Suleyman; Sahin, Yakup; Ozgenel, Mehmet Cihat
A novel soft-switched three-level T-type inverter is proposed in this article. The proposed inverter provides turning-on by zero-voltage transition and turning-off by zero-voltage switching (ZVS) for main switches without any voltage or current stresses. The switching energies are transferred to the snubber capacitors, so the turning-off process of the main switches is improved by these snubber capacitors. Besides, the auxiliary switches are turned on by zero-current switching and turned off by ZVS. Furthermore, all snubber diodes are operated by soft-switching (SS), and the proposed SS snubber cell decreases the electromagnetic interference noises. The novel snubber cell has a simple structure, ease of application, common-ground switches, and low-cost features. The theoretical analysis of the inverter is clarified, and the operating modes for steady-state analysis are presented in detail. The experimental results rated 1-kW output power and 100-kHz switching frequency are provided to justify the theoretical analysis. The proposed unique snubber cell can be easily implemented in other three-level inverters, and the practice is demonstrated in the article.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2018Increasing power and torque capability of brushless direct current motor by employing 150-degree conduction mode controlled three-phase voltage source inverter
Ozgenel, Mehmet Cihat
With the reduction of magnet costs and the production of high-energy magnets in small sizes, permanent magnet brushless motors are used widely in various applications from household to medical, industrial, and automation applications. Furthermore, permanent magnet brushless motors have some significant advantages over the other conventional motors such as induction and brushed motors. Due to the popularity of brushless motors, they have become the focus of interest of researchers. From the past 30 years to today, the researchers have carried out numerous studies in relation to brushless motors. These studies are generally sensorless control, adaptive control, different Proportional Integral and Derivate (PID) applications, fuzzy control, PI-fuzzy and PID-fuzzy control and different Pulse Width Modulation applications and to eliminate torque ripple and other control algorithms. Permanent magnet brushless motors can be divided into two main groups. One is the permanent magnet synchronous motor and the other one is the permanent magnet brushless direct current motor (BLDCM). BLDC motors are the most preferred in applications due to their low cost and relatively simple drivers. BLDC motors are run with the classical 120-degree conduction mode voltage source inverter (VSI). Because BLDC motors run with 120-degree conduction mode inverters, power and torque produced by BLDC motors are less than their capacity, whereas BLDC motors can provide a better dynamic response, higher power, and torque by employing 150-degree conduction mode controlled VSI. In this experimental study, it is aimed to design and manufacture a versatile VSI which can control the BLDC motor in both 120 and 150-degree conduction modes. Then, BLDC motor is run in two conduction modes employing the purposed inverter under various loads, and the torque, power, and speed performance of the motor were analyzed to demonstrate the effect of the two commutation methods on BLDC motor performance. The results of this comparative experimental study have shown that the 150-degree conduction mode-controlled inverter provides with the BLDC motor generating higher power, torque, and speed than the inverter with 120-degree conduction mode.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2017Design and application of a novel high precision and low cost electronic tachogenerator for sensor-based brushless direct current motor drivers
Ozgenel, Mehmet Cihat; Bal, Gungor; Uygun, Durmus
This study presents a precise speed control method for Brushless Direct Current (BLDC) Motors using an electronic tachogenerator (ETg) instead of an electro-mechanical tachogenerator. Most commonly used three-phase BLDC motors have three position sensors for rotor position data to provide commutation among stator windings. Aforementioned position sensors are usually Hall-effect sensors delivering binary-high and binary-low data as long as the motor rotates. These binary sets from three Hall-effect sensors can be used as an analogue rotor speed signal for closed loop applications. Each position sensor signal is apart from 120 electrical degrees. By using an electronic circuitry, a combination of position sensor signals is converted to the analogue signal providing an input to a PI speed controller. To implement this, a frequency to voltage converter has been used in this study. Then, the analogue speed signal has been evaluated as rotor speed data in comparison with the reference speed. So, an ETg system has been successfully achieved in place of an electro-mechanical tachogenerator for BLDC motor speed control. The proposed ETg has been tested under various speed conditions on an experimental setup. Employed tests and obtained results show that the proposed low-cost speed feedback sub-system can be effectively used in BLDC motor drive systems. Through the proved method and designed sub-system, a new motor controller chip with a speed feedback capability has been aimed.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2017Design, implementation, and application of 150-degree commutation VSI to improve speed range of sensored BLDC motor
Ozgenel, Mehmet Cihat
Permanent magnet brushless dc (BLDC) motors are very convenient for many applications such as industrial, medical, robotic, aerospace, small electric vehicles, and home applications because of their inherent satisfying dynamic characteristics. There are numerous studies about these motors and their control schemes such as sensorless control and different speed and torque control schemes. All electric motors need commutation in order to produce speed and torque. Commutation in brushed DC motors is performed by means of a brush and collector. In BLDC motors, commutation is provided electronically in contrast to the brushed dc motors. In BLDC motors, motor phase windings are energized according to the information of the rotor position by inverter transistors. Rotor position information is used for commutation. Therefore, rotor position information is required to produce speed and torque for BLDC motors. The easiest and cheapest way to obtain rotor position information is to use Hall-effect or optical sensors. BLDC motor manufacturers generally produce BLDC motors equipped with three Hall-effect position sensors. Having three position sensors on BLDC motors provides six-step commutation which ensures two phase windings are energized in each moment. The third phase is empty. In this study, all phase windings are energized in the same time. This commutation method is twelve-step or 150 degrees commutation. So that more speed can be achieved from the same BLDC motor by comparison with six-step commutation. In this paper, both six-step and twelve-step commutation methods applied to the same BLDC motor and obtained experimental results from this study were presented, examined, and discussed.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2016Low-resolution and low-cost position sensor implementation for permanent magnet synchronous motor driver
Ozgenel, Mehmet Cihat; Bal, Gungor; Uygun, Durmus
Permanent magnet synchronous motors (PMSM) are recently getting involved in many usage areas such as industrial, robotic, home and office applications due to the fact that they have several advantages like fast dynamic response, low size, high efficiency, high power density and more reliability. Since PMSMs require rotor position information for phase current commutation, a position encoder is used on the rotor. Unfortunately, position sensor increases the size and cost of the driver system. In this study, a simple low cost position sensor based on photomicrosensor is proposed to replace the position encoder. A driver system for 12 poles PMSM with developed position sensor was set up and tested under different speed and load conditions. The experimental results proved that the PMSM driver is able to deliver sinusoidal currents to stator phase windings along with demonstrating the effectiveness of the proposed sensor.
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