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.

Gecmez, Hilal Sebnem; Ting, Naim Suleyman; Sahin, Yakup

In this paper, a new active snubber cell for DC-DC boost converters is introduced for the purpose of soft switching. The introduced snubber cell ensures lossless turning-on by zero-voltage transition (ZVT) and turning-off by zero-voltage switching (ZVS) of the main switch. Besides, it enables turning-on by ZVS and turning-off by zero current switching (ZCS) of the main diode. None of the semiconductor power devices are subjected to extra voltage stress, and all of them operate by soft switching (SS). The converter can successfully maintain the SS even under light loads. Furthermore, the proposed converter structure is advantageous in terms of simplicity and low cost. The operating modes and theoretical analysis of the introduced converter are presented and it is validated using a prototype with a 500 W output power and at the 100 kHz switching frequency. Owing to the proposed active snubber cell, the converter efficiency is achieved as 97.2%.

Sahin, Yakup; Ting, Naim Suleyman

Soft-switching (SS) boost converters are extensively utilized in applications such as renewable energy systems, electric vehicles, and high-efficiency power supplies, as they offer reduced switching losses and enhanced overall efficiency. Zero-voltage transition (ZVT) snubber cells that used SS operation perform poorly in zero-voltage switching (ZVS) turn-off at light load, although they perform well at heavy load. This study proposes a novel SS snubber cell for the PWM-DC boost converter, ensuring excellent ZVS turn-off performance under all load conditions. The main switch is turned off with ZVS at heavy and light load, so the turn-off performance is independent of the load conditions. In addition, the main switch is switched on with ZVT, and the main diode is switched with SS. The main and auxiliary semiconductor components do not expose additional voltage. In addition, the semiconductor switches are switched on with zero-current switching (ZCS) and switched off with ZVS, whereas the auxiliary diode is switched with SS. The theoretical analysis of the converter is presented, and an experimental study is conducted to demonstrate the analysis. The proposed converter is operated with an output power of 500 W and a switching frequency of 100 kHz.

Korkmaz, Muhammet Oguz; Babacan, Yunus; Yesil, Abdullah

In this paper, a new floating memcapacitor emulator that consists of a single multiplier and only four transistors without using passive elements is proposed. While two of these transistors work as MOS capacitors, two of them are used to provide transconductance gain. Moreover, the proposed memcapacitor operates at high frequencies thanks to having simple structures. Furthermore, fix and variable parts of memcapacitance can be tuned electronically by changing DC bias voltages. In order to investigate the performance of the proposed memcapacitor, simulation results are given for different operating frequencies, radical temperature changes, memory effects, and Monte Carlo analysis. Moreover, to confirm the practical realization of the proposed memcapacitor, the proposed floating memcapacitor is implemented by using commercial devices as AD633, ALD1106, and ALD1107. Experimental results of the proposed circuit are given for different operating frequencies and DC supply voltages. Also, a memcapacitor-based circuit that emulates the relationship between the amoeba's locomotive speed and temperature is given as an application of the proposed memcapacitor. The results for the proposed memcapacitor are in good agreement with theoretical data.

Sahin, Yakup; Ting, Naim Suleyman; Yesilyurt, Huseyin

A novel capacitor-voltage reduced bidirectional (CVRB) PWM DC-DC buck-boost converter is presented in this study. Compared to the conventional bidirectional buck-boost converter, the proposed converter has a lower voltage rating filter capacitor. Accordingly, the given converter has a lower cost and higher power density than the conventional buck-boost converter. Additionally, the proposed converter is more efficient due to the direct power transfer feature. Besides, the semiconductor switches have no extra voltage/current stress. The theoretical analysis of the converter is made, and its mathematical analysis is presented. The novel converter is experimentally operated in both the buck and boost modes. The experimental waveforms are shown for both operations. The proposed converter is operated in 100 W output power and 20 kHz switching frequency conditions. The efficiency of the proposed converter is 95.6% for the boost mode operation and 95.1% for the buck mode operation at the nominal output power.

Ertay, Agah Oktay; Simsek, Serkan

The significant contribution of this paper is to present a comprehensive analysis and design of π-point and band edge frequencies of reported helix SWSs including not only a microwave but also millimeter-wave operation frequencies considering the methods in available literature which are the Coupled Mode Analysis (CMA), the Exact Floquet Approach (EFA), and the Auxiliary Functions of Generalized Scattering Matrix (AFGSM) as a comparative study. A different approach called as effective rod model is applied to circular/T-shaped dielectric support rod helix SWSs in order to obtain ladder circuit representation of one turn of related helix SWSs for the first time. Scattering matrices of equivalent circuit representation of interested helix SWSs are obtained by using microstrip line model of helix SWS which slits helical tape at the effective helix radius along the direction normal to the helix winding direction and flattens it out for the EFA, the AFGSM, and the CMA methods. Additionally, comparisons are given for investigated methods together with the results of Computer Simulation Technology (CST) design environment, and good agreement has been observed among numerical results of different helix SWSs in a broad frequency range.

Ting, Naim Suleyman; Aslay, Fulya; Sahin, Yakup

In this paper, a novel zero voltage transition (ZVT) boost converter is proposed, and the overall efficiency of the converter is predicted with an artificial neural network (ANN) model. In the proposed converter, the main switch is turned on by ZVT and turned off by zero voltage switching (ZVS). Also, the other semiconductor elements operate by soft switching (SS). Besides, the proposed snubber cell has the bidirectional direct power transfer feature. The theoretical analyzes of the converter are verified by an prototype having 50 VDC input voltage, 100 VDC output voltage, 250 W output power, and 100 kHz switching frequency. The overall efficiency of the converter in hard switching (HS) condition is increased from 87.2% to 95.4% thanks to proposed snubber cell. Moreover, the efficiency of converter at HS operation is estimated with ANN. For this estimation, 110 efficiency values are obtained based on the different switching frequency and the output power values. When the actual efficiency measurements and the estimation results obtained with the ANN model are compared, it is seen that the results overlap and is obtained very close result to the truth by ANN. Thus, owing to the ANN model, the semiconductor power elements will not need to be operated at high frequencies and overheating, and the damaging to the elements will be prevented. Finally, the efficiency curve measurement of the converter takes long time in the experimental study when it takes highly short time as a few minutes in the estimation with ANN.

Bodur, Haci; Yesilyurt, Huseyin; Ting, Naim Suleyman; Sahin, Yakup

In this paper, soft switching isolated half-bridge converter with a new active snubber cell that uses switched capacitor for renewable energy applications is proposed. The proposed snubber cell does not consist any magnetic element so that its structure is quite simple. Furthermore, the auxiliary switches in the proposed active snubber cell are exposed to only half of the input voltage. There is no additional voltage and current stress on any semiconductor devices. All semiconductor power devices in the proposed converter are operated by soft switching. The proposed converter is analyzed thoroughly, and the theoretical analyzes are affirmed by an implementation having 300-VDC input, 20-VDC output, 75-W output power, and 150-kHz switching frequency. The overall hard switching efficiency of the converter is increased from 86.4% to 92.9% by aid of the proposed soft switching snubber cell.