This article introduces a nonisolated, high step-up voltage multiplier cell (VMC)-based dc–dc converter for applications such as module-integrated converter and power optimizers. The VMC combines switched capacitor with autotransformer techniques and active clamp circuit. The autotransformer tertiary winding is employed to increase voltage gain without operating the main switch under extreme duty cycle condition, to reduce the current through the main switch before it turns off and to ensure its zero-voltage switching (ZVS) operation on a wide operation range. The auxiliary switch in the clamp circuit provides ZVS for the main switch and vice-versa. Thus, both switches are turned on with zero voltage and there is no switching loss. Hence, high switching frequency is used to reduce the passive components’ volume and weight. Besides, the low dc-bias and bidirectional magnetizing current allows a smaller magnetizing inductance in the autotransformer to further minimizing the dimensions of the magnetic core. The leakage inductances are used to provide zero-current switching condition for the diodes, eliminating their reverse-recovery losses. The operation principle, steady-state analysis, and design guidelines are depicted and validated through experimental results obtained from a 350-W prototype of the proposed converter. Efficiency of 96.5% at full load is also reported.

This article proposes a hybrid global maximum power point (MPP) tracking technique, named improved global fractional characteristic curve (IGFCC), which combines the advantages of both the model-based and heuristic techniques. The IGFCC technique aims to achieve high speed and accuracy in tracking the MPP of photovoltaic (PV) modules. The model-based technique employed in the IGFCC technique utilizes a precise single-diode model that considers the effects of irradiance and temperature to estimate the MPP voltage. This model-based approach ensures accurate tracking of the MPP and is particularly suitable for PV series applications with string inverters. One of the advantages of the IGFCC technique is its computational efficiency. It involves solving simple equations derived from the single-diode model, which reduces the computational effort required for MPP tracking. This makes the technique practical and feasible for real-time implementation.

This article proposes a current-fed high-gain high-efficiency dc–dc converter for renewable energy applications such as photovoltaic energy. The converter is based on the modified SEPIC, in which the secondary inductor is replaced with a built-in transformer with differentially connected windings (mSEPIC-DBT). The high voltage gain is achieved through a magnetic-coupling-based VMC, in which the built-in transformer is paired to diodes and capacitors. The capacitors, alongside the leakage inductances of the transformer, form a resonant tank, allowing for the zero-current switching of the diodes, while also blocking dc currents from circulating through the transformer windings, which, in turn, allows employing gapless cores for the transformer, reducing its size. The converter operational stages are discussed and steady-state analysis is performed, from which the design guidelines are derived. The theoretical analyses are validated by an experimental 300-W, 50-kHz laboratory prototype. The experimental results show a full-load efficiency of 96.6% and a maximum efficiency of 96.8% at 90% of the full load, which demonstrate that the proposed converter is a strong candidate for applications that require high voltage gains.

This paper proposes a high step-up high-efficiency converter, comprised of an active switched coupled-inductor cell. The secondary windings are integrated into a rectifier voltage multiplier cell in a boost-flyback configuration, allowing the operation with high voltage gain with low switches duty cycle and low turn-ratios on the coupled-inductors. Both coupled-inductors are integrated into a single core due to the parallel operation of the switches. The leakage inductances of the coupled-inductors are used to mitigate the reverse recovery currents of the diodes, while regenerative clamp circuits are used to protect the switches from the voltage spikes caused by the leakage inductances. The operation of the converter is analyzed both quantitatively and qualitatively, and the achieved results are validated through experimentation of a 400 W prototype. A 97.1% CEC efficiency is also reported.

The present paper endeavors to make a significant contribution to the field of high-voltage non-isolated dc-dc converters. This is achieved by utilizing a voltage multiplier cell based on the three-winding coupled inductor technique. Unlike more widely adopted topologies in recent literature, the proposed configuration features a reduced number of components. The proposed converter also aims to achieve high voltage gain without operating under high duty-cycle and without negatively impacting in the voltage stresses on the semiconductor devices, thereby reducing conduction and switching losses. Additionally, it employs only a single switch, thereby simplifying the circuit while enhancing power density. The operation principle, steady-state analysis, power loss analysis and design guidelines are depicted and validated through experimental results obtained from a 200 W prototype of the proposed converter.

Neste trabalho é apresentada uma família de conversores C.C./C.C. de alto ganho com chave única semicondutora. A variação dos conversores propostos é obtida ao alterar o posicionamento dos capacitores e o alto ganho é atingido através do acoplamento magnético. As perdas por condução são minimizadas devido à blackução dos esforços de tensão na chave pelos circuitos grampeadores. Ainda, todos os diodos operam com comutação sob zero de corrente, eliminando as perdas por recuperação reversa. O artigo apresenta a descrição dos conversores propostos, suas principais equações, formas de onda em modo de condução contínua e uma análise comparativa com conversores similares publicados na literatura. Além disso, os resultados experimentais obtidos de um protótipo projetado para operar com potência nominal de 140 W, frequência de comutação de 100 kHz, tensão de entrada de 14,8 V e tensão de saída de 220 V validam os conversores propostas. A eficiência a carga plena é de 91,84 % e a eficiência máxima 93,77 % foi atingida com 51,27 W.