Equalizing charger based on multi-windings transformer and voltage-doubler rectifiers

This study developed a novel, high-efficiency, high step-up DC–DC converter for photovoltaic (PV) systems. The converter can step-up the low output voltage of PV modules to the voltage level of the inverter and is used to feed into the grid. The converter can achieve a high step-up voltage through its architecture consisting of a three-winding coupled inductor common iron core on the low-voltage side and a half-wave voltage doubler circuit on the high-voltage side. The leakage inductance energy generated by the coupling inductor during the conversion process can be recovered by the capacitor on the low-voltage side to reduce the voltage surge on the power switch, which gives the power switch of the circuit a soft-switching effect. In addition, the half-wave voltage doubler circuit on the high-voltage side can recover the leakage inductance energy of the tertiary side and increase the output voltage. The advantages of the circuit are low loss, high efficiency, high conversion ratio, and low component voltage stress. Finally, a 500-W high step-up converter was experimentally tested to verify the feasibility and practicability of the proposed architecture. The results revealed that the highest efficiency of the circuit is 98%.

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Switched Capacitor DC-DC Converters: A Survey on the Main Topologies, Design Characteristics, and Applications

Energies ◽

10.3390/en14082231 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2231

Author(s):

Alencar Franco de Souza ◽

Fernando Lessa Tofoli ◽

Enio Roberto Ribeiro

Keyword(s):

Voltage Regulation ◽

Inherent Difficulty ◽

Practical Applications ◽

Dc Power ◽

Higher Power ◽

Voltage Doubler ◽

Converter Design ◽

Design Characteristics ◽

And Performance ◽

Full Charge

This work presents a review of the main topologies of switched capacitors (SCs) used in DC-DC power conversion. Initially, the basic configurations are analyzed, that is, voltage doubler, series-parallel, Dickson, Fibonacci, and ladder. Some aspects regarding the choice of semiconductors and capacitors used in the circuits are addressed, as well their impact on the converter behavior. The operation of the structures in terms of full charge, partial charge, and no charge conditions is investigated. It is worth mentioning that these aspects directly influence the converter design and performance in terms of efficiency. Since voltage regulation is an inherent difficulty with SC converters, some control methods are presented for this purpose. Finally, some practical applications and the possibility of designing DC-DC converters for higher power levels are analyzed.

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Optimal Operation of the Voltage-Doubler Boost Converter through an Evolutionary Algorithm

Mathematics ◽

10.3390/math9040423 ◽

2021 ◽

Vol 9 (4) ◽

pp. 423

Author(s):

Cesar Ibarra-Nuño ◽

Alma Rodríguez ◽

Avelina Alejo-Reyes ◽

Erik Cuevas ◽

Juan M. Ramirez ◽

...

Keyword(s):

Evolutionary Algorithm ◽

Numerical Optimization ◽

Boost Converter ◽

Optimal Operation ◽

Input Current ◽

Voltage Gain ◽

Duty Cycles ◽

Switching Functions ◽

Voltage Doubler ◽

Current Ripple

This manuscript presents the numerical optimization (through a mathematical model and an evolutionary algorithm) of the voltage-doubler boost converter, also called the series-capacitor boost converter. The circuit is driven by two transistors, each of them activated according to a switching signal. In the former operation, switching signals have an algebraic dependence from each other. This article proposes a new method to operate the converter. The proposed process reduces the input current ripple without changing any converter model parameter, only the driving signals. In the proposed operation, switching signals of transistors are independent of each other, providing an extra degree of freedom, but on the other hand, this produces an infinite number of possible combinations of duty cycles (the main parameter of switching signals) to achieve the desired voltage gain. In other words, this leads to a problem with infinite possible solutions. The proposed method utilizes an evolutionary algorithm to determine the switching functions and, at the same time, to minimize the input current ripple of the converter. A comparison made between the former and the proposed operation shows that the proposed process achieves a lower input current ripple while achieving the desired voltage gain.

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