This paper presents three unidirectional step-up ac–dc converter topologies with voltage multiplication on their outputs. The first topology is the hybrid boost rectifier and the other two are novel bridgeless structures, all based on the integration of boost rectifier and the ladder switched-capacitor (SC) cell. The new hybrid structures provide high voltage gain with low voltage stress across the switches, high-power factor, and output voltage regulation. This paper presents the principle of operation, steady-state and dynamic analysis, design methodology, and experimental verification. A different approach is also presented for the design methodology of the SC cell and for the analysis of its influence on the dynamic model. Three 1000-W prototypes with a 220-V input voltage, 800-V output voltage, and 100-kHz switching frequency were designed to corroborate the theoretical study. The best efficiency was 97.1 $\%$ in the proposed bridgeless versions and the voltage stress across the switches stands around 400 V. Furthermore, a comparison between the proposed structures and previous topologies is also presented.

A Family of Voltage-Multiplier Unidirectional Single-Phase Hybrid Boost PFC Rectifiers

This paper discusses a switched inductor design for a non-isolated multilevel boost converter. A Non-isolated proposed multilevel boost converter is suitable to provide a high conversion ratio which essentially benefits renewable energy systems. In addition to the voltage stress reduction, the proposed switched inductor MBC has shown an improvement in voltage gain. The new switched inductor model has been inserted as an input into the multilevel boost converter. The proposed converter consists of 2N-1 capacitors, 4N-1 diodes, three inductors and a single switch. The proposed model is a three-level boost converter which is supplied by 12 V to produce 280 V at a 50 KHz switching frequency. A MATLAB/SIMULINK simulator was used to evaluate and test the proposed switched inductor model.

A switched-inductor model for a non-isolated multilevel boost converter

Novel dc-dc converters with a single input and multiple outputs has been proposed in this paper. The features of the proposed topology are (a) reduced part count leading to compact and lightweight circuit, (c) high voltage gain, (d) single input double output, (e) low ripple in the input as well as output side, and (f) a minimal number of active switches. Apart from this, the paper highlights the modifications of the proposed converter to incorporate the advantages of interleaving as well as generate two independently controllable output voltages. The method of generating two equal and opposite output voltages with the help of a single switch has also been proposed with the addition of minimal circuitry. Operating modes of the proposed converters have been explained followed by a detailed steady-state and the dynamic modeling. To verify the validity of the proposed converters, simulations has been carried out using Matlab-Simulink and experiments have been carried out through a hardware laboratory prototype, whose results are included in the subsequent sections of the paper.

Highly efficient and compact single input multiple output dc-dc converters

A Sepic converter with both of its inductors replaced by the Flyback transformer has been proposed here. Outputs of the two Flyback sub-parts are connected in series along with the normal Sepic converter output to result in a high positive overall output voltage. The Sepic converter portion acts as a passive clamp to both the Flyback converters. During the switch turn-off instant, the leakage inductor current of the Flyback transformers doesn't get interrupted. Hence, no spike can appear in the drain to source voltage of the switch. Due to the presence of the two transformers as the energy storing elements, the converter can be used for applications requiring higher power handling compared to the conventional Flyback converters. The proposed circuit has got the features like less leakage inductance transformers, less rating devices, low component count and provide high overall gain at high efficiency. In the subsequent sections of the paper, the working principle of the converter has been explained and validated through open loop simulations were done using Matlab-Simulink. The introduction part highlights the advantages of the proposed circuit over the other circuits used for similar purposes. Considering the effect of some of the parasitic elements of the circuit, the converter has been analyzed in detail for the steady state operating condition.

High gain and efficient integrated flyback-Sepic DC-DC converter with leakage energy recovery mechanism

This paper presents a novel of a transformerless step-up DC-DC converter based on a switched-inductor (SL) and switched-capacitor (SC) techniques. The main advantage of the proposed SLSC step-up converter is the ability to achieve very high voltage gain (>20) with reasonable voltage stress across the semiconductor switches. The presented paper shows a detailed analysis of the proposed SLSC step-up converter and a comparison considering other published step-up converter topologies. Theoretically, the proposed SLSC step-up converter can boost the input voltage to 23.5 times when $\mathbf{D}=0.75$, which D means the duty cycle of the MOSFET. Such a large voltage gain can be used in renewable energy applications such as photovoltaic application to boost the output voltage which the output voltage is low. The proposed converter is analyzed in continuous conduction mode (CCM). The proposed converter has been designed for 12V input voltage, 280V output voltage, 200W rated power, 50kHz switching frequency, and 75% duty cycle. The proposed converter has been simulated in MATLAB/SIMULINK.

A Non-Isolated High Gain Switched-Inductor Switched-Capacitor Step-Up Converter for Renewable Energy Applications

This paper presents a novel high step-up DC-DC multilevel buck-boost converter using voltage-lift switched-inductor (VLSI) cell. To achieve high conversion ratio cascading of conventional DC-DC converter is not a practical solution. Thus high step-up multilevel buck-boost converters are employed to achieve high conversion ratio. The proposed high step-up DC-DC multilevel buck-boost converter is a non-isolated topology which combines the function of voltage-lift switched-inductors (VLSI) cell and voltage multiplier. In this paper voltage-lift switched-inductor (VLSI) cell is used to advance the boost capability of multilevel buck-boost converter. 2N+3 diodes, 2N capacitors, two inductors and single switch are needed to design proposed N-level buck-boost topology. Proposed DC-DC multilevel buck-boost topology can be synthesized by using low voltage rating devices because voltage stress across each power devices is less. The main advantage of proposed DC-DC multilevel topology is high conversion ratio is achieved without using coupled inductor, transformer and extreme duty cycle. The voltage gain of proposed buck-boost multilevel converter is depends upon the duty cycle and number of levels. The proposed buck-boost multilevel converter has been designed for three levels with rated power 200W and output voltage is 220V Input supply voltage is 12V, duty cycle is 70% and switching frequency is 50KHz. The proposed buck-boost multilevel converter topology is simulated in MATLAB/SIMULINK.

A novel high step-up DC-DC multilevel buck-boost converter using voltage-lift switched-inductor cell

In this paper a novel high gain buck-boost multilevel converter using double voltage-lift switched-induct or (D-VLSI) cell is proposed. Series connection of conventional DC-DC converter is not a viable solution to achieve high voltage gain. Thus, DC-DC multilevel converters are employed to achieve high voltage gain. The proposed high gain multilevel buck-boost converter combines the function of double voltage-lift switched-inductor (D-VLSI) cell and voltage multiplier cell. In this paper double voltage-lift switched-inductor (D-VLSI) cell is used to enhance the boost capability of multilevel buck-boost converter. 2N+1 capacitors, 2N+3 diodes, two switches and two inductors are required to design the proposed N-level buck-boost converter topology. Proposed buck-boost multilevel converter circuit can be designed by using low voltage rating devices, because voltage stress across each power devices is low. The main advantage of proposed converter circuit is high voltage is achieved without using transformer, coupled inductor and extreme duty cycle. The voltage gain of proposed buck-boost multilevel converter is depends upon the duty ratio and number of levels. The proposed high gain multilevel buck-boost converter has been designed for three levels with rated power 200W, output voltage is 300V, input supply voltage is 12V and switching frequency is 50kHz. The proposed buck-boost multilevel converter circuit is simulated in MATLAB/SIMULINE.

A novel high gain buck-boost multilevel converter using double voltage-lift switched-inductor cell

In this paper a novel high step-up multilevel boost converter using double voltage-lift switched-inductor (D-VLSI) cell is proposed. Series connection of conventional DC-DC boost converter is not a proper solution to achieve high voltage gain. Thus, DC-DC multilevel converters are employed to achieve high voltage gain. The proposed high step-up multilevel boost converter is a combination of double voltage-lift switched-inductor (D-VLSI) cell and voltage multiplier cell. In this paper double voltage-lift switched-inductor (D-VLSI) cell is used to enhance the step-up capability of multilevel DC-DC converter. Two switches, 2N+3 diodes, 2N+1 capacitor and two inductors are required to design the proposed N-level high step-up multilevel boost converter topology. Proposed high step-up multilevel converter circuit can be designed by using low voltage rating devices because blocking voltage across each power devices is low. The main advantage of proposed converter circuit is high voltage is achieved without using transformer, coupled inductor and high duty cycle. The gain of proposed multilevel converter is depends upon the duty ratio and levels present in voltage multiplier cell. Proposed DC-DC converter is designed for unidirectional power transfer applications. The proposed high step-up multilevel converter has been designed for three levels with rated power 300W, output voltage is 324V, input supply voltage is 12V, and switching frequency is 50kHz. The proposed high step-up multilevel converter circuit is simulated in MATLAB/SEVIULINK.

Y. Bhaskar S S Gupta

Papers

A novel high step-up DC-DC multilevel buck-boost converter using voltage-lift switched-inductor cell

A novel high gain buck-boost multilevel converter using double voltage-lift switched-inductor cell

A novel high step-up multilevel boost converter using double voltage-lift switched-inductor cell