This article offers a new high step-up dc–dc converter based on a coupled inductor. The proposed single-switch converter employs different inductive and capacitive techniques to transfer the input power to the output load in operational modes. It reaches to high output voltage gains in lower duty cycles, which results in lower switch loss for a specific voltage gain. Two output ports are utilized to share the overall output voltage, reduce the voltage stress of each port components and decrease the total output voltage ripple in high voltage gain ratios. Continuous input current, recycling the stored energy of magnetizing and leakages inductances, alleviating the switch voltage spikes, no circulating current, low input current ripple, high power density, wide output voltage range and simple pulse width modulation with a vast control area are the other features of the proposed converter. In this article, the proposed converter is analyzed in the steady-state operation of continuous and discontinuous conduction modes, and comprehensive comparisons are performed to evaluate its capabilities. Moreover, power loss calculations and design procedure are followed with experimental results to verify theoretical analytics.

High Step-Up DC–DC Converter With Efficient Inductive Utilization

In this article, an interleaved high-voltage gain dc–dc converter is proposed for use with photovoltaic (PV) systems. By integrating two three-winding coupled inductors (CIs) with switched capacitor cells, the voltage gain is further extended. Through passive diode-capacitor clamp circuits, the energy stored in the leakage inductances is absorbed; additionally, the voltage stress of the power switches is clamped to a value far lower than the output voltage, which enables designers to select switches with low-voltage ratings. Due to the interleaved structure of the proposed converter, the input current has a small ripple, which leads to the increased lifespan of the PV panels. In addition, the current stress on the components is reduced. Thanks to the leakage inductances of the CIs, the zero-current switching condition is intrinsically provided for the diodes; accordingly, the adverse impact of the diodes’ reverse-recovery is alleviated. The operating principles, steady-state analyses, and design considerations of the proposed converter are presented in this article. A comparison with other similar converters is carried out to verify the merits of the proposed converter. Finally, the theoretical analyses are confirmed through the experimental results of a 400-W prototype with an output voltage of 400 V.

A Three-Winding Coupled Inductor-Based Interleaved High-Voltage Gain DC–DC Converter for Photovoltaic Systems

The concepts of dual coupled inductors and voltage multiplier cell are integrated to derive a novel non-isolated interleaved high step-up boost converter in this paper. At the input, due to the interleaved dual coupled inductors and voltage multiplier cell, the converter inhibits current ripple and reduced voltage stress for the power devices; At the output, the secondary sides of the two coupled inductors are connected in series to achieve the purpose of much higher voltage gain and lower voltage stress on the power devices. Therefore, lower voltage rating MOSFETs and diodes can be selected to reduce both switching and conduction losses. In addition, the leakage inductance energy of two coupled inductors can be absorbed and recycled to the output, and the reverse-recovery problem of diodes can be effectively suppressed. Zero current switching (ZCS) turn-on is realized for the power switches to reduce the switching loss. The working principle and steady-state characteristics of the converter are analyzed in detail. The voltage balance of the output capacitors and input current sharing by two interleaved phases are realized through the double closed-loop control of voltage and current. Finally, a 400 W laboratory prototype with 25~30 V input and 400 V output is built to verify the significant improvements of the proposed converter.

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Interleaved High Step-Up Converter With Coupled Inductor and Voltage Multiplier for Renewable Energy System

This article proposed a novel hybrid-connected boost converter (HCBC) with ultrahigh step-up and ultralow voltage stress. At the input part, a traditional interleaved boost converter structure is adopted based on dual coupled inductors, which can reduce the input current ripple and ease the current stress flowing through main switches and magnetic elements. Then, the voltage doubling capacitors embedded in this circuit can lift voltage and clamp the voltage stress on switches. Therefore, it will not only increase the voltage gain, but also recycle the leakage energy of coupled inductor to alleviate the voltage spikes across the power switches. At the output, the dual secondary windings of coupled inductors are connected in series and combined with a capacitor-diode to form a voltage multiplier module, which is stacked on the output for higher voltage gain. The working principle and steady-state performance of the proposed converter are analyzed in detail, and a 400-W experimental prototype based on HCBC is built to verify the correctness of theoretical analysis.

An Ultrahigh Voltage Gain Hybrid-Connected Boost Converter With Ultralow Distributed Voltage Stress

In this article, an interleaved high-voltage gain dc–dc converter is proposed for use with photovoltaic (PV) systems. By integrating two three-winding coupled inductors (CIs) with switched capacitor cells, the voltage gain is further extended. Through passive diode-capacitor clamp circuits, the energy stored in the leakage inductances is absorbed; additionally, the voltage stress of the power switches is clamped to a value far lower than the output voltage, which enables designers to select switches with low-voltage ratings. Due to the interleaved structure of the proposed converter, the input current has a small ripple, which leads to the increased lifespan of the PV panels. In addition, the current stress on the components is reduced. Thanks to the leakage inductances of the CIs, the zero-current switching condition is intrinsically provided for the diodes; accordingly, the adverse impact of the diodes’ reverse-recovery is alleviated. The operating principles, steady-state analyses, and design considerations of the proposed converter are presented in this article. A comparison with other similar converters is carried out to verify the merits of the proposed converter. Finally, the theoretical analyses are confirmed through the experimental results of a 400-W prototype with an output voltage of 400 V. 

In this article, a hybrid interleaved connecting boost converter (HIBC) with a wide step-up regulation range is proposed, which is suitable for the low-voltage distributed generation applications. In the input of the HIBC, the primary windings of the double-coupled inductors are interleaved parallel connection, inheriting shared current and reduced current ripples. Then, the lossless passive clamped circuits are used to recycle the leakage energy of the coupled inductor and to reduce the voltage stress on the semiconductor devices to a very low level. The secondary windings of the coupled inductors are, respectively, combined with a capacitor–diode to form the two voltage multiplier units, which are again, respectively, connected with an output capacitor for a voltage-doubling module. These two voltage-doubling modules are connected in interleaved series for supplying power to the output, whose structure enhances the voltage gain greatly without adopting an extreme duty cycle and reduces the output voltage ripples. In addition, the main switches of the proposed converter can be operated in zero-current switching and full duty cycle range in theory, achieving a wide step-up regulation range with the high efficiency. Finally, the theoretical behaviors of the presented converter are described in detail and some experimental results are also shown to demonstrate the effectiveness of the proposed converter.

A Hybrid Interleaved DC–DC Converter With a Wide Step-Up Regulation Range and Ultralow Voltage Stress

A novel transformerless boost inverter for standalone photovoltaic generation systems is proposed in this paper. The proposed inverter combines the boost converter with the traditional bridge inverter. The switch S1 not only realizes the boost function but also participates in inverting process. The inverter has a higher voltage gain and good characteristics when the inductor L1 is operated in discontinuous mode (DCM) and the nonpolarized capacitor can be chosen as bus capacitor, which makes the volume smaller and the service life of the inverter is increased. The inverter consists of five switches in which only two switches are operated at high frequency state and a monopole sinusoidal pulse width modulation (SPWM) strategy is used. Therefore, the modulation strategy of switches is very simple and the switching loss is reduced. The principle of inverter is described in detail and mathematical models are built by small-signal analysis. Finally, the correctness of the theoretical analysis is verified by simulation and experiment.

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Analysis and Design of a Transformerless Boost Inverter for Stand-Alone Photovoltaic Generation Systems

a novel transformerless boost inverter for standalone photovoltaic generation systems is proposed in this paper. The proposed inverter combines the boost converter with the traditional bridge inverter. The switch S1 can not only realize the boost function but also participate in inverting process. The inverter has a higher voltage gain and good characteristics when the inductor L 1 is operated in discontinuous mode (DCM) and the nonpolarized capacitor can be chosen as bus capacitor, which makes the volume smaller and the service life of the inverter is increased. The inverter consists of five switches in which only two switches are operated at high frequency state and a monopole SPWM strategy is used. Therefore, the modulation strategy of switches is very simple and the switching loss is reduced. The principle of inverter is described in detail and the correctness of the theoretical analysis is verified by simulation and experiment.

A Transformerless Boost Inverter for Stand-alone Photovoltaic Generation Systems

A novel non-isolated interleaved boost converter is proposed with high step-up conversion ratio, which integrates two coupled inductors and voltage multiplier cells. At the input, the primary sides of the double coupled inductors are connected in parallel, and the two blocking capacitors are separately embedded into every phase. So the converter inhibits current ripples of input, and reduced voltage stress for the semiconductor devices; At the output, the secondary sides of the two coupled inductors are connected in series to achieve the purpose of much higher voltage gain and lower voltage stress on the semiconductor devices. In addition, the leakage inductance energy of two coupled inductors can be absorbed and recycled to the output, and the problem of reverse-recovery for diodes can be effectively suppressed. The voltage balance of the output capacitors and input current sharing by two interleaved phases are realized through the double closed-loop control of voltage and current. Finally, a 400W laboratory prototype is built to verify the correctness of theoretical analysis.

Xuefeng Hu

Papers

A Hybrid Interleaved DC–DC Converter With a Wide Step-Up Regulation Range and Ultralow Voltage Stress

Analysis and Design of a Transformerless Boost Inverter for Stand-Alone Photovoltaic Generation Systems

A Transformerless Boost Inverter for Stand-alone Photovoltaic Generation Systems

An Interleaved Boost Converter with Parallel Input and Output Series for Renewable energy system