High Step-up Gain Research Articles

A Single-Switch Converter With High Step-Up Gain and Low Diode Voltage Stress Suitable for Green Power-Source Conversion

This paper proposes a single-switch converter with high step-up gain and low diode voltage stress, suitable for green power source conversion. By employing a coupled inductor and switched capacitor, the proposed converters achieve high step-up conversion ratio without adopting extremely high duty ratio or high turns ratio. The voltage spike that occurs on the power switch is alleviated, which allows a low-voltage-rated power switch with low $R_{\rm DS(\mathrm{\scriptscriptstyle ON})}$ to be adopted, thus reducing the conduction losses. Because the energy of the leakage inductor is recycled, the efficiency is improved. In addition, all diodes’ voltage stresses are lowered and are the same, so the selection of power diodes is convenient. Finally, a 300-W prototype circuit with an input voltage of 24 V and an output voltage of 400 V is implemented to verify the performance and functionality of the presented converter. Moreover, the measured highest efficiency is 95.4%.

Soft‐switched non‐isolated high step‐up DC–DC converter with reduced voltage stress

In this study, a novel soft-switched high step-up DC/DC converter is presented. This converter is suitable to be employed in photovoltaic and fuel cell systems. The proposed topology is based on coupled inductors and switched-capacitor techniques to provide high step-up gain. Also, due to high conversion ratio, and symmetrical structure of the proposed topology, the voltage stress of semiconductor elements is low; therefore, high performance metal–oxide–semiconductor field-effect transistors with low ON-resistance, and also low-voltage rating diodes can be utilised to reduce the circuit cost, conduction, and reverse-recovery losses which improve the converter efficiency and power density. Furthermore, by adopting an active clamp circuit, the stored energy in the leakage inductance of coupled inductors is recycled and zero-voltage-switching turn-on condition for both main and clamp switches are provided. Operating principle and steady-state analysis of the converter are discussed in detail. Finally, an experimental prototype of the proposed converter with 200 W output power is implemented which verifies the theoretical analysis.

A High Step-Up Converter With Voltage-Multiplier Modules for Sustainable Energy Applications

This paper proposes a novel isolated high step-up converter for sustainable energy applications. Through an adjustable voltage-multiplier module, the proposed converter achieves a high step-up gain without utilizing either a large duty ratio or a high turns ratio. The voltage-multiplier modules are composed of coupled inductors and switched capacitors. Due to the passive lossless clamped performance, leakage energy is recycled, which alleviates a large-voltage spike across the main switches and improves efficiency. Thus, power switches with low levels of voltage stress can be adopted for reducing conduction losses. In addition, the isolated topology of the proposed converter satisfies electrical-isolation and safety regulations. The proposed converter also possesses continuous and smooth input current, which decreases the conduction losses, lengthens life time of the input source, and constrains conducted electromagnetic-interference problems. Finally, a prototype circuit with 40 V input voltage, 380 V output, and 500 W maximum output power is operated to verify its performance. The maximum efficiency is 94.71% at 200 W, and the full-load efficiency is 90.67% at 500 W.

Analysis and Design of Charge Pump-Assisted High Step-Up Tapped Inductor SEPIC Converter With an “Inductorless” Regenerative Snubber

This paper introduces a SEPIC-derived converter suited for alternative energy generation applications. The proposed converter utilizes tapped inductor and charge pump techniques to achieve high step-up gain and a passive regenerative snubber to attain high efficiency. Compared with earlier counterparts, the proposed converter has the advantage of continuous input current, which can be helpful in attaining accurate tracking of maximum power point of solar panels. The paper presents principle of operation, theoretical analysis, and design guidelines. Theoretical expectations were confirmed by simulation and experimental results.

High step‐up passive absorption circuit used in non‐isolated high step‐up converter

To obtain a high step-up gain with high efficiency in distributed power sources application, such as photovoltaic (PV) and fuel cells, a passive absorption circuit with voltage step-up character is inserted in the interleaved flyback-forward converter for leakage energy recycle and voltage gain extension. By applying the high step-up passive-clamp circuit, the voltage spike on the metal-oxide semiconductor field-effect transistor is clamped and the energy stored inside the leakage inductance of the coupled inductor can be recycled to get high-output voltage. Moreover, it offers another design freedom to obtain higher voltage-conversion ratio. The operational principle and characteristics of the improved flyback-forward converter are presented, and verified experimentally with a 500 W prototype converter. The proposed high step-up passive-clamp can be widely used in high step-up DC-DC converter applications, and a new high step-up topology is deduced to illustrate the theoretical analysis.

High Step-Up High-Efficiency Interleaved Converter With Voltage Multiplier Module for Renewable Energy System

A novel high step-up converter, which is suitable for renewable energy system, is proposed in this paper. Through a voltage multiplier module composed of switched capacitors and coupled inductors, a conventional interleaved boost converter obtains high step-up gain without operating at extreme duty ratio. The configuration of the proposed converter not only reduces the current stress but also constrains the input current ripple, which decreases the conduction losses and lengthens the lifetime of the input source. In addition, due to the lossless passive clamp performance, leakage energy is recycled to the output terminal. Hence, large voltage spikes across the main switches are alleviated, and the efficiency is improved. Even the low voltage stress makes the low-voltage-rated MOSFETs be adopted for reductions of conduction losses and cost. Finally, the prototype circuit with 40-V input voltage, 380-V output, and 1000-W output power is operated to verify its performance. The highest efficiency is 97.1%.

High Step-Up DC/DC Topology and MPPT Algorithm for Use With a Thermoelectric Generator

A thermoelectric generator (TEG) is a low-voltage high-current dc power source with a linear V–I characteristic, and therefore, it is desirable to create a power converter with a topology and control method suited to these attributes. Due to the TEG’s low voltage, a topology that produces a high step-up gain for a moderate duty cycle is required to reduce voltage and current stresses within the converter. The linear V–I characteristic produces a P–I characteristic with a flatter peak relative to other sources. This can result in large operating point variations while performing maximum power point tracking (MPPT); thus, an algorithm with low steady-state error is desired. This paper presents a novel high step-up dc/dc converter topology operating with a fractional short-circuit MPPT algorithm for use with a 4.2-V, 3.4-A (for matched load at <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\Delta T = \hbox{270}\,^{\circ }$</tex></formula> C) TEG module and a converter output of 180 V. Compared to existing high step-up dc/dc converters, the proposed converter achieves higher gain with similar component count. Experimental results are reported to confirm the converter analysis and better performance of the short-circuit MPPT algorithm over the perturb and observe algorithm.

A High Step-Up Converter With a Voltage Multiplier Module for a Photovoltaic System

A novel high step-up converter is proposed for a front-end photovoltaic system. Through a voltage multiplier module, an asymmetrical interleaved high step-up converter obtains high step-up gain without operating at an extreme duty ratio. The voltage multiplier module is composed of a conventional boost converter and coupled inductors. An extra conventional boost converter is integrated into the first phase to achieve a considerably higher voltage conversion ratio. The two-phase configuration not only reduces the current stress through each power switch, but also constrains the input current ripple, which decreases the conduction losses of metal-oxide-semiconductor field-effect transistors (MOSFETs). In addition, the proposed converter functions as an active clamp circuit, which alleviates large voltage spikes across the power switches. Thus, the low-voltage-rated MOSFETs can be adopted for reductions of conduction losses and cost. Efficiency improves because the energy stored in leakage inductances is recycled to the output terminal. Finally, the prototype circuit with a 40-V input voltage, 380-V output, and 1000- W output power is operated to verify its performance. The highest efficiency is 96.8%.

Novel power electronic interface for grid-connected fuel cell power generation system

A novel power electronic interface for the grid-connected fuel cell power generation system is proposed in this paper. This power electronic interface is composed of a DC–DC power converter and a DC–AC inverter. A voltage doubler based topology is adopted to configure the DC–DC power converter to perform high step-up gain for boosting the output voltage of the fuel cell to a higher voltage. Moreover, the input current ripple of the fuel cell is suppressed by controlling the DC–DC power converter. The DC–AC inverter is configured by a dual buck power converter and a full-bridge power converter to generate a five-level AC output voltage. The DC–AC inverter can perform the functions of DC–AC power conversion and active power filtration. A 1.2kW hardware prototype is developed to verify the performance of the proposed power electronic interface for the grid-connected fuel cell power generation system. The experimental results show that the proposed power electronic interface for the grid-connected fuel cell power generation system has the expected performance.

Evaluation of High Step-Up Power Electronics Stages in Thermoelectric Generator Systems

To develop practical thermoelectric generator (TEG) systems, especially radioisotope thermoelectric power supplies for deep-space exploration, a power conditioning stage with high step-up gain is indispensable. This stage is used to step up the low output voltage of thermoelectric generators to the required high level. Furthermore, maximum power point tracking control for TEG modules needs to be implemented into the power electronics stages. In this paper, the temperature-dependent electrical characteristics of a thermoelectric generator are analyzed in depth. Three typical high step-up power converters suitable for TEG applications are discussed: an interleaved boost converter, a boost converter with a coupled inductor, and an interleaved boost converter with an auxiliary transformer. A general comparison of the three high step-up converters is conducted to study the step-up gain, conversion efficiency, and input current ripples. The interleaved boost converter with an auxiliary transformer is found to be the most suitable topology for TEG applications, which is verified by experiments.

Novel Isolated High-Step-Up DC–DC Converter With Voltage Lift

A novel two-switch high-step-up isolated converter with voltage lift is proposed in this paper. The proposed isolated converter utilizes a transformer with low turn ratio to achieve high step-up gain. The secondary winding charges two boosting capacitors in parallel as switches during the switch-on period, and two boosting capacitors are discharged in series during the switch-off period. Thus, the converter has high voltage gain with appropriate duty ratio. In addition, by using two clamping diodes and a capacitor on the primary side, leakage energy is recycled, and the voltage spikes of the two active switches are clamped, thereby improving conversion efficiency. Finally, experimental results based on a prototype implemented in the laboratory with an input voltage of 24 V, an output voltage of 200 V, and an output power of 200 W verify the performance of the proposed isolated converter; full-load efficiency is nearly 93%.

Nonisolated High Step-Up Stacked Converter Based on Boost-Integrated Isolated Converter

To obtain a high step-up gain with high efficiency in nonisolated applications, a high step-up technique based on isolated-type converters is introduced in this paper. By stacking the secondary side of an isolated converter in addition to its primary side, a high step-up conversion ratio and a distributed voltage stress can be achieved. Moreover, a careful choice of an isolated converter can provide zero-voltage switching, continuous input current, and reduced reverse recovery on diodes. Based on a conventional voltage-doubler-rectifier boost-integrated half-bridge converter, the derived converter satisfies all these features, which make it suitable for high step-up applications. The operational principle and characteristics of the proposed converter are presented, and verified experimentally with a 135-W, 24-V input, 250-V output prototype converter for a LED driver.

Interleaved Converter With Voltage Multiplier Cell for High Step-Up and High-Efficiency Conversion

A novel interleaved high step-up converter with voltage multiplier cell is proposed in this paper to avoid the extremely narrow turn-off period and to reduce the current ripple, which flows through the power devices compared with the conventional interleaved boost converter in high step-up applications. Interleaved structure is employed in the input side to distribute the input current, and the voltage multiplier cell is adopted in the output side to achieve a high step-up gain. The voltage multiplier cell is composed of the secondary windings of the coupled inductors, a series capacitor, and two diodes. Furthermore, the switch voltage stress is reduced due to the transformer function of the coupled inductors, which makes low-voltage-rated MOSFETs available to reduce the conduction losses. Moreover, zero-current-switching turn- on soft-switching performance is realized to reduce the switching losses. In addition, the output diode turn-off current falling rate is controlled by the leakage inductance of the coupled inductors, which alleviates the diode reverse recovery problem. Additional active device is not required in the proposed converter, which makes the presented circuit easy to design and control. Finally, a 1-kW 40-V-input 380-V-output prototype operating at 100 kHz switching frequency is built and tested to verify the effectiveness of the presented converter.

An Interleaved Winding-Coupled Boost Converter With Passive Lossless Clamp Circuits

An interleaved winding-coupled boost converter is proposed in order to realize ZCS turn-on condition and to achieve high step-up gain. The voltage gain is extended easily and the voltage stress on the switches is reduced with different turns ratios of the coupled inductors. The output diode reverse-recovery problem is alleviated due to the inherent leakage inductor of the winding-coupled inductors. The simple but effective passive lossless clamp circuits are introduced to limit the voltage stress on the switches when they turn off so that the low-voltage, high-performance devices with low conduction resistor can be used in the proposed converter to reduce the relative losses. The leakage energy is ultimately recovered to the load. The high efficiency of 90.7% at full load and the maximum efficiency of 92.6% are achieved in a 1-kW 40-V-input-to-380-V-output prototype for front-end application. There is more than 10% efficiency improvement with the passive lossless clamp circuits compared to the case with RCD dissipated snubbers. The efficiency of 5% improvement at full load is achieved with the proposed converter with passive lossless circuits compared to the conventional interleaved boost converter.