Non-isolated High Step-up DC-DC Converter Research Articles

Analysis and Implementation of a DC-DC Converter for Hybrid Power Supplies Systems

A new DC-DC power converter is researched for renewable energy and battery hybrid power supplies systems in this paper. At the charging mode, a renewable energy source provides energy to charge a battery via the proposed converter. The operating principle of the proposed converter is the same as the conventional DC-DC buck converter. At the discharging mode, the battery releases its energy to the DC bus via the proposed converter. The proposed converter is a non-isolated high step-up DC-DC converter. The coupled-inductor technique is used to achieve a high step-up voltage gain by adjusting the turns ratio. Moreover, the leakage-inductor energies of the primary and secondary windings can be recycled. Thus, the conversion efficiency can be improved. Therefore, only one power converter is utilized at the charging or discharging modes. Finally, a prototype circuit is implemented to verify the performance of the proposed converter.

High step‐up pulse‐width modulation DC–DC converter based on quasi‐Z‐source topology

In this study, a new high step-up non-isolated DC-DC converter is proposed. This converter is derived from quasi-Z-source inverter and quadratic boost converter. Compared with these converters, it gives higher gain at the same duty ratio. Steady-state analysis for the proposed converter operating in continuous conduction mode is presented. Expressions for power loss in each component and gain for non-ideal converter are derived. Design expressions for various elements of converter are derived. A small-signal model is derived and controller design is discussed. A prototype is implemented in laboratory to verify the performance of the converter. Experimental results show good agreement with the theoretical analysis and simulation results.

A High Voltage Gain DC–DC Converter Integrating Coupled-Inductor and Diode–Capacitor Techniques

The high-voltage gain converter is widely employed in many industry applications, such as photovoltaic systems, fuel cell systems, electric vehicles, and high-intensity discharge lamps. This paper presents a novel single-switch high step-up nonisolated dc-dc converter integrating coupled inductor with extended voltage doubler cell and diode-capacitor techniques. The proposed converter achieves extremely large voltage conversion ratio with appropriate duty cycle and reduction of voltage stress on the power devices. Moreover, the energy stored in leakage inductance of coupled inductor is efficiently recycled to the output, and the voltage doubler cell also operates as a regenerative clamping circuit, alleviating the problem of potential resonance between the leakage inductance and the junction capacitor of output diode. These characteristics make it possible to design a compact circuit with high static gain and high efficiency for industry applications. In addition, the unexpected high-pulsed input current in the converter with coupled inductor is decreased. The operating principles and the steady-state analyses of the proposed converter are discussed in detail. Finally, a prototype circuit is implemented in the laboratory to verify the performance of the proposed converter.

Nonisolated ZVZCS Resonant PWM DC–DC Converter for High Step-Up and High-Power Applications

The demand for nonisolated high step-up dc-dc converters in applications such as dc backup energy systems for UPS, photovoltaic and fuel cell systems, and hybrid electric vehicles has been gradually increasing. This paper proposes nonisolated step-up dc-dc converters with an improved switching method. The proposed converter shows zero-voltage switching turn-on of the switches in continuous conduction mode as well as reduced turn- off switching losses owing to the switching method that utilizes Lr-Cr resonance in the auxiliary circuit. Also, as a result of the proposed switching method, the switching losses associated with diode reverse recovery become negligible even in the small duty cycle. The capacitance in the auxiliary circuit is significantly reduced compared to the pulsewidth modulation method. The duty cycle loss is further reduced resulting in increased step-up ratio. Experimental results from a 2-kW prototype of a two-phase interleaved version are also provided to validate the proposed concept.

High Step-Up DC-DC Converters Using Zero-Voltage Switching Boost Integration Technique and Light-Load Frequency Modulation Control

This paper describes nonisolated high step-up DC-DC converters using zero voltage switching (ZVS) boost integration technique (BIT) and their light-load frequency modulation (LLFM) control. The proposed ZVS BIT integrates a bidirectional boost converter with a series output module as a parallel-input and series-output (PISO) configuration. It provides many advantages such as high device utilization, high step-up capability, power and thermal stress distribution, switch voltage stress clamping, and soft switching capability. As an example of ZVS BIT, a flyback converter with a voltage-doubler rectifier (VDR) as a series output module is presented and analyzed in detail. In addition, to overcome the efficiency degradation at a light load due to the load-dependent soft switching capability of the proposed ZVS BIT, a control method using a frequency modulation (FM) proportional to the load current is proposed. By means of ZVS BIT and LLFM control, the overall conversion efficiency is significantly improved. The experimental results are presented to clarify the proposed schemes.

Non-Isolated High Step-up DC-DC Converter with a Coupled Inductor

A non-isolated high step-up DC-DC converter with a coupled inductor is proposed in this paper. The proposed converter provides high voltage gain and soft-switching operation of all semiconductor devices. A voltage doubler and a coupled inductor increase the voltage gain. Zero-voltage-switching (ZVS) of all switches and zero-current-switching (ZCS) of all diodes are achieved. Also, the voltages across the semiconductor devices are effectively clamped. Due to the soft-switching operation of all switching devices, the switching loss is significantly reduced and the high efficiency is obtained. The feasibility and performance of the proposed converter were verified on an experimental prototype

High step-up boost converter with passive lossless clamp circuit for non-isolated high step-up applications

Non-isolated high step-up DC-DC converters are required widely in the industrial applications. Many of these conventional DC-DC converters have the disadvantages of operating at high duty-cycle, high switch voltage stress and high diode peak current. The proposed converter can provide very high voltage gain without operating at high duty-cycle by employing a coupled inductor, a switched capacitor and an additional diode. At the same time, the switch voltage stress is reduced greatly, which is helpful to reduce the conduction losses by using a low on-resistance switch. The presented converter employs a passive lossless clamp circuit instead of an active clamp circuit to recycle the leakage energy, which is simpler and easier to design. Zero-current switching turn on performance is achieved due to the leakage inductance, and the switch voltage is clamped to the voltage on the clamp capacitor, which is helpful to reduce the switch voltage stress. Moreover, the reverse-recovery energy of the output diode and the leakage inductance energy are recycled. Finally, a 500-W prototype has been built to verify the analysis. The maximum efficiency of the prototype is 96.9% and the efficiency is higher than 96% over a wide load range.

High Conversion Ratio DC–DC Converters With Reduced Switch Stress

In this paper, a new class of single-switch nonisolated high step-up DC-DC converters with simple topologies is proposed. The proposed topologies utilize a hybrid switched capacitor technique for providing a high voltage gain without extreme switch duty cycle and yet enabling the use of a lower voltage and RDS-ON MOSFET switch so as to reduce cost, switch conduction and turn-on losses. Other advantages of the proposed topologies include: continuous input/output current, simple structure and control. The principle of operation in continuous conduction mode and discontinuous inductor current mode are analyzed. Experimental results obtained on a 45-W prototype are also presented.