In this paper, a new high voltage gain step-up dc-dc converter is proposed for interfacing renewable power generation. The configuration optimally integrates both the coupled-inductor and switched-capacitor techniques to achieve an high step-up gain of voltage conversion with low voltage stress and high efficiency. It consists of a voltage boost unit, a passive clamp circuit, and a symmetrical voltage multiplier network. The structure becomes modular and extendable without adding any extra winding for ultra-high step-up voltage gain. The proposed topology not only reduces the voltage stress on the main switch but also maintains it steady for the entire duty cycle range. Furthermore, the reverse recovery issue of the diodes is alleviated through the leakage inductance of the coupled inductor. The operation principle and steady-state analysis are presented in detail. Experimental evaluation validates the claimed advantages and demonstrates a well-distributed efficiency curve and the peak of 96.70%.

A family of transformer-less single-switch dual-inductor high voltage gain boost converters is proposed in this paper. The proposed configurations can realize high voltage gain with low voltage and current stresses. The voltage gain of the proposed converters is analogous to the switched inductor boost converter; therefore, the proposed boost converters are suitable for high gain applications. The proposed family of converters has low component counts and reduced voltage stress on devices compared to three typical transformer-less single-switch high voltage gain converters including switched inductor boost converter, quadratic boost converter and quasi-Z-source boost converter. Moreover, the current stress of the front-end diode and the rear-end inductor is also relatively low. Therefore, the conversion efficiency is enhanced while keeping the cost low. The operation principles and steady-state characteristics analysis of the proposed converters under the inductor current continuous conduction mode (CCM) and continuous bidirectional conduction mode (CBCM) are discussed in detail. A prototype of 300V, 250W/100kHz is developed to verify the performance of the proposed converter. The experimental results substantiate the effectiveness and advantages. The prototype achieves a peak efficiency of 97.5%.

A DC-DC converter is proposed to achieve a high voltage conversion ratio for bidirectional power flow applications. The non-isolated topology is optimally designed to integrate both the switched capacitor and coupled inductor techniques for high efficiency. The windings of the coupled inductor are stacked at the low voltage source, which transfers any leakage energy of the coupled inductor directly into the output port and simplifies the clamping circuit. The optimal design keeps the voltage stress on the main switches low for the entire duty cycle operation. Thus, the converter demonstrates the advantage of wide-voltage gain based on common ground and low and steady voltage stress in both buck and boost modes of its operation. Furthermore, the converter can realize zero voltage switching (ZVS) through the synchronous rectifiers without requiring extra hardware circuitry to enhance conversion efficiency. The operation principle, including the steady-state analysis, dynamic modeling, controller design, efficiency analysis, and optimization, are discussed in detail and verified by the experimental test. The prototype substantiates the theoretical analysis and soft-switching operation. The converter exhibits the capability for load and line regulation and demonstrates a peak efficiency of 96.38% in the boost mode and 95.61% in the buck mode of operation.

This article proposes a high-gain flyback-type microinverter for photovoltaic (PV) power generation. The proposed topology integrates a voltage-doubler circuit with the flyback converter to produce the high voltage conversion gain. The solution is effective to minimize the high demand of the winding turns ratio in the flyback transformer. Besides, an active-clamp circuit is employed in the primary side for the resonant operation. The solution reduces the voltage and current stress and supports zero voltage switching of the power switching. The stress reduction achieved by the resonant operation further minimizes the conduction loss of the converter. A prototype is constructed and tested to show the experimental performance, which verified the advantages of the proposed solution for PV microinverter applications.

This study proposes and analyses the integration of soft‐switching technique with a single switch, non‐isolated, coupled inductor DC–DC converter to achieve high efficiency and high step‐up conversion ratio. The topology optimally integrates the coupled inductor and soft‐switching technique using a parallel LC resonant tank circuit to maintain zero‐current switching (ZCS) for on/off switching. The leakage inductance of the coupled inductor alleviates the reverse‐recovery issue of diodes, and diodes can operate under ZCS condition. Moreover, the converter operates in a lower frequency range due to high step‐up voltage gain. The principle of operation and steady‐state analyses of the proposed converter are presented. A prototype validates the theoretical analysis and demonstrates a higher peak efficiency of 96.43% than the corresponding hard‐switched converter.

With the rapid development of photovoltaic systems, high step‐up dc–dc converters draw significant attention, which shows the design challenges for simple topology, high efficiency, reduce voltage stress, and long lifespan. This study proposes a new high voltage gain converter that utilises the primary boost conversion cell and integrates with both switched‐capacitor and coupled‐inductor techniques. The proposed topology is modular and extendable for ultra‐high step‐up voltage gain. The leakage energy is recycled by a clamp circuit to minimise the switch voltage stress and power loss. One distinctive feature is that the voltage stress on the diodes and switch becomes low as well as constant against the variation of the duty cycle. Furthermore, the coupled inductor alleviates the diodes reverse recovery losses. The steady‐state analyses, operation principles, and design guidelines are presented comprehensively. A prototype circuit is constructed to test the maximum power point tracking operation with voltage conversion from 30 to 380 V at 300 W. Experimental results substantiate the theoretical analysis and claimed advantages. The proposed converter demonstrates maximum power point tracking capability and high conversion efficiency over a wide range of power. The prototype shows the weighted efficiency of 96.3% according to the EU standard.