This article proposes a high step-up dc–dc converter with a continuous input current that is suitable for sustainable energy systems. A three-winding coupled inductor, two power switches, three diodes, and three capacitors are utilized to perform the functions of active switched inductor and switched capacitor. By charging the two primary windings in parallel, and discharging the two primary windings in series to the intermediate capacitor and the output, the conversion ratio can be further improved with lower voltage stresses and current stresses on its power switches. In addition, the energy stored in the leakage inductance is recycled to reduce the voltage spikes of the power switches. Eventually, a laboratory prototype with an input voltage of 36–48 V, and output voltage of 400–600 V with a rated power of 600 W is implemented to validate the correctness and effectiveness of the theoretical analyses. The maximum efficiency and full load efficiency are 97% and 96.2%, respectively.

In this article, an ultrahigh step-up quadratic boost converter is proposed for photovoltaic systems. By integrating with a coupled inductor and a voltage multiplier, the voltage gain can be improved significantly without high turns ratio and the voltage stress across the power switches are alleviated. Thus, low on-resistance of the power switches is available to enhance efficiency. Common ground structure of quadratic boost and synchronous operation of the two switches facilitate the control. Also, the continuous input current promotes the maximum power point tracking (MPPT). Detailed description of the operation principles and steady-state analysis of this converter in continuous conduction mode and discontinuous conduction mode are presented. A 250-W rated laboratory prototype is fabricated and verified, demonstrating a maximum efficiency of 96.5%. Moreover, the dynamic response is tested to prove the stability of the proposed converter. Finally, a simulation is built to evaluate the feasibility of MPPT function.

In this paper, a high step-up dc-dc converter is presented. The proposed converter features a with high voltage conversion ratio and high efficiency with a reasonable duty cycle by adopting an active switched inductor and a coupled inductor. The voltage stresses on the power switches are lower, and with the energy stored in the leakage inductor being recycled, its efficiency is improved. Moreover, current stresses of the power switches are greatly reduced as caused by inductors parallel charging and series discharging on the active switched inductor. Loss analyses of its components are also presented. A comparison including component counts, voltage gain and voltage stresses of power switches with other relevant converters are analyzed. Eventually, a laboratory prototype with an input voltage of 24 V-36 V and an output voltage of 400 V with 400 W rated power is implemented to validate the correctness and effectiveness of the theoretical analyses.

This paper proposes a non-isolated three-port converter which integrates the input port, battery port, and load port into one converter for renewable energy applications. The coupled inductor and switched capacitor are used to achieve high voltage gain and three power switches can be utilized to realize the power flows between the sources, the battery, and the load. The energy stored in the leakage inductance is recycled to reduce the voltage stress of the power switch. In addition, various operating stages are analyzed and design considerations are presented. Compared to the relevant converters, the proposed converter can realize power flows and achieve high voltage gain by using few components. Finally, a laboratory prototype of the proposed converter with input port voltage 24 V, battery port voltage 48 V, and output voltage 400 V with 200 W rated power is implemented to validate the feasibility and effectiveness of the theoretical analyses.

This article proposes a systematic method to construct three-port converters (TPCs) and bidirectional three-port converters (BTPCs) by integrating two dc–dc converters including nonisolated and isolated types. By adding extra one power switch and one diode, the TPCs can be constructed by the dc–dc converters. A series of the proposed TPCs can provide independent power flow control of single-input to single-output, single-input to dual-output, and dual-input to single-output. By adding extra two power switches, the BTPCs can be constructed by the dc–dc converters. The power flows between any two ports can be controlled bidirectionally without significantly altering their architecture. Finally, a typical nonisolated BTPC is analyzed and implemented with rated power of 300 W and three ports voltages of 48, 72, and 200 V to verify the feasibility and effectiveness of the theoretical analyses. The highest measured efficiency is 98.4%.