Hamed Moradmand Jazi

This paper introduces a non-isolated high step-up DC–DC converter suitable for distributed generation system applications. The proposed topology uses the zero-voltage-transition (ZVT) technique to achieve soft-switching conditions over a wide range of output power levels, resulting in improved efficiency and reliability. Since the main switch turns on under ZVS conditions, the capacitive turn-on loss is eliminated, thereby reducing switching losses. In addition to the soft-switching capability, the converter provides a continuous input current, which reduces the input filter requirement and improves both power density and cost-effectiveness. Moreover, the converter design effectively increases the voltage gain by utilizing coupled-inductor, switched-capacitor, and voltage-multiplier techniques, allowing the proposed converter to be used in high-voltage applications. The proposed converter employs an independent input inductor and a four-winding coupled inductor implemented using two magnetic cores. Furthermore, the proposed converter features lower voltage stress across the switches, enabling the use of cost-effective, low-resistance MOSFETs, which further improve efficiency. Finally, a common ground structure, the absence of floating switches, and the elimination of the reverse-recovery problem in all diodes are additional valuable advantages of the proposed converter. Comprehensive analytical investigations, together with experimental evaluations conducted at a power level of 200 W, demonstrate that the proposed converter achieves enhanced performance characteristics and outperforms previously reported converter topologies.

In this article, a fully soft switched high step up three level converter based on a Quasi-impedance source is introduced for use in photovoltaic applications. In the proposed converter, since an active switch is used instead of the diode in the impedance network, conduction loss associated with the diode is reduced, and zero-voltage-switching characteristics are provided in a wide range of output power for power switches, resulting in the improvement of efficiency. The proposed converter takes advantage of three level structure and it experiences much lower voltage stress on semiconductor elements compared to existing high step-up structures. This allows the use of mosfets with lower on the resistance, leading to reduced conduction losses and cost. Furthermore, the boost inductor in the input section not only maintains continuous input current, avoiding the need for bulky input capacitors, but also significantly optimizes power density and reduces cost. Other advantages of the proposed converter include high voltage gain with low duty cycle and the ability to turn off all diodes under ZCS condition. Experimental results from a 200-W laboratory prototype are provided to validate the proposed converter’s performance.

This paper presents a non-isolated high step-up DC-DC converter that achieves a high voltage gain through the application of coupled inductor and multiplier techniques. Also, in this topology continuous input current and a shared ground between input and output is obtained which enhances reliability of the proposed converter. Moreover, by utilizing ZVT technique, soft switching performance for both switches are achieved across the entire range of output power which reduces switching losses and improves efficiency significantly. Furthermore, the output diodes of this converter are turned off under ZCS condition, considerably reducing reverse-recovery losses. The paper includes an analysis of the proposed converter’s operation, a comparative study with existing high step-up converters and experimental results for 200 W laboratory prototype.

This paper presents a novel single-switch soft-switching high step-up DC-DC boost converter. By utilizing a coupled inductor and series capacitors in the output stage, the converter achieves soft switching performance for the power switch during turn-on and turn-off, along with a high step-up voltage gain. The design of the coupled inductors enables simultaneous achievement of soft switching and high voltage gain without the need for additional auxiliary circuits, ensuring circuit simplicity and high efficiency. Furthermore, the converter maintains continuous input current, similar to a boost converter, improving battery lifespan and renewable input power source operation. The proposed converter addresses diode reverse recovery issues and incorporates a common ground between input and output stages, simplifying the feedback circuit. Comparative analysis with similar high-efficiency high step-up boost converters is performed, and a 200W laboratory prototype is implemented.

In this article, a novel soft switched interleaved boost structure with a simple auxiliary circuit is proposed which is suitable for stand-alone loads or ac grid applications. In this topology, coupled inductors and switched capacitor cells of parallel modules are merged to obtain high voltage conversion ratio. The converter also has the capability of adding extra switched capacitor cells to attain very high voltage gain. To provide soft-switching condition in the wide range of output power, a new zero-voltage transition auxiliary circuit is employed which is responsible for soft switching of both phases and benefits from low conduction losses, the minimum number of semiconductor elements, and only one auxiliary gate-driver. These merits provide very high efficiency at both full-load and light loads. More importantly, no auxiliary magnetic components are utilized by taking advantage of the leakage inductance of coupled inductors for the resonant network. All semiconductor components operate under soft switching alleviating the reverse recovery problem and switching losses. Besides, the converter benefits from common ground between input and output which simplify voltage feedback. The experimental results of the interleaved converter prototype with 400-V output voltage at 400 W and 100 kHz switching frequency are provided. The full load efficiency of 98% was achieved and the power density was observed 1.9 W/Cm ³ .

In this paper a high-efficiency, high step-up DC-DC converter is introduced utilizing a new soft switching circuit based on the zero voltage transition (ZVT) technique. Soft switching performance is independent of the output load and input voltage. The simple auxiliary circuit benefits from a low number of components. The resonant circuit comprises merely one switch and one small capacitor and in comparison to the existing ZVT high step-up converters, no extra auxiliary diode and resonant inductor are used to provide soft switching. The proposed auxiliary circuit can be applied to coupled-inductors based step-up topologies, because of exploiting the leakage inductance of the coupled-inductor cell in the resonant network. Providing soft switching performance for all the semiconductor elements alleviates the reverse recovery and switching losses, which considerably enhances the efficiency. The proposed topology is a competitive structure in terms of efficiency, voltage gain ratio, and the number of components due to the mentioned features. The theoretical results are validated on a 200 W laboratory prototype with a 400 V output voltage.

Increasing the voltage gain by means of Z-source network will provide some features such as low voltage stress of semiconductor devices, low duty cycle of the switch and low reverse recovery problem of output diode that leads to improve the converter performance and efficiency. The proposed converter in this paper employs a Z-source network with coupled inductors integrated with flyback converter to make it appropriate for high step-up applications. One magnetic element is used in this converter, which is its main advantage over previously introduced Z-source converters. Steady state analysis and operation principles of the proposed converter in continuous conduction mode that leads to low current ripple, and low conductive losses for semiconductor devices due to decreasing the RMS currents are presented. In order to verify the theoretical analysis, experimental results of a prototype are provided. This converter’s high voltage conversion ratio will result in 300 V output from 20 V input voltage source for 100 W output power.

Here, a soft switched three‐level boost converter with high voltage gain is proposed which is suitable for high step‐up applications with wide output power range. In this converter, a ZVT auxiliary circuit is used which provides soft switching in a wide range of output power independent of load variation. Utilizing coupled‐inductors with one magnetic core removes extra auxiliary core in the soft switching circuit and provides high voltage gain in conjunction with size reduction. Also, the secondary and tertiary leakage inductances of the coupled‐inductors minimize the reverse recovery problem of the output diodes. Due to its three‐level structure, it has very low voltage stress over semiconductor elements in comparison to the existing interleaved structures, resulting in using MOSFETs with low on‐resistance and thus lower conduction losses and cost. Operating modes as well as analytical analysis of the proposed converter are discussed. Finally, in order to validate the proposed converter performance, experimental results from a 200‐W laboratory prototype are presented.