This paper proposes a new isolated high step-down DC-DC converter based on the phase-shift full-bridge converter. The proposed converter has some properties very suitable for high step-down applications including a high step-down ratio, low transformer turns ratio, low voltage stress on power switches, wide soft-switching range, and no saturation problem. These attractive features are achieved by a simple pulse-width modulation control method and a unique split-capacitor structure on the input side. By split-capacitor structure, both switching voltage and stress voltage are decreased significantly. As a result, the required ZVS energy is reduced greatly, which means that an extended ZVS range can be obtained. This structure also leads to an inherent high step-down ratio, low transformer turns ratio, and de-saturation feature because the primary transformer voltage is decreased to a quarter of the input voltage and there are capacitors in series with the primary winding in power modes. In this paper, the operation principle is presented; the ZVS range and de-saturation feature are discussed in detail. In addition, a comprehensive comparison with some new isolated high step-down converters in the literature is also completed. Finally, a simulation verification using the LTSpice simulation program and an 800 W, 400 V input, and 48 V output prototype are developed and tested to verify the salient features of the proposed converter.

This paper proposes an isolated DC–DC converter to cope with 800 V input voltage and 48 V output voltage conditions of the auxiliary power module in the next generation 800 V electric vehicles. On the primary side, a split-capacitor structure and a series capacitor are utilized while on the secondary side, a current doubler rectifier is designed, which repeats a part of the primary structure. Compared with existing isolated converters, the proposed converter has attractive characteristics: 1) a double step-down ratio; 2) the voltage stress on all primary switches and primary transformer are reduced to half of the input voltage; 3) the power switches have soft-switching capability by ZVS characteristic in the primary side, ZV-ZCS in secondary side; 4) the soft-switching range is wide, which maintained even at light-load conditions. 5) allow reuse conventional devices of 400 V system in the updated 800 V system. These characteristics are achieved with a simple control strategy by the pulse width modulation method for switches on the primary side and only repeating primary gating signals for switches on the secondary side. In this paper, the operation and performance of the proposed converter are presented. Besides, an experiment at 800 V input, 48 V–1.2 kW output is also completed to validate the operation and effectiveness of the proposed converter.

Transformerless inverters (TIs) are widely employed in photovoltaic (PV) applications due to their cost-effectiveness, compact size, low weight, and high efficiency. However, the absence of electrical isolation can result in ground leakage current due to the parasitic behavior of PV systems, resulting in safety concerns and compromised power quality. Conventional five-level common-ground inverters can eliminate ground leakage current through the common-ground technique and achieve double voltage boosting capability. However, this topology necessitates a considerable amount of capacitance to efficiently minimize voltage ripple due to the extended discharge time during the negative half-cycle. Moreover, the high capacitance raises concerns regarding the potential for high current stress on switches during charging modes. In this article, a new single-stage common-ground boosting transformerless inverter is introduced. The proposed topology has fewer components, a lower number of conducting devices, and reduced capacitance requirements. The proposed topology can also be extended to three-phase applications using a single power source. The article includes explanations of the proposed topology, the control method, the component design process, and the power loss calculations. In addition, a comparison with similar topologies is conducted to highlight the advantages and disadvantages of the proposed topology. Simulation results are included to confirm the functionality and practicality of the proposed topology. Finally, experimental results for a 500-W prototype operating in a closed-loop system under different loads and load changes are presented. The converter demonstrates its capability in both buck and boost modes, achieving a high efficiency of over 95%.

Multilevel inverters are widely used in renewable-energy conversion systems; however, many existing solutions rely on additional DC-DC boost stages, multiple isolated sources, or bulky transformers. This paper proposes a transformerless six-level switched-capacitor inverter supplied by a single DC source. The proposed topology integrates a reduced-switch-count power stage with a switchedcapacitor structure employing floating capacitors and diodes to achieve a voltage boosting gain of 2.5 without using inductive components. The floating-capacitor voltages are naturally balanced by the defined charging and discharging sequence of the switching states, eliminating the need for voltage sensors or auxiliary balancing control. The voltage stress of the switches and floating capacitors in the switchedcapacitor network is limited to the input-voltage level, resulting in a competitive total standing voltage and improved efficiency. The inverter generates a high-quality six-level output waveform with a lower component count compared to conventional switched-capacitor multilevel inverters. Furthermore, extended configurations for higher voltage gains and a three-phase implementation sharing a common dc-link are presented to demonstrate scalability. Detailed operating principles, modulation strategy, and design considerations are discussed. Simulation and experimental results confirm the feasibility and effectiveness of the proposed inverter for low-voltage photovoltaic applications.

This paper proposes a single-stage common-ground series-capacitor-compensated buck–boost inverter (CG-SCC-BBI) for wide-input DC–AC applications. Featuring a common-ground neutral and a series-blocking film capacitor, the topology inherently suppresses high-frequency common-mode leakage-current excitation and blocks the structural DC offset. To counteract frequency-dependent voltage attenuation caused by the output network, a fundamental-frequency equivalent model is derived to pre-scale the modulation reference and fully restore output voltage amplitude. The four-switch power stage operates with single-active-leg PWM, confining high-frequency switching to a single half-bridge at any instant to significantly reduce the switching-loss budget. Furthermore, by eliminating the conventional line-frequency output filter choke and utilizing film capacitors exclusively, the topology completely avoids electrolytic capacitors, thereby enhancing long-term operational reliability and lifespan. The proposed inverter supports seamless transition between boost and buck operating modes across the entire input-voltage range. Its operating principles are validated through time-domain simulations, and these were experimentally verified on a 300 W SiC MOSFET standalone laboratory prototype. Experimental results confirm correct operation from 95 V to 400 V DC input, achieving maximum measured efficiencies of 96.79% at the rated 300 W under low-input operation and 97.66% at the rated 300 W under high-input operation, while maintaining an output-current total harmonic distortion (THD) below 2.5%.