A High Step-Down Transformerless Single-Stage Single-Switch AC/DC Converter

Abstract

This paper presents a high step-down tranformerless single-stage single-switch ac/dc converter suitable for universal line applications (90-270 V rm s ). The topology integrates a buck-type power-factor correction (PFC) cell with a buck-boost dc/dc cell and part of the input power is coupled to the output directly after the first power processing. With this direct power transfer feature and sharing capacitor voltages, the converter is able to achieve efficient power conversion, high power factor, low voltage stress on intermediate bus (less than 130 V) and low output voltage without a high step-down transformer. The absence of transformer reduces the component counts and cost of the converter. Unlike most of the boost-type PFC cell, the main switch of the proposed converter only handles the peak inductor current of dc/dc cell rather than the superposition of both inductor currents. Detailed analysis and design procedures of the proposed circuit are given and verified by experimental results. Index Terms-Direct power transfer (DPT), integrated buckbuck-boost converter (IBuBuBo), power-factor correction (PFC), single-stage (SS), transformerless.

Low‐power single‐stage power factor rectifier based on discontinuous capacitor voltage mode double‐ended forward converter

“…The theoretical duty cycle was calculated by (14) for the desired conversion ratio μ with K = 94 and η = 0.8. The theoretical value of maximum voltage stress on C 1 was calculated by (20). The theoretical V Q s1 was calculated by (35).…”

“…For ac input, the maximum v Q p2 over half line cycle is V C 1 s /2. V C 1 s is the maximum voltage across C 1 over half line cycle defined by (20). We define a parameter v Q s1 as the maximum v Q p1 over half line cycle.…”

“…To reduce component count and complexity, a number of single-stage ac/dc converters have been proposed [14][15][16][17][18][19][20][21][22][23][24]. The idea is that a boost PFC stage and a cascaded dc/dc converter are combined into one stage by sharing common switches and control circuit to perform input current shaping, isolation and output voltage regulation in a single step.…”

Soft-Switching Two-Switch Resonant AC–DC Converter With High Power Factor

“…In the single-stage AC-DC converters, DC-DC converters such as a buck converter and a boost converter, and their modified versions are adopted as a PFC preregulator. When a buck converter is adopted as a PFC preregulator, high power factor cannot be achieved due to dead angle of the input current [8], [9]. Therefore, its applications may be limited.…”

Study of An Improved Dual-Switch Converter With Passive Lossless Clamping

“…In practical situations, affected by the equivalent series resistance (ESR) of the devices, traditional boost converter is hard to provide a large voltage-conversion ratio [1], [2], a large duty cycle is introduced that brings high conduction loss, and the large peak current may impact the capacitors seriously Various topologies have been developed to provide a high step-up voltage without an extremely high duty ratio [3]- [5]. The isolated converters boost the voltage by increasing the turns ratio of the high-frequency transformer [6], [7]. However, with the multistage dc/ac/dc power conversion, the cost is increased because many isolated sensors or feedback controllers are required.…”