An Improved Bridgeless SEPIC Converter Without Circulating Losses and Input-Voltage Sensing

In order to overcome the drawbacks of conventional bridgeless single-ended primary inductance converter (SEPIC) power factor correction (PFC) circuits, an improved bridgeless SEPIC PFC circuit is introduced by adding an additional output diode and an inductor. The undesired capacitive coupling loop and the circulating loss are removed. Thus, the high efficiency can be achieved. The operation principle and design consideration of the proposed converter are introduced in detail. Furthermore, a novel control method is employed to control the current continuous mode bridgeless SEPIC PFC circuit without input-voltage sensing. Meanwhile, the UCC28019-based modified hardware implementation circuit is designed and described. A 100-W prototype with 90–135 V
_rms
input line voltage and 60-V output voltage is built and tested. The corresponding experiment shows the validity of the proposed circuit topology and control strategy. A peak efficiency of 94% and power factor above 0.99 are achieved under 65-kHz switching frequency operation condition.