AC-DC Buck-type power factor correction (PFC) converters are widely applied in low-voltage scenarios. However, they typically suffer from low power factor(PF) and high total harmonic distortions of input current(THDi) caused by the input current dead zones. To solve this problem, firstly, a high PF Buck-type bridgeless PFC converter with hybrid operation modes is proposed by introducing a Buck-Boost converter cell, which operates in the Buck and Buck-Boost modes in the positive and negative half-line cycles, respectively. Although the Buck-Boost cell's efficiency is inferior to that of the Buck cell, the proposed converter can operate in the Buck-Boost mode in the negative half-line cycle, thereby minimizing the dead zones to improve PF and reduce THDi. The proposed converter operates in the Buck mode in the positive half-line cycle, inheriting the high efficiency of the Buck cell. Secondly, the operation modes and PF of the proposed bridgeless converter are analyzed to show its high PF feature. Finally, simulations and experimental tests were conducted to verify the feasibility and theoretical analysis of the proposed converter, and a comparison of performance between the proposed and conventional Buck-type PFC converters was also performed.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |