Abstract
This paper presents and analyzes an AC-DC power converter structure, which is comprised of a Power Factor Correction (PFC) module and a LLC resonant DC-DC converter module. This converter only uses two switches, and requires three less diodes and one less switch compared to popular LLC resonant converter solutions. Compared to its conventional counterpart, the rectifier of interest has high energy efficiency while a smaller size, owing to the soft-switching in the LLC resonant converter. Detailed theoretical analyses are conducted in this study, followed by software simulation and hardware experimentation, which demonstrate that the single stage double-switched (DS)-LLC rectifier is able to realize unity power factor and a wide output range, indicating its effectiveness and applicability.
Highlights
Due to unique advantages, LED lighting has been recognized as the most promising fourth-generation lighting solution, which has seen rapid development in recent years [1]–[3].low efficiency and high cost are deemed the biggest problems in current LED drivers, especially for highfrequency operations
LLC resonant converters are often used as LED drivers in high-frequency conditions
Since the LLC resonant converter works in a wide frequency range, the switching frequency fS may affect the realization of the Power Factor Correction (PFC) in pre-stage PFC module
Summary
LED lighting has been recognized as the most promising fourth-generation lighting solution, which has seen rapid development in recent years [1]–[3]. Taking the positive half cycle as an example, when the switch S1 is turned on and the S2 is turned off, the operation of the converter is shown, and the relationship between inductor current and the input voltage can be expressed as: va. When switch S2 is turned on and S1 is turned off, the operation of the converter is as shown as Fig. 9, and the relationship between inductor current and output voltage of the pre-stage can be expressed as: uL. To ensure the PFC module is functional, the inductor current should be reduced by adjusting vCd, that is, the energy stored in the inductor is transferred to the linking capacitor vCd. The following relationship shows the vCd and other factors, and the average input power of every switching cycle during the positive half-frequency cycle is: 2N Pin = T Um sin (π n/N )iLP(d1 + d2)TS/2, (15). The relation between vCd and L can be analyzed with a similar procedure
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