Analysis and Design of Single-Stage AC/DC LLC Resonant Converter
Date Issued
2009
Date
2009
Author(s)
Li, Zhu-Rong
Abstract
A conventional power supply was designed with two stages, the former stage function as a power factor corrector (PFC), and the latter stage is a DC/DC converter which regulates the output voltage of the system. However, the cost and energy conversion efficiency of the two-stage system is higher than a single-stage one.LC resonant converters not only have characteristics of high efficiency and low noise but also are easy to control. This circuit topology is becoming more and more widely used in application of power conversion. The duty cycle of both MOSFETs of a LLC converter is 50% that is different from a traditional PWM converter. The output regulation is control by modulation of frequency, in the ZVS region, the energy from primary side to load increases as the switching frequency decreases.n this thesis, a single-stage LLC resonant converter which combines a boost-type PFC cell and an LLC resonant DC/DC cell is proposed. The control method of it is the same as a conventional LLC resonant converter that regulate output voltage by modulating switching frequency. When the load increases, the switching frequency decreases so that the LLC gain increases and more energy can be transferred by input inductor due to longer charging time. The proposed circuit could not only reduce components and circuit size but also increase the power conversion efficiency.t has no control of the voltage of the DC-bus capacitor because there is no separate converter that can control it as there is in a two-stage converter. The capacitor voltage is dependent on the energy equilibrium established between the energy flowing into the capacitor from the input inductor and the energy flowing out of the capacitor and transferred to the output. Therefore, the characteristics of LLC tank are investigated and a new LLC design consideration is proposed, which insures the DC-bus capacitor voltage can be kept in a tolerable region.inally, an experimental circuit is implemented to verify the analysis.
Subjects
single-stage
LLC resonant converter
power factor
total harmonic distortion
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-98-R96943149-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):d3d0c7329ef495dba33f380923736176