| Summary: | 碩士 === 義守大學 === 電機工程學系碩士班 === 99 === Compared with traditional lighting sources, the light-emitting-diodes (LEDs) have features of smaller size, longer lifetime, higher brightness, harder to be broken and free of mercury; they are suitable for energy-saving lighting applications nowadays. The traditional three-stage LED driver is composed of an AC-DC boost converter for power factor corrections, an isolated DC-DC converter as a power control stage, and a buck converter for achieving constant current control. The drawbacks of the conventional driver are bulky volume, large losses, and large number of circuit component.
The interleaved boost converter operated in discontinuous mode allows the input current in phase with input voltage for achieving high power factor and obtaining zero-voltage-switching. The LLC resonant converter has the advantages of low switching losses, high efficiency and low electromagnetic interference, etc., so the converter is widely used in various power conversion systems. The proposed driver in the thesis, which combines above two converters into a single-stage structure, not only has the advantages of both converters, but also reduces the number of circuit component. Finally, experimental results from a prototype driver are compared with simulated ones from the IsSpice software to verify the feasibility of the presented circuit.
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