| Summary: | 碩士 === 義守大學 === 電機工程學系 === 101 === Compared with traditional lighting sources, the light emitting diode (LED) 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. Usually, commercial LED drivers for street lighting applications are three-stage or two-stage circuit topology. The disadvantages of conventional LED drivers are the large volume, large numbers of circuit components, and limited circuit efficiency due to multi-stage power conversions.
Therefore, this thesis presents a single-stage LED driver for street lighting applications with high power factor, which is combined an improved bridgeless converter with a half-bridge LLC resonant converter. The features of the proposed LED driver are reduced numbers of circuit components, cost-effectiveness, and high efficiency. In addition, the inductor of the improved bridgeless converter is designed to be operated at discontinuous conduction mode (DCM) in order to naturally obtain high power factor and low total harmonics distortion of input current (THD). Moreover, the half-bridgeless LLC resonant converter has soft-switching function to lower the switching losses resulting in high circuit efficiency.
Besides, descriptions and analysis of the proposed LED street lighting driver are included in this thesis and a prototype driver for providing with a 144W LED street lighting lamp has been implemented and testified. Finally, experimental results are compared with the IsSpice-based simulated ones in order to verify the functionality of the presented circuit.
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