| Summary: | 碩士 === 明志科技大學 === 機電工程研究所 === 100 === LED is well expected for lighting thanks to the energy-saving and environmental pollution-free of the LED light source. The commercial LED light sources are drived by driver composed of constant current IC, electrolytic capacitor and resistance as well as the AC/DC transformer. The cost of the driver is about 15 to 20 % of a whole LED light source. Moreover, the electrolytic capacitors used within the driver would shorten the life of LED lighting source. In this study, a full-wave bridge rectifier composed by LEDs is developed for directly driving the LED light source without electrolytic capacitor. Four schemes of the LED light bulb sources are derived and then tested for its electrical and optical properties. The comparison of the developed LED bulb light sources and the commercial ones are taken finally. The pulse waveform of the DC is formed by the LED composed bridge full-wave rectifier. The theoretical voltage ripple and ripple factor of this bridge full-wave rectifier can be derived. The bridge full-wave rectifier is built by the 24 pieces of LED and then connected to the parallel strings. Each string has 30 pieces of LED. Results show that the luminous flux of each LED within the bridge full-wave rectifier is 3.6 (lm), while the one in the 30 pieces of LED is 4.9 (lm). The scattering structure of the plastic cover may reduce the luminous flux of 17%. Besides, the efficiency and luminous flux of the cool white LED bulbs light source with the scattering plastic cover are 82 (lm/W) and 328 (lm), respectively. A 7W bulb light source composed by 5630 LEDs is driven under constant current situation by LM 317 IC. The constant current is obtained successfully by varying of the input AC voltage. This study shows well in development of the non-isolated driver without electrolytic capacitor for LED bulbs light source. The contribution of this study is therefore concrete.
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