A high efficiency driver is designed for light emitting diode (LED) street lamps in the thesis. The main power conversion circuit employs a phase-controlled rectifier to convert the power from the ac mains of 110/220 V, 60 Hz directly into a dc source, providing the required output current for the street lamps formed by arrayed high brightness white LEDs. The phase-controlled rectifier of the LED driver circuit can be a conventional semi-converter or a rectifier with symmetrical phase control, which makes use of thyristors and power transistors, respectively, to regulate the LED current by means of adjusting the conduction angles in a cycle of the ac line. The phase-controlled rectifiers may exclude the use the bulky electrolyte capacitor with acceptable variation in the chromaticity and the color temperature. Operating at the low frequency, the phase-controlled rectifiers can avoid the problems of electromagnetic interference caused by high-frequency switching and adopt low cost power switches. Furthermore, a relatively high power factor can be achieved when the line source voltage varies within a small allowable range.
The research is targeted to a design of a 200 W LED street lamp. To facilitate the changes of the control functions and circuit parameters, the control circuit is realized with a microcontroller. In addition, over-voltage/current protections can be included easily. Experimental results demonstrate that the phase-controlled rectifiers with appropriately designated circuit parameters can approach a power factor of 0.92 and a circuit efficiency of 93% at the rated output.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0813112-062507 |
| Date | 13 August 2012 |
| Creators | Lin, Wen-Chih |
| Contributors | Horn-Nan Chen, Jen-Hao Teng, Jia-You Lee, Chin-Sien Moo, Jiann-Fuh Chen |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0813112-062507 |
| Rights | user_define, Copyright information available at source archive |
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