A stand-alone solar LED lighting system usually consists of a DC/DC converter to convert the floating battery voltage into a constant current to drive the LED. A 15% energy loss of the DC/DC converter will be introduced. The DC/DC converter may also increase system costs and reduce system reliability due to its additional components. The present study develops a PWM technique to drive the LED luminaire directly from the battery output using the PWM's constant average current. However, the instantaneous current stress may decrease the overall light efficiency of an LED luminaire when it is driven by a PWM current. The result shows that the overall lighting efficiency loss is between 10.7% to 13.1% for a junction temperature at 70 degrees C when using a 24V battery system. This study shows that the direct PWM driving technique is feasible and able to drive an LED directly from battery output in a stand-alone solar system. Removing the traditional DC/DC converter increases system reliability and reduces system costs.
|Number of pages
|JOURNAL OF THE CHINESE SOCIETY OF MECHANICAL ENGINEERS
|Published - 2009
Bibliographical noteKAUST Repository Item: Exported on 2021-09-16
Acknowledged KAUST grant number(s): KUK-C1-014-12
Acknowledgements: This publication is based on work supported in part by Award No.KUK-C1-014-12, granted by King Abdullah University of Science and Technology (KAUST) and Project No. 97-D0137-1, provided by the Energy Bureau, Ministry of Economic Affairs, Taiwan.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
ASJC Scopus subject areas
- Mechanical Engineering