LED Driving Circuit with Stand-Alone Photovoltaic Power

• Main Authors: Hsuan Liao, 廖軒
• Other Authors: Chin-Sien Moo
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/aspx69

碩士 === 國立中山大學 === 電機工程學系研究所 === 103 === The research proposes an LED driving circuit with stand-alone photovoltaic (PV) Power. A bi-directional converter is incorporated to adequately distribute powers among the solar-cell panel, the battery and the LED lamp according to the sunshine intensity, the battery state-of-charge as well as the load requirement. The proposed LED driving circuit is applied to two exemplar applications of the traffic light and the garden light. By matching the voltage-current (V-I) characteristic curves, the capacities of the solar-cell panel and the battery are specified to mostly operate the solar-cell panel around the maximum power point. The traffic light needs to work 24 hours a day. During the daytime with strong sunshine, the solar-cell panel is operated near the maximum power point, providing the LED power and delivering the excess energy to the battery. If the battery might not have enough power to supply what LEDs need at night, then the load shedding and battery can have more power. However, the solar-cell panel doesn''t have enough power to the load, the battery set would supply what the load required. The garden lights work at night. All the power from solar-cell panel needs to store in the battery with the bi-directional converter, providing LED power from battery. User also can decide whether turn the garden lights off or dimming. To verify the theoretical analyses of the LED driving circuit, a laboratory system is set up for experimental tests. The tested results demonstrate that the system can perform the designated functions in accordance with different states. The measured efficiencies are always over 88%. The maximum efficiency is 97% when the solar-cell panel provides power to the LED strings.