A study of Power-driven LED and Protective Control Circuit
Date Issued
2008
Date
2008
Author(s)
Du, Bo-Han
Abstract
The main purpose of this research is to investigate the protective circuit of the high power LED in order to prevent LED from being permanently damaged. During the abrupt breakdown of LED or the ambient temperature change, the controller will adjust the output power from the power supply to avoid the rise of the junction temperature of LED. High junction temperature may cause the permanent breakdown of LED easily.his plant of the control system is a 100W LED street light. The controller designed by PIC microprocessor maintains the output power stable. At first, the system dynamics model for a LED luminaire is constructed. The feedback control system using PI control is designed and analyzed according to stability criterion and simulating. At last, optimal parameters in the controller can be determined, and successfully stabilized the system.s for the protective circuit, the controller can detect the sudden breakdown and the junction temperature of LED through output voltage and then adjust the power output accordingly. The controller with system diagnosis can prevent the probability of misjudgments. xperimental results show that the control system can maintain the output power stably at 100W?2W in normal conditions even with the variation of surrounding temperature. Moreover, when one column of LED is damaged or when the junction temperature is too high, the controller can detect the situation and turn down the output power. This will avoid the overload of LED and light decay.
Subjects
LED
Protective Control Circuit
Type
thesis
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