해상용 고휘도 LED 등명기의 방열 시스템 개발에 관한 연구

Abstract

In the Korean coast and approaches many types of light aids to navigation have been installed and been operated to guide vessels into fairways, channels, or harbours safely and to identify the hazards to navigation. Because the aids to navigation lights give the information of their position, the lamps of them are not heavy and driven with a low electric power and their luminous intensity has to be more than the given value.

In the past the electric bulbs were used as the sources of light. The disadvantage of them is that they have are usually replaced by new ones frequently and also need a high electric power. Because of this the LEDs have been introduced and have the advantage of a long life and low power. The problem is that they are not suitable for the lamps with a high luminous intensity. Nowadays the aids to navigation lights need LED lamps with a high luminous intensity of more than 1 W. The demerit of the high intensity LED is that it consumes a high power and also radiates a high heat which drops its intensity and reduces its lifespan.

This paper is to develop the thermal management or cooling system in the LED lamp with high luminous intensity of more than 1 W to solve the problem of high heat, The target of the system is to maintain the temperature of less than 50 ℃ and the luminous intensity of 1500 cd. The high temperature of more than 50℃ causes the deterioration of luminous intensity and the reduction of the lifetime of LED lights. The procedure of developing the system is done as follows. Firstly, this paper is to develop two types of heat sink, considering the enclosed structure of the maine lamp, limited supply of electric power, weight and size. The heat radiation of the two heat sinks are examined by simulation respectively. And then through experimental test they are investigated again. The result shows a temperature of 62.2 ℃ in the junction of the LED.

Secondly, to drop the temperature the cooling fan is added to the heat sink. The heat radiation of the cooling system by a fan is examined through simulation as similarly as in the heat sink. And also the experimental test is carried out. The result shows that the LED light keeps temperature of some 34 ℃ and works satisfactorily. However the cooling system has a disadvantage of additional power for driving the cooling fan. To minimize the consumption of power the control circuit of on-off method is devised.

The paper is to limit the heat sink, only two types of it and the material of aluminum. It means that the thermal management is not sufficient. We can consider the heat pipe instead of heat sink, various types heat sink of different fin intervals, and other material like copper. These will be dealt with in the future study.