Comparison of 5 radiators of indoor LED lighting fixtures
At present, the biggest technical problem of LED lighting fixtures is heat dissipation. Poor heat dissipation has led to LED driving power supplies and electrolytic capacitors that have become shortcomings in the further development of LED lighting fixtures, and the cause of the premature decay of LED light sources.
In the luminaire solution using LV LED light source, because the LED light source works in a low voltage (VF=3.2V), high current (IF=300～700mA) working state, it generates a lot of heat, and the traditional luminaire has a small space and a small area. It is difficult for the radiator to dissipate heat quickly. Although a variety of heat dissipation schemes were adopted, the results were not satisfactory and became an unsolvable problem for LED lighting fixtures. We are always looking for materials that are easy to use, have good thermal conductivity, and low-cost heat dissipation materials.
At present, after the LED light source is powered on, about 30% of the electric energy is converted into light energy, and the rest is converted into heat energy. Therefore, to export so much heat energy as soon as possible is a key technology in the structural design of LED lamps. The heat energy needs to be dissipated through heat conduction, heat convection, and heat radiation. Only by dissipating heat as soon as possible can the cavity temperature in the LED lamp be effectively reduced, and the power supply can be protected from working in a long-lasting high temperature environment, and the premature aging of the LED light source due to long-term high temperature operation can be avoided.
The heat dissipation path of LED lighting
Because the LED light source itself does not have infrared or ultraviolet rays, the LED light source itself has no radiation heat dissipation function. The heat dissipation method of the LED lighting fixture can only extract heat through the radiator closely combined with the LED lamp bead plate. The radiator must have the functions of heat conduction, heat convection, and heat radiation.
Any radiator, in addition to being able to quickly conduct heat from the heat source to the surface of the radiator, the main thing is to dissipate heat into the air by convection and radiation. Heat conduction only solves the way of heat transfer, and thermal convection is the main function of the radiator. The heat dissipation performance is mainly determined by the heat dissipation area, shape, and the ability of natural convection intensity. Thermal radiation is only an auxiliary function. Generally speaking, if the distance from the heat source to the surface of the radiator is less than 5mm, as long as the thermal conductivity of the material is greater than 5, the heat can be exported, and the rest of the heat dissipation must be dominated by thermal convection.
Most of the LED lighting sources still use low voltage (VF=3.2V) and high current (IF=200～700mA) LED lamp beads. Due to the high heat during operation, aluminum alloy with higher thermal conductivity must be used. Usually there are die-cast aluminum radiators, extruded aluminum radiators, and stamped aluminum radiators. Die-casting aluminum radiator is a technology of pressure casting parts. The liquid zinc, copper, and aluminum alloy is poured into the inlet of the die-casting machine, and the die-casting machine is die-casted to cast a radiator with a shape limited by a pre-designed mold.
Die-cast aluminum radiator
The production cost is controllable, and the heat dissipation wing cannot be made thin, and it is difficult to enlarge the heat dissipation area. The commonly used die-casting materials for LED lamp radiators are ADC10 and ADC12. Extruded aluminum radiator
The liquid aluminum is extruded through a fixed die, and then the bar is machined and cut into the required shape of the radiator. The later processing cost is relatively high. The radiating wing can be made many and thin, and the heat dissipation area is expanded to the maximum. When the radiating wing is working, air convection is automatically formed to diffuse heat, and the heat dissipation effect is better. Commonly used materials are AL6061 and AL6063.
Stamped aluminum radiator
is the use of punches and dies to press and pull up steel and aluminum alloy plates to form a cup-shaped radiator. The inner and outer periphery of the punched radiator is smooth, and the heat dissipation area is limited due to no wings. Commonly used aluminum alloy materials are 5052, 6061, and 6063. The quality of stamping parts is small and the material utilization rate is high, which is a low-cost solution.
The heat conduction of aluminum alloy radiator is ideal, and it is more suitable for isolated switching constant current power supply. For non-isolated switch constant current power supplies, it is necessary to isolate AC and DC, high-voltage and low-voltage power supplies through the structural design of the lamp in order to pass CE or UL certification.
