Analysis of LED street light solutions using graphite instead of aluminum substrate for heat dissipation

This solution includes LED constant current drive power supply . The circuit is connected in single series or parallel mode. The power supply efficiency is as high as 93% and the power factor is more than 90%. Compared with other solutions, this solution is more efficient and less costly. In terms of heat dissipation, this solution uses a new type of thermal conductive material to replace the traditional aluminum substrate, which greatly improves the heat dissipation effect of the product, reduces light decay, and ensures that the LED lamp is more stable. At the same time, this solution also provides a lamp breathing system to ensure the free exchange of gas inside and outside the lamp. In terms of light source, we can provide a full range of products with a light efficiency of 60--100LM/W and a color temperature of 2800-7000K. The products are widely used in street lights, tunnel lights, spotlights, downlights, flashlights, etc.

Solution Introduction:

1. LED Driver: NXP, R ic htek, Infineon, Microchip

A. LED street light Solution (smart solution): NXP+MICROCHIP

Currently, TEA1750 (NXP) + DSP IC30F2020 (Microchip) is used to implement multi-channel LED street lights and tunnel lights. The fully intelligent control multi-channel LED street light solution can automatically control the light brightness according to the needs of the surrounding environment, and each channel can be dimmed individually. It can realize functions such as temperature sensing, Usart communication , daylight sensing dimming, and key input.

The principle of dimming is to adjust the output current by adjusting the PWM duty cycle, and the full software can achieve stepless dimming. This solution can ensure the balance of current in each channel, and only requires one IC, which is lower in cost compared with similar multi-channel constant current solutions.

DEMO( Picture ) ：

B. LED street light solution (primary conversion): Infineon + NXP

IFX IC is used to implement a unipolar PFC solution to drive a single string of LEDs. Compared with other solutions, this solution has higher power conversion efficiency and lower overall cost. At the same time, in order to ensure the stability of the single string LED circuit , an LED protection circuit is provided. When one or more LED lamps are damaged (open circuit), other LED lamps are not affected, minimizing the impact of the bad lamp on the overall circuit.

Product appearance:

C. LED street light solution (secondary conversion): RICHTECK

We use NXP IC to achieve constant voltage conversion of AC-DC, and RICHTECK constant current IC is used for secondary conversion to achieve constant current output of 0.35A-1.5A. This solution can output 60V high voltage and 1.5A high current, and the overall cost is cheaper. At the same time, RT8450 has two dimming methods to meet various dimming needs. 1. Adjust the light output by adjusting the current flowing through the LED. The advantage is that the output is stable and the probability of encountering EMI problems is low. The disadvantage is that when the current flowing through the LED is different, the chromaticity of its light output will change. 2. Adjust the light output by adjusting the time ratio of the constant current flowing through the LED. Its advantages and disadvantages are just the opposite of method 1.

2. LED heat dissipation solution (graphite material)

We use graphite material to replace the traditional aluminum substrate for heat dissipation. The thermal conductivity of this material is twice that of the aluminum plate. Different from the heat conduction method of metal spheres such as copper and aluminum, it adopts horizontal heat conduction method to effectively ensure the thermal uniformity of the product.

Appearance:

Graphite material molecular structure DEMO board

3. Respiratory system

LED street lights and tunnel lights are required to meet IP65 rating (waterproof and dustproof), and the fully enclosed environment prevents gas exchange between the inside of the lamp and the outside environment. When LED lamps work for a long time, the temperature and pressure inside the lamps increase, which creates a pressure difference with the outside air, increases the pressure on the inner wall of the lamps, and accelerates the aging of the lamps. We use a special breathing system that can completely solve the problem of pressure imbalance inside and outside the lamps, and further improve the stability of the lamps.

This solution can filter water molecules and dust from entering the lamp, allowing air molecules to flow freely inside the lamp and the external environment.

Overall effect diagram

Summarize

The article first selects the street lamp drive system through three LED drive solutions, including the selection of LED driver chips and dimming application methods. The method of using graphite materials to replace the traditional aluminum substrate heat dissipation is a development trend and an important reference for future LED lamp design.