High-performance low-cost LED street light era has arrived

Author: Dr. Wu Chun Wei Guangzhou STSP Integrated Electronics Co., Ltd.
With the continuous improvement of the luminous efficiency of white LED chips, white light chips above 80lm/W have become the mainstream in the market, and the laboratory-level LED light efficiency has reached more than 200lm/W. These results make LED street lights close to the price/performance ratio of traditional metal nano lamps, and have a tendency to override traditional metal sodium lamps. At present, there are two main factors restricting the popularization of LED street lamps. Everyone is saying that the performance of LED street lamps is inferior to that of traditional street lamps. The second one is too high, far exceeding traditional street lamps. But what is the truth of the facts? This article compares the cost performance of Nanke LED street lamps with traditional street lamps. The results indicate that the era of high-performance low-cost LED street lamps has arrived.

LED street light design features and know-how

After four years of painstaking research, Nanke Group has successfully developed products that combine performance and cost, which are comparable to traditional metal sodium lamps. The above products are all independently developed by Nanke. Complete independent intellectual property rights, power between 40-200W. The techniques used include:

Chip-integrated high-power chip—Packages high-brightness LED chiplets on the aluminum substrate with integrated circuit packaging technology, shortening the heat transfer path, and making LED high-power chips with better heat dissipation. At present, Nanke Group's street lamp series chips use full-series high-power chips.

LED drive scheme for high voltage (constant voltage), low current (constant current) output with low power loss. The drive circuit of Nanke Group is different from the low-voltage constant-voltage (50~60V) but non-constant current switching power supply scheme commonly used in the industry. We use a proprietary high voltage (400V), low current constant voltage plus constant current drive circuit. The input voltage is 90-260 VAC wide, and the power loss includes only 5% of the power factor correction, that is, the power efficiency is as high as 95%.

In order to solve the problem of heat dissipation of LEDs, we have developed a needle-shaped heat sink (Nanke IP), which makes the total heat dissipation temperature 15 °C lower than the traditional chip radiator (160W). The heat dissipation problem of the LED is basically solved in a simple and cost-effective manner.

The lens light distribution technology independently developed by Nanke Group not only solves the problem of uneven light distribution, but also improves the utilization factor of LED street lamps to 70% or more, and the energy saving effect is more obvious.

Intelligent LED street light vs metal sodium lamp

Table 1 lists the comparison table of the Nanke Group's intelligent 160W LED street light and the equivalent performance 250W high-pressure sodium lamp, which is used in the two-way four-lane. Since the driving circuit of the LED semiconductor illumination is composed of semiconductor electronic components, it is easy to add and change the control circuit. In order to further achieve the purpose of power saving, a programmable timer can be added in the driving circuit, so that the street lamp can use different powers in stages during use. For example, in the first half of the night (18:00-24:00), the rated power is up to 160W due to more pedestrians, and the lower half of the night (24:00~6:00) can be used with 50% or less of rated power due to fewer pedestrians. The purpose of saving electricity.

It can be seen from Table 1 that the 160W LED luminaire has an average illuminance of 15lx when the light-emitting surface area is 490m2 (the illumination road is 14 meters wide and the lamp spacing is 35 meters), and the average illuminance of the 250W high-pressure sodium lamp is 18lx. . Although the average illumination of LED street lamps is lower than that of high-pressure sodium lamps, they all meet the national road lighting standards; while the illumination uniformity of LED street lamps is twice that of high-pressure sodium lamps, and the color rendering index of LED light is 3 times that of high-pressure sodium lamps. Whether it is from the safety or comfort of road lighting, the actual lighting effect of LED street lights is better than that of high pressure sodium lamps.

Energy-saving and economical comparison of LED street lamps and high-pressure sodium lamps

Although the price of Nanke LED street light is higher than that of high-pressure sodium lamp, it is far lower than the price of the industry peers. At the same time, Nanke LED street lamp recovers the initial investment higher than the high-pressure sodium lamp by saving electricity and maintenance costs within 2 years. . During its lifetime (5 years), each lamp saves more than 2,500 yuan in electricity and maintenance costs. In small and medium-sized cities with 40,000 street lamps, it can save more than 100 million yuan over the entire life cycle.

Taking into account the cost of the lamp and the power consumption factor and several factors that replace the light source at least once a year, Table 2 shows the comparison of the cost of using the 250W high pressure sodium lamp with the 160W LED street lamp. In the past five years, the initial investment of 160W LED street light plus the use cost is about 4,700 yuan, and the street light of 250W high-pressure sodium lamp is about 7255 yuan. (The maintenance fee of street lamps varies from place to place, the low is 150 yuan per year, the highest is 400 yuan per year. /盏, this watch takes 200 yuan / 盏); therefore, during the life of LED street lights, each lamp can save more than 2,500 yuan.

Note: (1) Annual electricity consumption per lamp (kWh) = power (kW) × 12 hours / day × 365 days;
(2) Saving electricity and maintenance fees within five years (yuan) = annual electricity savings per lamp × 5 years + annual maintenance cost per lamp × 4 years = 631 × 5 + 200 × 4 = 3955;

in conclusion

In summary, we can clearly see that with the current mature technology, Nanke Group independently develops intelligent LED street lamps with intellectual property rights, and its 160W average illumination can be compared with 250W high-pressure sodium lamp street lamps. If you consider power saving factors and maintenance costs, you can save a considerable amount of electricity during the life of the company (5 years). We can clearly see that under the same performance, Nanke LED street lamps are cheaper than traditional metal sodium lamp street lamps, and LED chip technology is still developing at a high speed, so we believe that high performance, low price, energy saving The era of LED street lights has already arrived in the land of China. 

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