Constant current solar powered led lights
Constant current source in the solar powered led street lights can be divided into the boost, buck, buck three kinds: the so-called step-up its output voltage is higher than the input voltage. Buck output voltage is lower than the input voltage. Buck is to automatically adjust its mode of operation according to the input voltage lower or higher than the output voltage boost or buck.
In the solar powered led street lights, commonly used lead-acid batteries as energy storage device, its voltage is typically 12V or 24V. The required output voltage is connected to the LED structure is determined. In order to make all LED forward current, typically in series with each LED, then the required output voltage is the sum of all series LED forward voltage. For example, suppose that the 10 LEDs in series (Figure 9a), the sum of the forward voltage of about 10¡Á3.3V = 33V. In fact, LEDs produced by various manufacturers vary, but also different between each LED. Therefore, the total of 10 led high bay lights forward voltage is not the same. In fact, the constant current source, the constant current rather than voltage. So, do not need to know the exact value of the sum of the forward voltage, and as long as the higher or lower than the input voltage can be. Here, 12V or 24V battery, it requires a boost type constant current source.
Sense resistor to be as small as possible, in order to avoid the above power consumption. As low as possible for the fact, which means that its internal reference voltage. For chip designers have a certain degree of difficulty. If the reference voltage of 0.1 volts, is a very good chip, this time, the external sense resistor with a very small value, which means the entire system is highly efficient.
Solar LED street lighting is an important factor in market
We know that the global lighting electricity consumption accounted for 20 percent of all electricity, of which a large part in solar LED street lighting. China is no exception. According to the statistics China has installed lights about as much as 200 million. The street lamp average power of about 200 watts, assuming the daily opening time of 10 hours, then two units of electricity a day, 365 days is 730 kWh, 200 000 000 146 000 000 000 kWh. The full production of 26 units of the Three Gorges Hydropower Station, China¡¯s largest hydropower station, the annual generating capacity to 84.7 billion kWh of electricity. All the street lamps which consumes huge quantities of about 2 of the Three Gorges power stations. This is not a small figure.
Moreover, now the street lights are still 20 million a year increase. But at the moment almost 90% of high-pressure sodium lamp. While its luminous efficiency is still high, but its short life, low power consumption, low color temperature, color rendering is poor, but also contain mercury and other toxic substances in the future, sooner or later be eliminated.
Since the Ministry of Science and vigorously developing LED lights Ten thousand ten cities ¡°program. Solar LED street lighting are now in full swing speed high-speed development. Unfortunately, more than 90% of the ¡°Ten City, 10000 or using the AC LED lights, or the transformation of the existing high pressure sodium lamps for led high bay lights. According to conservative estimates, the total number of 10 City, 10000, plans will be more than 2 million, but only one tenth of the total number of new street lights every year. As previously said that, if the annual increase of 20 million are using solar energy, then its total power will reach.
