Analysis Of Several Common LED Driving Methods Part Two

According to the power rules of the power grid and the characteristic requirements of the LED drive power supply, the following points should be considered when selecting and designing the LED drive power supply:

1. High reliability

Especially like the driving power of LED street lights, it is inconvenient to maintain and costly to maintain when installed at high altitude.

2. High efficiency

LED is an energy-saving product, and the efficiency of the drive power supply should be high. It is especially important for the structure where the power supply is installed in the luminaire. Because the luminous efficiency of the LED decreases with the increase of the LED 7 segment display module temperature, the heat dissipation of the LED is very important. The efficiency of the power supply is high, its power consumption is small, and the heat generated in the lamp is small, which reduces the temperature rise of the lamp. It is beneficial to delay the light decay of LED.

3. High power factor

The power factor is the requirement of the power grid on the load. Generally, there are no mandatory indicators for electrical appliances below 70 watts. Although the power factor of a single electrical appliance with low power is lower, it has little effect on the power grid, but if everyone lights up at night, if the load of the same kind is too concentrated, it will cause serious pollution to the power grid. For LED driving power supplies of 30 watts to 40 watts, it is said that in the near future, there may be certain index requirements for power factors.

4. Drive mode

Currently, there are two types: one is a constant voltage source for multiple constant current sources, and each constant current source individually supplies power to each LED. In this way, the combination is flexible, and the failure of one LED will not affect the work of other LEDs, but the cost will be slightly higher. The other is direct constant current power supply, with LEDs running in series or parallel. Its advantage is that the cost is a bit lower, but the flexibility is poor, and it must solve the problem of a certain LED failure without affecting the operation of other LEDs. These two forms coexist for a period of time. Multi-channel constant current output power supply mode will be better in terms of cost and performance. Maybe it will be the mainstream direction in the future.

5. Surge protection

The ability of LED to resist surge is relatively poor, especially the ability to resist reverse voltage. It is also important to strengthen protection in this area. Some LED lights are installed outdoors, such as LED street lights. Due to the initiation of the grid load and the induction of lightning strikes, various surges will be invaded from the grid system, and some surges will cause damage to the LED. Therefore, the LED drive power supply must have the ability to suppress the intrusion of surges and protect the LED from damage.

6. Protection function

In addition to the conventional protection function of the power supply, it is best to add negative feedback of the LED temperature in the constant current output to prevent the LED temperature from being too high.

7. Protection

For the external installation type of the lamp, the power supply structure should be waterproof and moisture-proof, and the shell should be resistant to sunlight.

8. The life of the driving power supply should be matched with the life of the LED.

9. To meet the requirements of safety regulations and electromagnetic compatibility.

With the increasing application of LEDs, the performance of LED drive power will be more and more suitable for the requirements of LEDs.