1、 What is LED drive power
In fact, LED driver power is a kind of power supply, just a specific power supply. This power supply drives LED to light with voltage or current. Therefore, the input part of LED driving power supply generally includes several parts: power frequency mains, low-voltage DC, high-voltage DC, low-voltage high-frequency AC, etc; The output is mostly a constant current source that can change the voltage with the change of the LED forward voltage drop value. The core components of LED driving power supply include input filter, switch controller, inductor, MOS switch, feedback resistor, output filter, etc. In addition, some drive power supplies also have input overvoltage/undervoltage protection, open circuit protection, overcurrent protection, etc.
2、 Characteristics of LED driving power supply
1. High reliability: especially the driving power supply of LED street lights, which is installed at high altitude, makes maintenance inconvenient and costly;
2. High efficiency: LED is an energy-saving product, and the efficiency of the drive power should be high. It is very important for the junction heat dissipation of the power supply installed in the lamp. If the power supply has high efficiency, its power consumption will be small, the heat generated in the lamp will be small, and the temperature rise of the lamp will be small, which will help delay the light failure of LED;
3. High power factor: power factor is the requirement of power grid for load. Generally, there is no hard target for electrical appliances below 70W. Although the power factor of a single electrical appliance with low power has little impact on the power grid, the large amount of lighting at night and the excessive concentration of similar loads will cause serious pollution to the power grid. For 30W~40W LED driver power supply, there may be certain index requirements for power factor in the future;
4. Drive mode: currently, there are two drive modes: ① one constant voltage source provides multiple constant current sources, and each constant current source provides power for each LED separately. In this way, the combination is flexible. One LED fault will not affect the work of other LEDs, but the cost will be slightly higher; ② Direct constant current power supply, LED series or parallel operation. Its advantages are low cost, but poor flexibility. It also needs to solve the problem of one LED failure without affecting the operation of other LEDs;
5. Surge protection: the anti surge capability of LED is relatively poor, especially the anti reverse voltage capability. It is also important to strengthen the protection in this regard. Some LEDs installed outdoors, such as LED street lamps. Due to the starting and dropping of power grid load and the induction of lightning stroke, various surges will invade from the power grid system, and some surges will cause LED damage. Therefore, LED driver power supply shall have the ability to inhibit the invasion of surge and protect LED from damage.
6. Protection function: In addition to the conventional protection function of the power supply, it is better to add LED temperature negative feedback in the constant current output to prevent the LED temperature from being too high;
7. Protection: For lamps installed outdoors or in complex environments, the power supply structure needs to be waterproof, moisture-proof and high temperature resistant;
8. Safety regulations: LED drive power supply products shall meet the requirements of safety standards and electromagnetic compatibility;
9. Others: For example, the LED drive power needs to match the LED life.