If you want to produce a LED lighting product, the most important parts are heat dissipation, driver, and light source(LED chips). At the same time, heat dissipation is particularly important. The heat dissipation directly affects the life quality of the lighting product, and the life of the driver itself. And the stability of output current and voltage also have a great influence on the lifespan of the product. The light source is the core part of the whole product.
LED driver is also a supporting product. The quality driver on the market are quite varies. Here we are going to analyze the driver below for your reference.
1、What is LED driver?
LED driver convert the power supply to a specific voltage current to drive the LED light-emitting voltage converter, in general: LED driver inputs include high-voltage industrial frequency AC (i.e., utility), low-voltage DC, high-voltage DC, low-voltage high-frequency AC (such as the output of electronic transformers), etc.
The output of the LED driver power supply is mostly a constant current source that can change the voltage with the LED forward voltage drop value.
LED dirver core components include switching controllers, inductors, switching components (MOSfet), feedback resistors, input filter parts, output filter parts, etc..According to the requirements of different occasions, there are also input overvoltage protection circuit, input undervoltage protection circuit, LED open circuit protection, overcurrent protection and other circuits.
2、Features of LED driver
Especially like the LED street light power supply, installed in the high side, maintenance is not convenient, the cost of maintenance is also high.
(2) High efficiency
LED is an energy-saving product, the efficiency of the driver should be high. It is very important for the driver in the luminaire to dissipate heat. When the efficiency of the power supply is high, its power consumption is small, and the heat generated in the lamp is also small, which reduces the temperature rise of the lamp. It is good to delay the light decay of LED.
(3)High power factor
The power factor is the requirement of the grid on the load. Generally, there are no mandatory indicators for electrical appliances below 70 watts. Although the power factor of a single consumer with low power is lower, it has little effect on the power grid, but the large amount of lighting used at night and too concentrated similar loads will cause serious pollution to the power grid. For LED driver of 30 watts to 40 watts, it is said that in the near future, there may be certain indicators requirements for power factors.
Currently, there are two types driver: one is a constant-voltage driver supply for some constant-current drivers, each constant-current driver separately supplies power to each LED individually.
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 little higher.
The other one is direct constant current power supply, which is mostedly adopted by many led light poruducts, LED series or parallel operation. Its advantage is that the cost is a bit lower, but the flexibility is not as good as first one, and it must solve the problem of one LED failure without affecting the operation of other LEDs.
Therefore, the analysis of “Zhongke Huibao” drive power supply in the surge protection should have a certain lack, and as for the power supply and frequent replacement of lamps and lanterns, LED drive power supply to have the ability to inhibit the intrusion of surges, protect the LED from damage.
In addition to the conventional protection functions of the power supply, it is best to add negative feedback of the LED temperature to the constant current output to prevent the LED temperature from being too high;
it must meet the requirements of safety regulations and electromagnetic compatibility.
3、Classified by driving method
(1) The output current of the constant current type driver circuit is constant, but the output DC voltage varies within a certain range with the size of the load resistance.
When the load resistance is small, the output voltage is low, and the load resistance value is like this :the value larger, the output voltage higher;
constant current circuit is not afraid of load short circuit, but the load is strictly prohibited completely open circuit;
constant current driver circuit to drive the LED is better, but with higher price; We should note the maximum withstand current and voltage value used, it limits the number of LEDs used.
(2)For constant voltage driver, when the various parameters in the voltage-stabilizing circuit are determined, the output voltage is fixed, but the output current changes with the increase or decrease of the load;
the voltage-stabilizing circuit is not much affected by load opening, but it is strictly forbidden to load completely Short circuit: Drive the LED with a voltage-stabilizing drive circuit, and each string needs to add a suitable resistance to make each string of LEDs show an average brightness; the brightness will be affected by the voltage change from the rectification.
4、The advantages and disadvantages of the overall constant-current and constant-current circuit-by-circuit operation
Compared with the constant current driver, although the circuit-by-circuit constant current has more disadvantages, the cost is also higher. But it can really protect the LED and extend the life of the LED, so the constant current is mostly popular.