LED driver power supply is the power supply is converted to a specific voltage and current to drive the LED light-emitting voltage converter, usually: LED driver power supply inputs include high-voltage frequency AC (i.e., utility), low-voltage DC, high-voltage DC, low-voltage high-frequency AC (e.g., the output of the electronic transformer) and so on. 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. The following for the first time in the industry to provide some knowledge of the LED driver power supply.
1, what is the LED driver power supply
LED drive power supply to convert the power supply to a specific voltage and current to drive the LED light-emitting voltage converter, usually: LED drive power supply inputs include high-voltage frequency AC (i.e., utility), low-voltage DC, high-voltage DC, low-voltage high-frequency AC (e.g., the output of the electronic transformer) and so on. The output of the LED driver power supply is mostly a constant current source that can change the voltage with the change of LED forward voltage drop value.The core components of the LED power supply include switching controllers, inductors, switching components (MOSfet), feedback resistors, input filters, output filters, etc. According to the requirements of different occasions, there should also be input filters, output filters, and so on. According to the requirements of different occasions, but also the input over-voltage protection circuit, input under-voltage protection circuit, LED open-circuit protection, over-current protection and other circuits.
2, LED drive power supply features
(1) high reliability
Especially like the LED street lamp drive power, installed in the high altitude, maintenance is not convenient, maintenance costs are also large.
(2) high efficiency
LED is an energy-saving products, drive power supply efficiency should be high. For the power supply installed in the lamps and lanterns within the junction heat dissipation is very important. High efficiency of the power supply, its power loss is small, in the lamps and lanterns within the heat is small, also reduces the temperature rise of the lamps and lanterns. It is beneficial to slow down the light decay of LED.
(3) high power factor
Power factor is the power grid requirements for the load. Generally 70 watts or less of electrical appliances, there is no mandatory indicator. Although the power factor of the individual appliances with low power factor is not much of an impact on the power grid, but the use of lighting at night, the same type of load is too concentrated, will produce more serious pollution of the grid. For 30 watts ~ 40 watts of LED driver power supply, it is said that in the near future, may be on the power factor aspects of the requirements of certain indicators.
(4) drive mode
Now there are two kinds of pass: one is a constant voltage source for more than one constant current source, each constant current source individually to each road LED power supply. This way, the combination of flexible, all the way LED failure, does not affect the work of other LED, but the cost will be slightly higher. Another is a direct constant current power supply drive, LED series or parallel operation. Its advantage is that the cost is a little lower, but poor flexibility, but also to solve the problem of a LED failure, does not affect the operation of other LEDs. These two forms, in a period of time co-exist. Multiple constant current output power supply method, in terms of cost and performance will be better. Maybe it is the mainstream direction in the future.
(5) surge protection
LED surge resistance is relatively poor, especially the ability to resist reverse voltage. Strengthen this aspect of protection is also very important. Some LED lights installed in outdoor, such as LED street lights. Due to the grid load start dumping and lightning induction, from the grid system will invade a variety of surges, some surges will lead to LED damage.
(6) Protection function
Power supply in addition to the conventional protection function, it is best to increase the LED temperature negative feedback in the constant current output to prevent the LED temperature is too high; to meet the requirements of safety regulations and electromagnetic compatibility.
3、Categorized by driving mode
(1) constant current
Constant-current drive circuit output current is constant, while the output DC voltage is different with the size of the load resistance changes within a certain range, the load resistance is small, the output voltage is low, the greater the load resistance, the higher the output voltage;
Constant-current circuit is not afraid of load short-circuit, but the load is strictly prohibited completely open circuit;
Constant-current drive circuit to drive the LED is more ideal, but relatively high prices;
Should pay attention to the use of the maximum withstand current and voltage values, which limits the number of LEDs used.
(2) voltage regulator
When the parameters of the voltage regulator circuit to determine the output voltage is fixed, while the output current with the increase or decrease of the load and change;
The voltage regulator circuit is not afraid of load open-circuit, but the load is strictly prohibited from being completely short-circuited;
Regulated drive circuit to drive the LED, each string needs to be added to the appropriate resistance in order to make each string of LED display brightness average;
Brightness will be affected by the voltage change from the rectifier.
4, the overall constant current and circuit-by-circuit constant current mode of operation advantages and disadvantages
Compared with the overall constant current, although the circuit by circuit constant current has more disadvantages, the cost is also higher. But it can really play a role in protecting the LED and extend the life of the LED, so the circuit-by-circuit constant current is the future trend.
5, LED power supply shortage
LED driver power supply currently exists for insufficient reasons:
Production of LED lighting and related products, the company's technical staff do not know enough about the switching power supply, to make the power supply can work properly, but some critical evaluation and electromagnetic compatibility is not enough to consider, there are still some hidden dangers;
Most of the LED power supply manufacturers are transformed from ordinary switching power supply to do the LED power supply, the characteristics of the LED and the use of knowledge is not enough;
At present, there is almost no standard on LED, most of them refer to the standard of switching power supply and electronic rectifier;
Now most of the LED power supply is not unified, so most of the volume is relatively small. Purchasing a small amount, the price is high, and component suppliers are not very cooperative;
Stability of LED power supply: wide voltage input, high and low temperature operation, over-temperature, over-voltage protection and other issues have not been solved one by one;
First of all, the overall life of the drive circuit, especially the key devices such as: capacitors at high temperatures directly affect the life of the power supply;
Is the LED driver should be challenged to higher conversion efficiency, especially in driving high-power LED is more so, because all the power not as light output as heat dissipation, power conversion efficiency is too low, affecting the LED energy-saving effect of play;
At present, in the smaller power (1-5W) applications, constant current drive power supply costs accounted for the proportion has been close to 1/3, has been close to the cost of the light source, to a certain extent, affecting the market promotion.
LED drive power supply of the two major classifications
LED driver power supply is the power supply is converted to a specific voltage and current to drive the LED light-emitting voltage converter, usually: LED driver power supply inputs include high-voltage industrial frequency AC (i.e., utility), low-voltage DC, high-voltage DC, low-voltage high-frequency AC (e.g., the output of the electronic transformer) and so on. 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.
Due to a variety of specifications of different LED power supply performance and conversion efficiency varies, so choose the appropriate, efficient LED special power supply, in order to truly reveal the characteristics of high-performance LED light source. Because the low efficiency of the LED power supply itself needs to consume a lot of electricity, so in the process of power supply to the LED will not be able to highlight the energy-saving characteristics of the LED. In short, the LED power supply in the LED work in the stability, energy saving, life expectancy, with an important role.
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