Industry news

2016August

Analysis on the advantages and inferior quality of LED drive power supply

From: www.szbako.com Data:06/08/2016

1, what is the LED drive power
LED driving power supply the power supply conversion for specific voltage and current to drive the light emitting LED voltage converter, usually under LED drive power input, including high voltage AC (i.e., power, DC voltage, DC high voltage, low voltage high frequency exchange, such as the output of electronic transformer and other. And the output of the LED drive power supply is most of the constant current source which can change the voltage with the change of the LED forward voltage drop. LED power core components include switch controller, inductor, switch components (MOSfet), feedback resistance, input filter, output filter and so on. According to the requirements of different occasions, but also have input over-voltage protection circuit, input under voltage protection circuit, LED open circuit protection, over current protection circuit.
2, LED drive power supply characteristics of
(1) high reliability
especially like LED street lamp driver power, installed in the high altitude, maintenance is not convenient, maintenance cost is also large.
(2) high efficiency
LED is the energy saving product, the drive power source efficiency must be high. For the power supply installed in the lamp is very important. The efficiency of the power supply of high power consumption, it is small, in the heat of the lamp is small, it reduces the temperature rise of lamps. Favorable to delay the LED attenuation.
(3) high power factor
power factor is the requirement of power grid to load. Generally less than 70 watts of electrical appliances, there is no mandatory indicators. Although the power is not a single power factor low power grid has little impact on the power grid, but the use of large lighting at night, the same kind of load is too concentrated, will have a more serious pollution of the power grid. For 30 watts ~40 watts LED drive power, it is said that in the near future, there may be some indicators of the power factor requirements.
(4) drive mode
now has two kinds: one is a constant pressure source for multiple constant current source, each constant current source to each road LED alone. This way, the combination of flexible, all the way LED fault, does not affect the work of other LED, but the cost will be slightly higher. The other is direct constant current power supply is “ in the Branch Hui Bao ” the drive mode, LED series or parallel operation. It has the advantage of low cost, but poor flexibility, but also to solve a LED failure, does not affect the operation of other LED issues. These two forms coexist in a period of time. Multi way constant current output power supply, in terms of cost and performance will be better. May be the future of the mainstream.
(5) surge protection
LED anti surge capacity is relatively poor, especially the anti reverse voltage capability. It is also important to strengthen the protection of this area. Some LED lights are installed outdoors, such as LED street lamps. Due to the load of the power grid and lightning induction, from the grid system will invade a variety of surge, some surge will cause damage to LED. Therefore, the analysis of & ldquo; Branch Hui Bao & rdquo; the driving power in surge protection should have a certain lack, and as the power supply and lighting frequent replacement, LED drive power to the invasion of surge suppression, led protection, which can not be damaged.
(6) protection function
power supply in addition to conventional protection function, it is best to increase the LED temperature in the constant current output feedback, to prevent the LED temperature is too high; to comply with the requirements of safety and electromagnetic compatibility.
3, driven by the classification
(1) constant current
a constant current drive circuit output current is constant, while the output DC voltage but with the load resistance of different sizes vary in a certain range, load resistance is small, the output voltage is low, the greater the load resistance, the output voltage is higher.
b constant current circuit is not afraid of load short circuit, but it is strictly prohibited to load completely open circuit.
c constant current drive circuit driver LED is more ideal, but relatively high price.
d should pay attention to the use of the maximum withstand current and voltage value, it limits the use of the number of LED.
(2) regulated
a when determining the parameters of the voltage stabilizing circuit, the output voltage is fixed, and output current but increase or decrease with load change;
b voltage regulator circuits are not afraid of open load, but strictly completely short-circuit the load.
c to the voltage regulator driver circuit driver LED, each string needs to be coupled with the appropriate resistance side can make each string LED display brightness average;
d brightness will be affected by the voltage change rectifier.
4, constant current and by way of constant current working pros and cons
from comparison of the above can also see, by way of constant flow although shortcomings, the cost is relatively high. But it can really protect the LED and extend the life of LED, so constant flow is the trend of the future.

5, LED power supply shortage of
LED power supply is a supporting products, currently on the market power is uneven in quality, according to the problems encountered in the existing data query and project execution of bad light about analysis of the LED drive power existing problems: the
a production of LED lighting and related products for the company's technical staff of switching power supply is not enough understanding of the, make the power supply is can work in normal, but the consideration of some key assessment and electromagnetic compatibility is not enough, there are still certain risks.
b most of the LED power supply manufacturers are switching from the general power supply to do the LED power supply, the characteristics of the LED and the use of knowledge is not enough.
c currently on the LED standard is almost no, most of them are the standard reference switch power supply and electronic rectifier.
d now most LED power is not uniform, so most of the volume is relatively small. The purchase quantity is small, the price is high, moreover the component supplier also does not cooperate with. The stability of LED
e power supply: wide voltage input, high temperature and low temperature work, over temperature, over voltage protection and other issues are not resolved one one.
f first is the overall life of the drive circuit, especially the key components such as: capacitor in the high temperature life directly affects the power of life.
g is led driver should challenge higher conversion efficiency, especially in the high power LED driver, because all is not as light output power are dissipated as heat, power conversion efficiency is too low, the impact of the LED energy-saving effect of the play.
h at present in the power of smaller (1-5W) applications, constant current drive power supply costs have been close to 1/3, has been close to the cost of the light source, to a certain extent, affected the market promotion.
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