Teach you how to choose LED driver power supply

LED load characteristics of itself greatly affects the reliability of it is driven by switching power supply. The load characteristics of the LED the volt-ampere characteristic, diode characteristic. In a certain range, LED the rise of voltage on both ends, the current increases exponentially in, explosive growth. So a lot of LED lamps and lanterns, driven by the switch power supply showed many unstable characteristics. Reason is that the output of the switch power supply, not very clean smooth dc voltage ( Current) Energy, it is a very complex signal, it can be roughly as smooth.

and the LED is very sensitive to changes in voltage, LED in a stable electricity back at work, both ends of the voltage is usually 3. 0 - 3. (between 6 v Slightly different size power LED) , when the voltage at both ends after a little fluctuation, both ends of the electric current will be dramatic changes, the output power of the power supply change drastically. Have a sudden change in the power grid voltage, small output voltage change, will produce a large output current, power surge, accidents happen.

the practice proved that in the circuit, to join all kinds of voltage inhibited type components, such as the TVR, TVS, the effect is not obvious, the damage will be damaged, LED drive power supply reliability is always can't do other power so good, this is the objective existence of the facts. Although a lot of people say that they do the LED power how to not have a problem, but actually is pale in comparison to comfort themselves, because he did not solve the fundamental problem.

the reliability and efficiency, are mutually restricted, high efficiency of power supply and reliability will be lower, improve reliability, must sacrifice power efficiency. Because want to reduce the effects of the input voltage to output voltage, electric energy to pass multiple transformations. Usually a simple example, BUCK circuit reliability is not high, but BUCK - The BOOST circuit, better reliability than BUCK, this is tested. Because understand the power of the principle of people know, BUCK circuit when the switch tube opening, the LED load and inductance is in high voltage of 300 v, the LED is directly by the 300 v power supply, and BUCK - BOOST circuit is separate to inductance impact energy storage at this time, during the period of shut off, BUCK circuit inductance is further extended to the load flow, and BUCK - The BOOST circuit is shut off, the energy inductance conduction to the LED load. Both difference, BUCK circuit for a time, is directly use 300 v power supply, while the latter is deposited in the inductance first, and then came out from the inductance in energy transfer to the LED load, so the reliability is high, because it passed through the long way. Long way of delivery, and can lower the efficiency, BUCK - commonly The efficiency of the BOOST circuit 2 - lower than the BUCK circuit 5%.

so now LED drive power supply, generally is the reliability of the isolation is better than that of unfenced, low reliability is better than that of high pressure, it is under the restriction of the law, which improved the efficiency, at the expense of the reliability, improve reliability, will reduce the efficiency.

in fact problems are caused by the load characteristic of LED, the fundamental method is to improve the load characteristics of the LED string but the way to improve load characteristic is still sacrificing efficiency as the means. The simplest way to improve load characteristic is in series with the LED string resistance, resistance of string, the greater the load characteristic is more stable. Of course this is to reduce the efficiency. There is also a good way, is to join the linear manostat, use triode, do adjust tube, triode is equivalent to a variable resistor, so, reliability should be higher, I in theory and practice experience not) 。 Therefore, basic can claim, the most reliable LED driven approach in fact or ordinary linear constant current, constant voltage power supply and, of course, the efficiency is not high. High efficiency, reliability, came down.

coordinating editor li jie

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