How to choose a power supply without electrolytic capacitors
Electroless capacitor power supply is a very important part of the LED display, many LED display manufacturers in the choice will encounter many troubles, what exactly as the standard, what kind of electroless capacitor power supply is excellent, cost-effective, long life, energy saving? After years of experience in the use of experience and feel, LED display manufacturers summarized the following several options.
First, due to the human eye on the light time interval resolution is not too high, that is, there is a visual phenomenon of temporary retention, at the same time led bulb light instantaneous response to nanoseconds, with a high frequency similar to the comb like pulse to drive the led bulb light, the human eye does not see led bulb light flickering. This program is more energy efficient than DC drive power supply, generally known as high frequency drive program.
Second, single-phase alternating current rectifier, the same frequency with its alternating current power supply, but the phase displacement of ninety degrees of alternating current rectifier synthesized ripple is not zero, with a non-electrolytic capacitor can be smoothed ripple.
Third, single-phase alternating current with a switching tube rectifier (rather than with a diode rectifier comb) circuit injected into the third harmonic of the exchange also has the effect of significantly reducing ripple.
Fourth, with two (group) led display chip reverse parallel with cross-frequency constant current AC light, each led bulb lamp single light half wave light, two groups of chips alternately light. This program reduces the power supply cost, increases the chip cost, when the led display chip significant price reductions in interest to be accepted, in addition to the whole lamp will be slightly flickering sense, generally known as the AC program.
Fifth, multiphase rectifier high frequency as high as possible (limited by the Shaw diode delay and synchronous rectifier field effect tube switching delay) then the above output DC envelope the smoother, do not have to use electrolytic capacitors.
Sixth, the output DC envelope of the multiphase rectifier for low ripple and not zero program.
Seven, inverted transformer to offset high-frequency ripple has been practical engineering, especially suitable for high-current load applications.
Eight, power electronics negative feedback technology can reduce ripple.
Nine, such as the load current is not too large, the ripple requirements are very strict, there is no harm in the back with a low-voltage electronic filter, in principle, can meet any ripple-sensitive users, but the led bulb cost is higher, the efficiency is also affected.
Ten, with the microcontroller with the same size and direction of the ripple of the digital active offset ripple “program, generally known as the composite IC program.
