Design Of High Power Factor Constant Flow Pattern LED Power Supply

With the rapid development of LED lighting technology,LED driving power supply has become an indispensable part in LED market.LED constant current drive is more suitable than the constant voltage driving its electrical characteristics.At the same time in the constant current power supply is introduced in the source power factor correction link,to avoid the noise caused by the input harmonic current and the harmonic of power grid "pollution ".This design uses two level converter,the front for the active power factor correction link,the main topology of Boost converter,the control unit selects a single cycle leading edge modulation type power factor control chip UCC28019,the inductor current in rectifier input voltage output boost adjustment rate,up to wave and rectifier inductor current average input voltage waveform phase consistency.After class for the DC/DC buck,the main topology for dual switch forward converter,can isolate the output side and the input side,the control unit using current mode control chip UC3844.By sampling the output side of the current as the feedback input,to achieve the output constant current,at the same time,sampling the output voltage when empty as the feedback input voltage to realize constant no-load output.Through the principle analysis and circuit design,the physical production and debugging,the results prove the feasibility and advantage of the scheme.