Study Of The Power Supplys For LED

With increasingly serious energy crisis and the issue of climate change, energy conservation has become a topic of common concern.Various means are sought new energy-efficient manners.Lighting that is about 20% of the world's total energy consumption is an important aspect of energy consumption,So the more and more attention to green energy-efficient lighting.Because green LED, long life, high efficiency photoelectric many advantages, it has become the focus of attention for the field of lighting and developed rapidly in recent years.If LED lighting to replace the current traditional lighting with low efficiency, undoubtedly it will play a pivotal role to ease the current energy shortage and environmental degradation.LED is cold light source driven by Low-voltage and its performance is influenced by the environment and performance of the drivers.To solve this problem that the power supplys for LED are cost,mainly the following work about the power supply for LED has been done in such occasions with AC voltage input.At first, the design without the isolation is brought forward to the LED reading lamp and wall lamp.The working principle and performance of the circuit is analyzed , and the parameters of the circuit is analyzed and simulation. To meet the higher output accuracy, a two step-down program is brought forward and the circuit is analyzed, simulated and experimented.Secondly, the self-oscillatiing circuit is brought forward to design the LED driver with isolation.A detailed analysis of the principle and a small signal analysis and modeling of self-oscillating circuit is done.The principles of quasi-resonant zero voltage opening of the self-oscillating circuit by using its characteristics of self-oscillation is Described.The conditions of realizing quasi-resonant ZVS and the means of designing parameters is deduced.Simulation and experiment are used to verify the correctness of the theory.To meet requirements of the LED driver for the Harmonic Standard, a project of a winding voltage feedback single-stage PFC circuit was made on the base of summing up the current status of the single-stage PFC circuit study and analyzing and comparing the several typical single-stage PFC circuits.The analysis, simulation, modeling and a detailied design of the parameters for the single-stage PFC circuit is provided.Meanwhile, a circuit of passive absorption (LCD) in the application of a single-stage PFC is studied.Finally, the analysis and simulation about a new double-winding voltage feedback single-stage PFC circuit is done.