Study On LED Driver Methods Applying Multiple-Output Switching Converter

In order to meet the needs of different occasion's application Multiple-Output LED(Light Emitting Diode)driver is researched. Taking the design of the Dual-Output LED Driver as an example,the thesis describes the the process of building mathematical models for the driver in detail,simulation and experimental results are taken to verify the the proposed technique.Based on the analysis of several conventional techniques of multiple-output,the dual-output Boost converter is researched,which is working in the current program mode and is controlled by the time-multiplexing singal.Small-signal model of the converter is made by the state-space averaging method.And the Open-loop Bode plot of transfer function of the converter is drawed,by which the stability of the conver is analyzed.At Last,the proposed technology of the converter is proved by the simulation and the experiment.Papers of Multiple Output Converter in the domestic and foreign are studied. Taking the design of the Dual-Output single stage flyback converter as an example,Small-signal model of the converter is made by the state-space averaging method.Based on the control object properties characteristic curve,compensation network is designed.Both the compensation network characteristic curve and the open-loop transfer characteristic curve are drawed.Finally,the proposed technology of the converter is proved by the simulation and the experiment.For LED drivers with an output power over 25 W in general lighting applications, the input line current harmonics need to satisfy the limits set by IEC 61000-3-2 Class C regulations,so it is necessary to use the Power Factor Correction (PFC) circuits.In order to realize Power Factor Correction,the conditions the converter has to meet are studied.Including the reasonable choice of the transformer inductance,bulk capacitance values and the duty cycle.It is also necessary to analyze the multiplexing time of the both outputs,because it is important to improve the utilization of the inductor.Finally,the simulation and the experiment results on a hardware prototype are given to confirm the theoretical analysis and performance of the proposed converter.