The Research Of Novel LED Driver And Control Technology

LED(Light Emitting Diode) is the 4th generation lighting source. Due to its high efficiency、high brightness、environmental frendliness、energy-saving、 long lifetime、high reliability and other advantages, traditional incandescent lamp、fluorescent tube、high intensity discharge lamp is being replaced by LED(Light Emitting Diode) in gradual. High power factor、long lifetine、high reliability、low-cost driving technology has became the key of LED driving source in its development.The dissertation introduced background and significance of researching LED driving power and evolutionary history of lighting source, analyzed variety of characteristics of LED in detail, stated the challenge in development of LED. Based on the problems existing in the development of LED at the present stage, the thesis discussed the direct current(DC) and alternating current(AC) driving methods of LED; Analyzed various topology of power factor correction(PFC), the traditional bridge-type PFC technology and bridgeless PFC technology.DC LED driver topology is studied based on bridgeless Pseudo-Boost PFC converter, and analyzed its control method, simulated the theoretical analysis is right. Aimed at the lifetime of electrolytic capacitor with large capacitance is short in the traditional DC LED lighting driver, two-stage AC LED driver under electrolytic capacitor-less condition is studied,theoretical analysis of the converter and its control strategy, simulated and experimental verification. At the same time, in order to reduce the conduction loss of switches and harmonic content of input current, bridgeless PFC technique is introduced, single-stage AC LED driver based on bridgeless PFC topology and its control strategy is researched.The DC LED driver based on bridgeless Pseudo-Boost PFC converter. The former stage is bridgeless Pseudo-Boost PFC converter, composed of one bidirectional switch and two fast recovery diodes and resonant branch, the later stage is Buck converter to realize step-down the voltage and make the constant current. traditional diode rectifier bridge of boost PFC converter is not existed in the topology, fast recovery diode can realize zero current turn-off.Operating characteristic、input current characteristic of converter in DCM is analyzed, control circuit is designed in this paper and the function of PFC in bridgeless Pseudo-Boost PFC converter and the constant current of DC LED driver are also simulated and verified.Two-stage AC LED driver is consisted of Buck PFC converter in front stage and half-bridge LCC resonant in last stage. Parameter of two-stage driver and control circuit is analyzed, and driving source is verified by simulation and experiment.Single-stage AC LED driver based on bridgeless Totem-pole Boost PFC and half-bridge LCC resonant converter, acted on switch conjointly, Totem-pole bridgeless Boost PFCdoesn’t need the specialized current controller when operated in DCM, half-bridge LCC resonant converter has smaller capacitance value, the thin film capacitor is instead of traditional electrolytic capacitor. The thesis analyzed the operating principle and the process of parameter for bridgeless Boost PFC and half-bridge LCC circuit, and verified the circuit by simulation.