High Power LED Power Supply Scheme Design And Application Of Environmental Research

With the development of the switching mode power supply, the soft-switching technology has been used widely in all kinds of the power supply in recent years. We can choose many efficient topologies, which are mainly resonance soft-switching topology and PWM ones. The parameters of the switching tube become better and better with the rapid development of the semiconductor device; especially under the circumstance that on resistance, stray capacitance and reverse recovery time are smaller and smaller, it provides a great platform for the development of LLC resonance topology. It can realize the conversion of the soft switching by the resonant converter, and can improve the overall efficiency greatly.There are many advantages of the LLC resonance circuit. Firstly, it can adjust the output, when the input and load change in a wide range, but the switching frequency only has a little change. Secondly, the ZVS can be come true in the whole work. Finally, all the junction capacitance of the parasitic element and semiconductor device, and the leakage inductance and magnetizing inductance of the transformer can realize the ZVS.This thesis analyzes the recent development tendency of the LED light source simply; expounds the requirement of the LED street lamp, and analyzes the merit and demerit of the LED street lamp power supply, which is based on the LLC half-bridge resonance circuit, and the selection of the circuit topology of it. It targets the 144W LED street lamp power supply, which has the following design indicators, the output voltage is 48V and the output current is 3A. It verifies the feasibility of the circuit scheme by testing all links and optimizing the complete machine to the whole power system.The part one of this thesis introduces its prospect to set up this topic and the framework of this paper. The part two introduces the development of the current LED market, and looks forward to the LED development tendency; meanwhile, expounds the key position of the LLC resonance circuit in LED street lamp. The part three introduces the topology type and basic principle of the LLC half-bridge resonance circuit; presents the advantages and disadvantage of all kinds of the LLC circuit topology, and elaborates and analyzes the operating characteristic and principle of each time period one by one. The part four simplifies the LLC circuit, and analyzes the frequency-domain DC characteristics of the LLC resonance circuit. The part six designs a 144W street lamp power that is based on the design requirement, including the PFC circuit design and LLC half-bridge resonance circuit; explains all the links of the design. The part seven is the systematic test to the whole power system. The part eight has a loss analysis to each module of the whole power system.The last part summarizes the problem which is found in the test and solves it. It shows that the 144W half-bridge resonance circuit has an obvious efficiency advantage, and has an excellent performance in other aspects, such as standby power consumption and so on.