Research On LED Landscape LAMP Constant Current Driving Power Supply

Based on the current study on need for high-power LED lamp,which is a new type of light source,applied in landscape lighting as well as its driving power supply status,this research has completed the study and hardware design on a 500 W three-way constant current output LED drive power.A modular approach is adopted so that the whole circuit is divided into four modules: EMI filter circuit,power factor correction(Boost PFC)circuit,LLC resonant half bridge converter,and BUCK constant current drive module.Firstly,analyses on the external characteristics and driving mode of high-power LED is conducted and the driving mode of constant voltage followed by constant current is selected through the comparison of different modes.Secondly,the study focuses on the advantages,primary structure,control strategy and basic principle of half-bridge LLC resonant converter.Meanwhile improvements are made in the traditional LLC through the following two efforts: synchronous rectification technology at its output is utilized to reduce the output rectification consumption and loss,achieving a higher power efficiency,A constant voltage module is added in the designs of hardware and parameters to maintain a constant output value for the design convenience of constant current in the latter stage.Thirdly,the BUCK constant current drive circuit is designed by contrsting the two ways of constant current control.With the efforts made above,the design of a high frequency enhanced EMI filter circuit is realized so as to reduce the interference of the mains harmonics to the driving power source and prevent the switching signal of the driving power source from penetrating into the commercial power.In the end,computer simulations are performed on the critical parts of the circuit as well as the overall circuit and a sampie machine has been made to verify the consistency between the results of the research and the design requirements.