Research On Energy Conversion Efficiency Of AC/DC 350W LED Switching Power Supply

Landscape lighting and building lighting projects are very important to urban construction and are receiving increasing attention.How to let landscape lighting and building lighting projects can both provide stable,reliable light source for the city and have the advantages of energy saving,high efficiency has become the focus of scholars.LED light sources are widely used in lighting systems because of high efficiency and long life compared with conventional light sources,which has driven a wide range of using in LED switching power supplies.In order to let LED lighting systems have high energy conversion efficiency,improving efficiency of LED switching power supplies is one of the most effective ways.In order to reduce power loss of LED switching power supplies,the high-frequency transformer’s loss,the primary-side switching tube’s switching loss and the secondary-side rectification loss were researched.The measures to reduce above three losses were proposed,the corresponding components and circuits were selected or designed.The circuits of other parts of LED switching power supply were designed and the simulation model basing on PSPICE software was built.The simulation results verify that the LED switching power supply prototype can operate normally,which confirms the feasibility of three kinds of measures to reduce losses.Finally,the LED switching power supply prototype was designed and produced,and the reliability and high efficiency of the LED switching power supply prototype were tested and verified,which confirmed the effectiveness of the measures to reduce losses.Firstly,the double transistors forward topology with the voltage level and power range required by the design was selected.Through the study of electrical and optical characteristics of the LED load,the requirements of the LED load for the LED switching power supply were obtained,and the electrical specifications of the LED switching power supply designed by this paper were summarized.Secondly,power losses of the LED switching power supply were analyzed,the high-frequency transformer’s loss,the primary-side switching tube’s switching loss and the secondary-side rectification loss were analyzed,and the corresponding measures to reduce above three kinds of losses were given.In order to reduce the loss of high-frequency transformer,after selecting core’s material and type reasonably,the relationship between distributed parameters and winding’s layout was analyzed.By selecting the appropriate winding’s layout,the high-frequency transformer with low distributed parameter and corresponding loss was designed.So as to decrease the switching loss of the primary-side switching tube,an optimized control method was proposed.Using the PWM control method to control the primary-side switching tube in heavy load conditions and using the optimized PSM control method in light load conditions were considered.The optimized PSM control method enriched the duty ratio of the conventional PSM control method,controlled the energy transmission gradually and obtained stable output voltage and current relatively.The optimized control method reduced switching times of the primary-side tube in the entire range of load and decreased the loss.For the purpose of reducing the secondary-side rectification loss,the MOS transistor with small resistance was substituted for the diode and the synchronous rectification chip was selected to control the MOS transistor.In order to realize the complete function of the LED switching power supply,the remaining circuits and components of the LED switching power supply were designed and selected.So as to verify that the LED switching power supply designed in this paper can operate normally with three kinds of measures to reduce losses.The overall simulation model of LED switching power supply was built in PSPICE software.The simulation experiments were carried out and the simulation results and analysis of three kinds of measures to reduce losses were given.To verify the reliability and high efficiency of the LED switching power supply prototype which was designed and produced,the key specifications of the LED switching power supply prototype were tested,and the efficiency tests in various load were added.The test results show that the LED switching power supply designed in this paper meets the requirements of the design,satisfies the reliability standards and has high energy conversion efficiency.