Research On Sampleless Resistor Flyback LED Drive Power Supply

With committing to peak carbon dioxide emissions before 2030 and achieve carbon neutrality before 2060,China has also accelerated the pace of low carbon emission.Energy saving and emission reduction is the trend.According to statistics,lighting electricity consumption accounts for about a quarter of the world’s total electricity consumption.On the basis of vigorously developing renewable energy and promoting technological upgrading,our country is also vigorously promoting green lighting projects.LED draws a lot of attentions in lighting because of their high light efficiency,long life and low energy consumption.Flyback topology is widely used in LED driver power supply because of its mature control scheme,high reliability and low cost.It is of practical significance to study new control methods to improve the efficiency of Flyback-based LED driver.In this paper,the principle of primary current emulation is analyzed,the control circuit is introduced in detail,and the feasibility of the non-sampling resistor to realize cycle by cycle over-current protection is demonstrated,and the protection logic is given.At the same time,the factors affecting the output constant current accuracy are analyzed and the solution is given.A 40 W prototype was designed out to verify the feasibility of the nondestructive testing scheme based on the current simulation technique.The experimental results show that the output current accuracy of the prototype using the primary side current emulation technology is less than 1.8%,and the efficiency can be improved by 0.9% compared with the traditional flyback.Finally,a new output current estimation scheme is proposed by deducting and extending the original current emulation idea,which is applied to the flyback with constant on-time control.In this paper,the working principle and output error compensation are analyzed in detail,a 40 W prototype is designed and manufactured,the prototype waveform is tested,and the experimental data are analyzed.The experimental results show that the output current accuracy of the prototype with the new technology is less than 1.3%,and the maximum efficiency can be improved by0.97% compared with the traditional flyback.