The Study And Design Of High Power Factor LED Driver

In the face of growing tensions in traditional energy sources and serious environmental pollution,energy conservation and environmental protection have become a topic of common concern to governments and the general public.As a kind of green light source with both energy saving and environmental protection,LED has been applied to all areas of our lives.According to statistics,the global lighting energy consumption has reached 19% of the total energy consumption,and LED replacement of traditional lighting is the general trend.LED is essentially a light emitting diode.Due to its special volt-ampere characteristics,it is sensitive to changes in current,and is easily affected by environmental factors such as temperature.Therefore,it is of great significance to develop an efficient and stable LED driving power supply.Aiming at the current problems of LED driving power supply,combined with its design requirements and application background,this paper developed a LED driving power source with high power factor and low load regulation rate.The power topology adopts Boost PFC as its predecessor and the latter stage is Buck.In order to obtain high power factor and low current distortion rate,this article studies the power factor correction circuit of LED driving power supply.The passive power factor correction circuit and the active power factor correction circuit are compared.Although the passive power factor correction circuit has the advantages of simple circuit structure and good stability,the PF is difficult to exceed 0.95.Although the active power factor correction circuit is relatively Complex,but it can improve the PF to close to 1,and also can obtain lower THD;Based on this,this paper compares the advantages and disadvantages of DC-DC topology PFC such as Boost PFC,Buck PFC and flyback,due to Boost topology inductance The connection to the input facilitates the increase of power and facilitates the drive.Finally,Boost is determined as the main topology for power factor correction.At the same time,the MATLAB/Simulink model of Boost PFC is built.The phases of the input voltage and current are compared,and the THD is measured.Finally,in order to verify the correctness of the theoretical analysis and simulation,a 200 W experimental prototype was made;both the simulation and the experimental results showed that the Boost PFC circuit has the characteristics of high power factor and low current distortion rate,meeting the design requirements and related Harmonic standard.To solve the problem of poor load regulation in traditional LED power supplies,an inductor current compensation control strategy based on output voltage feedback is used to compensate the output current offset caused by load regulation using the load voltage signal.This paper analyzes the factors affecting Buck constant-current topology load regulation ratio,and combines the engineering application data to optimize the control strategy of load regulation.Finally,the experimental results on the LED power supply prototype demonstrate that the load regulation rate is reduced from 0.03%/V to 0.01%/V,which verifies thecorrectness of the proposed control method and achieves the effect of optimizing the load regulation rate.In addition,this article analyzes and designs the EMI filter circuit of the LED drive power supply,gives the specific EMI filter circuit and the corresponding filter component model,and finally carries out the radiated interference test and conducted interference test on the experimental prototype in the anechoic chamber.The final test results show that the EMI filter circuit designed in this paper can control the electromagnetic interference within a reasonable range,in which the radiated interference satisfies the EN55022 RE-Class B standard,the minimum margin is also 7.26 d B,and the conducted interference complies with EN55022 CE.-The Class B_QP standard has a minimum margin of 13.62 d B.