Research On Multi-output High Efficiency Electroless Capacitor AC/DC LED Driver

AC/DC LED drive power is the core part of LED lighting products,which can ensure the long-term efficient and stable operation of the entire lighting system.It plays a vital role in extending the service life of LED lighting products,saving energy consumption and reducing post-maintenance costs..There are many factors that affect the reliability of the drive power circuit.Among them,the life is greatly affected by the working temperature,and the bulky electrolytic capacitor is a short board for the reliability of the drive power.In order to improve the overall life of the drive circuit,optimize the topology of the drive or optimize the control strategy,and replace the electrolytic capacitor with a long-life,high-stability capacitor.In this paper,the elimination of electrolytic capacitors is realized according to the three-port topology based on flyback,which is further studied and analyzed.The three-port converter firstly uses the auxiliary circuit to balance the ripple power between the input and output power,and then increases the average voltage and voltage ripple of the capacitor in the auxiliary circuit,thereby reducing the capacitance value and achieving the electroless capacitor.However,increasing the average voltage and voltage ripple of the auxiliary side capacitor causes loss of the switching device and the magnetic element,and reduces the overall efficiency of the driving.To this end,this paper proposes a self-adaptive control method for the auxiliary side capacitor voltage based on the Flyback+Buck three-port converter.While reducing the average voltage of the auxiliary side capacitor,it can also adaptively adjust the capacitor voltage according to the load change.In order to improve the static and dynamic stability of the converter,the small signal modeling and analysis of the Flyback converter is carried out,and the Bode diagram of the Flyback converter under different load conditions is obtained respectively.The corresponding compensation network is calculated and the controller is given.The proposed valley voltage control method is simulated and verified by saber simulation software.The three-port converter based on Flyback+Buck has a simple topology,and the auxiliary side capacitor and the main output are structurally independent of each other and do not interfere with each other.Therefore,the paper proposes to connect multiple Buck circuits in parallel on the auxiliary side of the three-port converter as current regulators for each output to achieve multiple constant current outputs.The working state of the topology at different times is analyzed in detail.In order to reasonably distribute the power flow and realize the constant current output,a carrier-based method is proposed for the circuit,and the method is verified by simulation.Finally,based on the above proposed control method and topology,a 48W two-output power supply experimental prototype was built and experimentally verified and analyzed.