Research And Design Of LED Driver Without Electrolytic Capacitor Based On Power Feedback Control Strategy

With the shortage of global resources,energy saving and environmental protection are becoming increasingly prominent.Light Emitting Diode-LED,as the most representative "green" light source in the field of lighting,has the advantages of energy saving,environmental protection and stability,and is entering millions of households.As an important part of the LED lighting system,the serious mismatch between the lifetime and the lifetime of the LED restricts the development of the LED lighting system.Therefore,the design of a long-life,high-performance LED driving power has important academic and application value.In the traditional AC/DC LED driving power supply,the function of electrolytic capacitance is to balance the power pulsation of twice power frequency ripple between input power and output power,but it is also affected by its own material and working temperature.The electrolytic capacitance is the main reason for the short life of the driving power supply.so eliminating the electrolytic capacitance in the driving power supply is key to match the long life of the LED.In addition,there are many kinds of non-linear elements in the driving power supply.In order to reduce the harmonic pollution to the power network when it is connected to the power supply,power factor correction(PFC)is needed to improve the power factor and the quality of power supply.In order to improve the power factor of the driving power supply and eliminate the influence of electrolytic capacitance,after reading a large number of relevant literature,this paper studies and designs a constant voltage high power factor non-electrolytic capacitance LED driving power supply.The main circuit uses Once-cycle control strategy Boost PFC topology and a Once-cycle control strategy.Because this control strategy does not contain a multiplier module and does not need to sample AC input voltage,it can effectively avoid the signal delay and error of the control system while meeting the high power factors,effectively improve the system response speed and reduce the volume of the control circuit.Secondly,a decoupled Buck-Boost bi-directional converter is designed for the bus current of Boost PFC circuit which contains twice the power frequency ripple,and is parallel to the output of Boost PFC circuit.Then,by comparing and analyzing the existing decoupling control strategies,it is found that the dual-loop decoupling control strategy has some drawbacks such as current inner loop tracking distortion and poor anti-jamming ability.By building the circuit model of the bidirectional converter and solving the problem of the dual-loop decoupling control strategy,a new control strategy is presented,which compensates the dynamic pulsating current with output power feedback,and the tracking and anti-interference ability of the current inner loop in the dual-loop decoupling control strategy are enhanced.Finally,the double power frequency ripple component in the bus current is transferred to the bidirectional converter to eliminate the electrolytic capacitance and obtain constant current output for the LED load.Finally,use Matlab/Simulink is built and a 300 W experimental prototype is designed.After simulation and experimental validation,the AC/DC LED driver power scheme with constant voltage and high power factor is feasible.