Research And Design Of Non-electrolyticcapacitors AC/DC LED Driver

As a storage element,Electrolytic capacitor is the main reason which restricted the lifetime of LED drivers.In order to ensure the luminous quality of the LED and the performance of the overall lighting system,it is very important to design a high quality and high efficiency non-electrolytic capacitors LED driving power supply.An electrolytic capacitor-less single-phase AC/DC driver for LED lighting has been proposed and it comprises an electrolytic capacitor-less PFC converter and a bidirectional converter.This thesis is dedicated to the design of optimization control for the bidirectional converter.The electrolytic capacitor-less AC/DC LED drivers include an electrolytic capacitor-less PFC and a bidirectional converter connected in parallel with the output.The bidirectional converter is used as a power coupling circuit to absorb two times of the power frequency ripple power in the output power of the PFC converter.In order to avoid the use of electrolytic capacitors,the energy storage capacitor at the output side of the bidirectional converter is small,and the minimum value of the storage capacitor voltage must always be higher than the output voltage of the LED drive power to ensure the bidirectional converter can normal operation.On the other hand,the control of bidirectional converter switch is difficult,and if the duty cycle is too large,easy to cause the system instability.Therefore,this paper proposes a pulse energy control strategy.The bidirectional converter adopts the pulse energy control strategy and calculates the pulse width of the switch according to the instantaneous power required by the bidirectional converter.This control strategy overcomes the difficulty in controlling the switch of the bidirectional converter,greatly reduces the pulsation of the output voltage current of the AC/DC LED driving power supply,the storage capacitor can use a small-capacity and long-life film capacitor to achieve the LED drive.The power supply removes electrolytic capacitors and high power density.Finally,the feasibility of this control strategy is verified by the simulation of the LED driver power supply model of the electrolytic capacitor-less controlled by the bidirectional converter pulse energy.