Research And Design Of Isolated High-Gain DC-DC Converters For Electronic Ballasts

Electronic ballasts are widely used in new energy automobile industry,industrial lighting,urban transportation and other occasions.With the popularization of green lighting and energy－saving lighting,the market of Electronic ballasts is becoming more and more large,which is developing towards miniaturization,lightweight and high efficiency.As a key component of Electronic ballasts,high-gain DC-DC converters not only need to be electrically isolated,but also ensure efficient and stable operation of the converter itself.Aiming at several problems of high-gain DC-DC converters in Electronic ballasts,this thesis improves the isolated high-gain topology based on the existing high-gain topology,combined with bidirectional positive and negative voltage doubler rectifier circuits.The improved high-gain topology not only ensures that the switch is turned on to achieve soft switching,but also reduces the turns ratio of the high-frequency transformer,further increasing the output voltage gain and reducing the output voltage ripple.According to the specific working environment and special requirements of Electronic ballasts,First,this thesis studies the advantages and disadvantages of various non-isolated and isolated high-gain DC-DC converters.The working principle of the improved high-gain DC-DC converter is analyzed,and the mathematical model is established by the generalized state space averaging method.The output voltage gain expression of the improved high-gain DC-DC converter is derived.The improved high-gain topology and the existing high-gain topology are compared in terms of output voltage gain and voltage ripple.By establishing the loss model of each part of the converter,the power transmission efficiency of the improved high-gain DC-DC converter is analyzed.The overall loss distribution of the improved high-gain DC-DC converter is calculated,which provides a theoretical basis for improving system efficiency.For the existing loss problem,the corresponding improvement measures are put forward in this thesis.Finally,in order to verify the correctness of the above theoretical analysis,the hardware experimental circuit is built according to the design requirements.The selection of main components,PCB board design and software design of high-gain DC-DC converter are introduced.The simulation and experimental verification were carried out by using MATLAB simulation software and experimental platform respectively.It is verified that the switch tube achieves soft switch,and it is proved that the theoretical analysis is the same as the experimental results.