Research On The High Efficiency And High Power Density DC-DC Power Supply

With the development of modern electronic devices, electronic equipment has ahigher requirement in the bulk of the power supply. And research on high efficiency,high power density of power supply is becoming more and more urgent. In the field ofaerospace, communications equipment, the power supply has an important impact onthe performance of the entire system. At present, the volume of switch power isrelatively large, efficiency and power density are could not reach the requirements.Tosolve these problems, we research active clamp technology, synchronous rectifiertechnology and flat transformer technology of switch power. Through these techniquescan improve the efficiency and power density of switching power supply.Based on the analysis of the working principle of active clamp flyback converter,we analyzed the soft switch of the power, and the leakage inductance of the transformeris recycled. Through the drive signals of the dead zone time design and transformerdesign, realized the soft switch of primary switch tube, and recycle the energy ofleakage inductance to input. It can improve the efficiency of the power supply, reducethe voltage stress of switching tube at the same time.Further, use synchronous rectifier circuit to solve the problem of high loss of theoutput diode. According to the characteristics of the active clamp circuit, coupling ofauxiliary switch tube drive signal drive synchronous rectifier. In order to make thepower supply to complications, we have designed planar transformer, it can effectivelyreduce the height of the power supply, increase the power density of power supply. Atthe same time, the leakage inductance of the planar transformer is low,the repeatabilityis good, suitable for mass production.Finally, in this paper, the design process of the power supply has detailedinstructions, make the power samples, test results are given. Power efficiency reachedmore than90%, the power density more than3.5W/cm3, ripple voltage less than50mv,it has reached the requirement of project.