Research On Quadratic DC-DC Step Up Converter

As social and economic development enters the fast lane,the demand for traditional energy consumption has increased sharply,which has brought about a series of energy and environmental crises,and promoted the development and application of new energy.Due to the low voltage and large fluctuation of output in the new energy power generation system,high efficiency and high boost ratio DC-DC converter are needed to improve.Single-switch cascading technology is very effective at increasing voltage gain while reducing losses.Therefore,this paper constructs a new DC-DC boost converter according to the different structure of the Boost converter,and uses the single-switch cascade technology to obtain the quadratic DC-DC step up converter studied in this paper.This thesis begins with the study of the working principle of the converter,and analyzes the supercharging ratio,tube and capacitor voltage stress in each mode.The results show that the converter not only has the high boost ratio of the quadratic Boost converter,but also has lower capacitance voltage stress,which effectively reduces the converter volume and improves the power density.The voltage ripple of the two capacitors is discussed according to different energy transfer modes,and the two-dimensional curve and three-dimensional surface are used for auxiliary analysis.The result shows that the capacitor voltage ripple is related to the corresponding inductance when the incomplete power mode is not available.Secondly,according to the switching element model method,a small signal model is constructed for the converter.The transfer function of each variable to the conduction ratio is obtained by Laplace transform.The logarithmic frequency characteristic curve is drawn by Matlab to determine whether the system composed of each transfer function is The minimum phase system provides a theoretical basis for the selection of the feedback amount in the following text.The results show that the system composed ofG_ov-d?s?is a non-minimum phase system,the system composed ofG_si-d?s?andG_Li1-d?s?is the minimum phase system,the system composed ofG_Li2-d?s?is the non-minimum phase system in CCM-CCM mode,and the minimum phase system in DCM-CCM mode.According to the three commonly used improvement measures of converter performance?optimized topology,suitable control strategy,low-power devices?,this paper adopts peak current control as the converter control strategy,and uses slope compensation and internal and external loop design to compensate for the defects of the control strategy.This article uses the PSIM simulation platform to test the waveform of each component.In order to improve the performance of the converter more effectively,a test sample with a power of 144W is fabricated by using all-SiC devices.The experimental results show that the quadratic DC-DC boost converter has high boost ratio,low capacitance voltage stress and High transmission efficiency characteristics.