Research On The DC Converter With Variable Gain For Electric Vehicle

The Vehicle promote the progress of human civilization, but also increase the demandfor energy and make environmental pollution. Electric vehicle and other green industriesare growing concerned by more and more people, The charging technology of Powerbattery has been the key of the electric vehicle technology. This paper aims to study theappropriate charging method and an efficient charging converter.According to the characteristics and requirements of battery, this paper choose aappropriate charging method which is a three-stage charging method. Base on theanalysis of the traditional converter, coming up with a new and efficient variable gain,high voltage input, wide range output staggered series-parallel forward converter. Theconverter is constituted by the bridge arm of two low-voltage arms and a high-voltagearm. Three arms form two forward units. The power switches’ voltage stress oflow-voltages switching-legs is half of the input voltage while the switches’ stress ofhigh-voltage switching-leg is input voltage. Staggered series-parallel forward converterretains the advantages as well as traditional two-switch forward converter, which is lowstress, high-efficiency, high reliability. Anti-parallel diode and body diode of powerswitch are used for the magnetic resetting. The demagnetizing voltage of the transformeris two times of the magnetizing voltages. Base on the voltage-second balance ofmagnetizing inductance and the relationship between the input and output, the maximumduty cycle of the switches can reach0.67, part of power MOSFETS can leadZero-Voltage-switching (ZVS). The boost converter is combined with the staggeredseries-parallel forward converter, change the gain of converter, which is applications ofhigh voltage and wide range of input voltage. The secondary side of the transform iswork by two groups of inductance in parallel, which can reduce the ripple of outputcurrent and the volume of the filter.This paper analyzes the charging circuit system, design the current regulator andvoltage regulator. The close-loop converter is effective. Base on the PSIM software, verifythe charging characteristics of the main circuit system as well as various properties of the charging system. Analysis the software and hardware in details, and produce aexperimental prototype. Make software programs with TMS320F28027. Relevantexperimental study was carried out. The experimental results proved that the accuracy ofthe theoretical analysis and simulation model. Verify the characteristics of the converter,three-stage charging mode is achieved. The result of experiment is coincided withtheoretical analysis.