| In recent years, the development of China’s urban rail transportation is rapid. With the help of new technology,the new generation of urban rail transportation system has been developing. So,there are new demands for urban rail equipments. This paper focuses on the research of the high-frequency isolated DC/DC phase-shifted full-bridge converter,which is used in Light Rail Vehicle(LRV).So as to reduce APS’s volume and ensure high efficiency.Firstly, several isolated converter topology structures was analyzed in this paper.The features of different topologies were discussed briefly. The high-frequency isolated DC/DC converter plus three-phase four-leg inverter solution was choosed. In addition, the mechanism of high-frequency isolated DC/DC phase-shift converter was discussed, including different switching states of phase shift zero voltage swithching. According to the particular application conditions of LRV’s auxiliary power system,high-frequency isolated DC/DC converter’s power stage circuit parameters were designed.Secondly, based on the main circuit parameters, a small-signal model of phase-shift converter was established. With the help of phase-shifted full-bridge converter small-signal model,the control to output voltage transfer function and the control to inductor current transfer function have been obtained. The impact on the effective duty cycle and zero voltage switching of input voltage, resonant inductor, output current has been studied. Also,the system damping and response speed have been disscussed with the influence of resonant inductor, as well as loop analysis and design. In the Matlab/Simulink environment, a high-frequency isolated DC/DC converter phase simulation model for zero-voltage phase shift zero voltage switching converter established, the duty cycle loss phenomena was simulated and the correction of conterver mechanism analysis parametric design.Effective duty cycle decreases as the increase of load current and resonant inductor,and it decreases as the input voltage decreases.Finally, based on the system parameters calculated above,a light rail auxiliary converter experimental platform was build. Control chip uses TI’s UCD3020digital power controller. The theory analysis of high-frequency isolated DC/DC zero voltage switching converter was verified. And ZVS-switching of this converter can be achieved in the case of more than one-third of the load. |
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