| Bidirectional DC/DC converters play an important role in energy bidirectional transmission, which are widely used in distributed energy storage system to bi-deliver energy between battery and the high voltage bus. As the output voltage of the battery is generally low and varies in a wide range, the bidirectional DC/DC converters are required to achieve a high voltage gain and regulate in a wide voltage range. Then the study of the bidirectional DC/DC converter in distributed energy storage system has always been a huge challenge.The traditional bidirectional Buck/Boost converter can regulate in a wide voltage range while the isolated half-bridge bidirectional DC/DC converter can achieve a high voltage gain by changing the turn ratios. The topology proposed in this paper is integrated by the above two converters. The operating principle and characteristics of the converter under phase-shifting control(PS) are analyzed in detail. However, the control strategy should be improved as it suffers narrow range of soft switching and high current ripple. PWM plus phase-shifting control(PPS) is employed to improve the performance of the converter. The operating principle and characteristics of the converter under PPS control are analyzed in detail, which has improved a lot compared to PS control. The experimental prototype is built to verify the analysis, which confirms the theory well. Afterwards, the power-transmit inductor and the transformer are magnetically integrated to improve the power density, high efficiency can also be achieved by applying PPS control. Finally, experimental prototypes of 40V-60V/400 V 1kW based on the two topologies are built to verify the analysis. |
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