Control Strategy for Bidirectional DC-DC Converter Based on Improved Extended Phase Shift
To achieve bidirectional control of the active power of the system and keep the stability of the DC bus voltage on the secondary side at the same time,the disturbances of the Power Electronic Transformer(PET)secondary bus that could affect the performance of other ports of PET is minimized.The operating mode and backflow power of the Dual-Active-Bridge(DAB)bidirectional DC-DC converter under the improved Extended Phase Shift(EPS)control is analyzed and the control point for zero reflux power region within the control region is designed.With the aim of system power balance,a power balance control strategy is investigated,which introduces the inverter power into the DAB converter to reduce the voltage fluctuation on the DAB secondary side.Under the improved extended phase shift control,when the system load power changes from 0 kW to 15 kW,the maximum variation of the secondary bus voltage is approximately 30 V,within a steady-state transition time of about 10 ms.When the system load power changes from 15 kW to 10 kW,the secondary bus voltage remains essentially unchanged.In the event of a sudden change in the primary bus voltage,there is no obvious fluctuation observed in the secondary bus voltage.
dual-active-bridgepower electronic transformerextended phase shiftpower balancezero reflux power region
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