基于改进扩展移相的双向DC-DC变换器控制策略

Control Strategy for Bidirectional DC-DC Converter Based on Improved Extended Phase Shift

为对系统有功功率进行双向调节,同时使二次侧直流母线电压保持稳定,并减小电力电子变压器(PET)二次侧母线的扰动对PET其他端口的性能所造成的影响,分析双有源桥(DAB)双向DC-DC变换器在改进扩展移相控制(EPS)下的工作模式和回流功率,设计了控制区域内零回流功率控制点。以系统功率平衡为目的,研究系统功率平衡控制策略,该策略将逆变器的功率引入DAB变换器,以减小DAB二次侧电压波动。在改进扩展移相控制下,系统负载功率从0kW突变至15kW时,二次侧母线电压最大变化约为30V,达到稳态过渡时间约为10ms;系统负载功率从15kW突变至10kW时,二次侧母线电压基本无变化;在一次侧母线电压发生突变时,二次侧母线电压无明显波动。

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.