新扩展移相角下的双有源桥DC-DC变换器优化控制策略

Optimal Control Strategy for Dual Active Bridge DC-DC Converter With New Extended-phase-shift Angle

为提高双有源桥(dual active bridge,DAB)DC-DC变换器的效率,降低其控制复杂度,提出一种基于扩展移相控制的最小电流应力闭环优化控制策略。首先,依据两侧全桥输出电压间的相位关系和桥内移相角的大小,重新定义新的移相比,以确保移相比与传输功率的正相关性;接着,基于开关管的通断顺序,对DAB的进行工作模态的划分,并择优选出两种作为其实际工作模态;然后,利用Karush-KuhnTucker条件法实现在软开关条件下全功率段的电流应力优化,并与新的移相比相结合设计出一种更为简洁的闭环优化控制策略;最后,搭建DAB仿真模型及实验样机进行验证,结果表明:所提控制策略不但具有控制简单、易实现的特点,同时能在全功率范围内实现最小电流应力控制和开关管的软开关特性。

In order to improve the efficiency of dual active bridge(DAB)DC-DC converter and reduce its control complexity,a closed-loop optimal control strategy for minimum current stress based on the extended-phase-shift control method is proposed.Firstly,according to the phase relationship between the output voltages of the full bridge on both sides and the magnitude of the phase shift angle in the bridge,the phase shift ratio of extended-phase-shift control is redefined to ensure the positive correlation between the phase shift ratio and the transmission power.Then,the operating modes of DAB are divided based on the on-off sequences of the active switch,and two of them are selected as the actual operating modes.Moreover,the Karush-Kuhn-Tucker condition method is adopted to optimize the current stress in the whole load range under the condition of soft switching,and a more concise closed-loop optimization control strategy is designed based on the combination with the proposed phase shift ratio.Finally,the DAB simulation model and experimental prototype are both established to verify the proposed control strategy.The results show that the proposed control strategy not only has the advantages of simple and easy-implementation,but also can realize the minimum current stress control and the soft switching characteristics of the active switch within the whole load range.