移相控制三电平双有源全桥直流变换器的软开关特性

Soft-switching Characteristics of Three-level Dual Active Bridge Converter under Phase-shift Control

变压器原副边桥臂电压不匹配时,移相控制三电平双有源全桥直流变换器(3L-DAB)的开关管可能会工作在硬开关模式,导致系统损耗增加、效率降低。针对这个问题,该研究对3L-DAB变换器的软开关工作范围展开详细的分析。首先,描述了移相控制下3L-DAB变换器的功率传输特性;在此基础上,基于稳态时域模型,推导了随着移相角和变压比的变化,变压器原副边所有开关器件的软开关工作范围。然后,对比分析了考虑开关管结电容前后变换器的软开关工作范围变化。最后,通过仿真和搭建的实验平台验证了理论分析的正确性。

The switches of a three-level dual active bridge(3L-DAB)converter under phase-shift control may operate in a hard-switching mode especially when the voltage conversion ratio is not equal to one,which will lead to high power loss and low efficiency of the system.To address the issue,a detailed analysis of the soft-switching operation range of the 3L-DAB converter is performed.First,the power transmission characteristics of this converter under phase-shift control are described.Then,the soft-switching operation range of all switches on the primary and secondary sides of the transformer varying with phase-shift angles and voltage conversion ratio are deduced based on a steady-state time-domain model.Afterwards,the soft-switching operation ranges of the converter with and without considering the junction capacitance of the switch are compared.Finally,simulations and experimental results based on an established experimental platform verified the theoretical analysis.