双有源桥四绕组变压器双向DC-DC变换器

Improved Dual Active Bridge Bidirectional DC-DC Converter with Four-Winding Transformer Structure

基于传统的双有源桥(DAB)电路在变压器一次、二次绕组均将中心抽头引出,分别连接到两侧分压电容中点处,提出一种具有四绕组变压器结构的双有源桥双向DC-DC变换器拓扑,其采用三重移相控制(TPS),在同时具有升降压增益特性的应用场合下,保留了传统DAB优点的同时,两侧引出的中心抽头在低功率等级下又能够为一次、二次侧最差软开关条件的功率开关管提供零电压开通的反向电流,进一步拓宽了软开关范围。本文首先介绍了改进型双向变换器的拓扑演化过程及基本电路构成,通过对电路进行等效化简,推导出其三角形等效电路模型;其次对电路在TPS调制方式下的工作模式进行分类,并以正向模式(Ⅰ-1)A为例对电路的稳态工作过程进行分析;然后分析变换器软开关特性,在电压增益分别处于升降压特性时,分别以桥内移相角φ1与φ2作为主变量进行控制,能够保证全功率范围下的所有功率管的软开关实现;最后建立了1kW实验样机,验证了上述分析的正确性。

In this paper,an improved dual-active bridge bidirectional converter(DAB)topology with four-winding transformer structure based on traditional DAB is proposed.It is based on the conventional DAB transformer that the center taps of the primary and secondary winding are taken out and are connected to the midpoints of the voltage dividing capacitors on both sides respectively.In the applications with both buck and boost requirements,triple phase shift(TPS)control is used,which retains the advantages of traditional DAB,and the center taps on both sides provide a zero voltage switching(ZVS)reverse current for the switches with the worst soft-switching condition on the primary and secondary sides at low power levels,further broadening the soft-switching range.In this paper,the topology evolution process and basic circuit structure of the improved bidirectional converter were introduced firstly,and the delta equivalent circuit model was derived by equivalent simplification of the circuit.The working mode of the circuit in the TPS modulation mode was classified,and the steady state working process of the circuit was analyzed by taking the forward mode(Ⅰ-1)A as an example.Next,the soft switching characteristics of the converter were analyzed.When the voltage gain was in the boost and buck characteristics respectively,the intra-bridge phase shift anglesφ1 andφ2 were used as the main variables in the control process to control the soft switching in the full power range.Finally,a 1kW experimental prototype was established to verify the correctness of the above analysis.