考虑不同软开关模式的双有源桥变换器电流应力优化方法

Optimization Method of Current Stress for Dual Active Bridge Converter Considering Different Soft Switching Modes

为了全面提高双有源桥(DAB)变换器的整体性能,在基于双重移相实现电流应力最小化的同时,对是否要确保所有开关管实现零电压开通(ZVS)进行了研究。首先建立了以传输功率为输入量的线性化大信号模型,基于该模型,可通过传输功率的直接调节实现输出电压的精准控制。以该模型为基础,通过分析4种功率模态中的软开关特性及电流应力特性,分别实现了基于完全ZVS的电流应力优化方法和基于自然软开关的电流应力优化方法。并完成了2种优化方法对于效率影响的分析和对比。结果表明,当采用开通损耗和关断损耗相近的开关器件时,确保所有开关管实现ZVS会使DAB变换器的电流应力大幅增加,进而对效率产生严重的负面影响。理论分析和实验结果均表明,自然软开关模式的电流应力优化算法能够最大程度地降低电流应力,减小损耗,提高变换器的性能。

To comprehensively improve the overall performance of the dual active bridge(DAB) converter, this paper focuses on the necessity of ensuring zero voltage switching(ZVS) operation for all switches while minimizing current stress based on dual phase shift. Firstly, a linearized large signal model with transmitted power as input is established and the precise control of output voltage is realized. Then, the characteristics of soft switching and current stress in four power modes are analyzed based on the proposed model by directly regulating the transmitted power. Two current stress optimization methods with full ZVS operation and natural soft switching operation are implemented, respectively. Moreover, the improvement of efficiency using two optimization methods is analyzed and compared. The results show that ensuring all switches to realize ZVS greatly will increase the current stress and decrease the efficiency of DAB converter, when switches with similar turn-on loss and turn-off loss are adopted. Both theoretical analysis and experimental results show that the current stress optimization algorithm with natural soft switching can significantly minimize the current stress, reduce the loss, and improve the performance of the converter.