Three-level dual-active bridge (3L-DAB) DC–DC converter under conventional phase-shift (CPS) control would produce large reflux power and current stress, especially when the voltage conversion ratio is varied in a wider range, which will lead to high power loss and low system efficiency. An optimised phase-shift (OPS) control strategy is proposed to control the 3L-DAB operating at the point with minimum reflux power. The power characteristics of 3L-DAB under CPS control are analysed. Then the mathematical model of the reflux power is established, and the relationship equations among the reflux power, phase-shift (PS) ratios, and voltage conversion ratio are deduced. The minimum reflux power and optimal PS ratio are calculated by using the segmentation optimisation algorithm in different ranges of transmission power and voltage conversion ratio. Performance comparative analysis between CPS and OPS controls is carried out later. Adopting the proposed OPS control strategy, the reflux power of 3L-DAB is minimised, as well as reducing the current stress and increasing the efficiency in a wide voltage conversion ratio range. An experimental prototype was developed to verify the effectiveness of the OPS control strategy and the correctness of the theoretical analysis.

中文翻译：

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适用于宽电压转换比范围应用的具有最小回流功率的三电平双有源桥式DC-DC转换器的最佳相移控制

在传统的相移（CPS）控制下，三级双有源桥（3L-DAB）DC-DC转换器会产生较大的回流功率和电流应力，尤其是当电压转换比在较大范围内变化时，会导致导致高功率损耗和低系统效率。提出了一种优化的相移（OPS）控制策略，以控制3L-DAB在最小回流功率下工作。分析了CPS控制下的3L-DAB的功率特性。然后建立回流功率的数学模型，推导了回流功率，相移比和电压转换比之​​间的关系方程。通过分段优化算法，在不同的发射功率和电压转换率范围内，计算出最小回流功率和最优PS比。CPS和OPS控件之间的性能比较分析将在稍后进行。采用提议的OPS控制策略，可最大程度地降低3L-DAB的回流功率，并在宽电压转换比范围内降低电流应力并提高效率。开发了一个实验原型，以验证OPS控制策略的有效性和理论分析的正确性。