双向全桥DC-DC变换器中大容量高频变压器绕组与磁心损耗计算

精确预估非正弦波激励下高频变压器绕组与磁心损耗、研究不同模态下变压器损耗的变化趋势,对于电力电子变压器(PET)精细化设计至关重要。在对PET中间级——隔离式双向全桥DC-DC变换器工作原理进行分析的基础上,建立变换器的近似等效电路模型,得到一种适用于隔离式双向全桥DC-DC变换器中高频变压器绕组损耗计算方法。在计算方波、梯形波电压激励下的磁心损耗时,推导出修正的Steinmetz经验公式简化解析计算式,引入仅与占空比和上升时间有关的修正系数,据此可直接利用正弦波激励下的损耗系数,快速获取典型工作模态下磁心损耗。设计制作一台1.2k V/0.3k V/5k V·A非晶合金磁心高频变压器试验模型,将所提方法的计算结果与有限元仿真和试验测量结果对比,验证了所提方法的有效性。

Calculation of High-Power High-Frequency Transformer's Copper Loss and Magnetic Core Loss in Dual-Active-Bridge DC-DC Converter

Regarding the elaborate design of power electronic transformer (PET), it is essential to accurately predicate the copper losses and magnetic core losses of high-frequency transformers under non-sinusoidal voltage magnetization, and analyze its variation with operation modes. Based on the analysis of operation principle and approximate equivalent circuit model of the isolated bidirectional dual-active-bridge DC-DC converter (IBDC) in PET, an analytical calculation method for copper losses is proposed. The extended expressions of modified Steinmetz equation are presented to determinate the magnetic core losses under rectangular and trapezoidal voltage excitations that are typical for PET. The correction-coefficients are introduced accordingly, which are only correlative with duty cycle and rising time. Simulation and experimental results on a 1.2kV/0.3kV/5kV·A high-frequency transformer test model with amorphous alloy core verify the effectiveness of the above methods.