一种基于损耗模型的双有源桥DC-DC变换器效率优化方法

An Efficiency Optimization Method in Dual Active Bridge DC-DC Converter Based on Loss Model

对双有源桥DC-DC变换器(DAB)系统中的各部分损耗进行建模,并依据此模型,以提升效率为目标,对DAB系统进行优化设计。首先,介绍单移相调制策略下的DAB工作原理,并推导漏电感电流有效值的解析表达式。为突出DAB的电流波形特征,引入电压转换比的概念,这一概念与变压器匝比相关。然后,介绍损耗建模方法。DAB系统的损耗主要分为两部分,一部分源于半导体器件;另一部分源于高频隔离变压器及电感。两者的损耗数值不仅由本身的材料特性决定,同时与运行工况紧密相关,如传输功率、电压、电流等。将单移相调制下的DAB电流、电压波形特征,与器件和变压器的本身特性结合考虑,解析建立DAB的稳态损耗模型。并在此基础上,通过数值计算的方法,对电压转换比进行优化设计,同时优化移相比的选择,增强软硬件的适配性,提升DAB的整体效率。最后,通过实验对所建损耗模型及优化方法进行了验证。

This paper focuses on the loss model and efficiency optimization of dual active bridge(DAB)DC-DC converter.First,the single phase modulation principle is shown and the current RMSvalue is derived analytically.Voltage transfer ratio is introduced to characterize the current waveform,which is related to the transformer ratio.The energy loss of DAB can be divided into two parts,onefrom device power dissipations,and the other from power loss in electromagnetic elements,such as thetransformer and inductance.Their loss values are both related to material choices,and also affected byoperation states including transfer power,voltage and current value.Combined the current and voltagewaveforms with element material features,DAB loss model is built in a steady operation.Furthermore,by numerical calculation of the loss model,voltage transfer ratio and phase shift duty are optimizedaiming at high efficiency.At last,a4kW-DAB platform is built and the optimization method is testedby experimental results.