PEMFC冷启动过程阻抗谱及特征频率分析

Impedance Spectroscopy and Characteristic Frequency Analysis of the PEMFC Cold Start Process

为优化质子交换膜燃料电池(PEMFC)冷启动过程,提供足量的反馈数据十分必要,常见的阻抗谱和等效电路因其获取周期较长,无法提供足量且实时的反馈。为此,本文在COMSOL中建立冷启动阻抗模型,结合试验分析其阻抗谱变化,分别在高、中、低频区间提出特征频率1 kHz、50 Hz和1 Hz用于表征燃料电池冷启动过程。研究发现,上述特征频率在冷启动的前、中、后3个阶段变化显著,在特征频率1 kHz、50 Hz和1 Hz下阻抗的变化倍率分别为0.38、0.31和1.47。相较于获取完整的阻抗谱和拟合等效电路,在保留了特征信息的情况下提高了采集数据的实时性。因此,可利用特征频率点的阻抗表征冷启动过程,为实时监测冷启动内部状态提供条件。

In order to optimize the cold start process of PEMFC,it is essential to provide sufficient feed⁃back data.Common impedance spectroscopy and equivalent circuits cannot provide sufficient and real-time feed⁃back due to long acquisition period.Therefore,the cold start impedance model is developed in COMSOL,and the change of impedance spectroscopy is analyzed in combination with experiments.The characteristic frequencies of 1kHz,50Hz and 1Hz are proposed in the high,medium and low frequency ranges respectively to characterize the cold start process of the fuel cell.The results show the above characteristic frequencies vary significantly in the pre-,mid-and post-cold start phases,with the change in impedance at characteristic frequencies of 1 kHz,50Hz and 1Hz of 0.38,0.31 and 1.47 respectively.It improves the real-time performance of data acquisition while retain⁃ing feature information compared to obtaining the full impedance spectroscopy and fitting the equivalent circuit.Therefore,the impedance at the characteristic frequency points can be used to characterize the cold start process,which provides real-time monitoring for the internal state of the cold start.