超级电容器分数阶模型的分频段参数辨识方法

Parameter-identification method for fractional-order models of supercapacitors based on frequency-band division

超级电容器的电阻与电容参数不是常数,受频率等因素影响。研究发现采用分数阶等效电路模型能够更加准确地描述超级电容器的非线性特性。针对超级电容器的分数阶模型参数难以获取的问题,提出一种分频段参数辨识方法。该方法根据不同频段下超级电容器的阻抗特性,提出了相应频段的等效阻抗表达式,进而根据典型频率的阻抗数据求解各频段阻抗表达式中的未知参数,实现超级电容器分数阶模型参数的全频段辨识,从而大大降低了分数阶模型参数辨识的难度。最后,对超级电容器进行动态应力(DST)测试和不同频率的恒流充放电实验,将辨识得到的超级电容器分数阶模型仿真输出电压与超级电容器的实测电压进行对比。结果显示在DST测试下,模型端电压的平均相对误差为1.52%,最大相对误差限制在4%以内;在恒流充放电实验中,最大相对误差限制在6%以内,验证了所提分频段参数辨识方法的有效性和准确性。

The resistance and capacitance of supercapacitors are not constant;they are affected by frequency and other factors.we realized that the fractional-order equivalent electricalcircuit models(ECMs)can describe the nonlinear characteristics of supercapacitors more accurately.To address the problem of solving the parameters of the fractional-order models(FOMs),a parameter-identification method based on frequency-band divisions is proposed.Based on the impedance characteristics of supercapacitors in different frequency bands,the equivalent impedance expressions at corresponding frequency bands are proposed.We found the unknown parameters in the impedance expressions at each frequency band using the impedance data at typical frequencies.Thus,the parameter identification of FOMs of supercapacitors in full-band is realized.This method reduces the FOM parameter identification difficulty.Finally,the dynamic-stress test(DST)and constant-current charge-discharge experiments at different frequencies are conducted on the supercapacitors.The output voltages of the solved FOMs are compared with the measured voltages of supercapacitors under DST.The results show that the mean relative error of the FOMs is 1.52%,and the maximum relative error is limited to 4%.Under the constant-current charge-discharge experiments,the maximum relative error is limited to 6%.The proposed method has high effectiveness and accuracy.