Energy Storage Science and Technology ›› 2022, Vol. 11 ›› Issue (10): 3371-3380.doi: 10.19799/j.cnki.2095-4239.2022.0236

• Energy Storage Test: Methods and Evaluation • Previous Articles     Next Articles

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

Qiao DENG(), Dongyuan QIU(), Wenchao GU, Yanfeng CHEN, Bo ZHANG   

  1. School of Electric Power Engineering, South China University of Technology, Guangzhou 510000, Guangdong, China
  • Received:2022-04-29 Revised:2022-05-26 Online:2022-10-05 Published:2022-10-10
  • Contact: Dongyuan QIU E-mail:202020114368@mail.scut.edu.cn;epdyqiu@scut.edu.cn

Abstract:

The resistance and capacitance of supercapacitors are not constant; they are affected by frequency and other factors. we realized that the fractional-order equivalent electrical-circuit 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.

Key words: supercapacitor, fractional-order model, frequency characteristic, impedance characteristic, parameter identification

CLC Number: