A probability density function(PDF)based area frequency method was proposed to solve the problem of inaccurate battery health state SOH assessment at low sampling frequency.The charging and discharging voltage data of ternary lithium batteries at different multiplicities were used for analysis with a sampling frequency of 1/60 Hz,and the PDF peak height and area frequency were extracted as health factors,respectively,and the relationship with SOH was established.The results show that the fit of PDF peak height as a health factor with SOH decreases as the charge/discharge current multiplier increases,especially in the discharge phase,the fit R2 is only 0.097 1 at 1C.When the regional frequency is used as the health factor,the R2 of the fit of the SOH model is above 0.95 at different multipliers of the charge/discharge phase.When the regional voltage increases from 100 mV to 400 mV,the fit of the model is above 0.98.Finally,the method is validated using battery aging data at 1/2C magnification,and the SOH evaluation error is within 2％,which shows that the method could improve the accuracy of SOH evaluation of batteries at low sampling frequency.
关键词
三元锂离子电池/区域频率/概率密度函数/电池健康状态评估/采样频率/充放电电流倍率
Key words
ternary lithium-ion battery/regional frequency/probability density function/battery assessment of state of health/sampling frequency/charge/discharge current rate
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