Method for estimating SOH of power lithium ion battery based on alternating current impedance test

The invention discloses a method for estimating the SOH of a power lithium ion battery based on an alternating current impedance test. The method comprises the following steps that the battery is charged at the constant current of 1 C to 0.5 C, the battery is discharged at the constant current of 1 C to 0.5 C, and the quantity of electricity discharged in the discharging process of each ring is recorded; the alternating current impedance test is conducted on the battery when the battery is discharged to the zero charge state and the charge transmission impedance of the battery is obtained from the NOV1.1 in a fitting mode through an alternating current curve of the medium frequency ranging from 0.25 Hz to 1.2 KHz; the discharging quantity of each ring, the charge transmission impedance and the number of rings serve as input parameters of an estimation function, and a capacity fading curve and a charge transmission impedance curve are obtained from the Origin 9 in a fitting mode; the capacity fading curve is corrected according to the charge transmission impedance curve, the estimation function of the battery SOH changing along with the number of the circulation rings is established, and judgment data for the SOH of a battery of the same type are calculated. According to the method, the SOH is estimated through the addition of the charge transmission impedance, an estimation result is more accurate, and the battery does not need to be detached.