| CPC G01R 31/389 (2019.01) [G01R 31/367 (2019.01)] | 14 Claims |
|
1. A method for measuring a battery impedance value, comprising:
performing multiple pulse discharges on a battery in multiple different discharge time periods respectively, and separately measuring multiple equivalent direct current resistance values of the battery, comprising measuring the voltage difference and discharge current within each pulse discharge time period to obtain the equivalent direct current resistance value;
obtaining an equivalent direct current resistance spectrum, the equivalent direct current resistance spectrum comprising a horizontal axis and a vertical axis, the horizontal axis comprising the multiple different discharge time periods, and the vertical axis comprising the equivalent direct current resistance values corresponding to the different discharge time periods;
obtaining an equivalent circuit model parameter value of the battery according to the equivalent direct current resistance spectrum, wherein, the equivalent circuit model parameter value further comprises: a battery ohmic resistance value Rn, an electric double layer capacitance value Cd and a charge transfer resistance Ret, obtaining the equivalent circuit model parameter value further comprises:
fitting the equivalent direct current resistance spectrum to an e-exponential function, and the value of an e-exponential fitting curve when it intersects the vertical axis is the battery ohmic resistance value Ra;
subtracting the battery ohmic resistance value Rn from a maximum value of the equivalent direct current resistance spectrum to obtain the charge transfer resistance Rct;
determining a discharge time constant according to the e-exponential fitting curve, and calculating the electric double layer capacitance value Cd according to the discharge time constant and the charge transfer resistance Rct; and
calculating an impedance value of the battery by an impedance calculation formula of a battery equivalent circuit according to the equivalent circuit model parameter value,
wherein the measuring multiple equivalent direct current resistance values of the battery, obtaining the equivalent direct current resistance spectrum, and obtaining the equivalent circuit model parameter value of the battery according to the equivalent direct current resistance spectrum are performed at time domain,
wherein the fitted e-exponential function of equivalent direct current resistance comprises the battery ohmic resistance value Rn, the charge transfer resistance Rct, pulse discharge time, and the discharge time constant,
wherein the multiple different discharge time periods have durations of adjacent discharge time periods being different from each other,
wherein the method further comprises obtaining the impedance value of a rechargeable power battery in real time, and
wherein the method further comprises evaluating a service life of the rechargeable power battery based on the impedance value of the rechargeable power battery.
|