Lithium ion battery health state on-line diagnosis method

Abstract

The invention belongs to the technical field of lithium ion batteries, and specifically discloses a lithium ion battery health state on-line diagnosis method. The method includes the steps of 1, performing total-interval direct current internal resistance testing on battery samples, and calculating to obtain direct current internal resistance of the batteries at different SOC points; 2, determining a stable SOC interval of battery direct current internal resistance; 3, in a cycle use process of the batteries, performing one-time pulse charging / discharging on the batteries, and recording battery voltage change in a current abrupt change process; 4, according to the data recorded in Step 3, using the formula R=[delta]U / [delta]I to calculate internal resistance of the batteries at different time; 5, according to internal resistance values of different batteries at different time, calculating and analyzing battery polarization internal resistance change; 6, performing differentiation on internal resistance and capacity relative to the number of times of cycles to obtain a change rate distribution diagram of internal resistance and capacity; and 7, comprehensively judging the health states of the batteries, and finally adopting two pieces of data of polarization internal resistance and the internal resistance change rate to perform double judgment on the health states of the batteries.

Description

Technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to an online diagnosis method for the health status of lithium ion batteries. Background technique [0002] With the development of cities and the improvement of living standards, society’s demand for energy continues to increase, and the impact of fossil energy on the environment has become increasingly prominent. In order to cope with the ever-increasing energy crisis and environmental pollution, the development and promotion of new energy vehicles is urgent. Power lithium-ion batteries have become one of the key technologies of new energy vehicle systems. As a complex electrochemical system, the health of lithium-ion batteries will gradually degrade with use. However, in actual use, it is difficult to directly test the parameters that characterize its health status, such as capacity. The problem of power battery state of health (SOH) diagnosis is a major p...

AI Technical Summary

Problems solved by technology

But the problem with this method is: this method must require the battery to be tested offline

The test process requires high time and operating costs, which affects the normal use of the car owner; the test frequency is highly subjective, and cannot track and predict the health status of the battery well, which is not conducive to formulating preventive measures in advance

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