Actual capacity estimation method of lithium ion battery for pure electric automobile

Abstract

The invention relates to an actual capacity estimation method of a lithium ion battery for a pure electric automobile, comprising the following steps of: a. acquiring a variable value of the residual capacity of the battery through an automotive battery management system during the online charging process; b. before battery charging and after battery operating, acquiring a first state charge state SOC1 of the battery by charging a part of electric quantity through the automotive battery management system; c. after the charging is finished, acquiring a second state charge state SOC2 of the battery through the automotive battery management system; and d. acquiring the ratio between the variable value of the residual capacity of the battery in the step a and the difference value of two charge states of the battery, namely, acquiring the actual capacity value of the battery. Compared with the prior art, the invention has the following advantages that: (1) the current controllability and the current stability during the charging are better; (2) the data processing time is plenty; and (3) the advantage (1) and the advantage (2) can be finished during the single charging.

Description

technical field [0001] The invention relates to a method for estimating the actual capacity of a lithium-ion battery for pure electric vehicles. Background technique [0002] Lithium-ion battery has become an ideal power source for the new generation of electric vehicles due to its excellent performance. When it is used in electric vehicles, it is generally monitored by a dedicated battery management system to improve the controllability and stability of the battery. However, when the battery is actually used in a pure electric vehicle, it is not fully charged and fully discharged according to a fixed working condition like the battery cycle test, so the actual capacity is not easy to obtain, so in actual use, the rated capacity is often used instead of the actual capacity for SOC. (State Of Charge, state of charge) estimation; however, as the number of cycles and usage time increase, the battery will gradually age and the actual capacity will decrease. If it cannot be upda...

AI Technical Summary

Problems solved by technology

However, when the battery is actually used in a pure electric vehicle, it is not fully charged and fully discharged according to a fixed working condition like the battery cycle test, so the actual capacity is not easy to obtain, so in actual use, the rated capacity is often used instead of the actual capacity for SOC. (State Of Charge, state of charge) estimation; however, with the increase of cycle times and usage time, the battery will gradually age and the actual capacity will decrease

If it cannot be updated regularly, the estimation accuracy of SOC cannot be guaranteed, which may lead to over-discharge of the battery, affecting the safety, stability and long life of the battery during use

The actual capacity of the battery can be obtained by fully charging and discharging. The operation is simple and accurate, but it takes a lot of time, wastes energy, and does not conform to the actual operating mode of the vehicle and increases the maintenance workload.