Power battery actual capacity estimation method

Abstract

The invention provides a power battery actual capacity estimation method. The estimation method is based on a battery mathematical model, the open-circuit voltage and capacity of a battery are identified by utilizing a system identification algorithm, the battery capacities, corresponding to the battery open-circuit voltages OCV1 and OCV2, are respectively recorded as Cap1 and Cap2, meanwhile the battery capacity Cap3 is estimated by utilizing an AH integral algorithm, and then the Cap1, Cap2 and Cap3 are weighted and filtered to obtain battery capacity Cap0, and finally, the Cap0 is filtered to obtain the actual battery capacity in accordance with the engineering application requirement. The power battery actual capacity estimation method has the advantages that the influence of the identification algorithm and the battery operating conditions on the actual capacity estimation can be avoided; and the estimation method is applicable to estimating the actual capacity of power batteries for pure electric vehicles and power batteries for hybrid electric vehicles.

Description

technical field [0001] The invention relates to a method for estimating the actual capacity of a power battery. Background technique [0002] With the increasingly prominent energy and environmental issues, pure electric vehicles and hybrid vehicles are highly valued by countries all over the world. Therefore, the development of electric vehicles with excellent performance lithium batteries as the power source has become the current research direction. In order to safely use lithium batteries during the operation of electric vehicles, it is necessary to use a dedicated battery management system to monitor lithium batteries. The key indicators monitored are the state of charge (State of Charge, SOC) and the state of health (State of Health, SOH) of the lithium battery, and the estimation accuracy of the SOC value and SOH value is directly or indirectly related to the actual capacity of the battery . The actual capacity of the battery is difficult to obtain when the battery...

AI Technical Summary

Problems solved by technology

However, as the number of cycles and usage time increase, the battery will gradually age and the actual capacity will gradually decrease

If the actual capacity cannot be updated regularly, it will affect the accuracy of estimating the battery SOC value using the AH integral algorithm and the accuracy of estimating the battery SOH using the actual capacity of the battery

As a result, errors in the monitoring and management of the battery lead to overcharging or overdischarging of the battery, which affects the stability, safety and life of the battery during use.

At present, the actual capacity of the battery is obtained by fully charging and discharging in the laboratory. This method is simple and accurate, but it is not suitable for the extensive and long-term use of the battery, and it is not suitable for the mass production and promotion of electric vehicles.

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