Power battery SOH (state of health) value estimation method and system

Abstract

The invention discloses a power battery SOH (state of health) value estimation method and system. The method includes the following steps that: step S1, it is confirmed that a power battery enters a slow charging mode; step S2, whether the SOC value of the power battery has been subjected to OCV correction before charging is judged, if the SOC value of the power battery has been subjected to the OCV correction before charging, a step S3 is performed; step 3, a first power correction value is obtained, wherein the first power correction value is an OCV-corrected SOC value; step S4, a cumulativedischarging capacity from a time point when OCV correction is performed to a time point before charging is acquired; step S5, a first charging capacity is acquired after the power battery is fully charged; step S6, the actual capacity of the battery is calculated according to the first charging capacity, the cumulative discharging capacity, and the first power correction value; step S7, the preset initial capacity of the battery is obtained; and step S8, the SOH value of the battery is obtained according to the actual capacity and initial capacity of the battery. With the power battery SOH (state of health) value estimation method and system of the invention adopted, a large quantity of calibration data or laboratory estimation is not required, estimation parameters can be obtained onlineduring normal use, and a process is simple and accurate.

Description

technical field [0001] The invention relates to the field of new energy vehicles, in particular to a method and system for estimating the SOH value of a power battery. Background technique [0002] As the capacity of the power battery continues to decline during use, the difference in the consistency of the battery gradually increases, and the SOH value of the pure electric vehicle battery pack is also constantly declining. During the driving of electric vehicles, it is necessary to be able to estimate the state of health (SOH) of the battery pack in order to evaluate how much capacity the battery pack can be effectively utilized. If the accuracy of SOH is not high, the state of charge (SOC) of the battery will be inaccurate, and the estimation error of SOC is large, which may cause the electric vehicle to be forced to stop halfway due to insufficient power. [0003] Although the SOH value of the battery can be obtained through experiments in the laboratory, there are no va...

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Problems solved by technology

[0006] It can be seen from the above that the evaluation of battery SOH in the prior art is mainly based on the estimated value of SOC of the battery management system and the measured value of the voltage of the battery pack and the internal resistance of the battery pack. Therefore, the basis for the evaluation is limited, and this The evaluation method is highly dependent on the knowledge and experience level of professional technicians

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