Estimation method for state of health (SOH) of battery

Abstract

The invention discloses an estimation method for a state of health (SOH) of a battery. The method specifically comprises the following steps of: 10, establishing a database which is composed of a battery SOH value and the maximum peak of a battery charging ICA curve corresponding to the battery SOH value; 20, constant-current charging the battery on line, thus acquiring the maximum peak of an online charging ICA curve; 30, finding whether the database has the SOH value corresponding to the maximum peak; 41, when the database has the SOH value corresponding to the maximum peak, acquiring the SOH value corresponding to the maximum peak; and 42, when the database does not have the SOH value corresponding to the maximum peak, finding the SOH values corresponding to the two maximum peaks close to the maximum peak, computing the SOH value corresponding to the maximum peak according to the SOH values corresponding to the two maximum peaks close to the maximum peak by using a linear interpolation method.

Description

[0001] 【Technical field】 [0002] The invention relates to the technical field of batteries, in particular to a battery SOH estimation method. [0003] 【Background technique】 [0004] The battery SOH (State of Health) surface refers to the health status of the battery, including capacity, power, internal resistance and other properties, and more often it is the prediction of the life of the battery pack. At present, there are mainly three ways to predict battery SOH at home and abroad. The first is to estimate battery SOH by studying the attenuation of battery capacity; the second is to estimate battery SOH by studying battery internal resistance characteristics; the third is to estimate battery SOH by studying battery internal resistance characteristics. Study the charge and discharge behavior of the battery and its cycle times to estimate the battery SOH. However, in the prior art, the first method is a direct discharge method, which requires off-line testing of the SOH of t...

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Problems solved by technology

However, in the prior art, the first method is a direct discharge method, which requires off-line testing of the SOH of the battery, which is inconvenient to operate, especially for vehicle power batteries, which is more difficult to implement, and the test load is heavy and inconvenient to operate; the second method The method is the internal resistance method. With the increase of battery usage time, the internal resistance of the battery increases, which affects the battery capacity to estimate SOH. The internal resistance of the battery is very small, generally milliohm level is a small signal, and it is difficult to accurately measure the internal resistance of the battery. , the accuracy is poor

The third method is the number of cycles conversion method. Under a certain depth of discharge, the percentage of the remaining rechargeable times of the battery to the maximum number of charging times is used to estimate the SOH. Deep discharge will affect the life of the battery.

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