SOH (state-of-health) online estimation method of battery pack

Abstract

The invention relates to an SOH (state-of-health) online estimation method of a battery pack. The SOH online estimation method comprises the following steps of: measuring temperature T, voltage V and current I of an electric automobile during actual operation to acquire the following function: SOC (state-of-charge)=f(T, V, I) by utilizing a normalization algorithm, establishing a database with one-to-one correspondence between the temperature T, the voltage V and the current I and the SOC, measuring the SOC of a monomer battery with lowest voltage in an online manner by utilizing the database, and further measuring the SOH of the battery pack. The SOH online estimation method disclosed by the invention has the beneficial effects that: 1) as the measured SOC is that of the monomer battery with the lowest voltage, which is a key factor for restricting the discharge capacity of the battery pack, a user can know the SOH of the batteries in a more visual manner, the remaining capacity of the batteries can be judged in a more accurate manner by combining with the SOC value, and the continue voyage course of the electric automobile can be estimated in a more accurate manner; and 2) if the problem is caused by attenuation of the battery capacity, the problem can be obviously seen through the SOH, and the efficiency of after-sale service is improved.

Description

technical field [0001] The invention relates to an online estimation method for the health degree of a battery pack. Background technique [0002] During the use of the battery pack, due to the impossibility of complete consistency of all battery cells, different charging and discharging temperatures, and different self-discharge rates, the capacity of the battery pack gradually decays, which affects the driving of electric vehicles. Mileage, for which it is necessary to be able to estimate the state of health (SOH) of the battery pack online to evaluate how much remaining capacity of the battery pack can be effectively used. The dischargeable capacity of the battery pack is restricted by the lowest voltage single cell. When the voltage of the lowest voltage single cell reaches the lower voltage limit, the discharge stops, so the dischargeable capacity of the battery pack is related to the lowest single cell. [0003] Due to the user's improper operation, the capacity o...

AI Technical Summary

Problems solved by technology

[0003] Due to the user's improper operation, the capacity of the battery pack is attenuated. When the battery system is fully charged, it will be used up soon. At this time, all parts of the battery management system are normal, and the battery management system will not show any failure. The user and after-sales service cause great trouble; the state of charge (SOC) of the battery only tells the user the remaining percentage of power, but cannot tell the user the exact remaining power. If the available capacity of the battery decays, it will cause users to miscalculate mileage, causing electric vehicles to be forced to stop halfway due to insufficient power