Battery capacity correction method based on improved ampere-hour integral method

Abstract

The invention discloses a battery capacity correction method based on an improved ampere-hour integral method. The method comprises the following steps: enabling a battery pack to run in a vehicle-mounted way; calculating the state of charge (SOC) by the ampere-hour integral method; judging whether the electric quantity of batteries is too low or not; judging whether the minimum battery voltage V<min> is lower than the threshold voltage V<mdy> in a capacity correction mode or not; entering the capacity correction mode; carrying out capacity correction, and then quitting the capacity correction mode; charging the batteries, and calculating the SOC; judging whether the maximum voltage V<max> of the battery pack is higher than charge cut-off voltage V<h> or not; finishing charging, storing the battery capacity Q accumulated in the charging process, and replacing the previous battery capacity Q<n> by the battery capacity Q; modifying the current battery capacity value to be Q, and modifying the value of the SOC. According to the method, the SOC values of the batteries and the stored electric quantity values are corrected at the end of the battery charging process, so that the accurate initial value of the SOC can be obtained after every time of charging is finished; furthermore, at the end of discharge, the batteries can select to enter the battery capacity correction mode, so that the current capacities of the batteries can be corrected, and thus the calculation error caused by battery aging can be eliminated.

Description

technical field [0001] The invention relates to a battery capacity correction method based on an improved ampere-hour integration method. Background technique [0002] The remaining power of the battery, also known as the State of Charge (SOC), is one of the parameters indicating how much power the battery can currently use for electrical equipment. The SOC can provide an important basis for the energy management strategy of the electric vehicle. Accurately estimating the remaining power of the battery can maintain the SOC within a reasonable range when the battery is in use, prevent overcharge or overdischarge from causing damage to the battery, and provide an important basis for rational use of the battery, prolonging the service life of the battery, and reducing the cost of battery use. Accurately estimating the SOC value is one of the important tasks of the battery management system. [0003] At present, a lot of research has been done on battery SOC estimation at home ...

AI Technical Summary

Problems solved by technology

[0008] (1) The discharge curve of lithium batteries, especially lithium iron phosphate batteries, has poor linearity, and the voltage difference between 90% and 20% of the battery capacity is only 200mV, which has high requirements for voltage sampling accuracy and is easy to cause Calculation error;

[0009] (2) The battery performance of various manufacturers is inconsistent, and the performance of the same battery will change greatly after long-term use, which requires a lot of testing work when adapting to batteries from different manufacturers, and cannot solve the problem of battery failure. The problem of the reduction of soc calculation accuracy after aging

[0011] (1) The method to calculate the aging battery capacity is This method determines the SOC value in the formula through the current battery voltage V1. The current voltage V1 is not the voltage after standing still, and it is not applicable to determine the SOC with the open circuit voltage, so the accuracy of this calculation method will be affected;

[0012] (2) The open circuit voltage method combined with ampere-hour integration method used in the patent is suitable for lead-acid batteries with good voltage linearity, but not suitable for lithium batteries

[0013] Chinese invention patent (patent number: 2013107193759, patent name: a self-correcting battery SOC estimation method based on Kalman filter), this patent can solve the problem that the ampere-hour integration method will produce cumulative errors after long-term operation, but it cannot solve the problem Influence of capacity change caused by battery aging on SOC calculation

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