Method for estimating charge state of power cell

Abstract

The invention provides a method for estimating a charge state of a power battery with relatively less errors, which includes the following steps: through fitting of measured data, a Ki curve of correction coefficient of charging-discharging efficiency at different rates, a Kw curve of the correction coefficient of the charging-discharging efficiency under different temperature as well as a Kc curve of the correction coefficient of actual electric quantity are obtained and a Kc value can be obtained through a historical record; according to the state of the power, the following formulas are applied: in the working state, Ct = (KCC0 + sigma KiIiti) Kw is applied; in the non-working state and when a self-recovery effect is completed, C = KWKCC0t is applied; in the non-working state and when the self-recovery effect is not completed, Ct = Cm is applied; Ki, Kw, Kc are called from the curves to obtain remaining capacity Ct at the moment of obtaining the power battery so as to complete the estimation of a SOC battery. The invention with easy industrial application of models is applicable to both working state and non-working state of the battery; the errors of the estimation result are relatively less and the relevant curves are established.

Description

technical field [0001] The invention relates to the field of power management systems for power batteries, in particular to a method for estimating the state of charge of a power battery. Background technique [0002] The estimation of the SOC-State of Charge of the power battery is a very important content in the power management system. At present, there are three commonly used power battery SOC estimation methods as follows: [0003] First, the ampere-hour measurement method, which adds the integral value of the charging and discharging current over time to the initial SOC to estimate the real-time SOC. This method has the following two defects: on the one hand, since the power battery may start working at any SOC, it is difficult to determine the initial SOC; Discharge, and in the case of different rate current discharge, especially in the case of high rate current discharge, the discharge efficiency of the power battery has a large change (such as figure 2 As shown),...

AI Technical Summary

Problems solved by technology

This method has the following two defects: on the one hand, since the power battery may start working at any SOC, it is difficult to determine the initial SOC; Discharge, and in the case of different rate current discharge, especially in the case of high rate current discharge, the discharge efficiency of the power battery has a large change (such as figure 2 As shown), at this time, only the direct integration of the cha

Images