SOC estimation of lithium battery based on double modified ampere-hour integral method

When the ampere-hour integral method estimates the battery SOC, the initial value of the SOC in the definition is difficult to determine and the cumulative error caused by the open-loop operation often makes the estimation result inaccurate, which is not conducive to the driver’s judgment of the actual remaining battery power, and the safety Adverse effects are coming. This paper uses the open circuit voltage method to modify the initial value of SOC by studying the characteristics of the SOC-OCV curve. And using the partial correlation coefficient to add different weights to the factors that affect the actual capacity of the battery to modify the actual capacity of the battery, thereby eliminating the ampere-hour integral Method due to the cumulative error caused by open-loop calculation. Experimental simulation shows that the ampere-hour integral method modified twice can accurately estimate the SOC of lithium battery, and the estimation accuracy is within 1.6%, which basically solves the problems of the initial SOC value inaccuracy of ampere-hour integral method and the accumulated error caused by the open-loop operation.