A Novel State-of-Charge Estimation Algorithm of EV Battery Based on Bilinear Interpolation

Accurate SOC estimation is the key function of a electric vehicle battery management system. The characteristics of EV battery in constant charge and discharge working conditions is investigated. And the the relationships between the battery SOC, terminal voltage and input/output current are established in the form of 3D lookup table. Then the basic principles of bilinear interpolation method are introduced. Finally, on the basis of the 3D lookup table, the bilinear interpolation method based battery SOC estimation algorithm is proposed. Computer simulation and real electric vehicle test tesults show that SOC estimation algorithm can obtain high estimation accuracy, and has high practical value in real-world electric vehicle working conditions.