Establishment and Testing Verification of Traction Battery Second-Order Resistor–Capacitor Digital Twin Model Based on Hybrid Pulse Power Characterization Test

Comprehensive traction battery testing and status monitoring capabilities have received widespread attention. However, obtaining more information through extensive parameter extraction and analysis while ensuring efficiency has become a significant challenge. The actual hybrid pulse power characterization (HPPC) test data of eight different types of lithium-ion traction batteries were collected and analyzed. This study identifies key parameters that effectively characterize the performance of traction batteries under different states of charge and builds a second-order resistor–capacitor (RC) equivalent circuit model. The Kalman filter algorithm was used to estimate the state of charge (SOC) of the battery, and the virtual simulation test results were compared with the actual bench test results. The results showed that the maximum voltage error was from 0.025 to 0.039 V, indicating that the simulation model effectively characterized the working characteristics of the actual batteries. The second-order RC digital twin model can replace actual batteries for virtual testing.