Kinetic Energy Recovery: Assessment on the impact of Permanent Magnet Synchronous Motor and Battery Dynamic models

This paper examines the influence of a detailed dynamic model of a Surface Permanent Magnet Synchronous Motor (SPMSM) on the accurate evaluation of kinetic energy recovery during braking in a mild hybrid vehicle. The model, implemented in MATLAB Simulink, is based on the motor's DQ equivalent circuit, accounting for transient effects, inductance variability, and magnetic saturation. Also, a 2nd Order Thevenin Equivalent model of the battery is used in order to take into account the bus voltage variability. Simulations reveal that the dynamic model predicts significant variations in energy recovery potential, with differences of up to 25% compared to static models under specific braking conditions. These discrepancies are particularly pronounced during high-speed high-torque transitions, where transient electrical behaviors strongly influence energy recovery. The model’s accuracy enhances the reliability of energy simulations, especially in scenarios involving frequent or intense regenerative braking. Additionally, the study applies the dynamic model to evaluate energy recovery under two main braking control strategies: parallel braking, where regenerative and mechanical braking coexist, and series braking, which prioritizes regeneration. While both strategies benefit from the dynamic model, the findings emphasize its importance in optimizing energy recovery independently of the control strategy adopted. This research demonstrates that advanced dynamic motor modeling is essential for the precise design and calibration of hybrid vehicle braking systems, enabling enhanced energy efficiency and reduced mechanical brake reliance.