Investigation of Permanent-Magnet Motor Drives Incorporating Damper Bars for Electrified Vehicles

Understanding the need for steady-state and transient performance improvement in an interior permanent-magnet synchronous machine (IPMSM) drive, this paper exclusively investigates the IPMSM incorporating damper bars in the rotor of electric motor for electrified vehicles (EVs). First, motivation for the employment of damper bars in IPMSM is provided and justified with a case study. Thereafter, a mathematical model of an IPMSM drive with damper bars in the rotor has been developed based on dq-axis theory and validated through experiments performed on a laboratory IPMSM containing damper bars. The validated mathematical model has been then employed to arrive at satisfactory rotor bar parameters for an existing IPMSM on board a commercially available EV. Moreover, a replica of the existing onboard EV motor with and without incorporating dampers have been designed, and finite-element analysis has been performed to investigate various performance characteristics. Comparative performance analyzes of both the machines with and without damper bars under steady-state and transient conditions have been performed wherever necessary, and the results elicited have been discussed.