کنفرانس بین المللی ماشین و محرکه های الکتریکی

صفحه اصلی / The 5th International Conference on Electrical Machines and Drives

Design, Simulation, and Performance Evaluation of a D77 DC Traction Motor Converted to AC Operation

نویسندگان :

Morteza Hemmati¹ Sara Javadianfar² Hosein Jamshidpour³

1- شرکت فن ژنراتور 2- شرکت فن ژنراتور 3- شرکت فن ژنراتور

کلمات کلیدی :

Traction motor،DC to AC conversion،D77،stator design،rotor design،ANSYS MOTORCAD

چکیده :

Nearly 45% of the Iranian railway traction fleet still operates with conventional D77 and D78 DC motors that use commutators and carbon brushes. These units, although once reliable, now frequently fail, require intensive maintenance, and exhibit limited efficiency compared to modern systems. In this study, we present a practical design and analysis procedure for converting the D77 DC traction motor into an equivalent AC motor while preserving the original housing and mechanical interface. Based on the D77’s dimensions and electromagnetic limits, a new three-phase, four-pole, squirrel-cage induction motor—named A77—was developed. The redesign encompassed key aspects, including stator slot geometry, winding layout, and rotor bar material selection. Detailed electromagnetic and thermal analyses were performed using ANSYS Motor-CAD to evaluate the proposed configuration. The simulations indicated an efficiency of approximately 95% and a power factor close to 0.78. In addition to better thermal balance, the new motor eliminates brush-related failures and significantly reduces maintenance requirements. The results confirm that upgrading existing DC motors to AC operation can be a technically and economically viable solution for extending the service life of Iran’s aging traction fleet. To the best of our knowledge, this work provides the first documented case of a D77-to-AC conversion and offers a framework that can be adapted to similar retrofit projects in the railway industry.