Improved hybrid loss control with optimized flux for traction induction motor under light load

With the fast development of rail transportation, it is of great significance to improve the efficiency of traction motors. The efficiency of the traction induction motor may drop drastically when the load is far away from the rated operating point, which is always the case when the vehicle is running under constant speed. This paper presents a loss model control method to achieve the balance between iron and copper losses for efficiency improvement under field‐oriented control. A steady‐state simplified loss model considering iron loss with an equivalent series resistor is built for the expressions of loss and efficiency. Then the optimal flux level is denoted, and the control performance is compared with that of the conventional flux control. The sensitivity of the motor parameters is also studied. Finally, simulation and experimental results validate the feasibility and effectiveness of the proposed control strategy. The experimental results in the laboratory determine the efficiency gains achieved with selected actual traction induction motors. Efficiency gain as high as 3–5% has been achieved under light load conditions. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.