Copper loss minimizing control of Doubly Fed Wound Machine

For efficient control of electrical machines, it is necessary to generate a current command set that satisfies a minimum copper loss condition, where the iron loss can be neglected. In Doubly Fed Wound Machine (DFWM), of which the stator and rotor are fed by two voltage sources, more efficient control is possible since the rotor currents are also controlled, but the calculation of the optimal current command set is more difficult than in the cases of single inverter fed systems. In this paper, the stator and rotor current command set for the minimum copper loss of DFWM is mathematically determined, considering constraints of the stator and rotor currents, the rotor flux, and the stator and rotor voltages. In addition, the torque control method based on the result is proposed. The experimental results of a wound machine are presented to show the feasibility of the proposed control method.