Single external source control of doubly-fed induction machine using dual inverter

This paper proposes a drive system and a control method for a double inverter fed wound machine, where the stator and the rotor are fed by two variable frequency inverters. Compared with the conventional induction machine drive system, the proposed system can improve the operating area and the efficiency because the rotor side inverter allows an additional degree of freedom in control. Also, it has no external power source for the rotor side inverter. Due to this feature, the inverter can be integrated on the rotor shaft and connected without any slip ring. In this paper, the possible operating areas in the topology are analyzed, considering the rotor power balance for the stabilization of the rotor side dc link voltage. In addition, vector control method is proposed to regulate the torque, the flux and the rotor side dc link voltage. The experimental results present the feasibility of the proposed system.