A Control Algorithm for Reducing the Size of Inverters in Drive Systems

This paper proposes a vector control algorithm based on overall current loop pre-excitation for a doubly-fed induction generator (DFIG) drive system used for transmission loading. Traditional full-power converter drive systems are costly in high-voltage and high-power applications and result in higher losses. Utilizing the structure of a DFIG directly driving an induction motor (IM), with the rotor side controlled by a small power inverter and the IM directly driven by the stator of the DFIG, can reduce the cost, size, and capacity of the inverter. However, the IM's voltage-to-frequency (V/F) control restricts dynamic performance under load variations. Addressing these issues, the algorithm proposed in this paper reduces system cost while enabling stable startup and improving the dynamic response of the control system.