Fast Flux and Torque Control of a Double Inverter-Fed Wound Machine Considering All Coupling Interferences

Abstract

For efficient operation of the squirrel cage induction motor, the flux must be properly adjusted according to the torque. However, in such variable flux operation, the performance of torque control is limited by the flux control because it is not possible to measure and control the rotor current that affects the flux. On the contrary, in a double inverter-fed wound machine (DIFWM), the inverter is connected to the rotor side, as well as the stator side, and the rotor current can be controlled. This controllability of the rotor currents improves the operation performance of a DIFWM. This article presents the decoupling current control method of a DIFWM for fast flux and torque control. Since the rotor flux is directly calculated by the stator and rotor currents, the bandwidth of the flux control can be improved to the bandwidth of the current controller, which means that the torque control also has the same bandwidth. In this article, a detailed current controller design method with a DIFWM feed-forwarding decoupling method to eliminate all coupling interferences is proposed. The simulation and experimental results regarding the DIFWM are presented to verify the torque and flux control performance of the proposed control method.