(A) new rotor flux controlled induction machine drive

Abstract

A new induction machine drive for high performance applications is proposed and described analytically in this thesis. The proposed drive is named as "rotor flux controlled induction machine drive (or shortly RFC IM drive) ". The RFC IM drive is different from the well known field oriented control principle. RFC IM drive has many advantages such as independent control of rotor flux and output torque even during transient interval, simple construction and robustness against rotor resistance variations. Also, the torque is directly proportional to the slip frequency without delay. Since the rotor flux can be controlled instantaneously without any coupling, the induction machine can be driven with in field weakening condition at light load. The ripple current magnitude becomes somewhat higher than that of the current regulated pulse width modulation type if single hysteresis control is used. However, it is also reduced successfully by employing double hysteresis control method. RFC IM drive for solving the coupling problems was very attractive. Besides, the ripple current was also reduced by employing double hysteresis control method. However, the theory of the control method is not well established when the rotor resistance deviates from its nominal value. Therefore, another drive scheme based on the RFC IM drive is proposed. In the proposed drive scheme, the rotor flux and the stator currents are simultaneously controlled. This scheme has many advantage such as the independent control of rotor flux and output torque even during transient interval, simple construction and robustness against the rotor resistance variation. Also, the dynamics performance of the drive scheme is improved further comparing with the simple RFC IM drive. In this proposed machine drive, the influence due to the variation of the rotor resistance is analyzed. A compensation method against the rotor resistance variation for accurate torque control is also presented and analyzed. Simulation ...