Stability Improvement of V/F Controlled Large Capacity Voltage-Source Inverter Fed Induction Motor

V/F control for voltage-source inverter fed induction motors have only a few adjustment parameters, and is often adopted in fan- or pump-drive applications that don´t need a fast response. Many methods have been proposed for stabilizing V/F control. This paper presents the stability improvement of a V/F controlled large capacity induction motor drive system with a pulse amplitude modulator that uses dc voltage feedback control through a thyristor rectifier. The characteristics of dc link voltage feedback control directly affect the stability of V/F control. Stability analysis is discussed, and the validity of the proposed method is shown by computer simulations and a 2500kW test model