Current control of voltage-fed PWM inverter for AC machine drives using integral variable structure control

A new current control technique of a voltage-fed PWM inverter is presented for a field oriented control of AC machines. The features of several existing approaches are analyzed and a variable structure control (VSC) with an integral action, so called an integral variable structure control (IVSC), is proposed as an effective way of realizing the high performance current control. The control characteristics of the proposed IVSC scheme are investigated and the design method is presented for the AC machine drive system associated with a voltage-fed PWM inverter. By employing the proposed control, a robust control performance against the uncertainties of the machine parameters is obtained in both transient and steady states. The proposed control scheme is applied to the direct field oriented control system of a three phase induction machine and the improvement of the control performance is well demonstrated through the simulations and experiments.