Improvement of flux regulation with adaptive pi controller and DTHB based direct torque control of induction machine

Abstract

This paper presents an adaptive PI based two control strategies of Dynamic Hysteresis Torque Band (DHTB) for improving flux regulation at low speed and zero speed in lookup table based Direct Torque Control (DTC) of an Induction Machine (IM). This is achieved by varying the band value of torque dynamically but it is limited with flux error range. With the conventional HTB based DTC, at low and zero speed, the regulation of flux will not be good. To overcome this drawback, a small alteration in the structure is done, i.e., DTHB, thus retaining the simplicity of DTC algorithm. The performance is verified by varying the speed at low values. At low speeds of IM, the flux regulation and the speed is improved with adaptive PI controller based DHTB-II compared to DTC with DHTB-I and DHTB-II.