High Performance Direct Torque Control of Induction Motors

Abstract

Direct torque control (DTC) of induction machinesis known to have a simple control structure with comparable
performance to that of the field-oriented control technique. Two
major problems that are usually associated with DTC drives are:
1) switching frequency that varies with operating conditions and
2) high torque and flux ripples. To solve these problems, and at
the same time retain the simple control structure of DTC, a
constant switching frequency torque controller is proposed to
replace the conventional hysteresis-based controller. In this
paper, the modeling of proposed controller followed by
simulation and experimental results are presented. The proposed
controller is shown to be capable of reducing the torque and flux
ripples and maintaining a constant switching frequency.