Flux Compensated Direct Torque Control of Induction Motor Drives for Low Speed Operation

Speed control of direct torque controlled (DTC) induction motor drives depends on effectively establishing the stator flux. However, it becomes difficult when the motor operates in the low speed region, because the voltage drop on the stator resistance is comparable with the input stator voltage. Therefore, this study proposes an easy but effective way to compensate the voltage drop on the stator resistance so that the stator flux can be constructed without identifying the stator resistance as done by most authors. As a result, motor torque is constructed due to the effective stator flux compensation, which makes the DTC applicable to induction motor drives in the low speed region. Moreover, a fixed-point digital signal processor (DSP)-based hardware experimental system is built to demonstrate the effectiveness of the proposed control method.