An improved single-vector-based Duty Cycle Control Method for Direct Torque Control of Induction Motor

فاقد چكيده فارسي

Duty cycle control (DCC) is an effective method to reduce the torque and flux ripples in classical direct torque control. In this method, a zero vector is inserted along with the active voltage vector to adjust the length of the applied voltage vector to the motor. In prior switching-table-based duty cycle methods, the active voltage vector is selected based on the sign of the initial torque and stator flux errors. However, this strategy does not work properly in the steady state, especially at high-speed operation. In this paper, first, a new method is presented to find the suitable active voltage vector that reduces the stator flux and torque errors under all operating conditions. Next, the minimum-torque-error optimization is employed to calculate the optimal duty cycle. Simulation studies are done to show the good performance and the superiority of the proposed method over classical DTC and prior duty cycle control methods. As a result, lower torque and flux ripples are achieved in the proposed method. Furthermore, the proposed method works with almost a fixed switching frequency for all speed ranges.