| Abstract |
This paper presents a modified direct torque control scheme for matrix converter drives. This method allows a reduction of the harmonic content of the input current without any negative effect on the drive performance and its simplicity. By using two switching configurations at each cycle, the synthesis of the input current vector is more accurate than the previous method at the same sampling period, allowing the instantaneous control of input power factor without the input displacement angle estimator, the low-pass filter or the input power factor hysteresis comparator, which are required in the classical switching table based direct torque control scheme for matrix converters. A two-level torque hysteresis comparator is adopted to reduce the torque ripple at high and medium speeds, an active vector selected to increase the torque while a zero vector to decrease the torque. Moreover, applying two switching patterns provides a higher switching frequency seen from the input side, with effect on reducing the input filter size. A comparison between the classical direct torque control and the proposed scheme is carried out. Simulation and experimental results are shown to demonstrate the effectiveness and improvement of the novel direct torque control method. |
