Simulation Of Direct Torque Control for Induction Motors Based on Minimum Voltage Vector Error

Electrical Engineering

The traditional direct toque control (TDTC) for induction motors (IM) is afflicted by large torque ripple, high current total harmonic distortion (THD) and variable switching frequency. Recently, some improved DTC methods have been proposed to address the above problems, but they often suffer from the obscure concept, intensive computation and poor robustness. To further improve the performance, this paper proposes a DTC method based on minimum voltage vector (VV) error. The proposed strategy effectively optimizes the duty ratio of fundamental VV to minimize the error between reference VV and final VV imposed on motor terminals. The optimization algorithm dose not increase the system’s complexity much and can be intuitively understood by a graphical interpretation. Experiment comparisons between the proposed strategy and some existing DTC methods are conducted on a 0.55-kW IM platform. The proposed DTC method is proved to achieve better steady-state performance, meanwhile retaining fast dynamic response of TDTC. Furthermore, the proposed method can obtain almost constant average switching frequency in the whole speed range especially with rated load, due to the utilization of proportional-integral type torque regulator.

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