A new full-speed range direct torque control strategy for induction machine

The large torque ripple exists in induction machine based on conventional direct torque control (DTC), especially at a low speed. On the basis of conventional DTC, the paper provides a new control strategy that can reduce the torque ripple. A full-speed range flux model is deduced. The fuzzy logic idea is adopted in the strategy in order to further improve the torque response and decrease the torque ripple, so a full-speed fuzzy model DTC (FSFDTC) strategy is presented based on the full-speed flux model. In the FSFDTC strategy, the stator flux angle, the stator flux error, and the torque error are reasonably fuzzified into several fuzzy subsets to optimize the selection of the voltage vector. The strategy is implemented with a single board microcomputer that uses TMS320LF2407A DSP. The experimental results illustrate that the torque response is improved, and torque ripple is effectively decreased. The system has a better dynamic and steady performance in full-speed range.