A novel direct torque controlled interior permanent magnet synchronous machine drive with low ripple in flux and torque and fixed switching frequency

A modified direct torque control (DTC) scheme for interior permanent magnet synchronous machine (IPMSM) is investigated in this paper, which features in very low flux and torque ripple and almost fixed switching frequency. It is based on the compensation of the error flux linkage vector by means of space vector modulation. Modeling and experimental results show that the flux and torque ripples are greatly reduced when compared with those of the basic DTC. With the new scheme, very short sampling time is not essential. All the advantages of the basic DTC are still retained. In addition, fixed switching frequency at different operating conditions becomes possible. The field-weakening control of this drive is also studied; an IPM DTC drive with a wider operation range and lower flux and torque ripple has been achieved experimentally.