An Improved Direct Instantaneous Torque Control of Doubly Salient Electromagnetic Machine for Torque Ripple Reduction

The doubly salient electromagnetic machine (DSEM) is a suitable candidate in many industrial applications due to its simple construction and low manufacture cost. However, the doubly salient structure and the conventional square-wave control method lead to the large torque ripple in the DSEM. In this article, an improved direct instantaneous torque control (DITC) method is proposed to suppress the inherent torque ripple and enhance the torque capability of the DSEM. The maximum torque characteristics of the DSEM are obtained and analyzed with the finite-element method. Besides, the ideal phase current waveform to realize the low torque ripple is constructed according to the maximum torque characteristics. Then, the operation principle of the proposed DITC method is derived from the maximum torque characteristics. The proposed DITC method is implemented on a prototype of 12/8-pole DSEM drive system. The influence of the commutation angle parameters on the proposed DITC method is analyzed through simulation and experimental results. The simulation and experimental results indicate that the proposed DITC method can realize the smooth torque operation and high torque–ampere ratio simultaneously. Finally, the simulation and experiment under the step reference torque condition are performed to test the dynamic performance of the proposed DITC method.