Analytical modelling of dynamic performance with harmonic current injection for doubly salient SynRMs

A new analytical torque model based on dq0-axis frame has been developed for 3-phase, 12-slot/8-pole single layer doubly salient synchronous reluctance machines. This newly developed torque model, compared to the one often based on abc-axis frame, is necessary to simplify the investigation of dynamic performance such as torque-speed curve and efficiency maps. It has been found that the 3rd order current harmonic injection not only improves the torque performance (increased average torque and reduced torque ripple) in constant torque region, but also maintains a similar torque level as the fundamental current supply in the flux weakening region. Moreover, although the 5th and 7th order current harmonic injection can reduce the torque ripple of machine, their dynamic performances are compromised due to low average torque and significant voltage distortion. Finite element simulations and dynamic tests have been carried out to prove the accuracy of the developed torque model and also the efficiency of the proposed current harmonic injection method.