Optimum Control for Minimization of Torque Ripple in Synchronous Reluctance Machines

This thesis provides an analysis for identifying the sources of torque ripple in electric machines. It includes the effect of conductor distribution in the machine, magnet flux density distribution, current harmonics and non-idealities in position and current sensors. Harmonic orders and magnitudes of torque ripple developed due to various sources are analyzed.
A new control strategy considering saturation is proposed for Synchronous Reluctance Machine (SyRM). The strategy considers the change in machine parameters due to saturation to obtain optimal torque. The proposed methodology also considers the effect of computation burden on the microcontroller. This ensures that the method can be implemented in automotive grade microcontroller. This thesis also provides an active torque ripple compensation method for minimizing the output torque ripple of SyRM. The proposed active cancellation method uses current injection either in the q- axis or in the d-axis. The influence of parameter saturation on both methods is analyzed. A strategy is proposed to choose the best method between the two based on the operating point of the machine. A 30 slot 4-pole Synchronous Reluctance machine is built and tested. The theoretical work provided in this thesis is supported by experimental results using the prototype machine.