Optimisation Method for an Asymmetric Rotor Design to Reduce Torque Ripple in Reluctance Synchronous Machines

Inhalt:
This paper focuses on reducing torque ripple in reluctance synchronous machines (RSMs). High torque ripple limites the viability of RSMs in many industrial and automotive applications. Conventional methods for torque ripple reduction include discrete skewing of the rotor or the use of alternative rotor geometries such as the Romeo and Juliet or the Machaon design, which have been explored in the literature. Another promising approach is the use of asymmetric flux barriers in the rotor design, which also simplifies rotor assembly. The key challenge for this geometry is selecting the optimal flux barrier angle. This paper addresses this challenge and presents a structured workflow for the rotor geometry optimization. To narrow the parameter range and streamline the design process, an analytical method for estimating torque ripple is introduced. Simulation and calculation results predict a torque ripple reduction of 86%, which demonstrates the significant potential of the asymmetric rotor structure. In comparison to a discrete skewed rotor with four stacks, an asymmetric rotor structure reduces the torque ripple by 4.4%.