Topology Optimization of Rotor Bars Geometry and Arrangement for a Line-Start Permanent Magnet Synchronous Machine

An optimally designed line-start permanent magnet synchronous machine may require a different squirrel-cage design than traditional induction machines. The objective of this paper is to apply topology optimization based on the normalized Gaussian network in order to find the optimal shape of the rotor bars for a line-start permanent magnet synchronous machine. This approach facilitates optimizing the shape of the bar, without the limitation of a predefined bar geometry and arrangement, as is usually considered for classic induction machine design. For this study, a previously designed four-pole line-start permanent magnet synchronous machine with a rated power of 1.5kW is used as an initial design. To verify the accuracy of performance evaluation by utilizing finite-element methods, a prototype of this machine was built and tested. Then, verified model of line-start permanent magnet machine is used for topology optimization of its rotor cage area. The outcome of the optimization is the Pareto front, from which three optimized designs are selected. Finally, these designs are analyzed and proved to have better steady-state performance than the initial machine. The results provide new insights for the design of squirrel-cage bars for line-start permanent magnet synchronous machines.