Optimization Framework for Dual-Pole Line-Start Permanent Magnet Synchronous Machines

Dual-pole permanent magnet synchronous machine is an emerging technology that is intended to replace induction machines and eliminate variable frequency drive in two-speed applications, such as fans, pumps, compressors, etc. Since the magnetic configuration and the winding arrangement of both the four-pole and the eight-pole structures compete for a same space in the rotor/stator, the optimal design is quite challenging and often requires a tradeoff between the performance characteristics of the low-speed and the high-speed operation. In addition, the conflicting impact of machine parameters on the steady-state and transient performances further complicates achieving the optimal design. This article presents a comprehensive optimization framework based on the optimal rotor magnetic structure and optimal stator winding arrangement to improve the transient startup process, enhance the synchronization capability, and boost the steady-state performance of the machine (i.e., efficiency and power factor). To avoid excessive computational volume associated with the finite element, an analytical model is stablished in both the steady-state and transient regimes and paired up with the optimization algorithm. The effectiveness of the optimal design is verified by a series of comparative analysis against the baseline structure and validated through experimental tests on the machine prototype.