Structural Expression Code Method and its Application in Optimal Design of Permanent Magnet

In the process of designing electromagnetic equipment how to obtain the satisfied distribution of magnetically dense precisely though the variation of permanent magnet structure is a big challenge. The existing methods only do optimization for parameters under a fixed or several fixed structures. However, no optimization is done concern both structure and parameters simultaneously. To address this, a structural expression code (SEC) method is proposed. It can encode the structure and parameters simultaneously, realizing the optimization of the real structural scheme and parameters at the same time. The SEC method can solve a large proportion of the optimal design of electromagnetic equipment with flexible structure. Of course, it can also be used in other mechanical structural optimal design. The SEC method is proved by optimizing the structure and parameters of a permanent magnet for permanent magnet synchronous motor (PMSM) combined with genetic operator and evolutionary framework. The simulation result obtained by finite element method shows the optimal designed permanent magnet shape produces an air gap flux density waveform whose sinusoidal distribution is 99.78%.