Preliminary Design and Comparative Analysis of a New Synchronous Reluctance Machine With Hybrid Cores

As no permanent magnet (PM) material is required and only silicon sheets are needed on the rotor core, the synchronous reluctance machine (SynRM) has received tremendous research attention in the past, and it can be used for many driving applications. However, compared with the electrical machine with PM excitation, its torque density, efficiency, and power factor are lower. In this article, a novel SynRM with hybrid cores (Hybrid-SynRM) is proposed. Specifically, its rotor core is made of a combination of non-grain-oriented (NGO) silicon sheets and grain-oriented (GO) silicon sheet cores. The magnetic circuit characteristic of the proposed Hybrid-SynRM is improved by taking the super high magnetization characteristic of the GO silicon sheet along its rolling direction. Moreover, an equivalent magnetic circuit (EMC) model considering the d-axis magnetic circuit saturation effect is proposed for the preliminary design. To verify the performance of the proposed Hybrid-SynRM, the traditional SynRM with NGO silicon sheet cores (NGO-SynRM) is employed as the benchmark comparison. For obtaining fair comparison results, both these two machines are optimized. Through the comparison, it can be seen that the torque ability, efficiency, and power factor of the SynRM can be improved greatly by employing the GO blocks in its rotor core. Therefore, the Hybrid-SynRM can output better performance than the NGO-SynRM especially when the applied current density is high.