*Article* **Analysis and Optimization of Axial Flux Permanent Magnet Machine for Cogging Torque Reduction**

**Hina Usman 1, Junaid Ikram 1, Khurram Saleem Alimgeer 1, Muhammad Yousuf 2, Syed Sabir Hussain Bukhari 3,4 and Jong-Suk Ro 4,5,\***


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**Abstract:** In this paper, a hexagonal magne<sup>t</sup> shape is proposed to have an arc profile capable of reducing torque ripples resulting from cogging torque in a single-sided axial flux permanent magne<sup>t</sup> (AFPM) machine. The arc-shaped permanent magne<sup>t</sup> increases the air-gap length effectively and makes the flux of the air-gap more sinusoidal, which decreases air-gap flux density and hence causes a reduction in cogging torque. Cogging torque is the basic source of vibration, along with the noise in PM machines, since it is the main cause of torque ripples. Cogging torque is independent of the load current and is proportional to the air-gap flux and the reluctance variation. Three-dimensional finite element analysis (FEA) is used in the JMAG-Designer to analyze the performance of the conventional and proposed hexagonal-shaped PM AFPM machines. The proposed shape is designed to reduce cogging torque, and the voltage remains the same as compared to the conventional hexagonalshaped PM machine. Further, optimization is performed by utilizing an asymmetric overhang. Latin hypercube sampling (LHS) is used to create samples, the kriging method is applied to approximate the model, and a genetic algorithm is applied to obtain the optimum parameters of the machine.

**Keywords:** Axial flux permanent magne<sup>t</sup> machine; 3D FEA; Genetic algorithm; hexagonal-shaped PMs; PM overhang
