Optimal design of BLDC motor based on Magnetic Equivalent Circuit considering the Halbach magnet array

Abstract

This paper deals with the design using the magnetic equivalent circuit (MEC) of an external rotor brushless DC motor (BLDC) for drones applied with a halbach magnet array. Since magnetic circuits are similar to electrical circuits, design elements can be parameterized by applying Kirchhoff's law, and saving time and simplifying preliminary design compared to finite element analysis (FEA). When the Halbach magnet array is applied to the motor, the characteristics of the motor can be improved according to the permanent magnet thickness and pole ratio. If the halbach magnet array is applied to the motor, the main magnetic flux can be improved, but most of the designs are intuitively designed by analyzing tendency through FEA. In this paper, to systematically analyze the halbach magnet array design, which relied on experience, a MEC was constructed through inductance analysis. A MEC was established in consideration of the number of segments and the magnetization angle of the halbach magnet array, and based on this, an optimization of motor design was conducted to prove the validity of the design and analysis.