Development of a High Power Density In-Wheel Motor using Halbach Array Magnets

In this study, a direct drive in-wheel system is proposed as a high power density system that can reduce the intermediate parts such as a speed reducer by increasing torque. We propose a design strategy that shows multipolarization and the improvement of the gap magnetic flux density are effective at increasing the power density. As a technique for improving the gap magnetic flux density, a Halbach array magnet rotor is used that combines the main pole magnets and spoke magnets with the core. We compare the Halbach array magnet rotor with the conventional surface-mounted permanent magnet (SPM) rotor by using finite element method (FEM) analysis. An in-wheel motor prototype of the actual size with the developed Halbach array magnet rotor was also fabricated and used to measure the no-load induced back electromotive force (EMF).