Distributed cast tooth-coils in electrical machines: Opportunities and Challenges

This paper focuses on advantages and disadvantages of cast tooth-coils in permanent magnet synchronous machines and explores solutions to enhance their benefits through the optimization of the winding scheme by shifting the tooth-coil layers. This approach aims to decrease the harmonic content by rearranging four-layer tooth-coil windings to shifted arrangements, thereby addressing a drawback of tooth-coil windings. The idea is analyzed and validated using electromagnetic 2D-FEM simulations. It can be demonstrated that harmonics can be reduced, leading to minimised torque ripple and core losses. Future challenges, due to the doubling of cast coils, lie in the optimal connection and manufacturing process of the coils.