Development of a compact and low cost axial flux machine using soft magnetic composite and hard ferrite

Especially for automotive applications, the request for small, lightweight, powerful and cheap electrical machines is tremendous - not only for the drivetrain in electrical vehicles but also for ancillary components like air conditioning compressors, starters/generators or pumps. In terms of small size and high power to weight ratio, the use of permanent magnets, especially rare earth magnets is essential. However, rare earth permanent magnets(PM's) have several concerns caused by a very concentrated resource market, which has already caused unpredictable price increase or export restrictions. Therefore, it is the goal to avoid rare earth magnets on the one hand but, on the other hand, keep the characteristics of a machine for the automotive industry. The combination of hardferrite magnets and soft magnetic composites, combined in an axial flux motor topology is a promising approach to fulfill the requirements of a high power density, low-cost and rare earth magnet-free machine. The designed motor structure with ferrite PMs replacing the rare earth PMs and the results of three- dimensional finite element analyses are introduced in detail in this paper. Moreover, a prototype with 600W nominal output power was produced and tested.