Investigation of permanent magnet synchronous machines with buried magnets and carbon fiber sleeve for automotive application

Abstract

Due to the limited space available in vehicles, traction drives with high torque densities are a key objective of machine design in the automotive sector. In order to be able to dispense with a multispeed transmission and still achieve high vehicle end speeds, there is also the design objective of a high motor speed. Therefore, permanent magnet synchronous machines with buried magnets are preferred. In the following, a rotor concept is presented as a combination of buried rotor magnets and a carbon fiber sleeve in order to eliminate the radial and tangential rotor iron ribs. The resulting reduction in magnetic flux leakage, in combination with high mechanical strength, leads to an increased magnet utilization for the air-gap field and, thus, allows for a high torque density as well as high maximum speed. A disadvantage, however, is the increased manufacturing effort required for the production and assembly of the carbon fiber sleeve.