Classification of field-weakening solutions and novel PM machine with adjustable excitation

This paper gives a comprehensive overview about the concepts and the implemented designs of synchronous machines with high field weakening capability already presented in literature. Moreover, important characteristics of machines are discussed regarding the application of drives in electric and hybrid electric vehicles. For an existing series production vehicle with a parallel hybrid drive topology a new rotor design is introduced, substituting the cage rotor of an 85 kW continuous power asynchronous machine with a rotor incorporating a segmented internal permanent magnet design. The novel rotor design is based on a variable arrangement of magnets using a simple turn of bars. This idea fills a gap in an offered classification of flux-weakening solutions. In comparison to state of the art machines, the novel design offers substantial advantages especially when incorporated into drive-trains of vehicles. Finally, exemplary results of measurements with the new 150 kW prototype are given.