Experimental study on windage loss reduction using two types of rotor for hybrid excitation flux switching motor

This paper presents experimental studies on windage loss reduction using two types rotor for hybrid excitation flux switching motor that is intentionally designed so as to compete with an interior permanent magnet synchronous motor installed on TOYOTA PRIUS-2010. This machine makes it possible to vary its field flux by combining the two different mmf sources such as field excitation coils and permanent magnets. Generally, as hybrid excitation flux switching motors have a rotor with salient pole structure like a switched reluctance motor, a large amount of windage loss at high speed region damages motor efficiency. In this paper, two types of rotor, one with cylindrical shape and the other with covered by only shroud located at both axial end of rotor core are built and tested. Compare with a conventional salient pole rotor, it is found that the rotor with only shroud can dramatically reduce windage loss while keeping other drive performances as it is.