Theoretical analysis of synchronous machines with displaced reluctance axis

Abstract

 Abstract --This paper examines synchronous machines, whose excitation axis and reluctance axis can have an arbitrary angle. Basic equations for this machine type are set up and control strategies for maximum torque are derived. By using a normalized representation, it will be shown that machines with displacement angles of about 60° need up to 10% less permanent magnet material than conventional machines while yielding comparable motor performance.

A hybrid permanent magnet and wound field synchronous machine with displaced reluctance axis capable of symmetric four quadrant operation

“…This analysis suggested a hybrid excitation synchronous Basic reference frames of machines with a displaced reluctance axis according to [6]. machine with a displaced reluctance axis (HSM/DRA), which exhibits the same benefits as mentioned before, yet its main feature is the improved performance due to the magnetic asymmetry.…”

“…The basic idea behind synchronous machines with a displaced reluctance axis has been developed in [6]. Their concept is the spatial displacement of the two torque producing principles in synchronous machines -the synchronous torque, which is produced by the rotor excitation, and the reluctance torque, which is produced by the saliency of the rotor lamination.…”

“…While theoretical studies about the optimum displacement angle β regarding inverter utilization have been carried out in [6], a more practical approach concerning the feasibility of such machines has been made in [5]. It was proven that hybrid machines using both PM and electric excitation are most suitable for machine designs with a displaced reluctance axis.…”

Dynamic control of generalized electrically excited synchronous machines using predictive flux control

“…For further improvement, a concept additionally incorporating a displaced reluctance axis (HSM/DRA) which utilizes the reluctance torque more efficiently and therefore yields further improvements regarding torque and efficiency has been developed in [4], based on theoretical studies [5] and practical considerations [6]. A geometry of this kind of machines is depicted in Fig.…”

Increasing the operating range of permanent magnet synchronous motors by switching the winding configurations

“…For the calculation of the parameter plane, the following has to be assumed: All losses are set to zero, while the iron and permanent magnets are considered linear [9]. Moreover, the higher harmonics are set to zero and all physical values are sinusoidal respectively.…”