Extending the speed range of surface permanent-magnet axial-flux motors by flux-weakening characteristic modification

In many electric drive applications where demanding constraints are imposed on motor dimension, the use of axial-flux permanent-magnet synchronous machines is highly advantageous or even mandatory. A major criticality in the design of such machines is the high-speed operation, where a large stator demagnetization current is required for motor flux weakening. This paper describes how the appropriate choice of the flux-wealening characteristic, combined with the use of magnetic wedges, enables to significantly extend the speed range of these machines retaining a conventional motor design technology. And application of the proposed design strategy on a high-performance axial-flux motor is presented along with relevant testing results.