Analysis and Measurement of Permanent Magnet Synchronous Machines with Shielded Rotor

Abstract:
Permanent magnet synchronous machines are characterized by high power density, a robust rotor design and relatively low rotor losses. As a result, these machines enable very high output performance at high rotational speeds, often exceeding circumferential velocities of 200 m/s. Accurately determining the rotor losses remains a challenging task. In order to minimize these losses, the harmonic content generated by the inverter must be suppressed. This is typically achieved by implementing advanced power electronics; such as increased switching frequencies or multi-level inverter topologies, and through the additional use of sine filters. However, these approaches are associated with significant cost, increased component complexity(more material usage), and additional installation space. An alternative approach involves the use of shielding sleeves [1]. The entire rotor surface is covered with an electrically highly conductive shield, which leads to a reduction in power loss [2]. The extent of the effects of such a shielding sleeve will be demonstrated below using measurements and simulations on an example motor. The methods listed differ significantly in terms of the effort required. For this reason, the findings obtained in different ways are compared with each other, so that with this knowledge it is possible to describe the behavior of shielding sleeves in other machines without having to carry out all the work described here again.