Simple Production of Micro-Drives Using Plastic Bonded Rotor Magnets and Concentrated Stator Windings

Abstract:
The use of permanent magnets in synchronous machines can be problematic in terms of assembly, cost and environmental impact. However, efficient machine designs require permanent magnets. This proposal deals with a manufacturing method for the rotor and stator of permanent magnet synchronous machines with the aim of simplifying the production of micro drives. The main focus is on a permanent magnet synchronous machine design using injection-molded rotor magnets to reduce the production costs by simplifying the assembly process. Injectionmolded rotor magnets opens up further possibilities and degrees of freedom in the machine design. The manufacturing process can be considerably simplified by using concentrated windings and open slots. This results in a higher cogging torque and a higher torque ripple compared to distributed windings with pole shoes. In the present work, the simplest possible concentrated winding arrangement with only three windings and six stator slots was used. The shape of the rotor magnets has been modulated in such a way that the torque ripple could be minimized, reaching values comparable to standard comercial motors of the same size. Both the construction of the prototype and the design of a magnetization device for magnetizing the rotor magnets were optimized on the basis of verified simulation models.