On the effect of design tolerances on the performance of synchronous PM machines evaluated according to the IEEE Std 1812

In the process of designing an electric machine, the systematic study of tolerances for the design variables and material properties is of the utmost importance. This paper proposes a method by which possible variations of the design variables and material properties can be distinguished. The design of experiments (DOE) technique, open-circuit and short-circuit tests, with minimum instrumentation requirements, have been employed. Virtual tests are conducted based on the recently approved IEEE 1812 testing guide for PM synchronous machines. As a case study, a 100 hp 16-pole 18-slot spoke-type PM machine is discussed. It is shown that variation in magnet remanence, steel grade, as well as dimensional tolerances, may be identified. The ratings and magnetic loading of the machine plays a critical role in identifying manufacturing tolerances.