Influence of Demagnetization on Selecting the Optimum Slot/Pole Number Combination for 3MW Surface Mounted Permanent Magnet Vernier Machine

Scaling Effect on Electromagnetic Performance of Surface-Mounted Permanent-Magnet Vernier Machine

“…However, the influence of saturation at high normalized pole pitch (low slot/pole number combination) is clearly observed for the 500kW and 3MW machines which have much higher electrical loading than the 3kW machine as shown in TABLE I. The low slot/pole number designs are more prone to high saturation due to its large coil inductance and thereby high armature reaction [39]. Nevertheless, the SPM-V machine can still achieve excellent torque density of about 62% higher than that of the conventional SPM machine even at 3MW power level.…”

“…It is observed that with low values of (1) the power factor can be really high (close to unity) and with > 1, the power factor significantly drops below 0.6. From (39), it is observed that the value of is largely dominated by the product of electrical loading and operating gear ratio. For the same power rating (same electrical loading), the SPM-V machine with much larger gear ratio ( =5) is expected to have much lower power factor than the conventional SPM machine ( =1).…”

System-Level Investigation of Multi-MW Direct-Drive Wind Power PM Vernier Generators

“…Hence a gear ratio of 5 (the minimum gear ratio to realize an integer slot winding) has been chosen for this study to achieve a reasonably good power factor. Both the conventional SPM and SPM-V machines are globally optimized for maximum torque using the OPERA optimizer tool which uses a combination of deterministic and stochastic methods [17]. The geometric variables used for global optimization are the same as investigated in [4].…”

“…The mass density and cost of the generator active materials used for the calculation of torque to mass (T2M) and torque to cost (T2C) ratios are given in Normalized pole pitch ( ) length is also considered for the calculation as it can be significantly longer at lower slot/pole number combinations for the SPM-V machines [17]. The end winding length for each turn is assumed to be twice the circumferential coil pitch length.…”

“…The total iron losses (including stator and rotor core losses) is observed to increase for both low and high slot/pole numbers. This is mainly due to high armature flux density towards low slot/pole numbers and high operating frequency towards high slot/pole numbers [17]. Based on the above comparison of overall performances, the optimal slot/pole number combinations have been selected for the SPM-V machines with different power ratings, as shown in It is found that the optimal performance of the SPM-V machines is achieved when ̅ is around 3 for all the power ratings.…”