In this paper, an 18-slot/26-pole Vernier permanent magnet synchronous machine (VPMSM) with coil-pitch of two slot pitches is proposed based on a 9-slot/18-flux-modulation-pole/26-pole VPMSM with concentrated tooth-coil windings. Compared with the original VPMSM, the number of slots is doubled and the phase winding connection is adjusted to reduce the space harmonic content, the phase inductance, and hence, improve the power factor. The study shows that the proposed VPMSM increases power factor from 0.73 to 0.95 with better torque and flux weakening capability. Moreover, a series of VPMSMs with high power factor are proposed from the same design principle and given design guidelines.

In this paper, a performance comparison between the novel axial flux magnetically geared machines (AFMG) and the conventional axial flux YASA machine is presented. The AFMG and YASA machines have the same stator construction in which segments are equipped with concentrated windings to form the stator. However, the AFMG machine has two rotors with different pole-pair numbers. Magnetic gear effect can be obtained to increase the torque density. The performance comparisons at no-load and on-load conditions are then studied by 3D-finite element analysis (FEM). Moreover, both machines are prototyped, tested and compared.

This paper comprehensively studies the electromagnetic performance of flux reversal permanent magnet (FRPM) machines with different consequent-pole PM (CPM) topologies. Four CPM topologies are firstly introduced and classified by different numbers of PM pieces and PM locations on stator teeth. Then, the distribution and working harmonics of air-gap flux density of each CPM topology are analyzed and compared, and the CPM topology with the highest torque density is identified. The influence of critical design parameters on machine performance is also parametrically investigated. By comparing the torque performance of CPM topologies with their surface-mounted PM (SPM) counterparts, the advantages of CPM topologies, i.e. torque improvement and magnet volume reduction, are clearly revealed. Four FRPM prototypes are manufactured and tested to verify the analyses.

No abstract

This paper overviews the recent developments and various topologies of magnetically geared (MGd) machines. Particularly, current design trends and research hotspots of this kind of MGd machines are emphasized, with the aid of statistic summary of the published papers. According to different evolutions from a magnetic gear (MG), four mainstreams of MGd machines are extracted and compared in terms of both mechanical complexity and electromagnetic performance. By virtue of their inherent features, such as high torque density and multi-power port, the feasibility of MGd machines for applications, where continuously variable transmission (CVT) and power split are demanded, is also described.