This paper presents and compares two permanent magnet vernier (PMV) motors with fractional slot concentrated windings (FSCWs) and integral slot distributed windings (ISDWs). The ISDW PMV motor is newly proposed and optimized for a fair comparison with the existing FSCW one. The equations of back electromotive force of both motors are investigated and derived showing that the ISDW PMV motor has the potential to obtain higher torque capability. Also, their electromagnetic performances, such as torque capability, fault tolerance, loss, and efficiency, are calculated and compared by using the finite-element analysis. Then, the maximum power strategy for PMV motors operating at high speed is presented. The simulated results show that both motors possess excellent flux weakening capability. Finally, the effectiveness of the theoretical analysis is verified by the finiteelement analysis results and experiments on a prototype FSCW PMV motor.

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As members of doubly salient magnetless linear machines, linear variable flux reluctance (LVFR) and wound field flux reversal (LWFFR) machines inherit the merits of conventional magnetless linear machines such as low cost, high flux adjustment capability and high reliability. Furthermore, like linear switched reluctance machine, they have a very simple and compact long secondary, which are very attractive for long stroke applications. However, low force capability is their major defect. To solve this issue, new LVFR and LWFFR machine topologies were proposed in recent work, while lacking studies on their force improvement mechanism and further force evaluation. In this paper, LVFR and LWFFR machines with improved force performance are comparatively studied with the emphasis on their force capabilities. The operation principle of the two machines is analyzed based on magnetic field harmonics produced by flux modulation. Contributions of air-gap flux density harmonic components to no-load back electromagnetic forces of the two machines are analyzed and the average force equation is derived. Moreover, force capabilities of the both machines are investigated by means of the time-stepping finite-element analysis to verify the theoretical analysis.