A High-Power Factor Vernier Machine With Coil Pitch of Two Slot Pitches

Abstract

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.

Investigation of scaling effect on power factor of permanent magnet Vernier machines for wind power application

“…SPM-V machines, unlike conventional SPM machines, utilize the flux modulation principle for generating high torque [14], [15]. The stator open slot structure in Vernier machines (as shown in Fig.…”

“…However, a relatively low power factor compared to conventional permanent magnet (PM) machines currently prevents its penetration into wider industrial applications [9]- [11] due to the requirement for larger converter ratings, which could lead to increase in system cost and losses. Several novel Vernier topologies have been proposed in the past to improve the power factor of such machines [12]- [15] to address this critical issue. However, the review of literature reveals that most of the works related to power factor improvement and its analysis have been performed for relatively small scale (up to few kWs) Vernier machines.…”

“…Different slot/pole number combinations will be analyzed for each power rating to assess the optimal performance. In previous work, researchers have used simple power factor equations to qualitatively explain the poor power factor of SPM-V machines against the conventional SPM machines [6], [12], [15]- [17]. However, a detailed consideration of parameters like inter-pole magnet leakage and stator slot leakage fluxes across different slot/pole numbers for power factor calculation has not been performed before.…”

Design and Analysis of a Flux-Concentrated Linear Vernier Hybrid Machine With Consequent Poles

“…For this class of machine, high inductance and corresponding low operating power factor is inherent, and for a generator this means they can only be used when connected to an over-rated converter. For VPM machines, by ignoring the resistance of the stator winding the power factor can be improved by either increasing the flux linkage or minimising the inductance as stated in [1, 8,12,28], which can be verified by (4).…”

Axial-field Vernier-type Flux Modulation Machines for Low-speed Direct-drive Applications

“…To address such limitations, a three-phase radial-field vernier-type PM machine with 46 rotor poles, and only 6 stator coils has been proposed in [4]. Other recent papers on the subject with radial-and axial-field versions include [5], [6]. In addition, a three-phase axial-field version with a Dr. Vandana Rallabandi was with the SPARK Laboratory, ECE Department, University of Kentucky, Lexington, KY and is now with GE Research, Niskayuna, NY.…”