A New Efficient Permanent-Magnet Vernier Machine for Wind Power Generation

Abstract

This paper proposes a new outer-rotor permanent-magnet (PM) vernier machine for direct-drive wind power generation, which can offer low-speed operation to directly capture wind power, and enable high-speed rotating field design to maximize the power density. Compared with its mechanical gear counterpart, the proposed machine can eliminate the mechanical wear and tear as well as gear transmission loss, thus improving the generation reliability and efficiency. The key is to newly introduce the flux-modulation poles which can effectively modulate the high-speed rotating field of the armature windings and the low-speed rotating field of the PM outer rotor. By using the time-stepping finite-element method, the proposed machine can be accurately analyzed. Hence, its performances are quantitatively compared with other PM vernier machines, thus verifying its validity.

Design and Analysis of a Magnetless Flux-Switching DC-Excited Machine for Wind Power Generation

“…As expected, it overcomes the problem from the CSCF system and thus resulting with higher efficiency [10]- [11]. However, the natural wind speed (5-10 m/s) confines the turbine speed (around 200 rpm) such that a specific low-speed machine is favorable for the VSCF system [12].…”

Investigation on Slot–Pole Combinations of a PM Vernier Motor with Fractional-Slot Concentrated Winding Configurations

“…By using the principle that the induced voltage of a conductor e = vB, where v is the relative speed of B to the conductor. Since the relative speeds of the waves are given as vconv = −rgωm and vver = −rg pm/(pm − Qfmp)•ωm, the instantaneous voltage ea in the conductor with unit length is given by (9). …”

“…where rg is the air gap radius and Gr = −pm/(pm − Qfmp) which is the so-called gear ratio [9] which contributes higher back EMF of vernier PM machines than conventional PM machines.…”

“…According to the field-interaction principle, it is reasonable to think that the one with two PM pole has two winding poles, and the other with four PM poles has four winding poles, demonstrating the identical stators can have different winding poles. However, in quite many studies, the FSCW-PM vernier machines built upon the previous rule have been proposed under the assumption that three slots of a FSCW machine make up one winding pole pair [6][7][8][9][10]. This assumption is obviously useful as well as convenient to design the vernier machine, but there is still uncertainty whether the conventional rule under the assumption provides every available slot-pole combinations for the vernier machine.…”

Design Considerations and Validation of Permanent Magnet Vernier Machine with Consequent Pole Rotor for Low Speed Servo Applications

“…A Permanent magnet vernier machine (PMVM) is widely acknowledged as an attractive candidate for low speed applications due to several distinctive features that belong uniquely to this topology such as magnetic gear effect, and low number of windings with high number of poles [1][2][3][4][5]. Even today, new topologies are being studied and introduced based on PMVM topology since PMVM topology still offers design variants.…”