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

Abstract

This paper presents a new method to find available slot-pole combination of a permanent magnet (PM) vernier motor with fractional-slot concentrated winding (FSCW) configurations instead of the conventional design rule. To this aim, for a common structure of PM vernier machines with FSCW, the air gap flux densities including modulation flux due to vernier effects are investigated from the magnetic view points and then a general condition to effectively use the modulation flux is derived. Under the obtained condition, the specific design condition for slot-pole combinations are established for the most popular FSCW configurations with the coil spans of ±2π/3. Using the established condition, all available vernier structures including those which could not be found by the previous rule are obtained, and the back-electromotive force (EMF) of each structure is analytically estimated to check the vernier effects. During these procedures, it is also revealed that some of general FSCW-PM motors possess vernier effects and thus can be classified into vernier motors. To verify the proposed ideas, the characteristics of back EMF are analyzed through finite element (FE)-simulations for various models, and compared with their analytical calculation results. Finally, the characteristics of torque regarding to slot-pole combinations of the vernier motors are discussed.

Design, Analysis of the Location and Materials of Neodymium Magnets on the Torque and Power of In-Wheel External Rotor PMSM for Electric Vehicles

“…In practice, the torque and power generated by a three-phase electric machine depend mainly on its geometrical dimensions, the materials used and design features [14,30,57,[62][63][64][65][66][67][68][69] These parameters are determined by the internal apparent power P i of the machine and the associated internal electromagnetic torque of the machine:…”

An analytical formula for back EMF waveform of a counter‐rotating dual‐rotor non‐slotted axial flux permanent magnet synchronous machine

“…In [18], a generator with FSCW for use in low‐voltage applications in distributed generation has been proposed and designed based on Finite Element (FE) analysis. In [19], a new structure for PM vernier motor with FSCW has been introduced. The induced voltage has been analyzed through FE simulations and compared with analytical calculation results.…”

A Novel Dual-Permanent-Magnet-Excited Machine with Flux Strengthening Effect for Low-Speed Large-Torque Applications

“…However, since there exist multi-layer air-gaps [5][6][7][8][9][10][11], IMGMs suffer from complex mechanical structures, thus resulting in a decrease in practicality. On the contrary, PM vernier machines with simple structures are favored and widely investigated by researchers [12][13][14][15][16][17][18][19][20]. Only one set of PMs is employed in all of the aforementioned PM vernier machines, and the PMs are either on the stator or on the rotor.…”

“…Only one set of PMs is employed in all of the aforementioned PM vernier machines, and the PMs are either on the stator or on the rotor. Namely, one kind of machine is rotor type (RT) [12][13][14], and the other belongs to stator type (ST) [17][18][19][20][21][22][23]. The torque capability of these PM vernier machines is limited, as the precious spaces in stator and rotor for the assembly of PMs are not made full use of.…”