Abstract
In this paper, a hexagonal magnet shape is proposed to have an arc profile capable of reducing torque ripples resulting from cogging torque in a single-sided axial flux permanent magnet (AFPM) machine. The arc-shaped permanent magnet increases the air-gap length effectively and makes the flux of the air-gap more sinusoidal, which decreases air-gap flux density and hence causes a reduction in cogging torque. Cogging torque is the basic source of vibration, along with the noise in PM machines, since it is the main cause of torque ripples. Cogging torque is independent of the load current and is proportional to the air-gap flux and the reluctance variation. Three-dimensional finite element analysis (FEA) is used in the JMAG-Designer to analyze the performance of the conventional and proposed hexagonal-shaped PM AFPM machines. The proposed shape is designed to reduce cogging torque, and the voltage remains the same as compared to the conventional hexagonal-shaped PM machine. Further, optimization is performed by utilizing an asymmetric overhang. Latin hypercube sampling (LHS) is used to create samples, the kriging method is applied to approximate the model, and a genetic algorithm is applied to obtain the optimum parameters of the machine.
Highlights
Permanent magnet machines are divided into three categories—axial, radial, and transverse machines—depending upon the direction of flux through the air-gap
Similar to other machines, single-sided axial flux permanent magnet (AFPM) machines suffer from torque ripples, mainly due to cogging torque [10]
A symmetrical, sinusoidal-shaped radial flux permanent magnet machine (RFPM) was designed, which removes the harmonics of back-EMF more effectively and has been proposed as a method for obtaining reduced cogging torque [23]
Summary
Permanent magnet machines are divided into three categories—axial, radial, and transverse machines—depending upon the direction of flux through the air-gap. Investigating methods of cogging torque minimization is of high importance, and various methods are discussed and investigated in other work [14,15,16,17,18,19] Another technique of reducing cogging torque is the stator slots-to-rotor poles ratio. A symmetrical, sinusoidal-shaped radial flux permanent magnet machine (RFPM) was designed, which removes the harmonics of back-EMF more effectively and has been proposed as a method for obtaining reduced cogging torque [23]. A single-rotor, single-stator AFPM with a proposed PM shape is introduced It utilizes the arc profile for the conventional hexagonal-shaped PM. The proposed hexagonal-shaped PM decreases the air-gap flux density, decreasing the cogging torque and torque ripple, which improves the performance of the machine.
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