Modeling of Axial Flux Permanent Magnet Generators

Abstract

This article focuses on modeling of an Axial Flux Permanent Magnet Generator (AFPMG). The authors analyzed selected variants of disk generators, including coreless stator constructions and with iron core ones, also taking into account the Permanent Magnet (PM) arrangement in order to show the way to obtain the optimal machine characteristics based on analytical equations. In addition to the full model, which takes into account the higher harmonics of the magnetic field distribution, the paper presents a simplified mathematical model developed for generator operation cases such as standalone, connected to a 3-phase power grid and loaded with a diode rectifier. The analytical and finite-element method (FEM) calculations were performed as well as laboratory tests to confirm the correctness of presented model assumptions.

Application of the Harmonic Balance Method for Spatial Harmonic Interactions Analysis in Axial Flux PM Generators

“…In modern permanent magnets of rare earth metals, the return curves additionally coincide with the demagnetization curve for its rectilinear section. Therefore, it can be assumed that for changes induced by winding currents, the permanent magnet operating point moves along unique demagnetization curve, which corresponds to uniqueness of changes in the co-energy of a permanent magnet [11,31]. Since iron cores of the stator and rotor have very high magnetic permeability compared to air and rare earth magnet materials, it can be assumed that the energy of the magnetic field concentrates mainly in the air gap and permanent magnets, which means that magnetic voltage drops in the machine's iron yokes are linear and can be included in permeance function, which describes machine magnetic geometry or these drops can be neglected.…”

“…Generators in this class of applications typically have a cylindrical rotor with surface-mounted magnets, but axial magnetic flux disc generator solutions are also very popular [7,8]. For this reason, both design and mathematical modelling techniques of these machines are being constantly developed and improved [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. The Axial Flux PM (AFPM) generator deserves special attention due to their variety of designs and popularity in low-power home applications.…”

“…The Axial Flux PM (AFPM) generator deserves special attention due to their variety of designs and popularity in low-power home applications. This article is a continuation of the authors' papers [9][10][11] on AFPMG modeling, however it does not limit the possibility of applying the presented methodology to other constructions of PM generators.…”

“…Mathematical models of PM synchronous generators should provide the possibility of solving, in a relatively simple manner, various operational issues associated with the generation of electrical energy. For this purpose, the most suitable are so-called circuit models, commonly used in conventional machines [9][10][11][12]16,22] and the purpose of this paper is to extend the mathematical modeling methodology for this specific class of machines, i.e., axial flux PM synchronous generators operating in steady state.…”

The Effects of Cogging Torque Reduction in Axial Flux Machines

“…Recently, axial flux permanent magnet (AFPM) electrical machines have represented the most potential class of energy transforming appliances, which provide the best power/weight ratio and excellent efficiency for different applications [ 1 , 2 , 3 , 4 ]. The absence of rotor winding due to strong NeFe composite permanent magnets (PMs) and the optimal use of stator–rotor surface enables high torque at low velocities, good cooling possibilities, and high energy efficiency [ 5 ].…”