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The purpose of this paper is to present the performance characteristics analysis of a new type axial flux permanent magnet (AFPM) machine according to the geometric structure of rotor such as permanent magnet dimension, the air‐gap length and so on.

The 3D finite element method (FEM) is used to analyse electromagnetic fields with the aid of an ANSYS software package. The FEM is based on the magnetic vector potential and the governing equation can be obtained from the Maxwell equation. Using the dynamometer system, the characteristics of the AFPM machine were estimated according to load torque.

The AFPM machine characteristics with static torque, cogging torque and flux density according to rotor geometric dimensions are analyzed using a 3D FEM software package. And then, the prototype of an AFPM machine and several rotors with different PM structure are manufactured and tested. Resulting from the experiment, the characteristics such as EMF waveform, speed and efficiency curves according to load torque, and efficiency curves according to PM thickness, are obtained. The measured performance results verified the overhang effects and improved the efficiency of the motor.

The paper proposes a new type AFPM machine structure with T‐shape teeth and laminated back yoke and two types of rotor with fan‐shaped permanent magnets. It presents the results of characteristics of the proposed AFPM machine throughout the simulation and experiment.

The purpose of this paper is the fast and accurate modelling of surface-mounted Axial-Flux Permanent-Magnet (AFPM) machines equipped with cylindrical magnets using quasi-3D approach. Furthermore, the accuracy of the method is improved by using leakage coefficient, saturation coefficient and an appropriate permeance function.

Quasi-3D approach is used for fast and accurate modelling of AFPM machines. Air-gap flux density distribution, induced back EMF, and produced cogging torque are calculated using the proposed method with reasonable accuracy.

The results obtained by quasi-3D approach compared to Finite-Element-Analyses (FEA) shows how accurate, fast and efficient this method is. It is proved that, this method can be successfully applied to evaluate the performance of the AFPM machines.

Effectiveness and accuracy of quasi-3D approach is assessed on different AFPM machines. Furthermore, to increase the accuracy of computations, the effects of the magnetic potential drop at iron parts of the machine are taken into account by using a saturation coefficient. Besides, the influence of the slot opening on the flux density distribution is taken into account by using an appropriate relative permeance function.

The purpose of this paper is the investigation of eddy currents induced in the axial‐flux permanent‐magnet machine housing by the leakage flux and the introduction of permanent magnets in the steady‐state AC finite‐element analysis and coupling their effects with the transient thermal analysis.

The proposed approach is based on the finite‐element method as well as on using the basic analytical equations. The approach was first applied in the magneto transient analyses. Because of the different physical transient‐time constants, the steady‐state AC analysis coupled with transient thermal should be used.

The permanent magnets in the steady‐state AC analysis coupled with the transient thermal analysis can be simulated by coils with an imposed current of a frequency depending on the number of pole pairs and rotation speed. Using any of the electrically conductive materials for the axial‐flux inner slotless stator permanent‐magnet machine housing should be avoided.

The leakage flux induced by permanent magnets and spreading into the axial‐flux permanent‐machine housing is first defined by using the magneto‐transient finite‐element analysis and further used in the steady‐state AC analysis coupled with the transient thermal analyses, all in 3D. Based on the results of these analyses, the temperature distribution in entire machine is calculated and compared with the measurement results.

Consideration of leakage fluxes in the preliminary design stage of a machine is important for accurate determination of machine dimensions and prediction of performance characteristics. This paper aims to obtain some equations for calculating the average air gap flux density, the flux density within the magnet and the air gap leakage flux factor.

A detailed magnetic equivalent circuit (MEC) is presented for a TORUS-type non-slotted axial flux permanent magnet (TORUS-NS AFPM) machine. In this MEC, the leakage flux occurring between two adjacent magnets and the leakage fluxes taking place between the magnet and rotor iron at the interpolar, inner and outer edges of the magnets are considered. According to the proposed MEC and by using flux division law, some equations are extracted. A three-dimensional finite element method (FEM) is used to evaluate the proposed analytical equations. The study machine is a 3.7 kW and 1,400 rpm TORUS-NS AFPM machine.

The air gap leakage flux factor, the average air gap flux density and the flux density within the magnet are calculated using the proposed equations and FEM. All the results of FEM confirm the excellent accuracy of the proposed analytical method.

The new equations presented in this paper can be applied for leakage flux evaluating purposes.

This paper aims to propose an analytical model for the harmonic content no-load magnetic fields and Back electric motive force (EMF) in double-sided TORUS-type non-slotted axial flux permanent magnet (TORUS-NS AFPM) machines with surface-mounted magnets considering the winding distribution and iron saturation effects.

First, a procedure to calculate the winding distribution with a rectangular cross-section is proposed. The magnetic field distribution and magnetic motive force (MMF) drop due to saturation in iron cores are then exactly extracted in a 2-D analytical model. The consequent influence on air-gap magnetic field and Back EMF are also calculated using a new iterative algorithm. The results are compared with those of the conventional analytical model without saturation, 2-D finite element analysis (FEA) and an experiment on a fabricated prototype machine.

Unlike the conventional method, the new method yields the no-load magnetic field distributions in air-gap and iron cores and Back EMF very exactly such that the results well match to those of the FEA and experiment.

Unlike the conventional winding factor, the winding distribution is considered here along the both axial and circumferential directions, which improves the accuracy level of results for non-slotted structures with relatively large air-gaps. The magnetic field distribution and MMF drop-in iron parts are also calculated as the basis for exact recalculation of air-gap magnetic field and Back EMF. Because of small computational burden beside superior accuracy, the proposed model can be treated as an accurate and fast substitute for FEA to be used during the design procedure or for predicting the other performance characteristics of TORUS-NS AFPM machines.

This paper gives an overview of the design, manufacturing and testing of a high‐speed (16,000 rpm and 30 kW) AFPM synchronous machine, which is mounted inside, and as an integral part of, a flywheel. This system will subsequently be used for transient energy storage and ICE operating point optimization in an HEV. The paper focuses on the major design issues, particularly with regard to the high rotational speed, and investigates the loss mechanisms which are apparent therein, e.g. iron losses, rotor losses, and friction losses. The paper describes the high‐speed testing facility and includes measured results, which will be compared to calculated values.

The purpose of this paper is to compare the methods of calculating the parameters of air-cored stator flux permanent magnet generator and to compare these results with the measurements of the designed and manufactured generator. The generator is to be designed for operation in a wind power plant.

An analytical method and 2D and 3D finite element methods (FEMs) were used to calculate the parameters of the coreless permanent magnet axial generator. The analytical method and 2D FEM were applied to individual cross-sections through the air gap of the machine. After the design and construction of the generator and measuring station, the results of calculations and measurements were compared.

The results of investigated calculation methods and measurements were found to be mutually compatible. Analytical methods and 2D FEM required proper interpretation of the results when comparing them with the 3D FEM. The results of the measurements and calculations showed the usefulness of the generator for operation in a wind power plant.

Full comparison of results of 2D and 3D calculations with the results of the measurements on the machine model confirmed the usefulness of fast 2D methods for the analysis of coreless generators. The results differed by the effects of leakage inductance of windings’ front connections. The application of an axial generator designed with the described methods in a wind turbine showed its proper operation.

In this paper, an improved multiobjective particle swarm optimization (PSO) algorithm is proposed to optimize a three-phase, 12-slot, 19-pole, yokeless axial-field flux-switching permanent magnet (YASA-AFFSPM) motor.

Based on the structural characteristics of the YASA-AFFSPM, a mathematical model is established to calculate the main size of the YASA-AFFSPM motor. The split ratio, stator axial length, sandwiching pole angle, rotor pole angle, PM arc and number of conductors per slot are selected as optimization variables. Also, the efficiency, power factor, cogging torque and average torque are considered as the optimization objectives. The objectives are optimized by combining the improved multiobjective PSO algorithm with electromagnetic calculation.

Based on the proposed algorithm, the investigated motor is optimized. The on-load efficiency, power factor and average torque of the motor performance have increased by 0.87%, 3.13% and 10.39%, respectively. Moreover, the cogging torque and slot fill factor have undergone decreases of 8.57% and 3.34%, respectively. Finally, the effectiveness of the algorithm is verified using experiment results.

So far, no comprehensive report has been observed on the optimization of the YASA-AFFSPM motor using evolutionary algorithms and the study of the effect of the motor parameters. Therefore, in this paper, the authors decided to investigate the effect of YASA-AFFSPM motor parameters and improve motor performance with the improved PSO method.

This paper aims to propose a novel simple and efficient structure for line-start axial-flux permanent magnet (LSAFPM) synchronous motor, especially regarding the permanent magnets (PMs) demagnetization reduction.

At first, a primitive raw scheme of the new structure for the LSAFPM motor is introduced. Considering this raw scheme, the levels of irreversible demagnetization in various regions throughout the entire volume of each PM are evaluated using 3 dimensional (3D) finite elements analysis (3D FEA) in full loading condition during startup until reaching steady state. Based on the results of these analyses, the primitive structural scheme is then modified through segmenting (cutting into four pieces) each PM from where the worst irreversible demagnetization levels occurred.

As will be demonstrated by the results of 3D FEA, the proposed modified structure is not only capable of successful startup and synchronization of the motor but also it considerably reduces the PM demagnetization level. Thus, the performance of the motor is significantly improved.

The demagnetization of PMs is an important effect in PM synchronous motors, which can greatly affect motor performance. Therefore, it is necessary to be considered in the motor design processes. This effect becomes much more significant in the line-start PM motors because the usual high-magnitude startup induction current produces a strong armature-reaction magnetic field, which may cause the PMs to be irreversibly demagnetized. The approach proposed in this paper provides a structural solution to mitigate the PM demagnetization effect and thereby improve the performance of an LSAFPM motor through modifying the structure of the LSAFPM motor according to an FEA-based PM demagnetization analysis. As a considerable contribution, in this analysis, the variation of demagnetization level between different areas inside each PM is computed and is considered as a basis for proposing an appropriate structural modification to mitigate the PM demagnetization effect as much as possible.

This paper aims to present a modified MEC algorithm for demagnetization modeling of the PM motor. One of the major issues that the designers of the permanent magnet (PM) motors are faced with is the demagnetization of magnets because of high temperatures and armature reaction. Demagnetization will weaken the magnetic properties of the magnet and lead to a reduction in the performance of the motor. Therefore, it is essential to provide appropriate methods for modeling this phenomenon. One of these methods that has a compromise between accuracy and time consumption is the magnetic equivalent circuit (MEC). In this paper, the MEC method is used for modeling the demagnetization phenomenon for the newly introduced ring winding axial flux PM (RWAFPM) motor. The proposed algorithm can take the demagnetization into account through a time-stepping model and also correct the value of the knee point flux density.

The modified MEC method is used for demagnetization modeling. The modified algorithm can take into account demagnetization and also renew the knee point at each step to increase the accuracy of the modeling. In addition, the proposed algorithm has a very high and fast execution speed so that the computation time of the MEC algorithm compared to the FEM model is reduced from 3 h to 35 s. In this case, the simulations have been performed on a core i5@ 2.3 GHz/8GB computer. The FEM model is used to verify the validity of the MEC results.

The obtained results show that at the high temperature, RWAFPM motor is severely vulnerable to demagnetization. At the temperature of 140°C, the demagnetization rate of 35% has occurred. So, it is necessary to use the high-temperature magnet in this motor or modify the motor structure in terms of demagnetization tolerant capability.

The RWAFPM motor is introduced for use in ship propulsion and traction systems. For this reason, an accurate estimation of demagnetization tolerant of this motor in different working conditions can show the strengths and weaknesses of this structure.