Axial Flux Permanent Magnet Machine

This paper deals with the rough design of a Double-Stator Axial Flux Permanent Magnet Machine (DSAFPM) for a rim-driven Marine Current Turbine (MCT). The DSAFPM machine will be compared to a previously developed and realized Radial Flux Permanent Magnet Machine (RFPM); given the same rim-driven MCT specifications. For that purpose, a first-order electromagnetic design model and a thermal one are developed and used to compare active part mass, cost, and thermal behavior of the two machines.

Two original numerical techniques are developed for the finite element (FE) transient analysis of induction and permanent magnet motors operating in demanding aerospace applications. The first technique is the electromagnetic and thermal analysis weak coupling using a multiple slices 2D FE model. The advantage of the specific technique is the representation of complex actuator geometries including skewed magnets and winding ends, by using a low computational cost 2D model while taking into consideration temperature dependent material attributes. The second technique consists in the development of properly defined boundary conditions for the emulation of the cooling housing of actuators. Those boundary conditions are applied at the outer surface of the actuators in contact with the housing and eliminate the need of modeling complex 3D geometries of highly integrated actuator housings.

This paper proposes a method to estimate the magnet temperature in surface permanent-magnet machines using high-frequency carrier signal injection. The injection of a high-frequency signal, superimposed on the fundamental excitation, allows the estimation of the stator high-frequency impedance, which is a function of both the stator and rotor impedances. The temperature of the magnets is shown to have a significant weight on the overall stator high-frequency impedance, from which it can be estimated. The high-frequency carrier signal is injected intermittently in order to minimize potential adverse effects on the normal operation of the machine. This paper first explains the physics behind the magnet temperature dependence. Then, the principles of the method, as well as its practical implementation, are discussed. Experimental verification of the method is provided.

The paper presents a three-dimensional finite-element analysis-based optimization of the overlap between adjacent stator teeth of a claw pole transverse flux permanent magnet machine (TFPM). Two major optimization criteria are considered: 1) the maximization of the output torque and 2) the minimization of the cogging torque. The paper shows that an overlap of almost 30% fulfills both optimization criteria.

Permanent magnet machines for electric vehicles are often designed with a magnetic saliency to improve the torque generation as a result of the reluctance torque at field-weakening operation. The armature reaction is pronounced in such operation, leading to extensive magnetic field harmonics in the teeth and consequently iron losses. This paper analyses the iron losses in two designed machine topologies, inset and interior permanent magnet rotor structures, by measurements and finite element method computations. The measurements and calculations are performed on three prototypes -one with an inset design and two with an equal interior design, but different laminated stator core sheet thickness of 0,35 and 0,20 mm, respectively. The three machines have the same stator designs and water-cooled housings.

The interest in permanent-magnet synchronous motors (PMSMs) is increasing in a wide area of applications. Since most PMSMs will operate without a shaft sensor in the future, valuable information for experimental determination of machine parameters will be lost. In this paper, therefore, a method is presented where the induced EMF and the -axis reactance are determined in a no-load test and the -axis reactance is determined in a load test. The load angle is determined from the load test by means of a new analytical method. In this way, no separate measurement of the load angle is required. The method is especially suitable for line-start PMSMs which normally operate with negative -axis current and, therefore, are not saturated in the -axis flux paths. Moreover, the method is very simple to carry out for any laboratory technician, since the only tests that have to be made are standard tests which are made on standard induction motors on a regular basis.

We designed and tested a new axial flux permanent-magnet machine (AFPM) with field weakening capability. This paper provides a summary of key design features, optimization, and test results of an AFPM prototype. The proposed field weakening method is based on the control of the d-axis component of the armature reaction flux. The paper focuses on the air-gap flux control capability of the topology.

Like any other permanent magnet machines, Interior permanent magnet (IPM) motors also have high efficiency. Because of their high efficiency along with good performance characteristic makes them suitable for electric drive with wide speed range. The conventional IPM machine has very little constant power range. Many attempts have been made to improve the range by modification of rotor configuration. In

This paper presents a new control scheme for wide speed range operation of interior permanent magnet synchronous motor drives, where both torque and stator flux linkage are directly controlled. The proposed scheme possesses some attractive features when compared to the conventional current-controlled drives. Current controllers followed by pulsewidth modulation or hysteresis comparators and coordinate transformation are not used. This eliminates the delays through these networks and offers the possibility of dispensing with the rotor position sensor for the electronic commutator, if the initial rotor position is known only approximately. The scheme incorporates all the usual control regimes, such as the maximum torque per ampere operation in constant torque region, the flux-weakening region, and operates the drive within the voltage and current limits of the motor/inverter. The control scheme has been verified by simulation and experimental tests with a prototype interior magnet motor. This paper describes the scheme in detail, followed by results of its implementation.

In this paper, it’s mentioned about the design model for the one of the most appropriate motor for electric vehicles which is called as axial flux permanent magnet brushless dc motor. It is clarified why that kind of motor is favoured instead of  others and discoursed the basic design specs by taking account of the literature studies.The position of axial flux permanent magnet brushless dc motor in the electric machinery is showed and the regarding points of designing these kind of motors are pointed out. The road map of designing aspects are extracted step by step, from the determining of physcical parameters to building of a prototype.

Axial flux motors have many advantages according to conventional motors. But, as it's known in general, the most important reason not to use axial flux motors as much as radial flux motors, is fabrication difficulties. In this paper, it's shown how to prototype an axial flux permanent magnet motor. Because of that, the difficulties are identified after prototyping job of the axial flux motor. Results that are caused by these difficulties are written. Physical advantages of axial flux motor type is established with this application. A single rotor, single stator axial flux permanent magnet brushless dc motor is produced to prove all of these.

This paper presents a dc-bus voltage control technique for a new power conversion topology feasible for parallelintegrated permanent magnet (PM) wind generation systems. This technique is based on a master-slave hysteresis control scheme in order to solve discrepancy problems that could happen between the controllers. A three-phase semicontrolled rectifier topology is proposed here as an effective interface circuit between each wind generator and the dc-bus. The proposed system provides interconnection extension ability of multiwind converter units sharing the same dc-bus and more economic utilization of the wind generator; by ensuring unity power factor operation. More advantages include voltage disturbance compensation capability, robustness: since a short circuit through a leg is not possible and high efficiency: due to the reduced number of switching elements. The rectifier topology concept, the principle of operation, the control scheme, and test results are presented. The developed technique is also implemented on a 12 kW parallel-connected PM laboratory setup in order to confirm the effectiveness of the proposed system. Index Terms-Permanent magnet generators, power factor correction, three-phase ac-dc rectifiers, voltage control, wind energy generation.

The aim of this paper is to find the best concentrated windings layouts for high pole number permanent-magnet (PM) machines. Pole and slot numbers are varied from 4 to 80 and 6 to 90 respectively. Among all the pole/slot combinations, those giving the highest winding factors are provided. Harmonics in the magneto-motive force (MMF), torque ripple and radial magnetic forces

In this paper, pulsating torque components of permanent magnet machines and pulsating torque minimization techniques are discussed for axial flux surface-magnet disc-type PM machines. The pulsating torque analysis describing general instantaneous electromagnetic torque equation and torque ripple factor is briefly provided in order to analyze torque ripple component. Detailed finite-element analyses focusing on the minimization of cogging and torque ripple components using several techniques are also given. A detailed comparison of the two techniques is also illustrated in this paper.

The design of direct-drive wheel motors must comply with diameter restrictions due to housing the motor in a wheel rim and allow the achievement of very high torque density and overload capability. Slotless axial-flux permanent magnet machines (AFPMs) prove to be the best candidate for application in electric vehicles as direct-drive wheel motors, as in comparison with conventional machines they

Based on the concept of power converter-fed machines (CFMs), an optimal machine design can be considered as the best match of the machine topology, the power electronic converter and the performance specification. To compare the power production potential of machines with various topologies with different waveforms of back EMF and current, a general purpose sizing equation and power density equation are needed to compare the main dimensions and power of such machines. In this paper, a general approach is presented to develop and to discuss these equations. Sample applications of the sizing and power density equations are utilized to compare the induction machine and the doubly-salient permanent magnet machine

Permanent magnet synchronous machines are known as a good candidate for hybrid electric vehicles due to their unique merits. However they have two major drawbacks i.e. high cost and small speed range. In this paper an optimal design of a permanent magnet machine is presented. A reduction of permanent magnet material for a constant torque and an extension in speed and torque ranges are chosen as the optimization aims. For this purpose the analytical model of the permanent magnet synchronous machine is derived and the appropriate design algorithm is devised. The genetic algorithm is then employed to optimize some machine specifications. Finally the finite element method is used to validate the designed machine.

Abstrak Tujuan dari penelitian ini adalah merancang dan membuat generator fluks aksial putaran rendah serta mengamati grafik kinerja karakteristik yang diperoleh dari output generator. Penelitian ini merupakan jenis penelitian kualitatif. Penelitian yang dilakukan memiliki fokus pada disain sketsa perancangan dan pembuatan obyek komponen generator fluks aksial. Untuk mendapatkan data primer dan data sekunder, peneliti menggunakan teknik observasi, studi pustaka, serta teknik pengukuran dan pengujian. Tingkat performa generator dengan kemampuan sebagai prototipe atau purwarupa pada hasil akhir dari penelitian ini adalah pada putaran 800 rpm dengan frekuensi rata-rata 80 Hz generator dapat membangkitkan tegangan 128 VAC dengan nilai arus 24,5 mA. Kesimpulan penelitian ini adalah generator fluks aksial multi cakram 1 fasa untuk putaran rendah dapat dirancang dengan spesifikasi 6 buah stator dan 7 keping rotor berbahan aluminium menggunakan magnet neodymium (NdFeB) sebanyak 12 kutub. Masing-masing stator terdapat 6 buah kumparan kawat tembaga dengan diameter 0,6 mm memiliki jumlah lilitan rata-rata sebanyak 100 lilitan. Nilai perbandingan dari hasil perhitungan dan pengukuran pada generator tersebut adalah 5,69 % dan dikatakan telah mendekati nilai tingkat akurasi yang baik. Pada kecepatan 250 rpm nilai tegangan ketika sebelum diberi beban adalah 36,4 VDC dan pada saat diberi beban turun menjadi 16,46 VDC. Nilai faktor regulasi tegangan DC generator tersebut adalah 54,81 %. Drop voltage tersebut disebabkan karena generator tidak dilengkapi perangkat stabilizer tegangan. Kata Kunci: Generator Fluks Aksial, 1Fasa, Multi Cakram, Neodymium Magnet (NdFeB).

This paper presents a gearless wheel motor drive system specifically designed for fuel cell electric and hybrid electric vehicle propulsion application. The system includes a liquidcooled axial flux permanent-magnet machine designed to meet the direct-drive requirements. The machine design implements techniques to increase the machine inductance in order to improve machine constant power range and high-speed efficiency. The implemented technique reduces machine spin loss to further improve efficiency. The machine design also optimizes the placement of magnets in the rotor to reduce cogging and ripple torque. An original cooling system arrangement based on the use of high thermal conductivity epoxy joining machine stator and liquid-cooled aluminum casing allows the very effective removal of machine power loss. Design details and experimental results are presented.

An axial-flux permanent-magnet machine (AFPM) topology with coreless winding is proposed for generator units required aboard ships, aircraft, or hybrid electric vehicles. In the proposed AFPM configuration, the winding consists of rhomboidal-shaped coils encapsulated in fiber-reinforced epoxy resin. The coils have a double-layer arrangement to leave space for a cooling water duct being used to remove heat directly from the interior surface of the winding. The overall machine structure has high compactness and lightness and, due to the lack of the iron core, generator operation with power output at 400 Hz can be accomplished with high efficiency and acceptable voltage regulation. This paper discusses the basic design and construction of AFPM generators with coreless winding and experimental results taken from a 16-pole machine prototype rated 230 N1m, 3000 r/min are finally reported.

It has been well established in the literature that inverter nonlinearity effects afflict saliency-based sensorless drives. The inverter nonlinearity leads to the generation of signals that corrupt the useful position information. The resulting effect differs depending on the injection approach utilized in the drive. Various compensation techniques to overcome this effect have been published in the literature. This paper is concerned with the zero-vector current-derivative technique. The effect of the varying ON-state resistance of the inverter power devices on the position signal is investigated in detail. Knowledge of the source of the corrupting signals facilitates compensation and determines its applicability. Two approaches for inverter nonlinearity compensation are compared. The first approach utilizes a lookup table from offline-processed data, while the second one is a simpler approach based on the current-dependent resistance characteristic of the inverter switching devices. Experimental performance under sensorless condition is shown for both approaches.

In modeling axial field machines, three-dimensional (3-D) finite-element method (FEM) models are required in accurate computations. However, 3-D FEM analysis is generally too time consuming in industrial use. In order to evaluate the performance of the axial flux machine rapidly, an analytical design program that uses quasi-3-D computation is developed. In this paper the main features of the developed program are illustrated. Results given by the program are verified with two-dimensional and 3-D finite element computations and measurements. According to the results, it is possible to evaluate the performance of the surface-mounted axial flux PM machine with reasonable accuracy via an analytical model using quasi-3-D computation.

In this paper, we present a new tubular permanent-magnet linear machine with square-shaped cross section and derive its corresponding analytical model by solving Maxwell equations and applying the superposition theorem. The analytical field solution is necessary for obtaining an analytic form of the machine parameters and variables such as the self-and mutual inductances of the windings, the thrust force, and the windings electromotive force (EMF). These provide a valuable tool for tubular machine analysis, design, and optimization. In order to achieve maximum force density, we optimized the design parameters of the proposed machine using the analytical model. We used finite-element analysis and experimental results to demonstrate the validity of the developed analytical model. Again using the Fourier series of the cogging force and its harmonic analysis, in this paper, we introduce two techniques for cogging force reduction in the new tubular linear permanent-magnet machine. The first technique reduces the cogging force due to interaction between the permanent magnets and the stator teeth, and the other reduces the cogging force due to finite length of the armature. These techniques are straightforward, and their implementations in the tubular linear permanent magnet machine with square cross section are easy. We investigated the effectiveness of the proposed techniques in cogging force reduction by 3-D finite-element analysis and experimental measurements.

the paper presents an analysis of performances for studied electrical machine designed for the propulsion of a special electric vehicle. This special vehicle is an electric scooter, usually used by people with physical disabilities. This particular electric scooter can be used by elders as well, offering them greater mobility, since, due to their physical health they are becoming more isolated in society. The electrical machine under study in this paper is axial flux permanent magnet synchronous machine. The analysis of the studied machine will be made analytically, numerically and experimental. The obtained results of the proposed solution will be related to a special electric scooter, powered by a dc motor, bought from the market. Index Terms-permanent magnet synchronous machine with axial flux, small electric vehicle.

This paper presents a torque analysis of an axial flux permanent magnet synchronous machine (AFPMSM) based on analytical analysis of magnetic field. The proposed method for torque analysis requires less computational time and is more flexible than finite element method (FEM). This is important advantage, especially for the early stages of the design process. Torque measurements on prototype AFPMSM confirm the validity of the torque analysis method.

In designing new topologies for permanent-magnet machines based on rare earth magnets, it is necessary to diminish the undesired cogging torque. This paper presents a 3-D finite-element analysis to evaluate the effect of magnet shape and stator displacement on cogging torque reduction, for axial flux machines. It analyzes the final electromagnetic torque for the proposed configurations. Finally, it presents the resultant cogging torque waveform for a 5.0 kW prototype, based on our optimization techniques.

The application of concentrated windings in permanent magnet machines significantly reduces overall machine length, due to the elimination of end winding overlap making it more suitable for areas with space limitations. Efficiency is also increased due to the reduction of copper loss. In order to take full advantage of these benefits, optimization strategies have been implemented and its effects are

For the calculation of torque in brushless (BL) alternating current motors a local method is proposed, based on the Maxwell stress theory and the filtered contributions due to the harmonics of the magnetic vector potential in the motor air gap. By considering the space fundamental field only, the method can efficiently estimate the average synchronous torque for a variety or

El estudio eléctrico de un aerogenerador superconductor para bajas velocidades de viento, se

puede desglosar en dos etapas: diseño eléctrico y construcción. Para desarrollar el diseño eléctrico del

aerogenerador, es necesario comprender ciertos conceptos de estos; la parte eléctrica principal del

aerogenerador es el rotor y el estator el cual es el generador de una FEM y por el otro lado los materiales

necesarios para su construcción tomando en cuenta las condiciones de operación de las máquinas eléctricas

superconductoras. En el presente trabajo, se mencionan los componentes principales de una maquina

eléctricas y los materiales necesarios para la construcción de prototipos que nos sirvan como referencia para

poder innovar en un futuro en otros aerogeneradores superconductores.

Axial flux permanent magnet motors having a dual air-gap configuration have been designed and constructed to achieve high power density and used in industries interestingly and specially in the system of driving electrical vehicles. In this paper, the equation related to the design and dimensions of double-sided slotted axial flux synchronous motor with internal stator (TORUS) will be investigated. Then, an optimum design based on genetic algorithm with the purpose of increasing power density is presented. Two-dimensional finite-element analysis (FEM) is used to demonstrate these optimization and its results will be presented. Finally, it presents the resultant back emf waveform and current for a 1.0 kW, 48 V, 50 Hz, 4-poles/15-slots TORUS slotted axial motor prototype, based on our optimization techniques. KEYWORDS Axial Flux PM Motors (AFPM), Power Density, Genetic Algorithm and Finite Element method (FEM)

Direct-drive traction motors devoted to railway applications must be designed in order to comply with both machine diameter restriction and achievement of very high torque density, as well as they should have substantial flux-weakening capability in order to be operated over the required constant-power speed range. Concerning to that, this paper deals with the original solutions adopted for design and construction of an axial-flux permanent magnet machine (AFPM) prototype rated 8000 N-m, 682 rev/min. For such a demonstrator machine a 4-stack AFPM structure is adopted in order to overcome the design restriction on the machine diameter, whereas very efficient cooling arrangement of the machine stator is accomplished by means of a water-cooled toroidal plate. The paper outlines the design characteristics and reports experimental results of the above-mentioned railway traction motor prototype.

This paper presents a gearless wheel motor drive system specifically designed for fuel cell electric and hybrid electric vehicle propulsion application. The system includes a liquidcooled axial flux permanent-magnet machine designed to meet the direct-drive requirements. The machine design implements techniques to increase the machine inductance in order to improve machine constant power range and high-speed efficiency. The implemented technique reduces machine spin loss to further improve efficiency. The machine design also optimizes the placement of magnets in the rotor to reduce cogging and ripple torque. An original cooling system arrangement based on the use of high thermal conductivity epoxy joining machine stator and liquid-cooled aluminum casing allows the very effective removal of machine power loss. Design details and experimental results are presented.

This paper presents a gearless wheel motor drive system specifically designed for fuel cell electric and hybrid electric vehicle propulsion application. The system includes a liquidcooled axial flux permanent-magnet machine designed to meet the direct-drive requirements. The machine design implements techniques to increase the machine inductance in order to improve machine constant power range and high-speed efficiency. The implemented technique reduces machine spin loss to further improve efficiency. The machine design also optimizes the placement of magnets in the rotor to reduce cogging and ripple torque. An original cooling system arrangement based on the use of high thermal conductivity epoxy joining machine stator and liquid-cooled aluminum casing allows the very effective removal of machine power loss. Design details and experimental results are presented.

Nowadays the majority of electric drives work at variable speeds. In this kind of drives the electrical machines are supplied by inverters which generate modulated voltages. It is widely known that these non sinusoidal voltages cause additional current harmonics dealing to higher iron losses than with sinusoidal voltages. The iron losses affect to several design constraints as the efficiency and the thermal behavior of electrical machine. Hence, the accurate computation of the iron losses under different supply voltage conditions is very important in order to optimize the machine design as much as possible. This work deals with multi-domain simulations in order to calculate the iron losses in permanent magnet synchronous machines (PMSM) under Pulse Width Modulated (PWM) voltages. The current supplies are implemented in the simulation system MATLAB-SIMULINKreg. Whereas the electrical machine is simulated using the Finite Element Method (FEM). The iron losses are computed by a post-pr...

Permanent magnet machines for electric vehicles are often designed with a magnetic saliency to improve the torque generation as a result of the reluctance torque at field-weakening operation. The armature reaction is pronounced in such operation, leading to extensive magnetic field harmonics in the teeth and consequently iron losses. This paper analyses the iron losses in two designed machine topologies, inset and interior permanent magnet rotor structures, by measurements and finite element method computations. The measurements and calculations are performed on three prototypes -one with an inset design and two with an equal interior design, but different laminated stator core sheet thickness of 0,35 and 0,20 mm, respectively. The three machines have the same stator designs and water-cooled housings.

This paper deals with the design solution adopted for a high-speed axial-flux permanent-magnet generator devoted to supplementing power in automotive 42 V electrical systems through a low-voltage multilevel neutral-point-clamped converter. The axial-flux permanent-magnet generator is suitably designed to be directly coupled with a radial turbo-expander which provides recovery of kinetic energy available from the exhaust gases of an internal-combustion engine. The multilevel converter is properly sized for systems having low voltage and high first-order harmonic frequency. The paper describes the proposed 4-kW power rating generating system and discusses various issues resulting from electromagnetic, thermal, and mechanical design of the high-speed axial-flux permanent-magnet generator. As well, investigations on modulation strategy, total harmonic distortion, and power losses are presented for the low-voltage neutral-point-clamped power electronic converter.

This paper considers the semi-analytical field calculation of the armature reaction in brushless tubular permanent magnet actuators with rectangular slots. The tubular actuator is considered to have an infinite length and Fourier analysis is used to describe the current density distribution. The field solution is obtained by solving the Maxwell equations in the constant boundary value problem consisting of the airgap and the slot. The results are verified with finite element software, and analysis limitations and inaccuracies are addressed.

This paper describes a project which addresses the use of a small segmented oscillating water column with three sections. The turbine utilizes cascaded Savonius rotors (one for each section), and this system is developed and tested for validation of the performance algorithms. This paper shows that the system is easily described using a simulation, while a small-scale wave-tank-based system is shown to generate electrical power. The system is suitable for a shoreline location such as a harbor wall, where waves are random and not orthogonal to the column. Conversion rates in the region of 20% are tabulated with an output of 25 W peak. This paper reports on the operation of the column with respect to the wave frequency and wavelength. The peak tip speed ratio of the turbine is investigated in the application and found to correlate with published data when the turbine operates in free (rather than ducted) airflow conditions. The turbine is fully characterized-the generator is a brushless permanent-magnet machine connected to a diode bridge rectifier and a variable load.

This paper discusses three-phase topologies for modulated pole machines (MPMs). The authors introduce a new three-phase topology, which takes advantage of mutual flux paths; this is analyzed using 3-D finite-element methods and compared to a three-phase topology using three single-phase units stacked axially. The results show that the new “combined-phase MPM” exhibits a greater torque density, while offering a reduction

In this paper a new flux-switching permanent magnet (FSPM) machine with 12 stator poles and 14 rotor poles is investigated, and compared to a machine with the same stator but 10 rotor poles. Two prototypes are studied by both finite element method (FEM) analysis and experimental measurements. The results show that the 12/14 pole prototype can provide about 7-12% higher torque, the torque ripple reduces from 8.5% to 5.1% and its synchronous inductance is also 15% higher. After optimization, the FEM simulation results show the 12/14 pole machine could provide 19% higher torque than the 12/10 pole machine and the torque ripple is further reduced to 2.3%.