Flux Permanent Magnet Synchronous Generator Research Articles

RANCANG BANGUN GENERATOR MAGNET PERMANEN FLUKSI AKSIAL SINGLE STATOR SINGLE ROTOR

Permanent magnet synchronous generator is one type of generator that is widely used for small-scale power generation, because it can be operated at low speed, so it does not require a gearbox in its operation. This paper proposes the manufacture of a low speed axial flux permanent magnet synchronous generator that can be used for small-scale electric power generation. The generator is designed in the form of a single stator single rotor. The generator stator is designed using fiberglass as the holder for the nine coils, while the rotor is designed in a disc shape using aluminum as the holder for the Neodymium N52 permanent magnet. The generator design was validated through Finite Element Analysis simulation using solidwork and tested through experiments using an induction motor as the driving force. Tests were carried out with varying air gaps and rotational speeds. The experimental results show that the generator can produce a voltage of 15.4 Volts when the generator is rotated at a speed of 500 rpm. The generator can also produce a maximum power of 400 Watts with an air gap of 2 mm

Experimental Investigation of Magnet Grouping Technique in Reduction of Cogging Torque and Total Harmonic Distortions in the Axial Flux PM Generator for Direct Drive Wind Turbine

Generators that have been used in direct-drive wind turbines could be produced with a permanent magnet between the power ranges of 1 kW to 1 MW. The cogging torque is the most significant problem of these generators. In this study, the pole grouping method is suggested to reduce the cogging torque of an axial flux permanent magnet (AFPM) synchronous generator with open slotted. The suggested method includes magnetic analyzes and experimental results of the 14-pole open slotted AFPM generator rotor poles that grouped as 7-7, 4-3-4-3, 3-2-2-3-2-2 and named A, B, C, respectively. Besides obtaining the cogging torque (Tc) data, the most considerable part of the study is to get total harmonic distortion (THDV) and output power (Pout) data in which show the electrical performance of the generator for different grouping angles. The optimum ranges for an AFPM generator were determined as 80% reduction for Tc, 15% reduction for Pout, and below 3% for THDV. The optimum grouping angles for A, B, and C were obtained by experimental studies as 32°, 32°, and 30°, respectively. Experimental results and the magnetic analysis have been shown that optimum values are obtained when the ratio of the pole angle to the grouping angle is

The Neutral Voltage Difference Signal as a Means of Investigating Eccentricity and Demagnetization Faults in an AFPM Synchronous Generator

This article investigates the neutral voltage difference signal, VNO signal, for fault diagnosis. The aforementioned signal is the signal of the voltage between the common star point of the stator and the common star point of the load. The under-study faults are demagnetization and static eccentricity faults, while the machine in which the faults are investigated is an axial flux permanent magnet (AFPM) synchronous generator, suitable for wind power applications. This study was conducted using a 3D finite element method (3D-FEM), and the machine’s FEM model was validated through experiments. This method is one of the most accurate methods for electrical machine computation, allowing for a detailed study of electromagnetic behavior. The components that constitute the VNO signal were determined using a 3D-FEM software program (Opera 18R2). Subsequently, further analysis was performed using MATLAB R2022b software, and a fast Fourier transform (FFT) was applied to this signal. In all the investigated faulty cases, new harmonics appeared, and the healthy amplitudes of most of the already existing harmonics increased. These findings can be used for fault identification. The analysis revealed that the harmonic frequency of 1.5fs was the most dominant in the case of demagnetization, while in the case of static eccentricity, the most dominant harmonic was a frequency equal to the machine’s operating frequency, fs. The novelty of this study is that this signal has not previously been used for fault identification, especially in AFPM synchronous machines. This signal depends on EMF voltage and stator phase currents but is less sinusoidal. Consequently, it can detect faults in cases where the aforementioned signals cannot be used for detection.

Thermal Analysis for Improving the Design of Radial Flux Permanent Magnet Synchronous Generators

In this paper, the analytical thermal model of a radial flux permanent magnet synchronous generator (RF-PMSG) is developed for applications in variable speed direct-drive low-power wind turbines. The thermal model takes the form of a lumped parameter thermal network to estimate temperatures and heat fluxes for a wide operating range of the RF-PMSG. The proposed thermal model is fully coupled with the electromagnetic solution of a flexible analytical design methodology of RF-PMSGs and its algorithmic solution is coded in Matlab. The thermal analysis is an essential requirement for enhancing the design performance of radial flux permanent magnet synchronous generators. Finally, the performance of a 10 kW RF-PMSG is analyzed using the thermal model, for a wide steady-state operation range.

Design of Radial Flux Permanent Magnet Synchronous Generator as Wind Power Plant Using Finite Element Method

This research is concerned with analyzing and simulating a permanent magnet synchronous generator (PMSG) that holds significant potential for applications in small-scale wind turbines. Wind turbines are one of the most significant sources of energy in the world. There is a need for cheap and easy power plants that are highly efficient to meet the demands for electricity. This is one of the solutions to the problem of electricity demand. A PMSG is a permanent magnet machine that uses the finite element method as a tool for studying and designing it. This research aims to design a model of a PMSG according to available tools. The generator has 18 slots, 16 poles, and the flux is radial, which is used to create three phases. The PMSG is designed to deliver power at a speed of 1000 rpm with an efficiency of 81%. According to the models and simulation 234 Watts at a speed of 1000 rpm.

Axial Flux Permanent Magnet Synchronous Generators for Pico Hydropower Application: A Parametrical Study

A pico hydropower plant is an energy harvesting system that allows energy production using the power of the water flowing in small watercourses, and in water distribution network. Axial Flow Flux Permanent Magnet Synchronous Generator (AFPMSG) are particularly suitable for this application, being efficient machines that achieve high power with small dimensions. This paper presents a parametrical study of several configurations and topologies of three-phase and single-phase AFPMSG, for pico hydropower application, to assess the most suitable dimensional characteristics for the most energy production using a safe voltage of 25 V. The AFPMSGs here considered has a simple single stator and rotor configuration, commercial-type permanent magnets, and concentric windings, to facilitate their cost-effective construction and the spread of their use also in developing countries. For each AFPMSG considered, the power output was calculated using 3-D modelling and Finite Element Analysis; besides, the different parameters and features that affect the power output were evaluated at different rotational speeds. The results achieving a power density up to 100 W/cm3, at 1000 rpm with energy produced to 1.7 kWh/day.

An Integrated Elitist Approach to the Design of Axial Flux Permanent Magnet Synchronous Wind Generators (AFPMWG)

This paper addresses an integrated and developed approach to the design of an Axial Flux Permanent Magnet Wind Generator (AFPMWG). The proposed analytical method of design employs the size equations and precise inductance calculations simultaneously, as well as considering the mechanical constraints of the back-iron disc of the rotor. An Elitist Genetic Algorithm (EGA), such as a high capability optimization method, has been used to solve the equations and design of a wind generator with predefined rating power. The objectives of the coreless AFPMWG design process are minimizing the magnet consumption, maximizing machine efficiency, and achieving maximum sinusoidal induction voltage, considering the wind properties of the geographical area of utilization. The optimal calculation of the permanent magnet thickness is also taken into consideration in this work. The flux density distribution in all parts of the machine has been investigated for the magnetic saturation phenomenon. In this regard, special attention is paid to rotor back discs, which are made from nonlinear material with an optimum thickness. The inductance of the leakage flux of the coreless machine has been considered by parallel computation via the Finite Element Method (FEM) and analytical equations. Finally, three-dimensional and two-dimensional finite element analyses are used to validate the performance of the machine design according to the characteristics of Iran wind resources. The results show the high ability of the proposed approach in AFPMWG design and in considering the objectives and constraints carefully.

Detection of Demagnetization Faults in Axial Flux Permanent-Magnet Synchronous Wind Generators

A new method for detecting demagnetization faults in axial flux permanent magnet synchronous wind generators is presented in this study. Demagnetization faults occur in the case of total or partial loss of the magnetic properties of one or more permanent magnets of the machine. Fault signatures appearing in the current or voltage signal due to a demagnetization fault can often be confused with those produced by eccentricity faults, making the discrimination between the two types of faults difficult. The proposed methodology is based on the analysis of the instant power spectrum of the generator, combined with an estimator to derive the permanent magnet flux, based on the machine equations. Short-Time Fourier Transform is proposed as the means for spectrum analysis to ensure performance during variations of the generator speed. Results derived from the experimental tests are presented, which show that the proposed methodology is capable of detecting demagnetization faults and distinguishing them from eccentricity ones under a wide variety of operating conditions.

Effect of the magnet shape on the performance of coreless axial flux permanent magnet synchronous generator

Effect of the magnet shape on the performance of coreless axial flux permanent magnet synchronous generator

Optimal mixed control of Axial Flux Permanent Magnet Synchronous generator wind turbines with modular stator structure

Wind turbine systems are constructed using different types of generators, aero-mechanical components and control systems. Due to their ability to work in low speed, Axial Flux Permanent Magnet (AFPM) generators are becoming widespread in wind energy systems which contributes to eliminating the gearbox from the system, noticeable increase in efficiency and decrease in system weight. Due to the modular nature of the stator in AFPM generators, it is possible to control each module independently. In this paper, in addition to obtain the dynamic model of the turbine and AFPM generator, a control strategy is designed based on Mixed Integer Nonlinear Programming (MINLP) to incorporate both pitch angle and the number of active stator modules as control input signals. These control signals are used in order to maximize system efficiency and regulate output voltage in different wind speeds and electrical loads. Simulation results for a typical generator shows the effectiveness of the proposed method in speed control of the generator.

Study of a Combined Demagnetization and Eccentricity Fault in an AFPM Synchronous Generator

This article investigates the combined partial demagnetization and static eccentricity fault in an Axial Flux Permanent Magnet (AFPM) Synchronous Generator. The machine is simulated using 3D FEM, while the EMF spectrum is analyzed in order to export the fault related harmonics using the FFT analysis. Firstly, the partial demagnetization fault, without the coexistence of eccentricity, and both the static angular and axis eccentricity faults, without the coexistence of partial demagnetization, are studied. In the case of eccentricity fault, the phase EMF sum spectrum has also been used as a diagnostic mean, because, when only eccentricity fault exists in the generator (either angular or axis) new harmonics do not appear in the EMF spectrum. Secondly the combination of partial demagnetization fault with static axis and static angular eccentricity is investigated and different comparisons are made when the demagnetization and the eccentricity level changes. The investigation revealed that the combination of eccentricity and demagnetization creates new harmonics in the EMF spectrum. The novelty of the article is that these combined faults are studied for the first time in the international literature, and the phase EMF sum spectrum has not been previously used for eccentricity diagnosis in this machine type.

Study of the Total Demagnetization Fault of an AFPM Wind Generator

This article investigates the total demagnetization fault in Axial Flux Permanent Magnet (AFPM) synchronous generator, suitable for wind power applications, using the three-dimensional Finite Element Method (3D-FEM). The machine, in which the demagnetization diagnosis has been investigated, consists of one coreless stator with concentrating winding, embed in resin and two rotors. In the current study, faulty cases of different number and relative position of total demagnetized magnets are studied. Finally, simulation results are compared to experimental results for validation. The stator current spectrum is studied as fault identification mean and it is shown that the fault signatures depend on the number of total demagnetized magnets, the relative position of the magnets on the rotor and the stator winding topology. In addition, there is an investigation of the partial demagnetization fault for comparison purposes. Moreover, analytical expressions for the magnetic flux density in the healthy case and in every faulty case are exported. These novel expressions, related to every demagnetized case, are presented for the first time in the literature.

The electromagnetic modeling and the co-simulation of a direct drive axial flux permanent magnet synchronous generator

Direct drive gearless axial flux permanent magnet synchronous generators (AFPMSG) are designed as multi-pole for use in vertical axis wind turbines. In particular, there are multi-pole core/coreless stator structures with axial flux for use in vertical axis wind turbines (WT) that can be designed in a compact structure at low wind speeds. In this study, the parametric simulation studies have been carried out according to rotor mechanical speeds with certain linear steps depending on different wind speed scenarios for an AFPMSG designed with 16-pole and cored stator for 5 kVA rated power with the finite element analysis (FEA) software. According to the analysis results obtained, the performance of the generator is reported and current, voltage, power losses and flux distribution are investigated. In addition, the DC bus voltage at the output of the DC-DC boost converter circuit due to wind speed changes is adaptively controlled for AFPMSG, which is co-simulated with the power electronics interface used at the generator output. Thus, both power electronics circuit performance and generator side have been simulated simultaneously with electromagnetic modeling. Therefore, the performance of the designed AFPMSG, which is modeled in three dimensions (3D) before the prototype stage, can be determined under more realistic conditions.

Comparative Analysis of Coreless Axial Flux Permanent Magnet Synchronous Generator for Wind Power Generation

A 90° Halbach permanent magnet array coreless axial flux permanent magnet synchronous generator for wind power generation is compared with a conventional axial flux permanent magnet generator with cut cake type permanent magnet. 2D analytic model of generator is established. The air gap magnetic fields of two generators are analyzed by analytical method, and the air gap magnetic density and harmonic content are analyzed. Then the influence of different parameters on voltage total harmonic distortion is analyzed by changing the pole arc coefficient, air gap length, permanent magnet thickness and number of turns. Two prototypes of generators are manufactured, and the correctness of the simulation results is verified by experiments.

REDUCTION OF COGGING TORQUE AND IMPROVEMENT OF ELECTRICAL PARAMETERS IN AXIAL FLUX PERMANENT MAGNET (AFPM) SYNCHRONOUS GENERATOR WITH EXPERIMENTAL VERIFICATION

REDUCTION OF COGGING TORQUE AND IMPROVEMENT OF ELECTRICAL PARAMETERS IN AXIAL FLUX PERMANENT MAGNET (AFPM) SYNCHRONOUS GENERATOR WITH EXPERIMENTAL VERIFICATION

Direct power control strategy for an axial flux permanent magnet synchronous machine

This paper presents a direct power control strategy for a variable speed axial flux permanent magnet synchronous generator. The method consists on calculating the instantaneous power by measuring the machine currents and estimating the back electromotive force (back-emf). The real-time back-emf estimation is based on tracking the no-load voltage through off-line harmonic analysis, and the mechanical position and speed, obtained with an incremental encoder. A 3 kW laboratory prototype has been built to verify the performance of the proposed strategy. Experimental results are shown and discussed.

Design and analysis of a new axial flux permanent magnet synchronous generator for wind

The paper deals with a new design of a low-speed disk permanent magnet axial flux synchronous machine for decentralized power generation, which has improved weight-size parameters. In the new design the value of the air gap value is reduced by removing all inter-coil connections from the gap and also a concentrated winding with a high winding coefficient is applied. A two-rotor prototype of this design is created (150 W, 83 V, 250 rpm) and its magnetic circuit and the concentrated windings arrangement are described, as well as the results of the machine experimental study. The 2D finite element analysis is used to determine the effect of the air gap value effect on the disk slotless generator parameters. The method of rational choice of the machine main dimensions and the parameters of its winding according to nominal data and electromagnetic loads limitations are presented. Comparison of parameters and characteristics of a 20-pole-pair 5 kW synchronous wind generator with the new design and cylindrical one with tangential magnetization is performed. The proposed slotless design exceeds the cylindrical one in efficiency and requires less material costs. The limitations are the higher value of the outer machine diameter and the required large magnets mass.

Voltage regulation Rate and THD optimization analysis of coreless axial flux PM synchronous generator for wind power generation

The basic design and characteristic analysis of the coreless axial flux permanent magnet synchronous generator (AFPMSG) for small wind power generation are carried out. The prototype is manufactured and tested to verify the designed generator. In addition, to reduce the voltage regulation rate and harmonic content of the generator, the optimal design is carried out on the basis of the original generator. The voltage regulation rate and THD of a coreless AFPMSG using the Halbach permanent magnet array are studied. The effects of different generator parameters such as pole arc coefficient, air gap length, permanent magnet thickness, and number of turns in series per phase on the voltage regulation rate and THD are analyzed when the generator is loaded with pure resistance. Because the various parameters of the generator are affected each other, the Taguchi algorithm was adopted for multi‐objective optimization. The influence proportion of different generator parameters on the voltage regulation rate and THD was analyzed. According to the results, the parameters are reasonably selected to design the generator and improve the performance of the generator. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Sensitivity Analysis and Optimal Design of a Stator Coreless Axial Flux Permanent Magnet Synchronous Generator

In this paper, the modified initial design procedure and economic optimization design of a stator coreless axial flux permanent magnet synchronous generator (AFPMSG) are presented to improve the design accuracy, efficiency, and economy. Static magnetic field finite-element analysis (FEA) is applied to the magnetic equivalent circuit (MEC) method to increase the accuracy of electromagnetic parameters and reduce the iteration times. The accuracy and efficiency of the initial design is improved by the combination of MEC method and static magnetic field FEA in the design procedure. For the economic optimization, the permanent magnetic (PM) material volume model, which affects the cost of the AFPMSG the most, is derived, and the influence degree of the main structure parameters, to the performance, is distinguished and sorted by sensitivity analysis. The hybrid genetic algorithm that combines the simulated annealing and father-offspring selection method is studied and adopted to search for the best optimization solution from the different influence degree and nonlinear interaction parameters. A 1 kW AFPMSG is designed and optimized via the proposed design procedure and optimization design. Finally, 3D finite-element models of the generator are simulated and compared to confirm the validity of the proposed improved design and the generator performance.

Study and Optimal Design of a Direct-Driven Stator Coreless Axial Flux Permanent Magnet Synchronous Generator with Improved Dynamic Performance

In this paper, the study and optimization design of stator coreless axial flux permanent magnet synchronous generators is presented for direct driven variable speed renewable energy generation system applications while considering the requirement of reliability and dynamic performance with unstable input conditions. The dynamic analytical model is developed based on the investigation of the axial flux permanent magnet synchronous generator (AFPMSG) structure and basic electromagnetic equations to find out the relationship between generator parameters and dynamic performance. Simulation via the MATLAB/Simulink platform is carried out to obtain the sensitivity of dynamic performance to generator parameters. An integrated optimization model that takes the key parameters as variables is proposed, aiming to improve the mechanical dynamic performance of AFPMSG. For accurate design, the design procedure is modified by combining the nonlinear iterative genetic algorithm (GA) to perform the calculation. A 3_kW AFPMSG is optimally designed to minimize the output voltage overshooting—the index of dynamic performance for direct driven variable speed generation application. Finally, a three-dimensional (3D) finite element model of the generator is established by Maxwell ANSOFT, and the simulation results confirm the validity of the dynamic performance analysis and optimal design procedure.