Number Of Pole Pairs Research Articles

Space Harmonics Effects on Performances of Linear Induction Motors: Modelization and Characterization

This article presents the impact analysis of space harmonics’ presence on a single-sided three-phase linear induction motor, along with a comprehensive parametric investigation. The presence of space harmonics often reduces the linear induction motor’s performance. The electromagnetic phenomena are governed by Maxwell’s equations. The chosen mathematical model uses a 2D formulation with magnetic vector potential. The model implementation is performed using the finite element method on the free Gmsh-GetDP platform. The electromagnetic thrust is calculated in the current excitation case using two numerical models of the finite element method with and without term-generating space harmonics in order to highlight their effect. The adaptation to voltage supply operation is obtained via equivalent electric circuits through the calculation of the operational impedance. The choice of the machine’s parameters by the designer in order to enhance its performance or reduce energy consumption is a difficult task. The analysis and the determination of the dependence of the parameters and the performance are necessary. The main objectives of this study are to determine this dependency and to analyze the space harmonic impact of the linear induction motor’s parameters on its performances. A comparative exploration of space harmonics’ presence using two numerical models (single and multiharmonics) and an assessment of the parametric effect of space harmonics’ presence on various machine characteristics such as thrust, efficiency, and power factor have been carried out. The motor’s characteristics (i.e., thrust, efficiency, and power factor) strongly depend on parameters such as the pole pair number and conductivity. Improving the operation and maximizing the performance of such a machine for a given specification requires the use of optimization algorithms. Motor characteristics (thrust, efficiency, and power factor) are highly dependent on parameters such as the number of pole pairs and conductivity.

Improving Efficiency of a Pole-Changing Vernier Machine Considering Residual Magnetic Flux Density

This paper presents the efficiency improvement of a pole-changing vernier machine (PCVM) by considering the residual magnetic flux density (Br) of low coercivity force (LCF) permanent magnets (PMs). The PCVM operates in two modes: vernier machine (VM) mode and permanent magnet synchronous machine (PMSM) mode, achieved through pole-changing. Pole-changing involves reversing the magnetic flux direction of LCF PM to alter the number of rotor pole pairs. By changing the number of rotor pole pairs, the PCVM operates as a VM mode at low speeds, providing high torque, and as a PMSM mode at high speeds, offering high efficiency. To achieve this, a combination of high coercivity force (HCF) PM and LCF PM is utilized in a single structure. The magnetic flux direction in the LCF PM is determined by Br, and the highest efficiency is achieved when Br reaches its maximum value |Brm|. This paper focuses on improving efficiency by obtaining Brm in VM mode and −Brm in PMSM mode through the design process. Additionally, finite element analysis (FEA) is employed to compare the performance of the improved model, which considers Br, with that of the conventional model, designed without considering Br. The improved model achieves higher Br values in each mode compared to the conventional model, resulting in increased torque density. Consequently, this leads to improved efficiency.

Identification and Analysis of Noise Sources of Permanent Magnet Synchronous Traction Motor with Interior Permanent Magnet

The rapid development of electromobility is placing ever higher demands on new electric motor designs. This results in a gradual reduction in weight with a simultaneous increase in maximum torque. As a result, unfavorable phenomena, such as vibration and noise, can become apparent in the drivetrain. Modeling and evaluation of the acoustic noise sources of a traction motor are particularly important when it is used, for example, as the traction drive of an electric bus, where too high noise levels can have a negative impact on passengers. This article describes methods for analyzing and evaluating the root causes of noise that occurs in permanent magnet traction motors with a rotor in which the magnets have been placed inside the rotor (PMSM IPM). This paper presents an analysis of acoustic noise and forces acting in the air gap of a 240 kW motor with 60 stator slots and 2p = 10 (s60p20) as the number of pole pairs designed for bus and truck drives. To determine the dominant noise sources and evaluate their value, the forces acting in the air gap and their effect on the deflection of the outer surface of the stator yoke were calculated. The natural frequencies of the machine, their frequencies for the entire rotor speed range, and the frequency of vibration of the motor stator were calculated. Based on these data, the sound power level (A-SWL) was calculated at varying motor speeds. MANATEE software (EOMYS, 9, avenue de la Créativité, 59650 Villeneuve d’Ascq—FRANCE) from EOMYS was used to perform vibroacoustic calculations. The analysis results were also subjected to verification on a laboratory bench.

Rotor Winding Design and Standalone Operation Research of High Natural Synchronous Speed Brushless Doubly-Fed Generator Based on Differential Modulation

Differential Modulation Brushless Doubly-fed Machine (DMBDFM) can achieve smaller equivalent pole-pair number, which broaden the operating range and application of Brushless Doubly-fed Machine (BDFM). However, the existing basic theory of BDFM can not be directly applied to DMBDFM, and the design method of the modulated rotor with different combination of pole-pair numbers (PPN) is not complete. Therefore, in order to achieve the highest natural synchronous speed(<i>n</i>_s) of BDFM at power system frequency, the rotor winding of 3&#x002F;2 pole pairs is designed in this paper. Then the test prototype is developed with the designed rotor scheme and the relevant parameters are given. The validity of the rotor design scheme is verified by finite element simulation and test results.

Energy efficiency model-based Digital shadow for Induction motors: Towards the implementation of a Digital Twin

The 4th industrial revolution requires the tracking and optimization of energy consumption using an intelligent energy management system (IEMS). Such a system needs accurate real-time energy information to operate industrial machines, where Induction Motors (IMs) represent 42.2% of the global energy consumption. This paper addresses the problems of data acquisition for Induction motors in the context of Industry 4.0 (I4.0) where precision, real-time constraints, and optimal operations play a major role in decision-making. A new vision of Digital Shadow (DS) is proposed for the energy efficiency (EE) of IMs. A hybrid model consisting of a data-driven model and a physics-based model is developed to represent the machine efficiency information in real-time (RT). The proposed method is developed based on a two-stage procedure. Firstly, the IM EE model is established by considering Stator joule losses, core losses, rotor joule losses, friction, and windage losses, in addition to the stray losses to create an improved model. This was established based on the double cage model where core loss resistance is added. Secondly, the machine’s losses and efficiency are visualized using the 8 electrical circuit parameters (ECP) from the double cage model in addition to the rated speed and test temperature. The parameters estimation in RT incurred complexities and required the use of Adaptive Neuro-Fuzzy Inference System (ANFIS)-based modeling. The proposed model was developed using Fuzzy Logic Toolbox and Neuro-Fuzzy Designer app from MATLAB by training Sugeno systems. 8 ANFIS MATLAB models are trained to estimate each of the 8 ECP from the double cage model by using standard inputs. The training and testing dataset is constituted by the experimental data of the ECPs were calculated using the FSOLVE function to solve the nonlinear system formed by 60 motors from 8 manufacturers’ data such as voltage, number of pole-pairs, rated output power, rated torque, current, starting current, maximum torque and the power factor. Finally, the proposed method is validated experimentally using a 1.5 KW, 400/230 V, 50 Hz squirrel cage induction motor (SCIM) for linear speed control. The EE, Torque, and losses are visualized through the proposed model using MATLAB/SIMULINK. The mean value of the RMSE for the eight estimated ECPs are 7.57e-05, and 5.73e-01 respectively for training and testing while the mean values of the MAE are 2.06e-05, and 3.79e-01 respectively for training and testing. The errors of the EE estimation w.r.t the measured EE at rated condition, are RMSE = 0.205, and MAE = 0.1671. These results show that the proposed model can be implemented in the industry to monitor the machine EE and its losses.

Coil Winding Circuit Configurations for Permanent Magnet Synchronous Machines

The article outlines a procedure for drawing up the electric circuits of coil-type armature windings for salient-pole PM electric machines proceeding from the required number of pole pairs (the synchronous rotation frequency) and the number of phases. The procedure implementation algorithm is based on determining the stator teeth number as the one nearest to the number of rotor poles (2p) multiple to the number of phases. In this way, sufficient levels of coil pitch coefficient and winding coefficient are ensured. In accordance with the developed procedure, the coils in the phases can occupy one, two, or four phase zones from the adjacent coils connected into coil groups in a series opposition manner. The algorithm was tested on a few examples of drawing up the connection circuits of synchronous machine windings known from the electrical machinery construction theory and practice, including serially produced ones with the inner stator and for a pilot design of a high-capacity motor. For the latter one, its versions with three- and nine-phase windings for a 32-pole rotor (2p = 32) are compared. Numerical studies of the motor torque for both winding circuit versions carried out using the finite element method have shown that the version with the nine-phase winding produces a 20% higher torque. For one version of a serially produced motor, the winding electric circuit design validity was checked by calculating the torque-angle curves for different current densities. In all examples, formal compliance with the items of the outlined procedure has yielded correct circuit solutions. A criterion for evaluating the PM machine manufacturing complexity has been proposed, which depends on the winding type (distributed or coil-type) and on the number of PMs per magnetic system pole.

DIODE EXCITERS OF A BRUSHLESS MEDIUM POWER SYNCHRONOUS GENERATOR

The aim of the work is a comparative analysis of the parameters of the diode exciter of a brushless synchronous generator of medium power on the number of pole pairs of an auxiliary electric machine, the development of recommendations for choosing the number of pole pairs of an auxiliary electric machine and the design of the exciter.&#x0D; An improvement of the automated method of electromagnetic calculation of the exciter of a brushless synchronous machine has been carried out. The diode exciters of a brushless synchronous generator with a power of 250 kW with the number of pole pairs p = 2 based on a three-phase bridge rectifier and an auxiliary electric machine of a synchronous type with different numbers of pole pairs are compared. At the first stage, a preliminary electromagnetic calculation of the auxiliary electric machine is performed, taking into account the initial value of the relative magnitude of the resulting electromotive force, the allowable values ​​of inductions in all sections of the magnetic circuit in in forced mode, the length of the magnetic circuit and the rotor winding support are determined. According to the results of the calculation of the rectifier model in the quasi-steel mode of operation, the relative value of the resulting electromotive force of the auxiliary electric machine is specified. &#x0D; At the first stage, a preliminary electromagnetic calculation of the auxiliary electric machine is performed, taking into account the initial value of the relative magnitude of the resulting electromotive force, the allowable values ​​of inductions in all sections of the magnetic circuit in in forced mode, the length of the magnetic circuit and the rotor winding support are determined. According to the results of the calculation of the rectifier model in the quasi-steel mode of operation, the relative value of the resulting electromotive force of the auxiliary electric machine is specified pB = 4.

Parametric study on circularly abrupt magnetic flux density changes of electromagnetic energy harvesters via simulation

Energy harvesting has long been widely studied. In this paper, we systematically investigate the output performances of rotating electromagnetic energy harvesters (EMEHs) with different magnetic pole pairs and coil parameters via simulations. Different numbers of magnetic pole pairs obviously affect the abrupt magnetic flux density (MFD) change and the further output voltage. Hence, we set up finite element (FEM) models of proposed harvesters to compare the output voltage under different numbers of the magnetic pole pairs p in the same coil parameters conditions. Subsequently, to further study how the coil parameters affect the voltage and power of EMEHs, we conduct simulations using different coil heights h and wire diameters d with the same magnet array. The results of the magnet simulation indicate that in a certain volume, EMEHs yield a maximal output voltage of about 12.2 V in the case of p=4. In the best contrast, EMEHs produce a peak output power of about 26.36 W under the excitation of 180 rad/s. This study will be of great significance in improving power in the field of harvesting electromagnetic energy.

Analysis of the Impact of Design Parameters on the Power Density of the New Design of the Cogging Machine

The cogging machine is a new design of a machine with permanent magnets, which combines the advantages of a machine with transverse flux (TFM), eliminating its disadvantages. The biggest advantage of TFM machines is their high torque density, which varies with the design parameters. The developed machine retains these advantages while simplifying the construction of the stator core, which is the biggest disadvantage of TFM machines. This article presents the results of an analysis of the power density of the developed cogging machine as a function of a number of pole pairs and the basic design parameters. Analyses were carried out on the basis of the derived analytical equations, which make the generated torque depend on the construction parameters. Thanks to the derived dependencies, one can easily examine the effects of modifying the machine structure. The results presented in the article prove that the developed design of the cogging machine is competitive in relation to machines with permanent magnets existing on the market.

Design of Quasi-Halbach Permanent-Magnet Vernier Machine for Direct-Drive Urban Vehicle Application

Removing the gearbox from the single-motor configuration of an electric vehicle (EV) would improve motor-to-wheel efficiency by preventing mechanical losses, thus extending the autonomy of the EV. To this end, a permanent-magnet Vernier machine (PMVM) is designed to ensure such operation. This machine avoids the high volume and large pole-pair number of the armature winding since its operating principle resembles that of a synchronous machine with an integrated magnetic gear. Therefore, such a structure achieves low-speed and high-torque operation at standard supply frequencies. From the specification of an urban vehicle, the required specification for direct-drive operation is first determined. On this basis, an initial prototype of a Vernier Machine with permanent magnets in the rotor that can replace the traction part (motor + gearbox) is designed and sized. This first prototype uses radial contiguous surface-mounted magnets and its performance is then analyzed using finite element analysis (FEA), showing a relatively high torque ripple ratio. The rotor magnets are then arranged in a quasi-Halbach configuration and simulations are performed with different stator slot openings and different ratios of the tangential part of the magnet in order to quantify the effect of each of these two quantities in terms of average torque, torque ripples and harmonics of the back-electromotive force at no load. Since the design and optimization of this motor is finite element-assisted, a coupling process between FEA Flux software and Altair HyperStudy is implemented for optimization. This method has the advantages of high accuracy of the magnetic flux densities and electromagnetic torque estimates, and especially the torque ripples. The optimization process leads to a prototype with an average torque value that meets the specification, along with a torque ripple ratio below 5% and a high power factor, while keeping the same amount of magnet and copper.

Optimal Design of High-Speed Electric Machines for Electric Vehicles: A Case Study of 100 kW V-Shaped Interior PMSM

The need of compact machines increased in recent years due to increases in raw materials’ price. Hence, many studies are currently being conducted on high-speed challenges to propose an optimal design methodology. AC losses in windings are often not included in the optimization process and are treated in post-processing by choosing a suitable conductor’s diameter to mitigate skin and proximity effects. This paper presents an optimization and design methodology for high-speed electric machines considering these losses, using models with an interesting trade-off between computation time and accuracy, which is helpful for large-scale optimization, in which more than 9,600,000 machines are evaluated. Optimizations are conducted on 100 kW high-speed one-layer V-shaped interior permanent magnet synchronous machines, widely used in vehicles thanks to their high power density, based on the specifications of the Peugeot e208, for different values of pole pairs and maximum speed. The influence of lamination thickness, fill factor, and maximum current density on the optimal design is also investigated. This paper concludes the utility of increasing speed to achieve high power density and proposes best alternatives regarding automotive constraints. Results show that the number of pole pairs is not always a key parameter in obtaining the lowest volume, especially at high speed.

FEATURES OF THE DEVELOPMENT OF SLOTLESS BRUSHLESS MAGNETOELECTRIC TORQUE MOTORS

The structure of a brushless magnetoelectric torque motor with a slotless stator with a surface installation of permanent magnets on the rotor is considered. A motor model has been developed to calculate its characteristics in the COMSOL Multiphysics 6.0 software environment. The optimization of its structure was carried out, as a result of which the opti-mal number of pole pairs and such a ratio between the dimensions of the elements of the electromagnetic core of the motor were determined, at which the maximum electromagnetic torque per unit of power consumption is achieved. The paper also touches upon the problem of achieving the minimum value of the torque ripple factor in motors of a similar design. Ways of its solution are proposed both due to constructive changes in the magnetic system, and due to the syn-thesis of reference signals for the formation of such forms of currents in the stator phases, as a result of the interaction of which with the rotating magnetic field of the rotor, the motor torque characteristic the with a minimum value of the ripple factor can be obtained. Ref. 6, fig. 11.

Electromagnetic and Electromechanical Compatibility Improvement of a Multi-Winding Switch Control-Based Induction Motor—Theoretical Description and Mathematical Modeling

The main advantages of multi-winding (multiphase) induction machines include reducing torque ripple, decreasing rotor harmonics losses, reducing the current per phase without increasing the voltage per phase, reducing the current harmonics of the DC voltage source, and high fault tolerance. The authors propose a theoretical description for the harmonic content of the DC-link current, magnetomotive force, and electromagnetic torque of a multi-winding induction machine (IM), and an account of the interaction of the time harmonics for the power supply and the spatial harmonics for winding functions is presented. The proposed theoretical analysis has made it possible to substantiate supply-winding schemes for the compensation of higher harmonics (6th and 12th in the DC-link current and the IM’s electromagnetic torque) and the improvement of the electromagnetic and electromechanical compatibility of the multi-winding machine, which are justified according to the proposed theoretical description. Further, a schematic solution for the multi-winding induction motor with electronic changing of the pole number is proposed to provide a reduction in speed ripples at low rotation speeds. This decrease is ensured by increasing the number of pole pairs and increasing the frequency of the supply voltage. Mathematical models of multi-winding switch control-based induction machines are developed using the method of average voltages in the integration step for an investigation of electromagnetic and electromechanical processes. It is shown that the developed models are distinguished by high speed of response and accuracy. This is confirmed by the comparative analysis using known methods and models in the Matlab environment, as well as a comparison of the simulation results with the known results of physical experiments. The results of mathematical modeling show that the use of a multi-winding IM with appropriate supply-winding schemes stands to significantly reduce the ripples of the IM’s electromagnetic torque and DC-link current in the case of using six-step voltage source inverters. This makes this type of inverter suitable for use in a frequency-controlled electric drive as an alternative to using a PWM inverter, which has a negative influence on the IM’s state.

Investigation and comparison of the flux-switching permanent magnet machine and FSCW surface-mounted permanent magnet machine with close pole-pair number

Investigation and comparison of the flux-switching permanent magnet machine and FSCW surface-mounted permanent magnet machine with close pole-pair number

Modeling of Magnetic Fields in Deformed Air Gaps of Salient Pole Synchronous Machines

Large low-speed drives are designed with a high number of pole pairs, annular and magnetically saturated at rated operation. Large bore diameters tend to unwanted deformations of circular air gap (AG) circumference due to magnetic forces or gravitational forces. The electromagnetic computation with changing geometrical conditions therefore poses a cumbersome non-linear field problem due to its high amount of degrees of freedom. For an accurate predictive model of machine acoustics and vibrations, the study of these topological impacts on the magnetic AG field is indispensable. Particularly when considering an arbitrary AG deformation, related to additional spatial flux harmonics, the computational chain of the finite element method (FEM) involves adaptations at each stage (pre- and post-processing). The proposed modeling approach is universal and reduces the computational effort significantly using finite element (FE) solutions of symmetrical machine parts with varying AG widths. 2-D FE simulations are performed to study the impact of deformations. The results of the approach are compared with FE solutions of a complete 2-D model with an exemplary deformation for validation. The aim of this work is to study both magnetic AG fields and forces efficiently in an exemplary high-pole wind turbine generator with a deformed AG topology by interpolating and assembling appropriately partial model solutions.

A New Hybrid Magnet Dual Stator Field Modulation Machine With Different Split Ratios of Stators

A new type of hybrid magnet dual stator field modulation machine with different split ratios of stators (DSR-HMDSFMM) is proposed in this article, which has the merit of high torque density. The split teeth of stator sever as modulators to modulate air gap flux density based on the magnetic gearing effect for high torque production. The total split tooth number of inner stator is equal to that of outer stator because the pole pair numbers of armature reaction and permanent magnet (PM) excitation on rotor are equal. Furtherly, the inner and outer stators with different split ratios and same split tooth number are employed to increase torque production because armature windings with high winding factor and high turn number can be used. In addition, the employment of hybrid magnet excitation can increase space utilization and enhance the air gap flux density with low harmonic distortion. Therefore, the proposed DSR-HMDSFMM can achieve high torque production with the same volume and PM usage. In order to find the optimal split ratio match of stators, several DSR-HMDSFMMs with different combinations of split ratios are proposed and calculated. The configuration and operating principle are illustrated, together with electromagnetic performances of the proposed machines analyzed using finite element analysis (FEA). The FEA-predicted results show that the proposed HMDSFMM exhibits high air-gap flux density with low harmonic distortion and high torque density, which is promising for the direct-drive applications.

Investigation and Calculation of Electric Scooter Electromechanical Characteristics

The design of an electric scooter is presented. The advisability of using an inverted motor with an external rotor, which is part of the wheel, is shown. Permanent magnets producing a large number of pole pairs are installed on the rotor inner surface facing the air gap. With such design, low scooter motion speeds can be obtained without the need of using mechanical gearboxes. The choice of the rotor main dimensions based on the specific tangential force is considered. The stator consists of a core body with a winding, usually a three-phase one. In scooter motors, it is advisable to use a concentrated winding with a fractional q, which is wound around the tooth to form a separate coil on it, belonging to one of the phases. In such winding, the end turns do not intersect; its end-winding parts are much shorter than they are in distributed windings. The stator winding is powered by an inverter controlled synchronously with the rotor rotation. The considered electromechanical converter is nothing but a conventional synchronous machine. Constant torque operation is not typical for the scooter motor. When the user changes the scooter operation mode, for example, in changing over to another track section, all processes develop similarly to those that take place in conventional DC motors. To confirm this, the calculation of the motor is given, and its parameters are determined. An algorithm for calculating the scooter mechanical and performance characteristics has been developed.

An Approach to Designing the Stator Windings of High-Capacity Wind Generators

The capacity of a single offshore windfarm turbine has by now reached 10 MW, and its further growth is possible by making a shift for using superconducting synchronous generators. The article considers the factors that determine the choice of classical distributed and concentrated stator windings in designing high capacity superconducting wind generators. A 10 MW, 3300 V, 10 rpm superconducting wind generator with an excitation winding made of high temperature superconducting material Bi-2223 with ferromagnetic stator and rotor is studied. The stator volume and superconducting wire length were adopted as design selection criteria. It is shown that in the range of pole pair numbers 2p = 32-40, the use of a distributed two-layer winding has limitations in regard of the generator operation stability (the short-circuit current is less than the nominal value), and the use of concentrated windings has limitations due to a significant value of the differential leakage component. It has been found that for a distributed winding in the specified range of pole pair numbers, almost equivalent versions can be obtained with the stator volume equal to 78 m3 and superconductor wire length equal to 16 km. For a concentrated winding, it is preferable to choose a single-layer winding with the embodiment conditions Z = 12 + 6k, 2p = Z – 2, k = 0, l, 2,...; however, the obtained indicators are inferior to those in the case of using a classical distributed two-layer winding.

Design and Optimization of a High-Torque-Density Low-Torque-Ripple Vernier Machine Using Ferrite Magnets for Direct-Drive Applications

In recent years, Vernier permanent magnet machines (VPMs) have gained much interest in academia. However, due to the large leakage flux, the power factor of Vernier machines is too low to be applied in real industry. In this article, a novel split-tooth, concentrated-winding Vernier machine using ferrite magnets is proposed for high-torque, low-speed direct-drive applications in home appliance industry. It uses consequent-pole magnets in the rotor, as well as additional assisted magnets in the stator teeth, in order to reduce the leakage flux and boost the torque density. A systematic way of reducing the torque ripple from 40% to 4% is proposed by carefully choosing the right combination of stator/rotor pole-pair numbers. A comprehensive design optimization is conducted to achieve the optimal performance. Finally, the ac loading is carefully reduced to meet the torque, saturation, power factor and space requirements. The test results of a prototyped machine show that the proposed design can achieve 34% more torque and 20% less loss with a reasonable power factor of 0.63, compared with an optimized PM synchronous machine under the same volume. It is found that the significant torque boost is attributed to the multiple working harmonics of the air-gap flux density.

A Pole-Changing Doubly Salient Permanent Magnet Motor

This article presents a new pole-changing (PC) doubly salient permanent magnet (DSPM) motor. According to the general air-gap field modulation theory (GAFMT), the permanent magnet excitation field can be modulated by the stator and rotor teeth to a series of harmonics with different pole-pair numbers and different slot pitch angles. Thus, when the armature winding is connected and reconnected according to the different excitation field harmonics, the PC operation can be realized to obtain a high torque density at the low-speed region and a widened speed regulation range with a simple motor structure. According to the GAFMT, the operating principle of the proposed motor is introduced, and the winding connection is discussed. Then, to verify the validity, the electromagnetic performance of the proposed motor is analyzed by the finite element analysis. Finally, a prototype is built and tested.