Number Of Pole Pairs Research Articles

Analysis of rotor vibration characteristics of surface mounted permanent magnet synchronous motor under air gap eccentricity fault

Taking a permanent magnet synchronous motor as the research object, the effect of air gap eccentricity fault on the vibration response characteristics of the motor rotor is analyzed through theoretical calculations, numerical simulation and finite element simulation. First, the change of air gap magnetic field under air gap eccentricity fault is analyzed, and then further calculated to obtain the unbalanced magnetic force under air gap fault by the expression of air gap magnetic field, at last, the rotor’s vibration response characteristics under the action of unbalanced electromagnetic force are obtained by the Newmark- β calculation method. Detailed analysis of the effects of eccentricity distance, eccentricity angle and motor pole-pair number on motor rotor vibration. Finally, the synchronous motor eccentricity fault model is built in ANSYS Maxwell electromagnetic simulation software, and the change characteristics of rotor unbalanced magnetic force after eccentricity fault are calculated and the results are consistent with the theoretical calculations.

ОБЕРТАЛЬНИЙ МОМЕНТ БЕЗПАЗОВОГО МОМЕНТНОГО ДВИГУНА З ПОСТІЙНИМИ МАГНІТАМИ ТА МАСИВНИМ МАГНІТОПРОВОДОМ СТАТОРА

The properties of the solid magnetic core of the stator of a slotless torque motor with permanent magnets are considered. It is noted that the solid stator under the conditions of low rotation speed has some advantages over the traditional laminated magnetic circuit. These advantages consist in the cost reduction of the design, its compactness and the low time of production preparation. The mathematical model's assumptions and the input data's limitations are formulated. A model of a static magnetic field with a moving electrically conductive medium is chosen. The two-dimensional model is implemented in the "Magnetic fields" interface of the "COMSOL Multiphysics" software. The maximum torque values were obtained and the optimal number of pole pairs was found. The method of calculating the torque based on eddy current losses in the magnetic medium is used. The decrease in torque with increasing rotor speed is calculated. The correction coefficients of the maximum moment were obtained to correct the results of two-dimensional modelling using a three-dimensional model. References 5, figures 6, tables 1.

DECREASING TORQUE RIPPLE OF A SLOTLESS PERMANENT MAGNET TORQUE MOTOR USING A DOUBLE-LAYER WINDING

The torque of a magnetoelectric torque motor with surface-mounted permanent magnets on the rotor was studied. The sinusoidal current supply mode is considered. The torque was calculated according to the static model of the magnetic field. It was determined that the sixth harmonic makes a significant contribution to the torque ripple. To reduce the sixth harmonic it is proposed to use a winding with a shortened pitch, for which it is necessary to make this winding in two layers. The optimal values of the number of pole pairs, the angular width of the magnets of the magnetic field exci-tation system, and the shortening of the winding pitch were determined. It was found that shortening of the winding pitch decreases the torque ripple by 2 ... 2.5 times. References 7, figures 6, tables 3.

A hybrid wind and raindrop energy harvesting operating on Savonius turbine

In offshore environments, abundant wind and rainfall resources await development, representing significant untapped energy potential for powering Internet of Things (IoT) devices. Triboelectric Nanogenerators (TENGs) are particularly suited for capturing continuous motion in offshore environments, presenting a reliable solution for sustainable energy generation in IoT applications. Herein, we propose a wind-droplet hybrid generator (WDHG) tailored for adaptive environmental energy harvesting, explicitly targeting the demanding conditions prevalent in offshore environments. The WDHG combines the efficiency of a helical Savonius TENG with the versatility of an interdigitated electrode TENG, enabling simultaneous wind and rain energy harvesting. The helical Savonius TENG exhibits superior aerodynamic performance, producing an output power ranging from 0.39 to 2.10 mW with wind speeds increasing from 0.75 to 6.84 m/s. Additionally, the droplet TENG generates a power output of 35.90 mW/m2 under rainfall at 70 mm/min. Optimizations include not only the comparative analysis of helical Savonius turbines and the variation in pole-pair numbers but also adjustments in fluorinated ethylene propylene (FEP) film thickness and electrode gap length for interdigitated electrode, alongside the development of a tailored power management circuit (PMC) featuring dual bridge rectifiers, a buck circuit module, and a smart load switch. The PMC enables continuous operation of a low-powered digital thermohygrometer under conditions of 4.5 m/s wind speed, and drives a 20-second wake BLE server under 7.2 m/s wind speeds. Integration of the WDHG with offshore wind and raindrop extends energy harvesting capabilities, exhibiting a great potential of providing reliable power source for IoT devices.

Analysis of pole pair number impact on single-sided linear induction machine performances

This paper presents a parametric study of linear induction motor for design purpose. The chosen mathematical model uses a 2D formulation with magnetic vector potential A. The implementation of the model is carried out with the finite element method on the free platform Gmsh-GetDP. Circuit model is coupled to FE model so that constant voltage supply mode can be considered. This work aims to highlight the effect of the pole pair number on the characteristics and the performances of the linear induction machine through two numerical models associated to an analytical one. Furthermore, the study shows the effect of the pole pair number on the phase imbalance and the spatial harmonic spectrum of the machine. Reducing this imbalance and higher order harmonics presence will increase machine performances.

Analysis of torsional vibration characteristics for wind turbine drivetrain under external excitation

This work studies the torsional vibration characteristics analysis of the wind turbine drivetrain with the variation of internal parameter and external excitation. The electromechanically coupled torsional vibration model for wind turbine drivetrain is first established by taking into account the torsional vibration angle of the PMSG. Then, frequency response analysis of main parametric resonance is illustrated by multiple scale method, and the influences of the system parameters involving power factor angle, number of pole pairs, torsional stiffness, and wind speed excitation on the torsional vibration characteristics of wind turbine drivetrain are investigated. Moreover, the critical condition for homoclinic chaos in terms of the system parameters is derived by means of Melnikov’s method. The function relationship and the boundary curve of chaos threshold are obtained. Meanwhile, the effects of excitation amplitude and damping factor on the system transition to chaos are studied in detail. The analytical predictions including phase portrait, bifurcation diagram and Lyapunov exponent are investigated. The research results can offer a theoretical basis for further the parameter design and control of wind turbine drivetrain.

Analysis of longitudinal-vertical coupling vibration of four hub motors driven electric vehicle under unsteady condition

The influence of hub motor unbalanced magnetic force (UMF) on the vibration of electric vehicle under steady state conditions has been known, but under unsteady conditions, the hub motor UMF will change with the vehicle operation condition, and there would exist complex coupling vibration for the hub motors driven electric vehicle. Here, the longitudinal-vertical coupling dynamics of the four hub motors driven electric vehicle under unsteady condition is studied. Integrating the motor electromagnetic excitation and electric vehicle dynamics, a longitudinal-vertical coupling dynamics model of the four hub motors driven electric vehicle is established. Based on the variable switching frequency field-oriented control model, analytical model of the UMFs acting on the motor stator and rotor parts under unsteady condition are developed. For model validation, a four hub motors driven electric vehicle has been tested, the accuracy of the longitudinal-vertical coupling dynamics model established in this paper was verified. Then, longitudinal-vertical coupling vibration characteristics of the four hub motors driven electric vehicle under road excitation and coupling excitation are analyzed. The results show that the longitudinal and vertical movement of the four hub motors driven electric vehicle is coupled by hub motor. In addition, under unsteady condition, the motor UMFs will cause vertical vibration of the electric vehicle body and hub motor stator, the vibration shows order characteristics including low order harmonic hfc and inverter switching frequency sideband harmonic k1 fs±k2 fc ( fc = pn/60, fs is inverter switching frequency, k1 and k2 are positive integers, p is the number of pole pairs and n is motor speed.). The motor electromagnetic torque will cause longitudinal vibration of the electric vehicle body, the vibration shows order characteristics including harmonics fs±3 fc and 2 fs. The main harmonic of vehicle body pitch angle acceleration is 2 fs.

A pole-changing flux reversal permanent magnet motor

In this paper, a pole-changing (PC) flux reversal permanent magnet (FRPM) motor is proposed for obtaining a wide speed range. According to the general air-gap field modulation theory, the permanent magnet (PM) magnetic field is modulated into a series of harmonics with different pole numbers by rotor teeth. By introducing an especial PM arrangement, two groups of working harmonics with different pole-pair numbers are generated in the proposed 12-7 PC-FRPM motor due to the modulation of rotor teeth. Based on the calculated slot pitch angles of these harmonics, two winding connections can be obtained for PC operation to achieve two operating modes. The electromagnetic performance of PC-FRPM motor before and after PC are analyzed using finite element analysis and verified by the experimental test results.

Finite Element Analysis of a Three Speed Induction Machine

This paper deals with the Finite Element (FE) analysis of a special Three Speed Squirrel Cage Induction Machine (TSSCIM) with pole changing stator windings. Compared to classical multi-speed induction machines, the studied TSSCIM is designed so as to change in the same time the number of pole pairs (p) and the number of stator phases (m) so as to keep constant the product p x m. The numerical model of the machine used in this study is based on a 2D plane-parallel finite element approach and aims at finding some of the main steady state operation characteristics of the machine working both as motor and generator for three different running speeds. A comparison of the proposed TSSCIM with a classical inverter fed squirrel cage induction machine is also presented in order to underline some advantages and disadvantages of each solution.

Maximum Torque per Ampere Operation of Brushless Doubly Fed Induction Machines

In this paper, an analytical method for increasing the steady state torque per ampere capability for BDFMs, using equivalent circuit is presented. In this approach, uni-current proposition proposed to define a unique current value for optimization, and find the current angel corresponding to maximum torque. The accuracy of the proposition is verified by simulation. The effect of pole pair number selection of power and control windings on maximum torque is explained by dividing torque expression into synchronous and asynchronous terms. Finally, the optimal current values and optimal torque are achieved. Based on the optimal value of torque, or MTPA index, analytical optimization of machine design is suggested, which can be performed by manipulation of components of the MTPA index

Brushless Doubly-Fed Asynchronous Generator Model for Variable Speed Wind Generation Systems.

Because of the raising percentage of the wind energy in the total electrical energy, quality control and regulation of the provided energy will be needed for the electrical grid correct functioning. It is only possible using Variable Speed Wind Generation Systems (VSWGS). In this paper a new electrical generator, Brushless Doubly-Fed Asynchronous Generator (BDFAG) is proposed as a solution for a variable speed wind generation system. The stator of this machine is composed of two balanced three-phase windings with different pole pair number. The rotor is as robust as a conventional squirrel cage, but it has a special design. A steady state model of a BDFAG. is analyzed. Using this model the power balance in the stator windings and the rotor cage is evaluated. The evaluation results will be experimentally verified with a prototype of BDFAG.

Magnetic Decoupling: Basis to Form New Electrical Machines

Abstract Magnetic decoupling principle when applied to electrical machines states that if two windings are configured for different number of pole pairs, they would not interact with each other magnetically even though they share a common magnetic core. This principle forms the basis for developing special machines where two or more machines can be integrated with the same magnetic circuit. This paper deals with formulating the mathematical analysis that determines the validity of this principle during practical conditions (i.e. non-sinusoidal winding distribution, flux saturation, etc.). Extensive Finite Element Method (FEM) simulation results from the Ansys Maxwell-2D software platform closely obey the conclusions derived from the mathematical analysis. As an example, new brushless and magnetless synchronous machines (SMs) have been developed by using this principle. It is designed by embedding an induction machine (IM) with a SM. Experimental investigations conducted on the laboratory prototype support the mathematical analysis dealt with in this paper.

A Two Degree-of-Freedom Rotary-Linear Machine With Transverse-Flux Structure

This paper proposes a two-degree-of-freedom rotary-linear machine with transverse-flux structure. In the proposed machine, the rotary flux and linear flux are naturally decoupled, hence its linear force and rotary torque can be controlled independently. Unlike the conventional rotary-linear machines with 3D-flux pattern, the proposed machine with transverse-flux structure can employ circumferentially laminated steel sheets to provide outstanding electromagnetic performance. The topology and operation principle of the proposed machine are introduced, while the naturally decoupled-flux feature is explained by analytical modelling and 3D finite-element method. A parametric study of pole-pair numbers combination is conducted to obtain the optimal pole-pair numbers in both axial and circumferential directions. The optimal electromagnetic performances are quantitatively compared with other two conventional rotary-linear machines, while an experimental prototype is manufactured to verify the proposed concepts.

Induction Motor Vibrations Caused by Mechanical and Magnetic Rotor Eccentricity

Vibration reduction of induction motors is a significant problem that requires effective models for the effects of mechanical and electromagnetic unbalanced forces. This article presents a mathematical model of dynamics for induction motors with rotor mass eccentricity and static and dynamic magnetic eccentricity. The model allows for the influence of the gyroscopic torque of the rotor and considers the elastic-damping characteristics of each of the stator supports and their location. The model has eight degrees of freedom, which makes it possible to simulate transverse and axial vibrations of various designs’ rotors and housings of induction motors. The results of modeling the dynamics for a three-phase squirrel cage induction motor with 11 kW capacity agreed with those obtained by other authors. Simultaneously, new results were also obtained within the research. The simulation results showed that the static magnetic eccentricity causes the appearance of additional critical speed of the motor, and its value decreases in proportion to the growth of the number of pole pairs. The change of the moment of inertia of the motor at a mismatch of the main axis of symmetry of the stator and the rotor axis of rotation allowed for obtaining an actual frequency spectrum of free oscillations, including the rotational motion of the stator. Since the actual static magnetic eccentricity can additionally increase at operating frequencies due to the increase of bearing clearance caused by dynamic unbalanced load, it should be considered in the analysis of unbalanced magnetic pull. The angle of static magnetic eccentricity significantly affects the magnitude of radial vibrations. This feature should also be considered when selecting the locations of balancing weights during the rotor balancing procedure.

Zeroth-Mode Vibration Suppression for Integral-Slot Surface-Mounted PMSMs by Increasing the Vibration Mode from Zero to Number of Pole Pair

Zeroth-Mode Vibration Suppression for Integral-Slot Surface-Mounted PMSMs by Increasing the Vibration Mode from Zero to Number of Pole Pair

Force effect of a circular rotating magnetic field of a cylindrical electric inductor on a ferromagnetic particle in process reactors

The object of research is the force effect of a circular magnetic field of cylindrical inductors with alternating current windings on the actuator element of technological reactors – a ferromagnetic particle. Technologies using a rotating magnetic field and ferromagnetic particles (RMF and FP) are increasingly used in industry, in devices for fine and ultra-fine grinding, mixing and activation, in the construction and chemical industries, in energy-saving and environmental systems. In previous studies, the authors proposed a method for calculating the force effect on ferromagnetic particles (FP) of an elliptical rotating magnetic field (RMF) of an external cylindrical inductor with a symmetrical alternating current winding. In this work, based on this technique, formulas for the force effect on the FP of the fundamental harmonic of RMF of cylindrical inductors with different numbers of pole pairs are derived and analyzed. It is shown that for a hard magnetic and saturated magnetically soft (soft-magnetic) particle in a circular field of a cylindrical inductor with the number of pole pairs greater than one, the magnitude of the magnetic displacement force does not depend on the orientation of the magnetic moment of the ferromagnetic particle, and the direction of action of this force is determined by the angle between the circular field induction vector and the magnetic moment of the particle. While maintaining the similarity of the inductors and the equality of the amplitude of the magnetic induction on the surface of the inductor bore, the magnetic displacement force does not retain the similarity, in particular, while maintaining the values of the magnetic moment of the particle, this force is inversely proportional to the radius of the bore of the cylindrical inductor. Examples are given of the use of formulas for calculating the ratio of displacement forces to the weight of a particle and the calculation of forces for an unsaturated soft-magnetic particle, where, due to the dependence of the magnetic moment on the field strength, the calculation formulas are modified and take on a slightly different form than the formulas for a particle with a constant modulus magnetic moment. The research results will be useful for engineers and researchers involved in the research, development, design and operation of reactors with RMF and FP technologies.

Design and Optimization of a Pole Changing Flux Switching Permanent Magnet Motor

A flux switching permanent magnet (FSPM) motor is designed and optimized in this paper to achieve high torque density and expanded speed regulation range from a design viewpoint of pole-changing (PC). Based on the field modulation theory, the PM field in the FSPM motor is modulated by the stator and rotor teeth, generating rich harmonics with different pole-pair numbers in the air-gap flux density. By adopting an appropriate slot pole combination, working harmonics with different slot pitch angles are obtained to establish a basis of the PC-FSPM motor. Then, different working harmonics can be used to achieve different energy conversions with different winding configurations, so the PC operation can be performed to realize the high torque and wide speed regulation range by switching the working modes. Based on the field modulation theory, the operation principle of conventional and PC-FSPM motors are analyzed and compared. Then, according to the design principle of the PC-FSPM motor, a 24/22-pole PC-FSPM motor with the E-core is designed and optimized by a multi-level optimization method. Finally, the electromagnetic performances are analyzed by finite element analysis and the test results of the prototype have verified the feasibility of the motor.

Analysis of Stator-Slot and Pole-Pair Combinations in a Two-Degree-of-Freedom Split-Stator Induction Machine Based on Motion Coupling Model

2-degree-of-freedom split-stator induction machine (2DoFSSIM) exhibits high integration and material utilization for 2DoF motions, but the attractive topologies are difficult to determine due to exciting two different magnetic fields and two-directional motions. This paper investigates the helical motion coupling effect of rotary and linear motion parts, then the influence of stator-slot and pole-pair combinations on three motion characteristics is analyzed. Based on the proposed motion coupling model, the resistant torque and force production mechanism is revealed. It can be concluded that the output torque, force, and helical motion coupling effect are dominantly determined by the magnetic loading and pole-pair number of two motion parts. However, there is a tradeoff in choosing the pole-pair number to get the 2DoFSSIMs with high output performances and low helical motion coupling effect. Then, the stator-slot and pole-pair combinations selection method is proposed, and the topologies with attractive performances are chosen at different geometric diameters. Finally, the finite element analysis and experimental results are given to validate the proposed technique. <list list-type="simple" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <list-item> 2-degree-of-freedom split-stator induction machine, motion coupling model, helical motion. </list-item> </list>

Arranging coil winding circuits of synchronous permanent-magnet machines on rotor

&lt;span lang="EN-US"&gt;Methodology of constructing coil winding electrical circuits for salient-pole stator of electrical permanent-magnet machines on the rotor is proposed, which is based on the required number of pole pairs (synchronous speed) and the number of phases. The methodology algorithm is based on determining the value of the number of stator teeth as the closest to the number of rotor poles number value, multiple of phase number, which provides a sufficient level of pitch coefficient and winding coefficient. The algorithm was tested by several examples of constructing synchronous machines winding circuits, known from electrical engineering theory and practice, including mass-produced ones. In all the examples, if the proposed methodology guidelines were formally and strictly followed, the correct circuit designs came out as a result. For high power motor pilot design, one and the same machine design variants were compared, having thirty six slots on stator, three-phase and nine-phase windings, synthesized according to the proposed algorithm for thirty two-pole rotor. Engine torque calculation with both circuit options performed by finite elements method showed the nine-phase winding developed torque advantage by 20%, due to less discretion of MMF slot distribution.&lt;/span&gt;

Online position error correction technique for sensorless control of multipole permanent magnet machines

In order to improve the reliability of electric machine drive systems, the position encoder is often replaced with an estimator, such as the extended Kalman filter. However, estimation errors can still occur, especially in machines with high pole number, commonly used in renewable energy systems. The high number of pole pairs amplifies the effect of estimation errors, leading to a substantial divergence between actual and controlled currents, potentially causing harm to the machine through the excessive heat generation or demagnetization of permanent magnets. To address this issue, an error compensation method has been proposed and tested in a control scheme for a tidal stream system based on a multipole dual-star permanent magnet synchronous generator. The method estimates the position error by determining the q-axis permanent magnet flux and correcting it through a PI regulator. Simulation results demonstrate the effectiveness of the proposed method, even with a non-null initial rotor position.