Performance Of Permanent Magnet Motor Research Articles

Enhancing Performance of Permanent Magnet Motor Drives through Equivalent Circuit Models Considering Core Loss

Permanent magnet motors (PMMs) have emerged as key components in numerous industrial applications due to their high efficiency, compact size, and robust performance characteristics. However, to attain optimal performance in PMM drives, accurately predicting and mitigating core losses is paramount. This paper aims to provide a comprehensive review of advancements and methodologies for enhancing the performance of PMM drives by integrating equivalent circuit models (ECMs) that account for core losses. Firstly, the significance of core losses in motor drives is underscored, alongside a survey of research endeavors dedicated to core loss reduction. Notably, emphasis is placed on mathematical models offering both swift computation and reasonable accuracy. Subsequently, the paper delves into the development of ECMs, focusing on approaches adept at capturing core loss effects across diverse operating conditions. Moreover, this paper explores the utilization of these improved ECMs in the design and control of PMMs to achieve enhanced performance. By integrating core loss considerations into design and control strategies, PMM drives can optimize efficiency, torque production, and overall system performance. In summary, this paper may consolidate the current state-of-the-art techniques for enhancing PMM performance through the integration of core-loss-aware ECMs. It highlights key research directions and opportunities for further advancements in this critical area, aiming to foster the development of more efficient and reliable PMM-based systems for a wide range of industrial applications.

A new radial quadrupole Nd2Fe14B Halbach ring for application in motor

A new Nd2Fe14B Halbach cylinder ring is fabricated by combining with magneto-mechanical molding and sintered process. It does not only exhibit larger surface magnetic flux density (ca.401mT), but also shows better magnetic field homogeneity comparing to spliced Halbach magnets (ca.324mT). Furthermore, performance of motor based on spliced and integrated Halbach magnet is also characterized and compared in detail. The power and torque of motor based on integrated Halbach magnet are effectively improved to be 20% and 9.4%, respectively. Moreover, the working efficiency of motor based on integrated Halbach magnet increases from 90% to 96% comparing to spliced Halbach magnet. These results do not only confirm formation of integrated Nd2Fe14B Halbach cylinder ring with high performance, but also provide a new method to improve performance of permanent magnet motor.

Multiple load operation of indirect matrix converter for different frequencies using symmetrical space vector modulation

AbstractThis study describes an indirect matrix converter (IMC) that uses symmetrical space vector pulse width modulation (SSVPWM) to feed two loads from a single DC link at a variable frequency. Output stage‐I is connected to the static load, while output stage‐II is connected to the PMSM for speed control. It is appropriate for drive systems with variable frequency, such as those seen in wind power generation and aviation. In recent years, significant studies on AC‐AC converters have been conducted due to the rising interest in electric cars and renewable energy. The performance of permanent magnet motors is better than that of other types of AC motors due to their superior performance and residual flux permanent magnets. Contrary to normal back‐to‐back power conversion systems, IMC does not necessitate the use of capacitors in the DC‐link, decoupled control between the two‐stages, a simple clamping circuit or zero current switching in the rectifier stage, allowing the system's volume to be reduced. It is investigated how well the two output stages of the proposed IMC perform. To illustrate the benefits of the suggested IMC design, an improved SSVPWM is employed, and MATLAB/SIMULINK‐based simulations were performed to validate the efficacy of the modulation mechanism. In addition, the real‐time implementation of the work was validated using a real‐time simulator, OPAL‐RT (OP4510).

Enhancing performance of permanent magnet motor for electric vehicle drives using model predictive control

In the electric three-wheeler vehicular segment, permanent magnet (PM) motors are strong competitors for traction applications. The vehicular environment faces sudden load variations, where traditional control like field-oriented control (FOC) over-excites the machine. It also degrades the machine’s overall performance due to dynamic changes in the motor states with limited bandwidth of the cascaded proportional-integral (PI) controllers; this makes the overall motor operation inefficient. The paper proposes a model predictive control (MPC) based on torque ripple and over-current excitation minimization for permanent magnet motors to overcome these challenges. The proposed controller is tailored to improve the overall electrical efficiency of permanent magnet motors while considering the real back EMF. The performance of the proposed controller is tested in simulation, considering an electric three-wheeler as a load along with a European driving cycle. The feasibility of the proposed method is tested by deployment on (1) STM32F546ZG micro-controller and (2) Xilinx’s ZYNQ-7000 SoC ZC706 FPGA and validated the implementation results with hardware-in-the-loop(HIL) co-simulation. The implementation results show that the proposed MPC outperforms the conventionally used FOC in energy consumption, torque ripples minimization, and torque disturbance handling while tracking the desired speed accurately with load variations.

Method of Cogging Torque Reduction for Built-in Permanent Magnet Synchronous Motor

Cogging torque is one of the main factors that deteriorate the performance of permanent magnet motor. In order to reduce the cogging torque of built-in permanent magnet motor, a method of optimizing Rib and DminMag to reduce groove torque of built-in permanent magnet motor was proposed. Firstly, the relationship between Rib and DminMag and groove torque is analyzed through the expression of groove torque. Secondly, the optimal Rib and DminMag were found by finite element parametric calculation, and compared with the pre-optimization groove torque, the groove torque was significantly reduced. Finally, the main performance of motor before and after optimization is not significantly reduced.

Method of Cogging Torque Reduction for Built-in Permanent Magnet Synchronous Motor

Cogging torque is one of the main factors that deteriorate the performance of permanent magnet motor. In order to reduce the cogging torque of built-in permanent magnet motor, a method of optimizing Rib and DminMag to reduce groove torque of built-in permanent magnet motor was proposed. Firstly, the relationship between Rib and DminMag and groove torque is analyzed through the expression of groove torque. Secondly, the optimal Rib and DminMag were found by finite element parametric calculation, and compared with the pre-optimization groove torque, the groove torque was significantly reduced. Finally, the main performance of motor before and after optimization is not significantly reduced.

Analysis and design of electromagnetic vibration and noise reduction method of permanent magnet motor

Vibration and noise parameters have a significant influence on the performance of permanent magnet motor (PMM). A new method of reducing vibration and noise of PMM was proposed in this study by optimizing the stator teeth profile. The optimal offset distance was determined by finite element method, and the results indicate that the vibration and noise amplitude become larger when the frequency is an even multiple of the fundamental frequency. The maximum and average vibration acceleration of the optimized PMM is reduced by 22.27% and 11.11%, respectively, and the total sound pressure level (SPL) is decreased by 3.67%. Finally, the correctness of the theoretical parameters was verified by the vibration and noise measuring experiment. The experimental data suggest that the average acceleration error is 7.07%, and the average SPL error is 2.28%. The research methods and conclusions of this study may be extended to the vibration and noise optimization of other PMM.

Design Optimization of a PM Motor: A Practical Approach for Mass Production

This article discusses design and optimization of a permanent magnet (PM) motor for electric transmission oil pump (eTOP) applications. The PM motor is fed from the vehicle low voltage battery system (12 Vdc) and drives a mechanical pump assembly (MPA) in a generated-rotor (Gerotor) configuration. The eTOP is accommodated inside the transmission where it supplies required oil flows at specified pressures for lubrication and cooling purposes. The optimization is formulated as a multi-objective problem that is solved using a differential evolution (DE) algorithm. An existing PM motor is used as a benchmark machine against which an optimized solution for mass manufacturing considering real-world application constraints is proposed. A 3-phase winding approach that facilities a needle winding process is considered for the eTOP PM motor. Once the optimized solution is found the PM motor's performance is evaluated and presented. To validate the design a prototype PM motor with production materials and tooling is built and tested. The comparison of measured and predicted results shows good agreement.

Analysis for electromagnetic performance of PM motor with different metal nano-material bars

With the appearance of high-performance permanent magnet (PM) materials as well as the development of computer technology and nanotechnology and electricity machine theory, scholars have done a lot of research on the self-starting permanent magnet synchronous motor and have made many achievements. Although the starting permanent magnet synchronous motor has many advantages compared with the induction motor, there are also many problems. Since the self-starting motor needs to realise the self-starting and maintaining the synchronous speed operation, its rotor structure design is more complex. The rotor requires the starting winding and the magnets coexist, so there is 'space competition', especially the small motors with high power density. Nowadays, nano-materials are applied on a motor to improve its electromagnetic performance. In this paper, the electromagnetic performance of a PM motor with different metal nano-material bars is researched by finite element analysis (FEA). In this paper, the electromagnetic performance of a PM motor is researched when the rotor bars are with different sizes metal nano-palladium by FEA. The magnetic field distribution, the dynamic speed and torque variation and the eddy current losses are analysed respectively.

Comparison of Two Magnetizing Fixture Designs to Achieve Radial Magnetization Profile for Isotropic-Bonded Neo Magnets

The requirement of stringent environment and fuel efficiency target on automotive demand the use of lighter, smaller and efficient motors. The advantages like higher magnetic properties than ferrite, near net shape magnet production, and no use of heavy rare earth elements makes the use of bonded neo magnet in an automotive accessory motors very attractive. The isotropic nature of bonded neo magnets offers a feasibility to obtain wide range of magnetization profiles. The magnetization of the magnet influences the air-gap flux distribution and hence the motor performance 1. The performance of permanent magnet motors using isotropic bonded neo magnet can be improved by optimizing the air-gap flux profile using magnetization. Based on the magnet circumference touching the motor air-gap and the desired magnetization profile, an appropriate magnetization fixture needs to be designed. In an external rotor permanent magnet brushless (PMBL) DC motor and brushed DC motors, the inner circumference of the magnet touches the airgap and hence the magnet is magnetized using an inner-only fixture which has magnetization coils next to the inner circumference of the magnet. When the radial magnetization is desired, a double sided magnetization can also be used to magnetize bonded neo ring magnets 2. The use of double sided magnetization helps in enhancing the motor performance 3. To ensure that the bonded neo magnet is fully saturated a minimum magnetizing field of around 3T is to be generated throughout the magnet thickness 4. Considering this required magnetizing field, a fixture each offering inneronly and inner-outer magnetization (double sided magnetization) is designed using Finite element analysis (FEA) to achieve the radial magnetization. The simulation based results on the performance comparison of two fixtures is summarized. Figure 1 shows the simulated mid airgap flux density when magnet is magnetized with inner-only and inner-outer magnetizing fixtures. From this figure it is observed that, compared to inner-only fixture, the inner-outer fixture results in flat topped radial wave shape of flux density. Both designed fixtures are fabricated and the measured performance is used to validate the simulation results. It is observed that the peak magnetizing current and the energy required to achieve the magnet saturation in an innerouter fixture is 19.8% and 26.5% less respectively compared to inner only fixture. The reduction in peak magnetizing current and magnetization energy requirement will lead to reduced thermal stress and improved fixture reliability. It will also help in reducing the magnetization cycle time due to better heat dissipation in inner-outer fixture. During magnetization of the magnet, the effectiveness of the inner-outer fixture depends highly on the alignment of the inner and outer magnetization coils. The alignment and hence the performance of the fixture is influenced by the fabrication tolerances 5. Even a small misalignment between the coils on either side of the magnet will result in flux waveform distortion and reduction in magnetic flux. Considering the manufacturing tolerances, the effect of the various misalignment angles between the inner and outer magnetization coils on the magnet flux is arrived at using the FEA based simulation. The magnetization result is also measured by creating various misalignments between the inner and outer magnetization coils in the fabricated inner-outer magnetization fixture. Table I gives the measured magnet flux integral for various misalignment angles. It is observed from Table I that the $\pm 2 ^{circ}$ mechanical misalignment between the coils will not result in significant change in magnet flux and higher misalignment angles will result in considerable reduction of flux per pole. It is also observed that the misalignment effect is symmetric about the aligned position and higher degree of misalignment causes drooping wave shape on one side and a hump on the other side in any given pole depending on the direction of misalignment.

Optimal design for improving torque performance of permanent magnet motor

Optimal design for improving torque performance of permanent magnet motor

Analysis for electromagnetic performance of PM motor with different metal nano-material bars

With the appearance of high-performance permanent magnet (PM) materials as well as the development of computer technology and nanotechnology and electricity machine theory, scholars have done a lot of research on the self-starting permanent magnet synchronous motor and have made many achievements. Although the starting permanent magnet synchronous motor has many advantages compared with the induction motor, there are also many problems. Since the self-starting motor needs to realise the self-starting and maintaining the synchronous speed operation, its rotor structure design is more complex. The rotor requires the starting winding and the magnets coexist, so there is 'space competition', especially the small motors with high power density. Nowadays, nano-materials are applied on a motor to improve its electromagnetic performance. In this paper, the electromagnetic performance of a PM motor with different metal nano-material bars is researched by finite element analysis (FEA). In this paper, the electromagnetic performance of a PM motor is researched when the rotor bars are with different sizes metal nano-palladium by FEA. The magnetic field distribution, the dynamic speed and torque variation and the eddy current losses are analysed respectively.

A Study on Correcting the Nonlinearity Between Stack Length and Back Electromotive Force in Spoke Type Ferrite Magnet Motors

The accurate estimation of the performance change according to variations in stack length of motors is important in related industries. A permanent magnet (PM) motor usually represents a characteristic in which its back electromotive force (EMF) constant (K e ) is linearly proportional to stack length. It is an enormous advantage in designing and estimating the performance of PM motors. However, the linearity cannot be held in spoke-type ferrite magnet synchronous motors (SFMSM) due to the axial leakage magnetic flux that is irrelevant to the stack length. Thus, it is possible to accurately analyze the performance of SFMSM using a 3-D finite-element analysis (FEA) method but this method is very inefficient. In this paper, a new relationship formula that can consider the nonlinearity between stack length and back EMF constant in SFMSM is proposed. This formula can estimate the back EMF constant in a new stack length based on the results of 2-D-FEA and 3-D-FEA in a specific stack length. Finally, the validity of this formula is verified through analyzing its accuracy and testing it according to changes in motor parameters.

Effects of driving modes on permanent magnet motor electromagnetic and temperature fields at limit conditions

Purpose Taking a 2,000 r/min 10 kW permanent magnet motor as an example, the purpose of this paper is to study the influence of driving modes on the performance of permanent magnet motor at limit conditions, and researched the variation mechanism of motor performance influenced by different driving modes. Design/methodology/approach A two-dimensional electromagnetic field model of the permanent magnet motor was established, and a rectangular-wave driving circuit was built. By using the finite element method, the electromagnetic field, current, harmonic content and eddy current loss were calculated when the motor operated at rated load and limit load. On the basis of the motor loss calculation, the temperature field of the motor operating at rated condition and limit condition was researched, and the factors that influence motor limit overload capacity were analyzed. By analyzing the motor loss variation at different load conditions, the change mechanism of the motor temperature field was determined further. Combined with the related experiments, the correctness of the above analysis was verified. Findings Permanent magnet synchronous motor (PMSM) driven by sine wave is better compared with brushless direct current motor (BLDCM) driven by rectangular wave in reducing the magnetic field harmonics, motor losses and optimizing the temperature distribution in the motor. The method driven by sine wave could improve the motor output performance including the motor efficiency and the motor overload capacity. The winding temperature is the most important factor that limits the output capability of PMSM operating for a long time. However, because of the large rotor eddy current losses, the permanent magnet temperature is the most important factor that limits the output capability of BLDCM operating for a long time. Practical implications The influence of driving modes on the motor magnetic field, losses and temperature distribution, efficiency and overload capacity was determined, and the influence mechanism was also analyzed. Combined with the analysis of the electromagnetic and temperature fields, the advantages of different driving modes were presented. This study could provide an important basis for the design of permanent magnet motors with different driving modes, and it also provides reference for the application of permanent magnet motor. Originality/value This paper presents the influence of driving modes on permanent magnet motors. The limit output capacity of the motor with different driving modes was studied, and the key factors limiting the motor output capability were obtained.

Thermal analysis of high-speed permanent magnet motor with cooling flows supported on gas foil bearings: part II - bearing modeling and case studies

This paper presents the modeling of mechanical loss in Gas foil bearings (GFBs) that support a Permanent magnet (PM) motor. This paper also presents parametric studies to evaluate the effects of carrier harmonics in the input current and cooling-air supply on the motor thermal performance. Because GFB functions not only as a heat source but also as a thermal resistance, we model it as an equivalent element comprising a thermal conductor. The calculation of the bearing loss from the hydrodynamic analysis shows one-order-ofmagnitude smaller values than the electromagnetic losses, thus indicating a slight effect on the PM motor performance. A case study shows the strong effects of the carrier harmonics and cooling-air supply on the motor thermal performance at a rotor speed of 35 krpm. A further study at an increased speed of 60 krpm shows significant increases in the motor losses and temperatures.

Optimum Design for Slot-type of Stator Based on PM Motor with Halbach Structure

The performance of permanent magnet motor is directly influenced by the PM structure of rotor and the slot type of stator. An emerging rotor magnetization type of PM motor is Halbach structure, which has obvious advantages in comparison to ordinary permanent structures and in application, especially in the design of propeller integration system. Commonly, Halbach array is used in discrete permanent magnet structure on the rotor of machine. On the stator, air gap flux density varies as the slot type changes, and complex slot types will bring about complex air gap equivalent process of the motor, which will influence the procedures of simulation calculation and experiments. According to the characteristics of Halbach array, the intensifying effect of the Halbach array on magnetic flux density of air gap is analyzed in this paper, and the electromagnetic field of PM motor is calculated. By using FEM method, the magnetic flux density of air gap, back phase electromotive force and electromagnetic torque are compared under different slot types. Simulation result shows the peer slot is best. Experiments on a 60kW PM Motor with Halbach Structure and peer slot is in good agreement with simulation.

Influence of the Coil Pitch and the Slot/Pole Number Combination upon the Performance of Permanent Magnet Motors

Influence of the Coil Pitch and the Slot/Pole Number Combination upon the Performance of Permanent Magnet Motors

Phenomena of additional cogging torque components influenced by stator lamination stacking methods in PM motors

PurposeThe purpose of this paper is to estimate and evaluate how cogging torque in permanent magnet (PM) motor designs is sensitive to the number of applied interlocks in stator back‐iron, which is a standard method for stator lamination stacking.Design/methodology/approachThe PM motors exhibit inherent cogging torque, which creates torque ripple and prevents smooth rotation of the rotor resulting in undesirable vibration and noise. While cogging torque minimization is necessary to improve PM motor performance, several FEM models have been developed to study and present data demonstrating sensitivity of the cogging torque to the applied interlocks. A procedure that would predict and evaluate cogging torque components relative to chosen number and positions of interlocks was proposed.FindingsOn the basis of theoretical considerations, which were verified by numerous performed simulations using different FEM models, it was found out and proved that interlocks in the stator back‐iron cause the phenomenon of additional cogging torque harmonic components (AHC). Taking into account presented theoretical aspects motor designers can predict, which AHC will comprise the cogging torque. Each motor design has its own optimal value of interlocks, therefore a precise study should be performed during the design process.Practical implicationsBy utilizing presented method and considering recommendations, advanced designers of PM motors will have a reliable tool for predicting the order and the level of AHC in total cogging torque due to the stator lamination stacking methods.Originality/valueThe paper presents theoretical aspects and analytical equations of AHC of PM motors. So far, the authors dealing with the cogging torque of the PM motors did not take into account the influence of the stator lamination stacking method on the level of torque oscillations. The new contribution is also the study of the sensitivity of different motor designs to the number and position of interlocks, which enables the minimization of the AHC in order to fulfil stringent market demands for low‐cogging torque level.

Prediction of cogging torque level in PM motors due to assembly tolerances in mass‐production

Purpose – The purpose of this study is to estimate the sensitivity of cogging torque in permanent magnet (PM) motor designs due to PM assembly tolerance and/or PM imperfections and to evaluate how such faults can be reliably detected in simulated and measured cogging torque signals.Design/methodology/approach – PM motors exhibit inherent cogging torque, which creates torque ripple and prevents smooth rotation of the rotor, resulting in undesirable vibration and noise. While cogging torque minimization is necessary to improve PM motor performance, several FEM models have been developed to study and present data demonstrating the sensitivity of cogging torque to PM assemblies and/or PM imperfections. Some procedures that would predict and evaluate cogging torque components relative to measured PM positions on assembled PM motors were proposed.Findings – On the basis of numerous performed simulations using different FEM models and experimental results on rotors from mass‐production, it was found and proved t...

Numerical analysis of permanent-magnet motor performance considering rotor movement

The paper presents a numerical analysis of a permanent-magnet brushless motor. The goal of the research was to estimate and reduce the torque ripple of a motor under research. The rotor movement was also taken into account in order to consider all the prime causes for torque ripple production. Therefore, two different types of analysis were carried out. The first approach was based on a transient analysis of a two-dimensional (2-D) planar finite-element model coupled to a voltage-fed electric circuit. The second approach was based on a static analysis of 2-D and three-dimensional models where stator current waveforms were calculated separately by a circuit model. Both analyses enable a comprehensive study of the electric machine's performance under arbitrary load conditions considering the effects of the time-varying electrical variables as well as those due to rotor movement. An analysis was done of differently constructed varieties of motor model and different source voltage waveforms. Numerical results were verified by measurements in the laboratory.