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To maximize the performance of rotating machines, it is essential to establish a design method with minimal arbitrariness. This paper proposes a self‐assembling method to design stator slots for alternating current (AC) rotating machines. First, we develop a line‐current approximation model of the stator winding using pulse‐width modulation technique and realize an ideal spatial magnetic flux density distribution. Subsequently, we design the realistic stator with an acceptable current density of the winding by forming unique slot shapes in a self‐assembling manner under two synthetic conditions using the developed line‐current approximation model as the starting model. The designed stator realizes a rotating magnetic field similar to the conventional design results. Additionally, we perform an analysis of motor rotation characteristics by combining the self‐assembled stator with a surface‐mounted permanent magnet rotor to determine the possibility of a higher output compared to that when using a conventional stator. The self‐assembled motor without relying on empirical rules shows a possibility of further improving the torque characteristics, thereby contributing to designing the AC rotating machines. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

For an electric locomotive traction motor, it is necessary to maintain relatively low vibration and noise due to the higher design standards. By using effective motor control strategies and implementing current harmonic suppression schemes, motor efficiency and vibration and noise suppression can be effectively improved. This study investigates the current harmonic suppression strategy for permanent magnet synchronous motors by (1) constructing a mathematical model of the permanent magnet motor to explore the sources of low-order harmonics currents such as fifth and seventh harmonics, as well as high-order harmonics at switch frequencies and their multiples, and analyzing the electromagnetic force characteristics generated by the current, and (2) establishing a vector control system for the permanent magnet motor. To suppress the fifth and seventh harmonic components in the current, a resonance controller is constructed, which utilizes the parallel connection of a resonator and PI controller to achieve low-order harmonic suppression. The factors affecting the effectiveness of the resonance controller's suppression are also analyzed. The experiments are conducted, and the current harmonic suppression scheme constructed in this study can effectively reduce the harmonics in the current, thereby reducing motor vibration and noise. [ABSTRACT FROM AUTHOR]

In order to weaken the torque ripple caused by cogs torque and increase the output torque of permanent magnet synchronous motor, this paper proposes a multi-objective optimization method of permanent magnet synchronous motor based on Improved Multi-Objective Salp Swarm Optimization Algorithm (IMOSSA) and Spearman correlation analysis. Firstly, the improved strategy of Multi-Objective Salp Swarm Algorithm (MOSSA) was proposed, and the effectiveness of the improved algorithm was further verified by the performance test of the algorithm. Then, the motor simulation model was established, and the high correlation parameters were filtered out by Spearman correlation analysis. The response surface model was established by Response Surface Method (RSM), and the regression equation was given. The IMOSSA was used for iterative optimization. Through optimization, the experimental results show that under the premise of meeting the efficiency design requirements, the average output torque of the motor is increased by 21.35%, the torque ripple and cogging torque are reduced by 45.04% and 39.17% respectively, which verifies the effectiveness and feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

Hybrid and electric vehicles have been widely proposed in recent years. Considering the limited capacity of the batteries, the most requirement is designing a motor with high torque density and reasonable efficiency. To enable the motor to operate efficiently, the most operational condition of the vehicle is considered. According to the dominant urban cycle of operation, the electric motor is designed to have optimal performance in this cycle. The outer rotor configuration is adopted to increase the power density of the motor without increasing the electrical loading. A novel outer rotor fractional slot permanent magnet motor with fractional slot winding is introduced and its performance is compared with the Prius 2004 motor a well-known motor. As one of the main challenges of SPM motors is its demagnetization and this is not studied in detail. This paper proposes a comprehensive study of the airgap flux and decreasing the negative effects of harmonics. The proposed motor has 12% more efficiency at rated load compared with the Prius motor. [ABSTRACT FROM AUTHOR]

In order to reduce the torque ripple and the unbalanced electromagnetic force on the rotor of the dual‐parallel rotor permanent magnet motor, a dynamic Kriging surrogate model is proposed to optimize its structural parameters. In the process of constructing the dynamic Kriging surrogate model, the concept of key sampling space is introduced, which solves the problems of low optimization efficiency and poor model accuracy of the traditional static surrogate model based on ‘one‐time’ sampling. The topological structure of the dual‐parallel rotor permanent magnet motor is introduced, and a prototype is used to verify the accuracy of the numerical model. The optimization parameters are determined, and the initial sampling space of each optimization parameter is determined according to the influence law of a single parameter on the optimization objectives. The initial sample database of the Kriging surrogate model is established, and a dynamic criterion for adding sample points is proposed. Combined with the NSGA‐II algorithm, the surrogate model is constructed and solved. The optimal solution is substituted into the numerical model, which verifies the feasibility and correctness of the proposed optimization design method. The accuracy of the dynamic Kriging surrogate model is discussed and compared with the traditional static surrogate model. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Electric tractors have presented promising potential in modern agriculture, due to their energy saving, high efficiency, green and clean. The efficiency and accuracy can be further improved by the distributed drive electric tractors with a simple structure and many control dimensions. Among them, the hub motor drive system of electric tractors also requires high performance of speed tracking and disturbance rejection, when operating on complex roads and in various conditions. Linear active disturbance rejection control (LADRC) can be used to estimate the external disturbance of the drive system using an extended state observer (ESO). The external disturbance can be suppressed using feedforward compensation. Furthermore, the LADRC can be expected to serve as the hub motor drive system, in order to effectively improve the operation performance of electric tractors. However, the high-gain observer, ESO can amplify the high-frequency interference noise, and then enhance the speed detection noise amplitude of the system, thus causing the electric tractor to deviate from the preset trajectory. Fortunately, the low-pass pass filter (LPF) can be used as the common tool to eliminate the high-frequency noise caused by speed disturbance. But the detected speed can be caused to lag behind the actual, thus reducing the dynamic performance of the hub motor drive system. To this end, the LPF can be adjusted to the observation error filtering of ESO, where the detected speed can be synchronized with the actual. But the intermediate-frequency disturbance of the system can also be amplified as well. In this study, a sigmoid function ESO (SFESO) was proposed to realize the active disturbance rejection control of the permanent magnet hub motor. The experimental platform was designed and constructed with the RTU-BOX204 as the core controller. Three control strategies were selected under the speed mutation and load mutation, namely LADRC with the traditional ESO, LADRC with the filtered observation error ESO (FOEESO), and LADRC with the SFESO. The experimental results show that the speed pulsation of FOEESO-based LADRC with the time constant of 2ms decreased by 16% and 13.33%, respectively, compared with the ESO-based LADRC. While, the quadrature-axis current pulsation increased by 12.5% and 25%, respectively, and the speed drop and overshoot under the load mutation increased by 5.13% and 8.11%, respectively, where the speed recovery time increased by 1.16% and 5.81%, respectively. The variation amplitude of each data increased with the time constant of 10ms in the FOEESO-based LADRC. The speed pulsation decreased by 26% and 33.33%, respectively, whereas, the quadrature-axis current pulsation increased by 18.75% and 45.83%, respectively, and the speed drop and overshoot increased by 15.38% and 13.51%, where the speed recovery time increased by 17.44% and 21.29%, respectively. The speed pulsation of SFESO-based LADRC decreased by 32% and 41.67%, respectively, while the quadrature-axis current pulsation decreased by 6.25% and 4.17%, respectively, compared with the ESO-based LADRC. The speed drop and overshoot under the load mutation increased by 2.56% and 1.35%, respectively, whereas the speed recovery time increased by 1.74% and 1.90%, respectively. The SFESO-based LADRC effectively suppressed the system noise with less impact on disturbance rejection, compared with the ESO- and FOEESO-based LADRC. Therefore, the SFESO-based LADRC significantly improved the noise suppression of the hub motor drive system, while quickly and accurately tracking the given speed. The finding can also provide innovative ideas and technical references to realize the high-precision operation of electric tractors in complex environments. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Introduction: As the precision requirements of the machining industry continue to advance, the performance criteria for spindle motors are becoming increasingly stringent. Noise and vibration play a critical role in motor performance and must, therefore, be effectively reduced. Methods: The present study thus employs ANSYS simulations to examine the electromagnetic vibration and noise characteristics of a permanent magnet motor (PMM) with a rated power of 21 kW. The simulations are performed at both the rated speed of 6000 rpm and the maximum speed of 24,000 rpm. Based on the simulation results, the structure of the PMM is optimized in such a way as to reduce the vibration and noise of the motor. The optimization process considers three different structural arc modification strategies: (1) arc trimming of the rotor structure, (2) arc trimming of the stator structure, and (3) arc trimming of both the rotor and the stator structures. Results: The optimal performance improvement is obtained using the rotor/stator arc trimming strategy with a rotor arc trimming angle of 8° and a stator shoe offset of 32 mm. [ABSTRACT FROM AUTHOR]

Permanent magnet (PM) motors are gaining prominence in subsea applications such as drilling, pumping, and boosting for oil and natural gas extraction. These motors are gradually replacing traditional induction motors. However, starting and operating PM motors at low speeds under heavy loads poses significant challenges. This is because of unknown initial rotor positions and resistive voltage drops due to the presence of a sinewave filter, transformer, and long cable. An unknown rotor position may result in temporary reverse speed, which may cause a loss of synchronism; therefore, initial rotor position estimation is preferable. Additionally, addressing the voltage drop issue requires careful voltage compensation to avoid transformer core saturation. In this paper, an enhanced V / H z starting of a PM motor is proposed with initial position detection (IPD) and voltage compensation to start the motor reliably with a heavy load. The proposed control method is verified with controller hardware in the loop (C-HIL) real-time simulation using a Typhoon HIL-604 emulator and a Texas Instruments TMS320F28335 digital signal processor (DSP) control card. [ABSTRACT FROM AUTHOR]

This paper presents a new design concept for interior permanent magnet (IPM) rotor using the capabilities of additive manufacturing (AM). In conventional laminated IPM topology, the presence of rotor ribs is essential for maintaining the mechanical integrity of the rotor. However, these pole ribs are a primary contributor to flux leakage, leading to inefficient utilization of costly rare-earth PMs. Addressing this challenge, a rib-less IPM rotor is proposed that takes advantage of the AM potential which eliminates the need for traditional ribs while maintaining the structural integrity of the rotor. Nevertheless, the additively manufactured cores, in contrast to conventionally laminated rotor cores, demand specific design considerations, especially in terms of eddy current loss and structural performance. In this regard, a strategy involving the incorporation of shallow grooves on the rotor surface is employed to mitigate eddy current loss. The mechanical performance of the proposed topology is carefully examined, and the impact of pole geometry on rotor displacement induced by centrifugal forces is investigated. To evaluate the performance of the proposed topology, an optimization procedure based on response surface methodology is conducted for both the proposed rotor and a conventional IPM rotor. The results indicate that the proposed IPM topology can offer significantly more efficient utilization of PMs and enhanced torque rating by approximately 8% compared to the laminated IPM topology.

Optimisation, or optimal design, has become a fundamental aspect of engineering across various domains, including power devices, power systems, and industrial systems. Engineers and academics have been actively involved in optimising these systems to achieve better performance, efficiency, and cost-effectiveness. Optimising electrical machines, including permanent magnet motors, is a complex task. It often involves solving intricate problems with various parameters and constraints. Engineers use different optimisation methods to tackle these challenges. Depending on the specific requirements and goals of a design project, engineers may employ either single-objective or multi-objective optimisation approaches. Single-objective optimisation focuses on optimising a single objective, while multi-objective optimisation considers multiple conflicting objectives. In optimisation, objective functions are mathematical representations of what needs to be optimised. In this case, optimising the efficiency of the motor, reducing cogging torque, and minimising the total weight of active materials are defined as possible objective functions. Genetic algorithms are nature based algorithms that are commonly used in engineering to find optimal solutions to complex problems, including those with multiple objectives. In this paper, after conducting optimisations using different objective functions and methods, a comparative analysis of the results is performed. This helps in understanding the trade-offs and benefits of different design choices. Finite element analysis (FEA) is a computational method used to analyse the physical properties and behaviours of complex structures and systems. In this case, FEA is used to validate and analyse selected optimisation solutions to ensure they meet the desired characteristics and parameters. Overall, this work demonstrates the interdisciplinary nature of engineering, where mathematics, computer science (for optimisation algorithms), and physics (for FEA) converge to improve the performance and efficiency of electrical machines. It also underscores the importance of considering multiple objectives in design processes to find optimal solutions that strike a balance between competing goals.

In deep-sea operations, tethers play a vital role in providing energy supply and information transmission for remotely operated vehicles (ROVs). To further refine the collect and release planning of the tether and to regulate ROVs' underwater range of motion, this study proposes a novel tether management system powered by permanent magnet synchronous motors. The surface-underwater control systems and their logical control methods have been thoughtfully designed to meet the tether's working requirements. The electric tether management system comprises components such as a drum, sheave, permanent magnet motor, and respective drivers, presenting a more compact structure than traditional hydraulic-powered tether management systems. Through a sprocket, the system ensures synchronicity between the drum and the spooler for a corrugated motion, facilitating correct tether winding around the drum. By analytically considering the torque and speed statuses of the drum and sheave across typical tether pick-up and pay-out modes, this study validates the effectiveness of the electric tether management system's control and logic. The results indicate that the electric tether management system can efficiently collaborate with the ROV to perform underwater operations, thereby contributing to stable and efficient ROV system operation.

Permanent magnet motors have become very important in recent years due to the popularization of electric vehicles in the context of the efforts to transition to zero-emission transportation. This has encouraged researchers and hobbyists to learn about electric motor design. However, designing electric motors is not a simple task, as the information to achieve it is not easily available to everyone and it is usually complicated to understand. For that reason, this paper presents the equations and a basic process to design radial flux surface-mounted PM synchronous motors. This design method is the result of combining and organizing information from previous publications to create a relatively simple design guide. The result is a table of equations and a series of general guidelines that were verified by designing and simulating a 500 W eight-pole 2.6 Nm average torque dual-rotor motor and a 20 W four-pole 106 mNm single-rotor motor. The simulations validated the equations and the design method presented in this paper to be used by those interested in the field of electric motors and vehicles; therefore, in the future, others may contribute with improvements, particularizations or optimizations of this methodology, or even create their own.

For an electric locomotive traction motor, it is necessary to maintain relatively low vibration and noise due to the higher design standards. By using effective motor control strategies and implementing current harmonic suppression schemes, motor efficiency and vibration and noise suppression can be effectively improved. This study investigates the current harmonic suppression strategy for permanent magnet synchronous motors by (1) constructing a mathematical model of the permanent magnet motor to explore the sources of low-order harmonics currents such as fifth and seventh harmonics, as well as high-order harmonics at switch frequencies and their multiples, and analyzing the electromagnetic force characteristics generated by the current, and (2) establishing a vector control system for the permanent magnet motor. To suppress the fifth and seventh harmonic components in the current, a resonance controller is constructed, which utilizes the parallel connection of a resonator and PI controller to achieve low-order harmonic suppression. The factors affecting the effectiveness of the resonance controller’s suppression are also analyzed. The experiments are conducted, and the current harmonic suppression scheme constructed in this study can effectively reduce the harmonics in the current, thereby reducing motor vibration and noise.

Aiming at the high cost of permanent magnet synchronous motor and the reduction of motor output performance caused by high cogging torque and torque ripple, an asymmetric hybrid‐magnet offset motor is proposed. Based on the winding function theory and the equivalent magnetic circuit method, the expressions of stator and rotor magnetic potential are derived respectively, and the analytical model of torque ripple is established by combining with the Lorentz force law. By using the magnetic pole offset method, the phase offset model of the cogging torque is established, and the analytical expressions of the cogging torque and the magnetic pole offset angle are derived. The results of the simulation and experiments show that the asymmetric hybrid‐magnet offset motor has lower no‐load back‐EMF harmonic content and rare‐earth material ratio than the traditional permanent magnet motor, and its performance in terms of the cogging torque and the torque ripple is better than that of the traditional permanent magnet motor. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Permanent magnet motors have become very important in recent years due to the popularization of electric vehicles in the context of the efforts to transition to zero-emission transportation. This has encouraged researchers and hobbyists to learn about electric motor design. However, designing electric motors is not a simple task, as the information to achieve it is not easily available to everyone and it is usually complicated to understand. For that reason, this paper presents the equations and a basic process to design radial flux surface-mounted PM synchronous motors. This design method is the result of combining and organizing information from previous publications to create a relatively simple design guide. The result is a table of equations and a series of general guidelines that were verified by designing and simulating a 500 W eight-pole 2.6 Nm average torque dual-rotor motor and a 20 W four-pole 106 mNm single-rotor motor. The simulations validated the equations and the design method presented in this paper to be used by those interested in the field of electric motors and vehicles; therefore, in the future, others may contribute with improvements, particularizations or optimizations of this methodology, or even create their own. [ABSTRACT FROM AUTHOR]

Permanent magnet brush DC motor is widely used in the automotive field. "Carbon sink Plan" requires the further reduction of automotive energy consumption, so the optimization problem of motor efficiency is becoming increasingly prominent. Based on vehicle cooling fan with permanent magnet brush DC motor as the research object, in view of the motor inefficiencies, using the finite element analysis software Maxwell, through simulation and parametric analysis of the rotor lamination length, laminated slots, winding wire diameter, winding pitch, winding circle number influences the performance of motor, combined with the simulation results and actual production conditions, determine the feasible motor efficiency optimization scheme. According to the optimization scheme, the sample is made and measured. The test data show that the motor efficiency is improved by 4.8%, and the optimization effect of motor efficiency is obvious. [ABSTRACT FROM AUTHOR]

As the core component of the More Electric Aircraft (MEA) hydraulic system, the partial energy Electric Pump System (EPS) determines the performance of the hydraulic servo device. In this paper, a three-phase Fault-Tolerant Permanent Magnet Motor (FTPMM) for the partial energy EPS is proposed. The three-phase FTPMM drive system for the partial energy EPS can replace the traditional engine pump source hydraulic system, which can save costs, reduce weight and volume, and improve efficiency. Moreover, it can solve the problem of high reliability application of the motor drive system in aeroengine. The slot-pole combinations and centrifugal height are designed and analyzed for the proposed three-phase FTPMM, and a prototype model was produced based on this. Finally, the basic electromagnetic performance and fault-tolerant performance of three-phase FTPMM are verified through simulation and experiment. The results show that the proposed three-phase FTPMM has good fault isolation and suppression capabilities under winding fault.

This paper explores some design parameters of an interior permanent magnet synchronous motor that contribute to enhancing motor performance. Various geometry parameters such as magnet dimension, machine diameter, stator teeth height, and number of poles are analyzed to compare overall torque, power, and torque ripples in order to select the best design parameters and their ranges. Pyleecan, an open-source software, is used to design and optimize the motor for electric vehicle applications. Following optimization with Non-dominated Sorting Genetic Algorithm (NSGA-II), two designs A and B were obtained for two objective functions and the corresponding torque ripples values of the design A and B were later reduced by 32% and 77%. Additionally, the impact of different magnet grades on the output performances is analyzed.

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Today, electric motors play an important role in energy production in the world. For this reason, it is very important to improve the parameters of the electric motor in order to promote the performance of the motor. One of the ways to improve the performance of electric motors is to use permanent magnets in the structure of induction motors. These types of motors are known as line start motors. The use of permanent magnets eliminates ohmic losses and increases efficiency. Due to the fact that permanent magnetism plays the most important role in these motors, the smallest change in the magnetic properties of them will cause malfunction of the machine. One of the phenomena that changes the properties of the permanent magnet is demagnetization. Although this phenomenon has very destructive effects on machine performance, the design of electric motors is still done without considering this issue. In this paper, a line start motor is designed. This motor is simulated under different demagnetization conditions. The simulation results show that the performance and efficiency of the motor in the demagnetization mode is significantly reduced. Also, the increased current in demagnetized motors causes a further decrease in the magnet's properties. This effect is progressively repeated many times until the property of the applied permanent magnet is lost. Finally, an analytical model for examining and designing electric motors, considering the effects of demagnetization, was presented. The results showed that the use of the analytical model of motor design considering the effects of demagnetization can be a suitable alternative to the use of conventional methods in the design of electric motors. [ABSTRACT FROM AUTHOR]

This paper proposes a stator core design to achieve variable-flux characteristics enhanced by magnetic saturation in fractional-slot concentrated winding (FSCW) permanent-magnet (PM) motors without additional excitation systems, complicated structures, or active controls. Magnetic saturation induced at suitable locations can enhance variable-flux characteristics because the PM flux linkage is variable with the magnetic saturation in cores. In distributed winding configurations, magnetic saturation is induced symmetrically for each rotor pole by the fundamental that is dominant in the spatial distribution of the air-gap flux density. The magnetic saturation at each rotor pole can enhance variable-flux characteristics. In FSCW configurations, magnetic saturation is not induced symmetrically for each rotor pole because of several dominant space harmonics. The magnetic saturation at several rotor poles cannot enhance variable-flux characteristics. In the proposed design, the stator core has thin tooth tips for inducing magnetic saturation. The magnetic saturation in the stator core achieves the variable-flux characteristics that are effective for expanding the operating region or decreasing electromotive force and increasing torque. The efficacy of the proposed design is determined by estimating motor performance through a finite element method analysis and demonstrating the actual motor performance of a prototype. [ABSTRACT FROM AUTHOR]

Abstract Permanent magnet (PM) motor with consequent pole (CP) rotor can improve the PM utilisation ratio. However, one group of PMs with the same polarity is replaced by iron core, which deteriorates the electromagnetic performances of the motor, including asymmetric air‐gap magnetic field and larger torque ripple. To solve this problem, this study analyses the relationship between the torque ripple and the stator‐rotor magnetomotive force (MMF) harmonics, determines the harmonic orders causing the torque ripple of the CP PM (CPPM) motor, and proposes an unequal‐turn four‐layer winding structure which can eliminate the determining harmonics in the stator MMF. Furthermore, the electromagnetic performances of the CPPM motors with the proposed winding structure and traditional CPPM motors are investigated by the finite‐element analysis. It is verified that the CPPM motor with the proposed structure has better motor performances.

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.

Permanent magnet (PM) motors are gaining prominence in subsea applications such as drilling, pumping, and boosting for oil and natural gas extraction. These motors are gradually replacing traditional induction motors. However, starting and operating PM motors at low speeds under heavy loads poses significant challenges. This is because of unknown initial rotor positions and resistive voltage drops due to the presence of a sinewave filter, transformer, and long cable. An unknown rotor position may result in temporary reverse speed, which may cause a loss of synchronism; therefore, initial rotor position estimation is preferable. Additionally, addressing the voltage drop issue requires careful voltage compensation to avoid transformer core saturation. In this paper, an enhanced V/Hz starting of a PM motor is proposed with initial position detection (IPD) and voltage compensation to start the motor reliably with a heavy load. The proposed control method is verified with controller hardware in the loop (C-HIL) real-time simulation using a Typhoon HIL-604 emulator and a Texas Instruments TMS320F28335 digital signal processor (DSP) control card.

Copyright of Uranium Geology is the property of Uranium Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposes a novel torque measurement and control technique for cycling-assisted electric bikes (E-bikes) considering various external load conditions. For assisted E-bikes, the electromagnetic torque from the permanent magnet (PM) motor can be controlled to reduce the pedaling torque generated by the human rider. However, the overall cycling torque is affected by external loads, including the cyclist's weight, wind resistance, rolling resistance, and the road slope. With knowledge of these external loads, the motor torque can be adaptively controlled for these riding conditions. In this paper, key E-bike riding parameters are analyzed to find a suitable assisted motor torque. Four different motor torque control methods are proposed to improve the E-bike's dynamic response with minimal variation in acceleration. It is concluded that the wheel acceleration is important to determine the E-bike's synergetic torque performance. A comprehensive E-bike simulation environment is developed with MATLAB/Simulink to evaluate these adaptive torque control methods. In this paper, an integrated E-bike sensor hardware system is built to verify the proposed adaptive torque control. [ABSTRACT FROM AUTHOR]

The aerodynamic noise test platform for a certain type of unmanned aerial vehicle (UAV) imposes strict requirements on the drive motor, demanding high torque, small diameter, and low vibration. Compared to DC motors and induction motors, permanent magnet motors have advantages in terms of torque and volume, making them well-suited to meet the platform’s requirements. In response to the development needs of the test platform for the drive motor, this study systematically analyzes the key technologies that require special attention in the design process of the permanent magnet motor. Through proper electromagnetic design, structural design, cooling design, and vibration design, particularly by verifying the electromagnetic performance under rated load and weak magnetic conditions, a 180 kW permanent magnet motor was manufactured for experimental validation. The motor was successfully utilized for propeller aerodynamic noise testing. The experimental results demonstrate that the 180kW permanent magnet motor meets the technical requirements of the test platform, confirming the accuracy of the permanent magnet motor design methodology. It provides a valuable reference for the design of similar propeller drive motors and holds practical engineering significance.

The development of electrification has put forward higher requirements for the efficiency and power density of permanent magnet motors. The combination of formed flat wire windings and open slots with rectangular cross-sections has been applied in permanent magnet motors, which makes the motor torque fluctuate significantly, and the vibration and noise caused by it seriously influence the stability of operation. Therefore, it is essential to study the torque characteristics for permanent magnet motors with formed windings. The open slot brings rich tooth harmonics to the air-gap magnetomotive force. In this study, an analytical model of the motor magnetic field was established based on magnetic potential and relative permeance theory. According to the Lorentz force law, an analytical model of the instantaneous torque of the permanent magnet motor with a formed winding is derived. The model points out that under the modulation of the relative permeance function, the constant torque and torque fluctuation are generated after the interaction of the stator magnetomotive force and rotor magnetic potential that meet the corresponding harmonic order relationship, and the order of the torque fluctuation is a multiple of 6. According to the analytical model, different torque components of the permanent magnet motor with formed windings are calculated and verified by the finite element method.

In permanent magnet motors, the stator resistance and magnetic flux of the magnet change as the temperature increases. These changes result in a change in the maximum torque point per unit ampere (MTPA) of the motor. Without adequate compensation, this leads to a decrease in output torque. For this reason, look-up table (LUTs) are prepared over the temperature range and used for interpolation. This paper proposes a method to compensate for the output torque reduction due to a temperature increase using only a single LUT prepared at a base temperature. First, an estimation of the magnetic flux linkage and the output torque using a single LUT is performed. Second, the problem is modeled as a limited optimization problem to minimize the loss due to the torque reduction. The magnetic flux linkage and output torque are calculated in real time through the fundamental active power. The compensation value is calculated using the Lagrange multiplier method, an optimization technique, using the estimated magnetic flux linkage and output torque. The proposed method is verified by comparing it with other algorithms through simulation and experiment.

Split ratio, i.e. the ratio of stator inner diameter to outer diameter, has a closed relationship with electromagnetic performance of permanent magnet (PM) motors. In this paper, the toroidal windings with short end-winding axial length are employed in the 6-slot/2-pole (6s/2p) PM motor for high speed applications. The split ratio is optimized together with the ratio of inner slot to outer slot area, i.e. slot ratio, considering stator total loss (stator iron loss and copper loss). In addition, the influence of maximum stator iron flux density and tooth-tip on the optimal split ratio, slot ratio, and average torque is investigated. The analytical predictions show that when the slot ratio is 0.5, the maximum torque can be achieved, and the optimal split ratio increases with the decrease of slot ratio, as confirmed by the finite element (FE) analyses. Finally, some of predicted results are verified by the measured results of 6s/2p prototype motor with 0.5 slot ratio.

With the advantages of high power density, the hybrid axial transverse flux permanent magnet motor (HATF-PMM) is investigated in this paper. Eight topologies of the novel HATF-PMM are proposed, analysed and compared. The applicable scopes of different topologies are summarized and the optimal topology is selected. Based on the characteristics of hybrid flux motor, an indirect optimization method through magnetic circuit decoupling and recombination is proposed. The rotor parameter optimization is performed by the proposed indirect optimization method. In the end, the HATF-PMM scheme with high power density is obtained, and the optimization law of HATF-PMM rotor parameters is revealed through the optimization process, which proves that the HATF-PMM has great potential in the application of more-electric aircraft.

Aiming at the problems of large amount of rare earth materials and too high cogging torque of traditional rare earth permanent magnet motor,an asymmetrical hybrid magnetic pole permanent magnet motor structure was proposed.The equivalent magnetic circuit model was established,parametric modeling was carried out for the motor,and ferrite width and other motor parameters were selected for sensitivity analysis.According to sensitivity results,the hybrid algorithm combining the BBD algorithm and the MOGA- Ⅱ method and the CCD multi-objective algorithm were used for optimization,so as to determine the optimal size parameters of the motor,and analyze and compare the electromagnetic performance of the asymmetric hybrid permanent magnet motor and the traditonal V-type motor.The results show that compared with the traditional V-type motor,the torque ripple and cogging torque of the asymmetrical hybrid permanent magnet motor are reduced by 14% and 71%,respectively,and the amount of Ndfeb material used is reduced by 14.3%.The proposed new type of asymmetric hybrid permanent magnet motor for electric vehicles effectively solves the problems such as large amount of rare earth materials and too high cogging torque,which provides a certain theoretical reference for automobile permanent magnet motor.

Benefiting from driving by an electric motor, an electric tractor is one of the most effective means to realize green agricultural production with high efficiency, zero emission, and low noise. The field and road operating conditions can usually occur in electric tractors. Specifically, the typical speed of the former is 2-7, and 7-10 km/h, whereas, the latter is mainly used in the condition of transportation with the speed of 20-35 km/h. The speed of an electric tractor can be in the discrete form in the very wide range of speed regulation. In this study, a pole-changing doubly-salient permanent magnet (PC-DSPM) motor was proposed using the PC operation. Different output characteristics were also obtained to meet the special operation of electric tractors. The working components were firstly selected as the 2, 4, 10, and 16 pole-pairs harmonics with the higher amplitude, according to the general air-gap field modulation. Then, four working harmonics were divided into two groups, in terms of the slot pitch angles. As such, the coil electromotive force (EMF) phasor graphs under the working harmonics of Group 1 were totally different from that of Group 2, in order to achieve the PC operation using different winding connections. Three kinds of armature winding connections were then designed using the coil EMF phasor graphs. Thus, three operating modes of the PC-DSPM motor were achieved to select one or two groups of working harmonics in the electromechanical energy conversion using the filtering effect of armature winding. Two PC switching points were determined in the constant power region with the mechanical characteristic curves of the PC-DSPM motor under three modes. The motor speed was divided into low (0-920 r/min), medium (920-1 250 r/min), and high speed (1 250-3 900 r/min). In terms of the gear-box with a fixed ratio of 18 and the wheels with a diameter of 0.8 m, the speeds of electric tractors in the three modes were 0-7.7, 7.7-10.5, and 10.5-32.7 km/h, respectively, in order to meet the speed demands of field and road operations. Furthermore, an electronic PC method was proposed to change the current angles and the armature winding connection for continuous PC operation. Two sets of three-phase windings were controlled by a six-leg inverter under the dual three-phase control theory. The current angle in each coil was then controlled independently. Active disturbance rejection control (ADRC) was designed in the current loop of the control system for the PC-DSPM motor. The real-time disturbance was reduced and then suppressed during the PC process. In addition, a tracking differentiator (TD) was also used to arrange the switching of the current angle. The current was smoothed without overshoot after arrangement. The simulation and experimental analysis of the PC-DSPM motor were performed at the first PC switching point (920 r/min, 4.75 N·m), and the second one (1 250 r/min, 3.4 N·m). The operation transitions were shifted from mode Ⅲ to Ⅱ, and the mode Ⅱ toⅠ in the PC-DSPM motor under the current phase. The performances during TD-based electronic PC operation using ADRC were compared with the traditional step response. The current loop of the latter also adopted the ADRC strategy, indicating the better performance of TD electronic PC. The results showed that during the PC processes at the first switching points, although the PC transient time were prolonged to 400 ms when the tracking differentiator electric PC strategy was adopted, the switching of current in d-axis presented a smooth trend from 3.6 and 3 A to 4.6 and 0.2 A, and current in q-axis also presented a smooth trend from 2.7 and 3.2 A to 1.5 and 4.7 A. Similarly, the PC transient time were prolonged to 600 ms when the tracking differentiator electric PC strategy was adopted at the second PC switching point, but the switching of current in d-axis presented a smooth trend from 4.2 and 1.2 A to 0.2 and 4.2 A, and current in q-axis also presented a smooth trend from 0.2 and 4 A to 4 and 0.2 A, respectively, so that the torque ripple of PC-DSPM motor were reduced 8.5% and 11.8%, respectively, compared with those of the step PC method. Thus, the speed of motor can be stable at 920 and 1 250 r/min. The research provided a better solution to expend speed range for field operations and road operations of electric tractors and realize a smooth PC switching of PC permanent magnet motors. [ABSTRACT FROM AUTHOR]

Permanent magnet (PM) motor with consequent pole (CP) rotor can improve the PM utilisation ratio. However, one group of PMs with the same polarity is replaced by iron core, which deteriorates the electromagnetic performances of the motor, including asymmetric air‐gap magnetic field and larger torque ripple. To solve this problem, this study analyses the relationship between the torque ripple and the stator‐rotor magnetomotive force (MMF) harmonics, determines the harmonic orders causing the torque ripple of the CP PM (CPPM) motor, and proposes an unequal‐turn four‐layer winding structure which can eliminate the determining harmonics in the stator MMF. Furthermore, the electromagnetic performances of the CPPM motors with the proposed winding structure and traditional CPPM motors are investigated by the finite‐element analysis. It is verified that the CPPM motor with the proposed structure has better motor performances. [ABSTRACT FROM AUTHOR]