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Design and Optimization of High Power/Torque Density Permanent Magnet Machines

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A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "F: Electrical Engineering".

Deadline for manuscript submissions: closed (25 July 2023) | Viewed by 36785

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Special Issue Editors

Prof. Dr. Guang-Jin Li

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Guest Editor

Electrical Machines and Drives Group, Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
Interests: permanent magnet machines and switched reluctance machines; fault tolerance, fault modelling and diagnostics; thermal management; renewable energy; electrical/hybrid vehicles and more electrical aircraft

Dr. Xiao Chen

E-Mail Website
Guest Editor

Electrical Machines and Drives Group, Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
Interests: manufacturing-led innovation in electrical machines; multi-phase fault tolerant electrical machines for more electric aircraft; digital twin of electrical machines and drive; high-speed electrical machines for traction; low-cost electrical machines; powertrain energy management for electric vehicles

Special Issue Information

Dear Colleagues,

Electrical machines have long been regarded as the backbone of industry. This is particularly the case for permanent magnet (PM) machines, owing to their high torque/power density, high efficiency and also high fault tolerance capability. As we move towards a more sustainable carbon-neutral future, there exists enormous potential to exploit the benefits of PM machines across many different industries, including automotive (e.g., electric and hybrid electric vehicles), aerospace (e.g., more electric and all electric aircraft) and renewable energy (e.g., offshore wind, tidal power). Due to the sheer number of PM machines that will be employed in the coming decades, even a modest increase in their power density and efficiency achieved through novel design and optimization will bring significant benefits to our society. For these reasons, we are inviting submissions to a Special Issue of Energies, regarding the ‘Design and Optimization of High Power/Torque Density Permanent Magnet Machines’.

This Special Issue aims to provide a forum for researchers from both academia and industry to exchange their recent achievements within the scope of PM machine topologies, novel design and optimization approaches, novel machine topologies, multiphysics modelling, and the application of PM machines. Detailed topics include but are not limited to:

Novel PM machine and actuator topologies;
Machine design and optimization;
Machine performance analysis;
Analytical and numerical modelling;
Coupled multiphysics analysis;
Advanced thermal management of PM machines;
Fault modelling and diagnostics of fault-tolerant PM machines;
Other issues such as NVH in PM machines.

Prof. Dr. Guang-Jin Li
Dr. Xiao Chen
Guest Editors

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Keywords

novel design approach
analytical and numerical modelling
PM machines and actuators
novel PM machine topologies
optimization algorithm
magnetic materials
electromagnetic looses
power density
multiphysics modelling
thermal management
fault tolerant capability
fault modelling and diagnostics
NVH (noise, vibration, and harshness)

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Published Papers (12 papers)

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17 pages, 9896 KiB

Open AccessArticle

Electromagnetic Performance Investigation of Rectangular-Structured Linear Actuator with End Ferromagnetic Poles

by Zahoor Ahmad, Basharat Ullah, Faisal Khan, Shafaat Ullah and Irfan Sami

Energies 2023, 16(15), 5758; https://doi.org/10.3390/en16155758 - 2 Aug 2023

Cited by 1 | Viewed by 1703

Abstract

Saving energy from domestic appliances is a focus in the effort to combat energy challenges. Linear compressors are a more efficient alternative to the traditional compressors used in refrigerators, which account for 20–40% of all residential electricity use. This article investigates the new topology of the moving magnet (MM), dual-stator single-mover linear oscillating actuator (DSSM-LOA) for linear compressor application. Both the stators were C-shaped, with coils looped across their end sides. Two permanent magnets (PMs) that were axially magnetized were housed on the mover. The PM structural shape significantly affected its fabrication cost and magnitude of magnetic flux density (

B

). The DSSM-LOA makes use of axially magnetized rectangular-shaped PMs because they are inexpensive and generate high electromagnetic (EM) force density. End ferromagnetic core materials were used to improve the magnetic flux, linking from the stator to the mover. All the design parameters were optimized through parametric analysis using the finite parametric sweep method. Parameters present within the three primary parameters (length, height, and depth) that were assumed constants were optimized, and the optimal dimensions were selected based on the EM force. The investigated DSSM-LOA was contrasted with traditional LOA designs, and they showed significant improvement in EM force per ampere, generally named motor constant (MC), MC per PM mass, MC density, cogging force, and stroke. Additionally, the proposed DSSM-LOA had a simple structure and low cost, and it operated in a feasible range of strokes for linear compressor application. Full article

(This article belongs to the Special Issue Design and Optimization of High Power/Torque Density Permanent Magnet Machines)

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14 pages, 6989 KiB

Open AccessArticle

Optimizing the Design of an Interior Permanent Magnet Synchronous Motor for Electric Vehicles with a Hybrid ABC-SVM Algorithm

by Jong-Woon Park, Min-Mo Koo, Hyun-Uk Seo and Dong-Kuk Lim

Energies 2023, 16(13), 5087; https://doi.org/10.3390/en16135087 - 30 Jun 2023

Cited by 8 | Viewed by 2492

Abstract

This paper presents a comprehensive investigation of the optimal design of an interior permanent magnet synchronous motor (IPMSM) for electric vehicles (EVs), utilizing the hybrid artificial bee colony algorithm–support vector machine (HAS) algorithm. The performance of the drive motor is a crucial determinant of the overall vehicle performance, particularly in EVs that rely solely on a motor for propulsion. In this context, interior permanent magnet synchronous motors (IPMSMs) offer a compelling choice due to their high torque density, wide speed range, superior efficiency, and robustness. However, accurate analysis of the nonlinear characteristics of IPMSMs necessitates finite element analysis, which can be time-consuming. Therefore, research into methods for deriving an optimal model with minimal computation is of significant importance. The HAS is a powerful multimodal optimization technique that is capable of exploring several optimal solutions. It enhances the navigation capability by combining the artificial bee colony algorithm (ABC) with the kernel support vector machine (KSVM). Specifically, the algorithm improves the search ability by optimizing the movement of bees in each region generated by the KSVM. Furthermore, hybridization with the Nelder–Mead method ensures accurate and quick convergence at pointers discovered in the ABC. To demonstrate the effectiveness of the proposed algorithm, this study compared its performance with a conventional algorithm in two mathematical test functions, verifying its remarkable performance. Finally, the HAS algorithm was applied to the optimal design of the IPMSM for EVs. Overall, this paper provides a thorough investigation of the application of the HAS algorithm to the design of IPMSMs for electric vehicles, and its application is expected to benefit from the combination of machine-learning techniques with various other optimization algorithms. Full article

(This article belongs to the Special Issue Design and Optimization of High Power/Torque Density Permanent Magnet Machines)

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15 pages, 3874 KiB

Open AccessArticle

Modelling and Analysis of Inter-Turn Short-Circuit Faults for Large-Power SPM Wind Generators

by Zeting Mei, Guangjin Li, Ziqiang Zhu, Richard Clark, Arwyn Thomas and Ziad Azar

Energies 2023, 16(12), 4723; https://doi.org/10.3390/en16124723 - 15 Jun 2023

Cited by 2 | Viewed by 1421

Abstract

This paper proposes a general analytical model for large-power surface-mounted permanent magnet (SPM) wind generators under inter-turn short-circuit (ITSC) faults. In the model, branch currents rather than phase currents are used as state variables to describe the electromagnetic behavior of the faulty machine. In addition, it is found that the multiphase Clarke transformation can be used to simplify the proposed fault model with the inductances calculated analytically or numerically using finite element analysis. With the latter, both linear and nonlinear inductances can be obtained, and the non-linear inductances are used for the fault modelling of large power rating machines due to larger electrical loading and heavier magnetic saturation. With the developed fault model, studies of scaling effects (different power ratings such as 3 kW, 500 kW and 3 MW) and the influence of fault location on the electromagnetic performance of SPM generators with series-parallel coil connections have been carried out. The simulation results show that large-power SPM wind generators are vulnerable to ITSC faults when a relatively small number of turns are short-circuited and a single-turn short-circuit fault at the top of the slot is found to be the worst case. Full article

(This article belongs to the Special Issue Design and Optimization of High Power/Torque Density Permanent Magnet Machines)

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16 pages, 7225 KiB

Open AccessArticle

Coupled Electromagnetic–Thermal Modelling of Dynamic Performance for Modular SPM Machines

by Wei Zhang, Guang-Jin Li, Zi-Qiang Zhu, Bo Ren and Yew Chuan Chong

Energies 2023, 16(6), 2516; https://doi.org/10.3390/en16062516 - 7 Mar 2023

Cited by 2 | Viewed by 1701

Abstract

This paper presents coupled electromagnetic (EM)–thermal modelling of the steady-state dynamic performances, such as torque speed curve and the efficiency map, for surface-mounted permanent magnet machines. One important feature of such a model is that it considers the demagnetization caused by magnet temperature rise at different rotor speeds. EM-only simulations, which often assume that the machines operate under constant temperature, have been widely used in the literature. However, the interaction between EM and thermal performances could lead to very different dynamic performance prediction. This is because the material properties, e.g., magnet remanence, coercivity, and copper resistivity are temperature-dependent. The temperature rise within electrical machines reduces torque/power density, PM eddy current losses, and iron losses but increases copper loss. Therefore, the coupled EM–thermal modelling is essential to determine accurate temperature variation and to obtain accurate EM performances of electrical machines. In this paper, the coupled EM–thermal modelling is implemented for both modular and non-modular machines to reveal the advantages of the modular machine under different operating conditions. The results show that the modular machine generally has better dynamic performance than the non-modular machine because the introduced flux gaps in alternate stator teeth can boost both EM and thermal performance. Full article

(This article belongs to the Special Issue Design and Optimization of High Power/Torque Density Permanent Magnet Machines)

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40 pages, 20267 KiB

Open AccessArticle

Influence of Armature Reaction on Electromagnetic Performance and Pole Shaping Effect in Consequent Pole Pm Machines

by Ji Qi, Ziqiang Zhu, Luocheng Yan, Geraint W. Jewell, Chengwei Gan, Yuan Ren, Simon Brockway and Chris Hilton

Energies 2023, 16(4), 1982; https://doi.org/10.3390/en16041982 - 16 Feb 2023

Cited by 2 | Viewed by 2296

Abstract

Consequent pole permanent magnet (CPPM) machines can improve the ratio of average torque to PM volume, but suffer from more serious armature reactions. In this paper, the variations of electromagnetic performance of surface-mounted PM (SPM), conventional CPPM machines, and pole-shaped CPPM machines with armature reaction at currents up to 5 times overload are analyzed and compared. The flux densities, flux linkages, back EMFs, inductances, torque characteristics, and demagnetization withstand capabilities are analyzed by the finite element method (FEM) and frozen permeability method. It is validated that the third order harmonics in inductances for CPPM machines tend to be reduced as current rises since the saturation in iron pole is prone to reducing the saliency effect. But the armature reaction tends to result in the increase of torque ripple components for all the machines. It is also found that the overall torque ripple of asymmetric pole-shaped machine tends to increase significantly under overload conditions. On the contrary, the symmetrical pole-shaped machine can maintain a relatively stable torque ripple under overload conditions which is similar to the SPM counterpart. Additionally, due to the large armature reactions, CPPM machines suffer from weaker demagnetization withstand capabilities and weaker overload capabilities than their SPM counterparts. Four CPPM prototypes with and without pole shaping are tested to confirm the FEM analysis. Full article

(This article belongs to the Special Issue Design and Optimization of High Power/Torque Density Permanent Magnet Machines)

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11 pages, 3685 KiB

Open AccessArticle

Analysis and Comparison of Permanent Magnet Synchronous Motors According to Rotor Type under the Same Design Specifications

by Woo-Sung Jung, Hoon-Ki Lee, Young-Keun Lee, Su-Min Kim, Jeong-In Lee and Jang-Young Choi

Energies 2023, 16(3), 1306; https://doi.org/10.3390/en16031306 - 26 Jan 2023

Cited by 11 | Viewed by 9007

Abstract

A surface-mounted permanent magnet synchronous motor (SPMSM) is an electric motor with a simple magnetic circuit design, fast responsiveness, linear torque–current characteristics, speed–voltage characteristics, and constant operating speed. SPMSMs use only magnetic torque; however, interior PMSMs (IPMSMs) have high power densities because they can use reluctance torque. In addition, when flux-weakening control is used, the operating range is wide compared with the SPMSM. This study presents a comparative analysis of the characteristics of SPMSM and bar-type IPMSM. Characteristic analyses are performed by setting the same stator shape, rated speed, number of turns, winding specifications, voltage limit, and magnet usage in a pole/slot combination of six poles and 27 slots. Next, we compare the no-load back electromotive force, cogging torque, and loss characteristics, and perform a characteristic analysis of each model while satisfying the design specifications. No-load and load tests are performed using a back-to-back system. The results of the analysis and experimental results are in good agreement, and the reliability of the analysis results is guaranteed. The SPMSM is approximately 8.5% superior to the IPMSM in terms of core loss, and the eddy current loss is greater than that of the IPMSM. Full article

(This article belongs to the Special Issue Design and Optimization of High Power/Torque Density Permanent Magnet Machines)

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14 pages, 7677 KiB

Open AccessArticle

A General Pattern-Based Design Optimization for Asymmetric Spoke-Type Interior PM Machines

by Jiahui Huang, Weinong Fu, Shuangxia Niu, Xing Zhao, Yanding Bi and Zhenyang Qiao

Energies 2022, 15(24), 9385; https://doi.org/10.3390/en15249385 - 12 Dec 2022

Cited by 3 | Viewed by 1759

Abstract

A novel asymmetric spoke-type interior permanent magnet (AS-IPM) machine is proposed in this paper. It utilizes the magnetic-field-shifting (MFS) effect to improve the torque performance, which achieves a high utilization ratio of both permanent magnet (PM) torque and reluctance torque. In addition, a general pattern of rotor topologies is proposed to represent all possible machine structures. Various rotor structures can be obtained by changing the design parameters of the general pattern. A non-dominated sorting genetic algorithm II (NSGA-II) is adopted to automatically search for optimal rotor configurations. With the aid of the optimization program, an asymmetric spoke-type rotor structure with improved performance is obtained. To showcase the advantages of the proposed machine, the electromagnetic performance is compared between a conventional spoke-type interior permanent magnet (S-IPM) machine and a proposed AS-IPM machine. The finite-element simulation results show that the optimal design of the AS-IPM performs a 7.7% higher output torque ripple due to the MFS effect while the total PM volume remains the same. Meanwhile, the torque ripple of the proposed structure is significantly reduced by 82.1%. Full article

(This article belongs to the Special Issue Design and Optimization of High Power/Torque Density Permanent Magnet Machines)

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9 pages, 6101 KiB

Open AccessArticle

Design of a Chamfered Structure on Consequent-Pole Vernier Permanent-Magnet Machine

by Jien Ma, Bowen Xu, Qiyi Wu, Chao Luo, Qiu Lin and Youtong Fang

Energies 2022, 15(20), 7780; https://doi.org/10.3390/en15207780 - 20 Oct 2022

Cited by 2 | Viewed by 1851

Abstract

The consequent-pole (CP) Vernier permanent-magnet (VPM) machine has been developed over the last decade. In VPM machine, the CP structure can produce considerable torque with a half volumn of the PMs compared with the regular structure, so the cost is reduced and the mechanical strength is increased. In this paper, an improvement of chamfering structure on a CPVPM machine is proposed to alleviate the flux leakage and increase the torque density. The chamfered structure is easily machined and will not influence the robustness of the rotor. The comparison results show that under the same volume and copper loss constraint, the proposed structure has smaller cogging torque, smaller torque ripple, larger torque density and larger power factor. Full article

(This article belongs to the Special Issue Design and Optimization of High Power/Torque Density Permanent Magnet Machines)

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18 pages, 12263 KiB

Open AccessArticle

Vibration and Noise Optimization of Variable-Frequency-Driven SPMSM Used in Compressor Based on Electromagnetic Analysis and Modal Characteristics

by Jiabo Shou, Jien Ma, Zhiping Zhang, Lin Qiu, Bowen Xu, Chao Luo, Binqi Li and Youtong Fang

Energies 2022, 15(20), 7474; https://doi.org/10.3390/en15207474 - 11 Oct 2022

Cited by 2 | Viewed by 2022

Abstract

The high-frequency electromagnetic noise caused by a frequency converter power supply has become the main composition of the vibration and noise of frequency-converter-driven PMSMs. Determining how to reduce this kind of noise is very important to improve motor performance. This paper analyzes the frequency characteristics of the high-frequency noise generated by an inverter, using the magnetic circuit analysis and Maxwell tensor methods. The switching frequency and the natural frequencies of the main modes are optimized according to the modal characteristics of the motor in order to reduce the vibration and noise of the motor. The results show that the high-frequency electromagnetic vibration and noise generated by the inverter is mainly caused by the high-frequency switching harmonic current. The frequencies of the vibration and noise are related to the switching frequency and the modulation wave frequency. At the same time, the simulation calculation of the natural frequencies of the main modes and the noise spectrum obtained from the experiment provide direction for the optimization of the vibration noise near the switching frequency. The switching frequency optimization and the natural frequency optimization based on the main modes of the motor can effectively reduce vibration and noise. This work has certain reference significance for the design of low-noise PMSMs. Full article

(This article belongs to the Special Issue Design and Optimization of High Power/Torque Density Permanent Magnet Machines)

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18 pages, 7279 KiB

Open AccessArticle

A Balancing Method for Multi-Disc Flexible Rotors without Trial Weights

by Xun Sun, Yue Chen and Jiwen Cui

Energies 2022, 15(14), 5088; https://doi.org/10.3390/en15145088 - 12 Jul 2022

Cited by 2 | Viewed by 2177

Abstract

Rotor dynamic balancing is a classical problem. Traditional balancing methods such as the influence coefficient method and the modal balancing method, have low balancing efficiency because they need to run many times to add trial weights. Although the model-based balancing method improves the balancing efficiency, it cannot accurately identify the position, amplitude and phase of each unbalance fault for rotors with multi-disc structures, so it is difficult to apply it to actual balancing. To solve the above problems, based on the traditional modal balancing theory, this paper deduces that the continuous and isolated unbalance in the rotor-bearing system can be represented by isolated unbalance on several balancing planes approximately. The model-based method is used to identify the above-mentioned equivalent isolated unbalances, and then the corrected mass is added to the balancing planes so as to complete the balance of multiple flexible rotor without trial weights. Considering the practical situation, the proposed balancing method includes two steps: low-speed balancing and high-speed balancing. The proposed balancing method is verified using three and four-disc rotors. The simulation results show that the balancing method can effectively reduce the vibration of the flexible rotor after low-speed and high-speed balancing, and the amplitude at the measurement point is reduced by 79.74~97.60%, respectively. Full article

(This article belongs to the Special Issue Design and Optimization of High Power/Torque Density Permanent Magnet Machines)

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15 pages, 6925 KiB

Open AccessArticle

An n^th Harmonic Current Suppression Method Based on the Impulse Current PWM Technique for a Multi-Phase Permanent Magnet Synchronous Motor Fed with a Current Source Inverter

by Chao Chen, Zhen Chen, Congzhe Gao, Jing Zhao, Xiangdong Liu and Xiaoyong Sun

Energies 2022, 15(12), 4394; https://doi.org/10.3390/en15124394 - 16 Jun 2022

Cited by 3 | Viewed by 1870

Abstract

Among the existing harmonic current suppression methods, it is difficult and complicated to suppress any n^th harmonic current accurately for multi-phase permanent magnet synchronous motors (PMSMs). To solve this problem, this paper takes a five-phase dual-rotor PMSM fed with a current source inverter (CSI) as an example, and proposes an n^th harmonic current suppression method based on the impulse current PWM algorithm. Firstly, the analysis is conducted and presented for the n^th harmonic current in the m^th harmonic space. Then, based on the Sliding Discrete Fourier Transformation (SDFT), a low-pass filter (LPF) named SDFT-LPF is designed. Additionally, the impulse current PWM technique for the five-phase CSI is realized. In this paper, the experiments have confirmed that the SDFT-LPF has good filter performance. Compared with the SVPWM, the impulse current PWM technique has the same DC-link current utilization rate, but it is easier to implement. Moreover, the proposed harmonic current control method can accurately control any n^th harmonic current without changing the PWM technique, which has significantly reduced the complexity of the harmonic current control. Additionally, the proposed scheme is easy to implement and can be directly extended to the multiple harmonic current’s control. Full article

(This article belongs to the Special Issue Design and Optimization of High Power/Torque Density Permanent Magnet Machines)

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Review

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29 pages, 10208 KiB

Open AccessEditor’s ChoiceReview

Cooling Techniques in Direct-Drive Generators for Wind Power Application

by Petrica Taras, Reza Nilifard, Zi-Qiang Zhu and Ziad Azar

Energies 2022, 15(16), 5986; https://doi.org/10.3390/en15165986 - 18 Aug 2022

Cited by 13 | Viewed by 6725

Abstract

Direct-drive generators are an attractive candidate for wind power application since they do not need a gearbox, thus increasing operational reliability and reducing power losses. However, this is achieved at the cost of an increased generator size, larger inverter and decreased thermal performance. The associated cooling system is therefore crucial to keep the generator and inverter sizes down and to operate within the safe thermal limits. Various cooling techniques suitable for generators are therefore reviewed and analyzed in this paper. The performance and maintenance requirements are unavoidable compromises that need to be investigated together, especially for large generators. The location of the wind turbine is also important and dictates critical issues such as accessibility and maximum size. The key novelty in this paper is the assessment of the cooling methods based on generator size, reliability and maintenance requirements. Full article

(This article belongs to the Special Issue Design and Optimization of High Power/Torque Density Permanent Magnet Machines)

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