IPM Spoke Motor Performance Improvement Using a Normal Saliency Rotor Design

Introduction: The non-renewable nature of rare-earth materials and their increasing demand have led to rising prices for rare-earth Permanent Magnet (PM) materials, thereby increasing the manufacturing costs of the corresponding motors. Reducing reliance on rare-earth materials while ensuring the operating performance of motors has attracted significant research attention, resulting in fewer rare-earth permanent magnet synchronous motors emerging in this context. This paper introduces a less rare-earth Permanent Magnet Synchronous Motor (PMSM) with a novel rotor permanent magnet structure, which has been designed, analyzed, and optimized. The primary feature of this motor is the stepped structure of the rotor, composed of neodymium iron boron, which enhances overall performance. Methods: The proposed motor is designed, simulated and analyzed by using the finite element analysis method using ANSYS Maxwell electromagnetic simulation software. Results: By improving the shape of the rotor neodymium-iron-boron permanent magnets, the motor offers the advantages of low cogging torque, low harmonic reverse Electromotive Force (EMF) at no load, and a more sinusoidal air-gap flux density waveform. This paper provides effective verification through simulation analysis. Discussion: The optimisation results of the motor are analysed in terms of rotor permanent magnet shape, main stage NdFeB angle, air gap length, NdFeB material, and number of motor coil turns. Conclusion: The proposed motor not only reduces the cogging torque and no-load back EMF harmonics, but it also makes the air gap flux density waveform closer to sinusoidal by optimizing the rotor structure while achieving the rated load torque requirement.

Permanent magnet motors are widely used in drive technology. The use of ferrite magnets in this type of machine is attractive due to their low cost, but its performance is usually poor due to the low flux density in the airgap. A new topology for the magnetic circuit is proposed, which uses the concept of axial flux concentration. It enables a substantial increase in the flux per pole, even with ferrite magnets, thereby improving motor performance at a low cost. It is shown that the effect is equivalent to using a fictitious magnet material, with augmented remanence and recoil permeability. The proposed topology is applied in a prototype synchronous motor. The improvement in its performance is confirmed by both experimental procedure and finite element modeling in three dimensions

In this paper, an optimum design for a single-phase line start permanent magnet (LSPM) motor with respect to efficiency, maximum torque, and starting torque is proposed. The design variables, objective functions, and constraints are selected for this optimum design, which is divided into three steps. Step I maximizes the rated efficiency while maintaining a balanced operation and minimizing the stator copper loss. Step II utilizes equivalent circuit analysis to consider the efficiency and the maximum torque, while Step III calculates the precise starting torque using finite element (FE) analysis. The validity of the optimum design is verified by comparing the efficiency, maximum torque, and starting torque characteristics of the time-step FE analysis with experimental results.

This paper uses the Taguchi method to optimize the manufacturing process and robust design of a low-cost permanent magnet motor with soft magnetic composite (SMC) cores. For the manufacturing process, SMC cores are produced by using the molding technology without any wire cutting costs. To maximize the relative permeability and minimize the core loss, the Taguchi method is employed to identify the best control factor values for the heat treatment of SMC cores based on a series of experimental results. Due to the manufacturing tolerances, there are significant uncertainties in the core densities and motor dimensions, which will result in big performance variations for the SMC motors in the batch production. To obtain a robust design less sensitive to these tolerances, the conventional Taguchi parameter design method and a sequential Taguchi optimization method are presented to maximize the average torque and minimize the core loss of a low-cost PM motor. Through comparison, it is found that the proposed optimization method is efficient. It can provide an optimal design with better motor performance and manufacturing quality. The proposed method will benefit the industrial production of cost-effective PM-SMC motors with robust and compact designs.

This paper proposes a dual notched design of radial-flux permanent magnet (PM) motors with gear-shaped structures on the PM and stator teeth aiming at lowering down cogging torque and rear earth material (REM). Due to the restriction on export quotas of REM, its cost is expected to rise drastically in the near future. The low cogging torque and REM in PM motor design, therefore, are of high significance. This paper presents a design taking a big step toward that direction. Four models with different mechanical angles and depths were designed. With the aid of 3-D finite element analysis and simulation, the one that best matched objectives was selected which resulted in percentage reduction of the cogging torque and REM up to 62.8% and 6.7%, respectively. In the transient simulation, the output torque of a dual notched PM motor compared with a normal structured one was reduced to 6.5% in average. A prototype was also fabricated to validate the design.

Soft magnetic composite (SMC) materials and SMC electromagnetic devices have undergone substantial development in the past decade. Much work has been conducted on designing and prototyping various types of electrical machine. However, the iron cores were often made by cutting existing SMC preforms that were formed by compacting SMC powder in simple cylinder or bar-shape molds, and the magnetic properties of the cores may deteriorate significantly during the cutting process. To investigate ldquoindustry production-readyrdquo products, this paper presents the design and analysis of a claw-pole permanent magnet (PM) motor with a molded SMC core of low mass density to replace the existing induction motor in a dishwasher pump. The magnetic properties of the molded SMC core are measured and utilized in the motor design and analysis. Finite element analysis (FEA) of magnetic field is carried out to accurately determine key motor parameters, and an improved phase variable model is applied to predict the motor performance. Both parameter computation and performance prediction are validated by the experimental results on the prototype.

This paper describes the results of studies on higher torque density of automotive auxiliary motors based on electromagnetic field analysis. Dual stator axial-gap PM motors achieve higher torque density than radial-gap motors in a flat motor shape. Therefore, an axial-gap motor was designed based on a design policy different from that in the past to reduce its volume by half of the radial-gap motors for automotive applications and was experimentally evaluated using a prototype motor. In order to improve the torque density, a double axial-gap motor structure was adopted to achieve wide torque generation areas and was optimally designed, reducing the volume by 44% compared with the existing model. It was experimentally evaluated using a prototype motor.

In this paper, a new hybrid permanent magnet variable leakage flux (VLF-HPM) motor is proposed. In order to enhance motor speed range, short arc-shaped and elliptical-shaped magnetic barriers are placed on the q-axis magnet circuit, realizing the so-called leakage flux effect. In addition, ferrite PMs are artfully designed, so self-leakage flux can be reduced while main flux is enhanced. The relationship among PM topology, flux barrier and flux-regulation capability are also investigated in detail. Finally, the electromagnetic performance of VLF-HPM motor is evaluated by the finite element analysis and compared with a conventional V-typed PM motor. It is noted that, compared with conventional V-typed PM motor, the VLF-HPM motor possesses lower core losses and a wider speed range, which offers a new research path for high-performance PM motor.

This paper extends the theory of the air-gap magnetic field in permanent-magnet (PM) brushless motors. Scalar and vector potential solutions to the field equations are brought together to unify many of the important practical methods already in use. The theory admits a more general representation of the magnetization vector than has been previously assumed, including both the radial and tangential components, and variation with radius. The work is applied in the design of PM motors where there is a requirement to minimize noise and torque ripple, and maximize efficiency, and a continuing need for improvements in the accuracy and rigor of design calculations. The air-gap flux-density distribution is at the heart of the design process, and it is desirable to study different magnetization patterns, including imperfections in the magnetization, for a wide range of magnet shapes. This paper shows the application of the analytical solutions in comparison with a new finite-element procedure, with test results on a prototype motor, and with simpler, older methods of calculation based on magnetic equivalent circuits. The comparison brings out many interesting points in relation to the accuracy and the speed and practicality of the various methods.

This paper deals with the design of high force density tubular linear permanent magnet motors for aerospace applications. The main requirements of aerospace applications such as force density and fault tolerance are considered in a general review of recent high force density linear machines, highlighting the merits and disadvantages of each motor. Analytical considerations, including two dimensional finite element analyses are used to compare the performance of two main tubular machine topologies, namely a single air-gap tubular motor with inset permanent magnets and its double air-gap counterpart. An experimental validation is presented comparing the predicted analytical results with the measured results on a built motor prototype.

In high speed applications, slotless PM motors appear an attractive solution, being almost insensitive to MMF harmonics and to PWM current ripple and exhibiting lower stator iron losses and rotor losses (significant with squarewave current control). This paper illustrates advantages and drawbacks of a high speed drive using a slotless PM motor. The difficulties have been found during the realization of a 30-krpm 1-kW PM motor prototype are also highlighted. A low-cost commercial sensorless BLDC motor controller has been used to force squarewave currents without a significant PWM ripple. In order to recognize a possible unexpected rotor arrest, that is not detected by the IC, an additional control circuit has been designed to detect that anomalous condition and to restart the motor when it occurs.

For years, design of conventional permanent magnet motors has been limited mainly to the variation of the stator winding function and little research has been made on stator pole modification as an alternative for motor design. Soft magnetic composites (SMCs) have opened up new possibilities for the 3-D pole shape design of both DC and AC machines owing to their isotropic properties, while having low conductivity. Here, a PM motor with trapezoidal shaped poles is presented and simulated. A modified trapezoidal-shaped poles is also proposed as further work, to reduce the torque pulsation. The latter theoretically exhibits zero torque pulsations. Some FEA results are also presented

The increasing energy demand is in line with population growth as well as the development of science and technology, and the maximum utilization of energy derived from magnets. The purpose of this research is to design of permanent magnet motor that produces rotation that can be utilized as power plant propulsion, without using fuel oil. The method used is to examine and search the gap of existing patent design and develop it in the form of a new design, In the hope of increasing the potential of magnetic energy into a magnetic power plant. By designing the magnetic position and angle of attack on the rotor and stator motor magnet.

This paper deals with experimental works and analysis for influence of stator slot number on performance of interior PM (IPM) motor. First, for a conventional 6-pole IPM rotor, stators with 18, 27 and 36 slots satisfied with same required and restricted conditions are designed. And then, performances and parameters of each IPM motor such as cogging torque, torque ripple, d- and q- axis inductance, total harmonic distortion (THD) of back-emf, etc. are investigated using 2-d finite element analyses (FEA). Finally, test results such as d- and q- axis inductance, back-emf and efficiency measurements are given to confirm analysis results. It is concluded from the results obtained by this work that the influence of stator slot number on IPM motor behavior is very significant.

Recently, a motor for an in-wheel system—which is advantageous when applied to electric vehicles and self-driving systems—has received much attention. In this paper, we propose an analysis and design method that can be used for an in-wheel motor. In-wheel motors require high torque density and a compact form factor to be wheel-mounted. To meet these requirements, an axial flux permanent magnet motor is proposed for the in-wheel system. The end-winding length of the coil is a key factor to be considered in this design. Hence, we propose a novel method to study the end-winding length. Due to the structural characteristics of an axial flux permanent magnet motor, a three-dimensional finite element analysis, which requires much time and expense, is essential. To solve this problem, we propose a novel analytical method combined with finite element analysis to mitigate the time and cost factors in the development of the axial flux permanent magnet motor. The magnetic saturation and the slot opening effect, which are considered during the analysis and design phase, are extremely difficult to analyze due to their nonlinearity. Therefore, a novel analytical method and algorithm, which can consider nonlinear effects, such as the magnetic saturation and slot opening, is proposed. The usefulness of the proposed analysis and design method and the axial flux permanent magnet motor for an in-wheel system were verified via 3D finite element analysis using a commercial simulation tool (JMAG).