Advanced Electrical Machine Design and Optimization Ⅱ

This study focuses on the development of a body for an electric racecar, utilizing CAD software for the design. A simplified full-vehicle geometric model was constructed. Based on fundamental theories of computational fluid dynamics and using CAE software platforms, the shear stress transport (SST) k-ω physical model was chosen to establish a three-dimensional computational model of the racecar’s external flow field. Simulations were conducted to analyze the pressure, airflow streamlines, and velocity distribution around the body and its surrounding flow field, elucidating the impact of body shape structure on aerodynamic characteristics. Finally, a manufacturing process for the body was designed, and a prototype was produced and integrated into the complete vehicle for road testing. The results indicate that the designed electric racecar body maintained consistent airflow over its surface, meeting the basic requirements of aerodynamics. Full article

A new type of interior combined pole permanent magnet drive motor is proposed in this paper, which aims to improve the power and comfort of electric vehicles. In view of the complex magnetic circuit structure and rich harmonic magnetic field of the motor, the initial magnetic pole parameters of the rotor are determined by the equivalent magnetic circuit method. Then, aiming at the complex magnetic circuit and rich harmonic magnetic field, a multi-objective optimization method based on the Taguchi method and response surface method is proposed to reduce the cogging torque, high harmonic content in air gap magnetic flux density and increase the output torque. Based on the finite element analysis of the electromagnetic performance of the new type interior combined magnetic pole permanent magnet drive motor before and after optimization, it can be seen that the improved rotor structure can effectively reduce the torque ripple and increase the torque density. Finally, a prototype was developed and experiments were conducted, and experimental results verified the correctness of the proposed multi-objective optimization algorithm. Full article

In order to meet the necessities of steady and protected operation of a permanent magnet synchronous motor (PMSM) in electromechanical pressure gadget aviation beneath complicated working conditions, a three-phase four-arm inverter fuzzy self-disturbance suppression management (Fuzzy-ADRC) approach for PMSM is proposed to suppress the motor torque pulsation beneath complicated working conditions. Firstly, the defects of the common inverter are analyzed, the three-phase four-bridge inverter is changed via the standard three-phase three-bridge inverter, and the present-day harmonic suppression’s overall performance of the three-phase four-bridge inverter is modeled, analyzed, and verified. Secondly, the ADRC and fuzzy management approach is analyzed, the Kalman filter is delivered into the motor pace loop management to enhance the overall performance of ADRC, and then the fuzzy manipulate and ADRC are blended to similarly enhance the torque ripple suppression’s overall performance of the everlasting magnet synchronous motor. Finally, the proposed three-phase four-arm inverter and fuzzy-ADRC approach are combined, and contrasted with the normal three-phase three-arm inverter and ADRC method. The simulation consequences exhibit that the proposed manipulation technique can efficiently suppress the torque ripple of everlasting magnet synchronous motor and has robust reliability. Full article

The evolution of electric propulsion systems in the maritime sector has been influenced significantly by technological advancements in power electronics and machine design. Traditionally, these systems have employed surface-mounted permanent magnet synchronous motors (PMSMs) in podded configurations. However, the advent of permanent magnet Vernier motors (PMVMs), which leverage magnetic gearing effects, presents a novel approach with promising potential. This study conducts a comparative analysis between PMVMs and conventional PMSMs at a power level of 5 MW for podded ship propulsion, with a particular focus on the impact of gear ratios ($Gr$). An objective function was developed that integrates motor dimension constraints and the power factor (PF), a critical yet frequently neglected parameter in existing research. The findings indicate that PMVMs with lower $Gr$ have lower mass and cost compared to those with higher $Gr$ and traditional PMSMs, at a PF level of 0.7, which is high for Vernier machines. Moreover, PMVMs with lower $Gr$ achieve efficiencies exceeding 99%, outperforming both their higher $Gr$ counterparts and conventional PMSMs. The superior performance of PMVMs is attributed to lower current density and reduced copper loss, which contribute to their enhanced thermal performance. These details are elaborated on further in the paper. Consequently, these findings suggest that PMVMs with lower $Gr$ are particularly well suited for high-power maritime propulsion applications, offering advantages in terms of compactness, efficiency (EF), cost-effectiveness, and thermal performance. Full article

Axial flux permanent magnet motors have attracted increasing attention due to their compact topology and high torque density. Many topological variations have arisen over time; however, limited research has directly compared the differences in magnetic performance of these topologies. This paper carries out a comprehensive investigation, employing both analytical and 3D finite element analyses, to compare the magnetic performance of three topologies: yokeless and segmented armature (YASA), axial flux internal rotor (AFIR), and offset AFIR. The findings reveal that each topology offers specific advantages for different applications. The YASA topology excels in minimizing core losses; the AFIR configuration achieves the highest torque density; and the offset AFIR topology shows the highest efficiency. The offset AFIR topology appears to offer advantages for a wide array of applications due to its higher power factor and lower permanent magnet loss, leading to reduced costs for converter design and cooling system design. Full article

Based on the principle of eddy current braking and hydraulic braking, a new eddy current-hydrodynamic hybrid retarder (ECHHR) is proposed. Based on the introduction of the working principle and structure of the ECHHR, the finite element analysis models of the electromagnetic field and the flow field of the ECHHR were established, respectively. The electromagnetic field distribution, the flow field velocity, and the flow field pressure in the ECHHR were numerically simulated. The air gap magnetic density, the eddy current braking torque, and the hydraulic braking torque under different excitation currents and different liquid filling rates were calculated. Finally, the braking performance of the EHHR was tested via experiments, and the effectiveness of the finite element analysis method was verified. The test results indicated that as the speed increased, the composite braking torque of the ECHHR increased approximately linearly. When the speed was 1000 r/min, the composite braking torque reached 2100 N·m. Compared to separate hydraulic braking and eddy current braking, the composite braking torque was relatively high in the full-speed range. Full article

At present, a large number of inefficient induction motors (IMs) are still being used in various industrial fields, resulting in a huge waste of energy. Obviously, it is expensive to replace all these machines with high-efficiency motors. Therefore, this paper will investigate the method of low-cost modification of inefficient IMs and propose a low-cost permanent magnetization remanufacturing (PMR) method that can make full use of the original structure of IMs. The PMR method converts the IM’s rotor into a permanent magnet (PM) rotor by directly milling slots in the original rotor and embedding PMs, thus improving the efficiency of the original motor to meet the IE4 standard. Firstly, this paper proposes the PMR process of IM, and based on this process, a Y2-132M1-6 IM is designed for remanufacturing, and the performance of the motor before and after the PMR is compared through finite-element analysis. Then, this paper researches the factors that may affect the starting performance and rated performance of the motor in the PMR design. Finally, based on the PMR design scheme, the Y2-132M1-6 IM is remanufactured into an experimental prototype. The total cost of the PMR is calculated and the performance improvement is tested through experiments. Full article

A method is proposed to comprehensively study the eddy and circulating current losses of stator winding wound by multiple parallel strands, to further improve the power density of stator iron coreless permanent magnet brushless DC (PMBLDC) motors. Analytical models of the eddy and circulating current losses in stator winding are deduced firstly to explicitly express the influencing factors of these two losses. As is shown, these factors are mutually contradicting. While the eddy current loss can be greatly reduced by using multiple parallel conductor strands, the circulating current loss will be extensively increased. The factors influencing these two winding losses, such as the strand diameter, magnetization types, and rotating speed, are investigated. A prototype of stator iron coreless PMBLDC motor without an inner rotor core is manufactured and tested to validate the theory. The experimental results of winding eddy and circulating current losses with different combinations of strand diameters and parallel numbers agree well with the theoretical results. Full article

This paper proposes a model for the electromagnetic performance of the dual air-gap liquid-cooled eddy current retarder (DAL-ECR) considering the transient permeability. First, the structure and working principle of the DAL-ECR are introduced. Next, the analysis model of the static air-gap flux density considering the flux leakage and end effect is established based on the piecewise function method and the magnetic equivalent circuit (MEC). Then, based on the skin effect of the electromagnetic field in the retarder, an iterative method for solving the transient permeability of the stator is proposed. According to Faraday’s and Ampere’s laws, the analysis model of the static air-gap flux density, and the transient permeability, the analysis model of the transient air-gap flux density is established. The braking torque of the DAL-ECR is then calculated while taking the actual path of the eddy current and the skin effect on the permeability of the stator into consideration. Finally, the calculation accuracy of the model was verified by the finite element method (FEM) and the bench test. Full article

This paper presents two optimization methods of an interior permanent magnetic motor (IPM). The first method is based on the non-dominated sorting genetic algorithm II (NSGA-II), while the second one is based on the NSGA-III algorithm. The focus is on the reduction of the cogging torque (CT), which acts upon the rotor when the IPM is not powered, and the current that flows through the three windings is 0. The influence of the CT over the motor operation is a negative one, inducing vibrations that are not desired. The limitation of these influences is the desired way for improvement. The optimizations applied entailed the change of the geometrical configuration of the stator whilst maintaining the exterior dimensions unaltered. Through this simple but robust approach, the performance of the IPM proposed was improved. Full article

As a common fault of transformer winding, inter-turn short circuits cause severe consequences, such as excessive current and serious deformation of winding. Aiming to solve the problem of inter-turn short circuit at the end-winding and middle-winding of high frequency transformers (HFT), this paper considers the electromagnetic vibration characteristics of inter-turn short circuits (interleaved winding and continuous winding) at different positions, and the HFT is established by the multi-physical field coupling principle. Coupling equations for the inter-turn short circuit, as well as electromagnetic force and sound pressure level, are established to characterize the vibration noise mechanism of inter-turn short circuits. Furthermore, the HFT equivalent model is simulated in 3D finite element method (FEM) to emulate the real transformer operation and investigate the impact of interleaved winding and continuous winding under inter-turn short circuit faults. The short-circuit current and axial flux leakage, as well as the harmonic response of vibration acceleration and sound pressure level distribution, are obtained when inter-turn short circuits occur at different positions. Finally, the results show that the electromagnetic effect of the inter-turn short circuit in end-winding is worse than it is in middle-winding. Advantages in resisting impulse current make interleaved winding superior to continuous winding in terms of vibration and noise. Full article

A modular permanent magnet machine is composed of several stator modules, and the three-phase winding of each module can be controlled independently. The novel modular permanent magnet machine has good abilities in terms of fault tolerance when the machine is exposed to fault conditions. The current of each phase is different and will result in uneven loss distribution in each phase. Heat transfer occurs in the circumferential direction and temperature distribution will be asymmetric in the circumferential direction. This paper proposes a 3D finite element thermal model to accurately calculate the rise in temperature under open-circuit conditions for modular permanent magnet machines. When two modules are in operation, the machine can output rated torque. When one module is in operation and the temperature is 150 °C, the output torque is 0.76 times the rated torque. The temperature of the machine under the one-phase open-circuit condition with a zero-temperature-difference control strategy will be 0.8 °C lower than that with a minimum copper loss control strategy. Finally, a prototype with three stator modules is manufactured and the calculation results are validated by experimental test. It holds great significance for the accurate calculation of a machine with asymmetric temperature distribution in the circumferential direction. Full article

This document deals with the design of a Permanent Magnet Synchronous Motor (PMSM) to peripherally drive a counter-rotating pump inducer. The motor/pump is associated using a rim-driven principle where the motor’s active parts are located at the periphery of the inducer blades. It proposes using a Halbach array of permanent magnets for the active rotor of the motor. This solution allows the generation of a Sinusoidal Electromotive Force (EMF). Therefore, a more stable electromagnetic torque is reached. An optimum geometry suitable for the inducer specifications while respecting operational constraints is determined. The obtained geometry is then simulated using the Finite Element Method. The results are satisfactory in terms of average torque and EMF waveform. Use of the Halbach array allows a significant improvement of the flux density in the air gap compared to a designed surface-mounted machine. The experimental validation will be performed once the prototype is realized in the Laboratory of Fluid Engineering and Energy systems (LISFE). Full article