Search Results (18)

This paper proposes a two-dimensional (2D) generalized equivalent magnetic network (GEMN) model suitable for surface-mounted permanent magnet electric machines (SPEMs). The model divides the SPEM into eight types of regions: stator yoke, stator tooth body, stator tooth tips, stator slot body, stator slot openings, air gap, rotor permanent magnets, and rotor yoke. Each region is subdivided radially and tangentially into multiple 2D magnetic network units containing radial and tangential magnetic circuit parameters, forming a regular magnetic network covering all regions of the SPEM. The topology of this magnetic network remains unchanged during rotor rotation and can accommodate various surface-mounted permanent magnet structures including Halbach arrays, which enhances the generality of the model significantly. The proposed model can be used to calculate the 2D magnetic flux density distribution, winding electromotive force, electromagnetic torque, stator iron loss, and permanent magnet demagnetization in the influence of magnetic saturation, stator slotting, and current harmonic. Comparative analysis with the accurate subdomain method (ASDM) and finite element method (FEM) demonstrates that the GEMN model achieves a good balance between computational speed and accuracy, making it particularly suitable for efficient electromagnetic performance evaluation of SPEMs. Full article

In this paper, a new fault-tolerant consequent-pole hybrid excited (FTCPHE) machine with toroidal winding (TW) is designed for electric vehicles (EVs). In this proposed machine, U-type permanent magnets (PMs) are adopted in the consequent-pole rotor with the sequence of PM–iron–PM–iron. The stator tooth placed in the stator is classified into two groups to achieve hybrid excitation. The TW is positioned on the stator yoke to achieve the simple structure and excellent fault-tolerant ability. First, the topology of this proposed FTCPHE machine with the TW is briefly introduced and compared to that with the traditional combined winding. Second, the operation principle, the magnetic circuit, and the design procedure of the FTCPHE machine are analyzed and illustrated. Third, several key structural parameters of the proposed FTCPHE machine are discussed and designed to improve electromagnetic performances. Next, some electromagnetic properties, including the flux distribution, the no-load back-EMF, the electromagnetic torque, the cogging torque, and the fault-tolerant ability, are discussed in detail. Finally, a prototype of this proposed FTCPHE machine is manufactured to validate the simulated results. Full article

Quartz flexible accelerometers (QFAs) are a type of temperature-sensitive sensor, whereby a change in temperature will cause the key parameters of the accelerometer to drift and cause stability errors. Due to the absence of effective methods for sensing the temperature of internal accelerometer components, existing temperature error correction approaches primarily rely on shell temperature measurements to establish correction models. Consequently, most correction methods achieve higher accuracy during the steady-state heat conduction phase of the accelerometer, whereas the correction error markedly increases during the transient heat conduction phase. To elucidate the temperature discrepancy between the QFA shell and its internal components and to support the development of a temperature error correction method for QFAs based on the internal temperature as a reference, this paper investigated the heat exchange dynamics between the interior and exterior of a QFA. A thermal conduction simulation model of the QFA was established, from which the spatiotemporal distribution patterns of the internal temperature field were derived. The results indicate that the temperature of the QFA shell changes significantly faster than that of the internal meter head in the early stage of the temperature change. The temperature gradient between the shell and the meter head first increases and then decreases, and the rate of temperature change in the upper part of the accelerometer is faster than that in the lower part. Before thermal equilibrium is reached, the temperature distribution inside the accelerometer is uneven in terms of time and space. Inside the accelerometer, the yoke iron, swing plate assembly, servo circuit, and magnetic steel assembly are the main components that exhibit differences in the internal temperature change in the QFA. When developing the temperature error correction method, it was crucial to address and mitigate the impact of temperature variations among these components. The average RMSE between the predicted temperature from the heat transfer model established in this paper and the experimental results was 0.4 °C. This indicates that the model can accurately predict the temperature variation within the QFA, thereby providing robust support for investigating the temperature behavior inside the QFA and offering essential technical foundations for enhancing the accuracy of the temperature error correction method. Full article

Conventional stator–magnet moving−iron transverse−flux linear oscillatory machines (CSMTLOMs) are widely applied in directly−drive reciprocating devices due to the merits of easy fabrication and robust mover. However, in order to keep the mover vibrating at a certain resonance frequency to save the energy and enlarge the output power, they still suffer from a higher requirement on spring stiffness due to their thick and heavy mover core, which would also narrow the frequency band with a high power factor due to the large inertial energy storage of the heavy mover. Hence, to reduce the mover core weight to reduce the demand of the spring and improve the operation performance, an improved linear oscillatory machine featured by a spoke−type interior permanent magnet inner stator (ISMTLOM) is proposed. Benefiting from its separated two stators, the tangential flux in the radial plane can return through the inner stator core, so that the yoke of the mover core can be eliminated directly. Then, to analytically investigate the influence of the special axial local saturation effect, the segmental equivalent magnetic circuit (EMC) model of the ISMTLOM is established, wherein a saturation coefficient is introduced to quantitatively consider the local saturation effect on the output force. Consequently, several important size parameters are optimally selected when keeping the same outer diameter and copper loss as that of the CSMTLOM. Afterward, the three−dimension finite element algorithm (3D FEA) is adopted for the electromagnetic performance validation and comparison. Finally, it is found that the nonlinear segmental EMC corrected by the saturation coefficient can quickly predict the output force more accurately within the wide load range, and benefiting from the topology improvement, the ISMTLOM has the merits over the CSMTLOM in its smoother output force, much lighter mover core, and less demand of mechanical spring stiffness, whilst preserving the similar output force density. Full article

Induction motors are a significant consumer of electricity. Therefore, their energy efficiency level plays a vital role in the world’s energy balance. The world’s markets strive to produce motors of efficiency class IE3 or IE4 while maximizing the use of wire and magnetic materials. However, high induction values in the motor core can also lead to significant losses in construction materials, especially in the magnetic motor housing. This article aimed to show how it is possible to determine the distribution of the magnetic field and additional losses in the yoke and the cast-iron motor frame using field-circuit methods to model the motor and to refine the analytical method for calculating these losses at the motor design stage. Full article

The conceptual design study of a Future Circular hadron-hadron Collider (FCC-hh) to be constructed at CERN with a center-of-mass energy of the order of 100 TeV requires superconducting magnetic systems with a central magnetic flux density of an order of 4 T for the experimental detectors. The developed concept of the FCC-hh detector involves the use of an iron-free magnetic system consisting of three superconducting solenoids. A superconducting magnet with a minimal steel yoke is proposed as an alternative to the baseline iron-free design. In this study, both magnetic system options for the FCC-hh detector are modeled with the same electrical parameters using Cobham’s program TOSCA. All the main characteristics of both designs are compared and discussed. Full article

Recent developments in electromagnetic launchers have created potential applications in transportation, space, and defense systems. However, the total efficiency of these launchers has yet to be fully realized and optimized. Therefore, this paper introduces a new design idea based on increasing the magnetic flux lines that facilitate high output velocity without adding any excess energy. This design facilitates obtaining a mathematical equation for the launcher inductance which is difficult to analytically represent. This modification raises the launcher efficiency to 36% higher than that of the ordinary launcher at low operating voltage. The proposed design has proven its superiority to traditional launchers, which are limited in their ability to accelerate microsatellites from the ground to low Earth orbit due to altitude and velocity constraints. Therefore, an aircraft is used as a flying launchpad to carry the launcher and bring it to the required height to launch. Meanwhile, it is demonstrated experimentally that magnetic dipoles in the projectile material allow the launcher coil’s magnetic field to accelerate the projectile. This system consists of the launcher coil that must be triggered with a high amplitude current from the high DC voltage capacitor bank. In addition, a microcontroller unit controls all processes, including the capacitor bank charging, triggering, and velocity measurement. Full article

The core design elements of the motor for the co-robot joint are miniaturization and high torque. In this paper, a dual rotor axial-flux permanent magnet (DRAFPM) motor is proposed to improve the performance of robot joints. DRAFPM motors have the advantage of reducing iron loss and minimizing volume because they can remove stator yoke. When designing a motor with the same volume, it can be designed to increase the height of the fixed ruler by the thickness of the yoke of the fixed ruler and increase the number of turns. In the case of existing axial-flux permanent magnet (AFPM) motors, the shape of the three-dimensional structure is limited by radial laminating of stator. Therefore, considering the production of 3D printing, the shape of stator shoe is designed. The optimal design problem of DRAFPM motor consists of real and integer design variables. In addition, due to the structural characteristics of DRAFPM motors, 3D finite element analysis (FEA) is required, so it takes a long time to interpret. Therefore, this paper proposes an efficient optimal design process to optimize the remaining real design variables after prioritizing the integer design variables. The proposed optimization process is applied to the DRAFPM motor for robot joints, and the optimal design plan satisfying the design function is derived from various design variables to prove the validity of the optimization process. Full article

The temperature effect caused by high slip has an important influence on the operation performance and reliability of magnetic coupling. Taking the self-developed single disk asynchronous magnetic coupling as the research object, the heat loss equation of the magnetic coupling is established. Based on the three-dimensional transient magnetic field simulation model of the magnetic coupling, the eddy current loss, torque, and eddy current distribution law of the magnetic coupling are obtained through simulation. The space flow field and structure temperature field distribution of the magnetic coupling are analyzed by using the fluid-thermal coupling simulation method, and the heat dissipation coefficient and temperature distribution law of the structure surfaces such as copper disk, the back lining yoke iron disk, and the aluminum disk are obtained. The test platform was built to test the torque and temperature of the magnetic coupling. The results show that the error between the test and simulation is 4.8% in the torque aspect, and the maximum error between the test and simulation is only 8.1% in the temperature aspect of each component, which further verifies the effectiveness of the simulation method. On this basis, three heat dissipation improvement schemes are proposed, including installing heat dissipation blocks, setting semicircular grooves on the back lining yoke iron disk, and a hybrid design. The results show that the degree of improvement for each scheme is in the following order: hybrid design, setting semicircular grooves on the back lining yoke iron disk, and installing heat dissipation blocks. Under the hybrid design, the temperature of the back lining yoke iron plate and a copper plate of the magnetic coupling is reduced by about 8.5 °C compared with the original model, and the effect is ideal. The research results can provide an optimization reference for high-speed magnetic coupling and the temperature effect caused by an overload-locked rotor. Full article

In this paper, an axial slot-less permanent magnet synchronous motor (ASFPMSM) was designed to increase the power density. The iron core of the stator was replaced with block coils, and the stator back yoke was removed because 3D printing can provide a wide range of structures of the stator. The proposed model also significantly impacts efficiency because it can reduce iron loss. To meet size and performance requirements, coil thickness and number of winding layers in the block, the total amount of magnet, and pole/slot combinations were considered. The validity of the proposed model was proved via finite elements analysis (FEA). Full article

This paper presents a novel and improved configuration of a single-sided linear induction motor. The geometry of the motor has been modified to be able to operate with a mixed magnetic flux configuration and with a new configuration of paths for the eddy currents induced inside the aluminum plate. To this end, two slots of dielectric have been introduced into the aluminum layer of the moving part with a dimension of 1 mm, an iron yoke into the primary part, and lastly, the width of the transversal slots has been optimized. Specifically, in the enhanced motor, there are two magnetic fluxes inside the motor that circulate across two different planes: a longitudinal magnetic flux which goes along the direction of the movement and a transversal magnetic flux which is closed through a perpendicular plane with respect to that direction. With this new configuration, the motor achieves a great increment of the thrust force without increasing the electrical supply. In addition, the proposed model creates a new spatial configuration of the eddy currents and an improvement of the main magnetic circuit. These novelties are relevant because they represent a great improvement in the efficiency of the linear induction motor for low velocities at a very low cost. All simulations have been made with the finite elements method—3D, both in standstill conditions and in motion in order to obtain the characteristic curves of the main forces developed by the linear induction motor. Full article

Tooth coil winding machines offer a low cost manufacturing process, high efficiency and high power density, making these attractive for traction applications. Using direct oil cooling in combination with tooth coil windings is an effective way of reaching higher power densities compared to an external cooling jacket. In this paper, the validation of the electromagnetic design for an automotive 600 V, 50 kW tooth coil winding traction machine is presented. The design process is a combination of an analytical sizing process and FEA optimization. It is shown that removing iron in the stator yoke for cooling channels does not affect electromagnetic performance significantly. In a previous publication, the machine is shown to be thermally capable of 25 A/mm ${}^2$ (105 Nm) continuously, and 35 A/mm ${}^2$ (140 Nm) during a 10 s peak with 6 l/min oil cooling. In this paper, inductance, torque and back EMF are measured and compared with FEA results showing very good agreement with the numerical design. Furthermore, the efficiency of the machine is validated by direct loss measurements, using a custom built calorimetric set-up in six operating points with an agreement within 0.9 units of percent between FEA and measured results. Full article

This study focuses on the core losses in the stator region of high-speed permanent magnet synchronous motors, magnetic field characteristics in the load region, and variations in iron losses caused by changes in these areas. A two-pole 120 kW high-speed permanent magnet synchronous motor is used as the object of study, and a two-dimensional transient electromagnetic field-variable load circuit combined calculation model is established. Based on electromagnetic field theory, the electromagnetic field of the high-speed permanent magnet synchronous motor under multi-load conditions is calculated using the time-stepping finite element method. The magnetic field distribution of the high-speed permanent magnet synchronous motor under a multi-load condition is obtained, and the variations in iron core losses in different parts of the motor under multi-load conditions are further analyzed. The calculation results show that most of the stator iron core losses are dissipated in the stator yoke. The stator yoke iron loss under the no-load condition exceeds 70% of the total stator iron core loss. The stator yoke iron loss under rated operation conditions exceeds 50% of the total stator iron core loss. The stator loss under rated load operation conditions is higher than that under no-load operation. These observations are sufficient to demonstrate that the running status of high-speed motors is closely related to the stator iron losses, which have significance in determining the reasonable yoke structure of high-speed and high-power motors and the cooling methods of motor stators. Full article

A self-bearing motor (SBM) is an electric motor with a magnetically integrated bearing function, that is, it can provide levitation and rotation simultaneously as a single actuator. This paper presents the design, operating principle and control system for the slotless self-bearing motor (SSBM). In this design, the stator has no iron core but includes six-phase coils. The rotor consists of a permanent magnet and an enclosed iron yoke. Magnetic forces generated by the interaction between stator currents and the magnetic field of the permanent magnet are used to control the rotational speed and radial position of the rotor. In this paper, the torque and radial bearing forces are analyzed theoretically with the aim to develop an improved control system. In order to confirm the proposed control method, an experimental system was constructed and tested. Simulation and measurement results show that the SSBM can work stably in modes such as start, reverse, rotation load and external radial pulse forces. Full article

This study presents a modified annular electromagnetic stirring (M-AEMS) melt treatment suitable for a large-volume and high-alloyed aluminum alloy. A 3D computational model coupling an electromagnetic model with a macroscopic heat and fluid-flow model was established by using Ansoft Maxwell 3D and Fluent from ANSYS workbench, and the effects of the electromagnetic shielding ring, the height of the magnet yoke, the shape of the iron core, and the internal cooling mandrel on the electromagnetic, thermal and flow fields were studied numerically. Based on the optimal technical parameters, the effectivity of the M-AEMS process by using 7075 alloy was validated experimentally. The results show that a favorable electromagnetic field distribution can be achieved by changing the magnet yoke height, the iron-core shape and the electromagnetic shielding ring, and the melt temperature of the 7075 alloy can drop rapidly to the pouring temperature by imposing the internal cooling mandrel; compared with ordinary annular electromagnetic stirring, the M-AEMS process creates a lower magnetic strength near the melt top, beneficial for stabilizing the melt surface; meanwhile, it yields a higher magnetic strength near the melt bottom, which increases the shear rate and ensures an optimal stirring effect. Therefore, M-AEMS works more efficiently because the thermal and composition fields become uniform in a shorter time, which reduces the average grain size and the composition segregation, and a more stable melt surface can be obtained during treatment, which reduces the number of air and oxide inclusions in the melt. Full article