Auxiliary Slots Research Articles

Research on Cogging Torque Reduction Based on Multi-Parameter Optimization of Auxiliary Slots and Pole-Arc Coefficient

Research on Cogging Torque Reduction Based on Multi-Parameter Optimization of Auxiliary Slots and Pole-Arc Coefficient

Research on Electromagnetic Performance and Rotor Eddy Current Loss Suppression of Ultra‐Low Temperature and High‐Speed Permanent Magnet Motor Materials for LNG Pumps

AbstractThere is no unified material selection principle for ultra‐low temperature and high‐speed permanent magnet motors used in liquefied natural gas (LNG) pumps, and high rotor eddy current losses can easily lead to vaporization of the transported LNG. This article first studies the electromagnetic performance of motor structural component materials at room temperature and ultra‐low temperature environments, and proposes the material selection principles for this type of motor. Based on the experimental measurement results of material electromagnetic performance, the loss characteristics of motors under ultra‐low temperature and room temperature environments were compared. Based on the mechanism of rotor eddy current loss and considering the influence of environmental temperature on the material properties of motors, three optimization methods for rotor eddy current loss are proposed. The impact of different suppression measures on rotor eddy current loss is revealed. The suppression of magnetic conduction harmonics can be achieved by opening stator auxiliary slots and optimizing their size and position. High conductivity metal shielding layers are used and their materials and sizes are optimized, And the use of magnetic slot wedges can simultaneously suppress three types of harmonics. Finally, the suppression principles of different optimization methods on rotor eddy current losses were analyzed, and the optimization effects and advantages and disadvantages of different methods were discussed, providing theoretical reference for the optimization design of high‐speed permanent magnet motors operating in ultra‐low temperature environments. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Study on the vacuum arc characteristics between novel straight slot transverse magnetic contacts with auxiliary slots on the back

The motion stability of the vacuum arc between TMF contacts significantly affects the breaking capacity of vacuum switches. The vacuum arc movement can be effectively controlled by slots on the TMF contacts to provide the necessary driving force. However, the necessary cross-slot movement of the arc affects its stability. In this paper, a novel straight-slot transverse magnetic field (SSTMF) contact structure with additional auxiliary slots on the back is proposed to improve current distribution and avoid stagnation at the contact center. The simulation analysis was conducted on the force acting on the arc at different positions and the magnetic field distribution between the contacts. Additionally, the arcing experiments were performed in a demountable vacuum chamber for both novel and traditional SSTMF contacts. The SEM analyses were carried out for the contacts after the experiments. Combined with simulation and comparative experimental results, it is verified that the auxiliary slots can improve the control and driving effect on the arc. This can provide ideas and references for future contact design and improve the breaking performance of vacuum circuit breakers.

Research on torque ripple suppression of in-wheel fractional slot permanent magnet synchronous motors based on auxiliary slots

Research on torque ripple suppression of in-wheel fractional slot permanent magnet synchronous motors based on auxiliary slots

Forces achieved by different material and type of intrusion arches applied in different horizontal levels

Background: Intrusion is one of the most needed movements in orthodontics. It is possible to achieve this with arch wires, miniscrews, and bite-blocks. Purpose: This in vitro study aimed to evaluate forces achieved by different types of intrusion arches made of different materials and anchored in two different horizontal levels by either miniscrews or molar teeth. Methods: An upper jaw typodont was applied different types of intrusion arches: intrusion and utility arches, made of different materials (nitinol, beta III titanium, stainless steel) and different wire sizes (0.016” x 0.022” and 0.017” x 0.025”) to the incisors, both anchoring from molars and miniscrews respectively. Each application was measured by a Correx gauge. Each wire was applied to both the auxiliary slot of the triple tube and the slot in the head of the miniscrew. One-way analysis of variance (ANOVA), Tukey’s HSD test, and a paired two-sample t-test were used to analyze the data. Results: In the intrusion arches, the main effect of the material was found to be statistically significant on force values (p = 0.034) while the main effect of the size was not found statistically significant on force values (p = 0.083). In the utility arches, both the main effect of the material (p = 0.067) and the size (p = 0.140) were not found to be statistically significant on force values. Conclusion: Regardless of the anchorage unit level and size, nitinol was the material that applied the lowest forces among all materials. The material is the most effective factor in the force generated, while the anchorage unit level is the least.

Influence of Magnetic Pole Stepping Combined with Auxiliary Stator Slots on the Stability of Dual-Rotor Disc Motors

With the growing utilization of disc motors, the enhancement of their operational stability has become a critical research area. The existing studies usually focus on improving the pole structure of the rotor or the stator structure to optimize one performance of the motor and less on optimizing multiple performances. This paper simultaneously improves the rotor pole structure and stator tooth structure of the motor in order to optimize the sinusoidal waveform of the no-load back electromotive force and the cogging torque at the same time to achieve the goal of reducing the vibration and noise of the permanent-magnet synchronous dual-rotor statorless magnetically coupled disc motor and improve its operational stability. A finite element simulation model of a 20-pole, 24-slot permanent-magnet synchronous dual-rotor statorless magnetically coupled disc motor is established to analyze the influence of various factors, including the number of magnetic pole steps, the opening position, depth, and width of the stator auxiliary slot, on the motor performance. The results show that this stator–rotor combination improvement method effectively reduces the total harmonic distortion (THD) and attenuates multiple harmonics, and the peak cogging torque pulsation is significantly improved while other properties of the motor meet the technical requirements, and the motor performance is improved.

Analysis and Suppression of Thrust Fluctuations in Halbach-type Permanent Magnet Synchronous Linear Motors

To address the thrust fluctuation problem of a bilateral type permanent magnet synchronous linear motor (DSPMSLM) with a Halbach permanent magnet array, a DSPMLSM with Halbach permanent magnet array structure is designed using ANSYS software. And based on this motor, the thrust fluctuations of the DSPMLSM are suppressed by using methods such as changing the end tooth height of the armature core, the tooth slot structure, and the opening of an auxiliary slot in the primary yoke. Firstly, the causes of thrust fluctuations in these areas were analyzed. Secondly, MAXWELL simulations were used to demonstrate that the selection of a suitable end tooth height could suppress end forces and that the use of a suitable-sized half-open slot and an auxiliary slot in the primary yoke could effectively reduce slot forces. All three methods can be used to suppress motor thrust fluctuations, reducing the thrust fluctuations of the DSPMLSM from 11.4% to 3.28% and increasing the average output thrust, which provides a reference for further optimization of the output performance of the linear motor.

Study of the Effect of double slotted construction on motor slot torque

To address the problem of vibration and noise caused by high slot torque of stacked-in permanent magnet synchronous motor, a motor model with a rectangular slot in the stator and curved slot in the rotor is proposed to analyze the variation of slot torque with the auxiliary slot parameter based on the analysis of slot torque, taking an 8-pole 36-slot built-in permanent magnet synchronous motor as an example. The modeling results display that the slot torque reduces and then increases with the change of incomplete groove parameters. The slot torque is weakened by 92.01% when the stator with a rectangular slot rotor with a curved slot.

Detent Force Reduction Design for the C-Core Single-Phase Permanent Magnet Linear Oscillation Actuator

Single-phase permanent magnet linear oscillation actuators (SP-PMLOAs) have been paid extensive attention in the field of compressors and industry applications. However, the detent force of SP-PMLOA limits the effective stroke and affects the control accuracy of the system. The purpose of this paper is to present a novel C-core SP-PMLOA with double stators arc-teeth and auxiliary slots to reduce detent force. Firstly, the basic structure and dynamic equation of the traditional linear oscillation actuator are introduced. Then, considering the magnetic flux leakage, the detent force formulation is derived by the flux tube method, and a novel structure is presented to reduce detent force and increase the effective stroke by the parametric scan. In addition, the traditional and presented structures of C-core SP-PMLOA are analyzed by 2-D finite element analysis (FEA) mothed. Finally, a prototype is built and tested to verify the results of FEA and calculations. The experimental results show that the presented structure can significantly reduce the detent force and increase the effective stroke.

The Magnetic Field Analytical Calculation of Permanent Magnet Vernier Synchronous Machine With Saddle-Shaped Permanent Magnets

This article proposes a novel permanent magnet Vernier synchronous machine (PMVSM) with saddle-shaped PMs. The torque of the PMVSM with saddle-shaped PMs is increased by 35.4% and 45.6% compared with the PMVSM with V-shaped PMs and tile-shaped PMs, respectively. The torque ripple of the PMVSM with saddle-shaped PMs is reduced by 0.1% and 1.7% compared with the PMVSM with V-shaped PMs and tile-shaped PMs, respectively. To facilitate the analysis, the saddle-shaped PMs are equivalently transformed to the fan-shaped PMs, which ensures that the pole arc angles and air-gap magnetic flux are unchanged. The rotor flux saturation region is modeled to improve the analytical calculation accuracy. The Laplace and Poisson equations are established for each part of the machine, the general solutions of the respective parts are solved, and the boundary conditions and intersection conditions are utilized to solve the factors. Compared with the finite-element method (FEM) results, the torque difference is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.32~ \mathrm {N}\cdot \mathrm {m}$ </tex-math></inline-formula> , and the torque ripple difference is 0.2%. The correctness of the analytical calculation is verified by comparing with the FEM results. The auxiliary slot angle and slot depth can be optimized, resulting in a higher torque and a lower torque ripple.

Design and Analysis of Interior Permanent Magnet Motor With Magnetic Isolation and Heat Dissipation Integrated Auxiliary Slot

Design and Analysis of Interior Permanent Magnet Motor With Magnetic Isolation and Heat Dissipation Integrated Auxiliary Slot

Optimal design of permanent magnet motor based on Taguchi algorithm

Aiming at the optimization of cogging torque of 12 pole 36 slot embedded permanent magnet motor, analyzing the generation principle of cogging torque, putting forward the optimization design of auxiliary slot based on Taguchi method, using Maxwell finite element simulation tool, analyzing and selecting the optimized data, through orthogonal experiment and data processing, finding the final optimization scheme of auxiliary slot. The simulation results show that, the auxiliary slot optimization method based on Taguchi method can effectively suppress the cogging torque under reasonable slotting rules, which is also of reference significance to other types of parameter optimization.

Magnet Slotting Design to Reduce High Order Electromagnetic Force and Vibration of Permanent Magnet Motor

In this paper, a new method is proposed to suppress the vibration caused by the modulation effect of high-order electromagnetic forces in permanent magnet (PM) motors. Firstly, the modulation effect of the radial force was investigated, which indicated that the higher-order electromagnetic force could cause modulated vibrations through the modulation effect. Then, auxiliary slots on the magnet surface and their effect on vibration reduction were investigated. The optimal shape of the auxiliary slot was found to minimize the noise of motor vibration. Finally, the method was verified experimentally.

Method for weakening cogging torque of built-in permanent magnet synchronous motor by auxiliary slot

The cogging torque is an unavoidable property of the permanent magnet motor, which will cause the motor to generate vibration and noise during the movement, and deteriorate the motor performance. In order to decrease the cogging torque of the permanent magnet synchronous motor, by analyzing the cogging torque expression, it is known that opening auxiliary slots in the rotor can decrease the cogging torque. Influence of slot pitch on cogging torque. The simulation results show that when the slot depth is 0.6mm, the slot width is 1.7mm and the slot spacing is 1.56, the cogging torque is most obvious reduced, and the cogging torque is decreased by 53.6% compared to the non-grooved state.

A Double-Stator Single-Rotor Magnetic Field Modulated Motor With HTS Bulks

Double stator single rotor permanent magnet synchronous motor (DSSR-PMSM) has the disadvantages of large torque ripple and abundant back-EMF harmonic content. To improve the electromagnetic performance of the motor, a double-stator single-rotor magnetic field modulation motor (DSSR-MFMM) with high-temperature superconductor (HTS) bulks is proposed in this paper. The epoxy resin is replaced by superconducting materials, and the auxiliary slot is opened in the outer stator of the motor. Some parameters of the motor are optimized by genetic algorithm. Compared with DSSR-PMSM, the proposed model has the characteristics of large back-EMF amplitude and high sinusoidal degree. The output torque is increased by 4.36% and the torque ripple is reduced by 5.12%.

Investigation of PM Loss in Spoke-Type Permanent Magnet Vernier Motors With Different Stator Topologies for In-Wheel Direct Drive

In this article, the permanent magnet (PM) loss in spoke-type permanent magnet vernier motors (ST-PMVM) with different stator topologies is investigated and compared for in-wheel direct drive. First, four ST-PMVM with split-pole and open-slot stators are designed for the in-wheel limited requirements. Besides, based on the PM loss model, the dominant influences of both slot and subharmonics on PM loss are highlighted. Then, the quantitative contributions of the air-gap magnetic field harmonics on torque and PM loss are investigated, which embodies the inherent characteristic of larger PM loss in PMVM. Furthermore, the stator tooth parameters, the slot opening width, and auxiliary slot depth on torque and PM loss are described, and then a parameter titled as the slot opening ratio is introduced to evaluate the relationship of various slot opening width combinations. It shows that there exists an irreconcilable contradiction between the torque and PM loss in PMVM, especially in split-pole types. Finally, a prototype was manufactured, and the theoretical results and finite-element analysis results match well with the experimental results.

A Design Method of the Rotor Auxiliary Slot for the Water-filled Submersible Induction Motors

Aiming at the problem of electromagnetic vibration of the water-filled submersible induction motor (WSIM), a method of opening auxiliary slots on the rotor side is proposed to weaken the air-gap field harmonics caused by the rotor slot permeance harmonics. By analyzing the research status of electromagnetic vibration of the WSIM and the composition of the air-gap magnetic field of the motor, the idea that the auxiliary slots mainly affect the air-gap field harmonics by changing the air-gap permeance of the motor is put forward. The mathematical model of air-gap permeance of WSIM is established to simulate the influence of auxiliary slots on the air-gap permeance. Through the parametric analysis of the mathematical model, the change of auxiliary slot size is simulated. The air-gap permeance waveform is decomposed by the two-dimensional Fourier transform, and then the variation of the air-gap permeance harmonics with the size of the auxiliary slot is analyzed. Finally, the finite element simulation model of the WSIM with the auxiliary slots is established, and the waveform of the air-gap flux density of the motor is analyzed to verify the effectiveness of the mathematical model. Meanwhile, the results show that after opening the auxiliary slot, the radial electromagnetic force of the motor was reduced by 28.4%.

Minimization of Cogging Torque for V-Type IPMSM by the Asymmetric Auxiliary Slots on the Rotor

The interaction between the permanent magnets and the armature teeth of the PMSM generates cogging torque. It causes vibration and noise. Therefore, this paper establishes the analytical formula of the cogging torque of the motor with auxiliary slots on the surface of the rotor. It shows that reasonable slots can weaken the cogging torque. But it&#x2019;s essential to determine whether the air-gap flux density harmonics will increase appreciably by slotting. A V-type IPMSM with 8-pole, 48-slot is modeled to analyze the cogging torque. Two new rotor slot shapes&#x2014;inwardly biased slots and outwardly biased slots&#x2014;are proposed and researched to reduce the cogging torque of the V-type IPMSM. And they are compared with the traditional symmetrical auxiliary slots. Research shows that the inwardly biased slots and the symmetric auxiliary slots can obtain a better effect on the cogging torque than the outwardly biased slots. By the symmetrical auxiliary slots, the cogging torque is weakened by 75.88%, but the torque ripple increases from 22.36% to 29.60%. By the inwardly biased slots, the cogging torque is weakened by 75.64%, and the torque ripple drops from 22.36% to 12.95%. The inwardly biased slots could successfully suppress the torque ripple.

Numerical Investigation on Vibration Performance of an Improved Switched Reluctance Machine with Double Auxiliary Slots

Considerable vibration and acoustic noise limit the further application of Switched Reluctance Machine (SRM) due to its structural characteristics and working principle. An improved SRM model with double auxiliary slots (DAS) was proposed, in which the direction of the magnetic line of force was adjusted, and the radial magnetic density in the air gap was reduced by changing the local tooth profiles of the stator and the rotor. The effects of initial rotor position and turn-on angle and turn-off angle on radial Electromagnetic Force (EMF) and maximum torque were investigated. The results indicate the radial EMF and torque increase significantly with the advancement of the turn-on angle or the delay of the turn-off angle. In the orthogonal experimental design, initial rotor position, turn-on angle, and turn-off angle were taken as the factors, and the optimal set of parameters that minimized radial EMF was determined according to a greater output torque. In contrast to conventional SRM, the radial EMF of the SRM with DAS significantly reduces when the optimal set is applied.

Research on cogging torque of the permanent magnet canned motor in domestic heating system

The permanent magnet canned motor (PMCM) is a new type of energy-saving motor used in domestic heating system. Starting from the operating environment of the equipment, this paper studies the operating state of the motor. Based on the analysis of the motor structure and the maximum operating conditions, the method of weakening the cogging torque of the motor is studied, and the auxiliary slot method is selected to weaken the cogging torque of the PMCM. The finite element model of the motor is established, the influence of the number and type of auxiliary slots on the cogging torque is analyzed. Through analysis and calculation, it is concluded that the cogging torque of the motor can be reduced when the number of auxiliary slots is two. At the same time, compared with various slot types, the semicircular slot type has the smallest cogging torque. The circle helps to improve the flow of magnetic field and will not form corners and cause magnetic field deposition. This paper has certain engineering application value for the optimal design of the PMCM.