Torque Reduction Research Articles

Relationship Between Muscular Activity and Assistance Magnitude for a Myoelectric Model Based Controlled Exosuit.

The growing field of soft wearable exosuits, is gradually gaining terrain and proposing new complementary solutions in assistive technology, with several advantages in terms of portability, kinematic transparency, ergonomics, and metabolic efficiency. Those are palatable benefits that can be exploited in several applications, ranging from strength and resistance augmentation in industrial scenarios, to assistance or rehabilitation for people with motor impairments. To be effective, however, an exosuit needs to synergistically work with the human and matching specific requirements in terms of both movements kinematics and dynamics: an accurate and timely intention-detection strategy is the paramount aspect which assume a fundamental importance for acceptance and usability of such technology. We previously proposed to tackle this challenge by means of a model-based myoelectric controller, treating the exosuit as an external muscular layer in parallel to the human biomechanics and as such, controlled by the same efferent motor commands of biological muscles. However, previous studies that used classical control methods, demonstrated that the level of device's intervention and effectiveness of task completion are not linearly related: therefore, using a newly implemented EMG-driven controller, we isolated and characterized the relationship between assistance magnitude and muscular benefits, with the goal to find a range of assistance which could make the controller versatile for both dynamic and static tasks. Ten healthy participants performed the experiment resembling functional daily activities living in separate assistance conditions: without the device's active support and with different levels of intervention by the exosuit. Higher assistance levels resulted in larger reductions in the activity of the muscles augmented by the suit actuation and a good performance in motion accuracy, despite involving a decrease of the movement velocities, with respect to the no assistance condition. Moreover, increasing torque magnitude by the exosuit resulted in a significant reduction in the biological torque at the elbow joint and in a progressive effective delay in the onset of muscular fatigue. Thus, contrarily to classical force and proportional myoelectric schemes, the implementation of an opportunely tailored EMG-driven model based controller affords to naturally match user's intention detection and provide an assistance level working symbiotically with the human biomechanics.

Reduction of torque and flux ripples in direct torque control for three‐level open‐end winding PMSM drive

The direct torque control (DTC) of permanent magnet synchronous motor (PMSM) drives is a noticeable practice in industrial applications due to its quick dynamic performance. However, due to the presence of hysteresis controllers and inaccurate switching tables especially for the multilevel fed DTC drives are facing higher ripples in torque and flux response. An improved DTC for three-level open-end winding PMSM drive is proposed in this article and features reduction of flux and torque ripples. The torque and flux performances of the PMSM are directly controlled by the calculated reference voltage vector in the stationary reference frame. The voltage vector tables are proposed based on the length of the voltage space vectors and the actual voltage vector nearer to the calculated reference voltage vector is selected so that the minimum ripples exist in flux and torque responses. The steady-state and dynamic conditions of the proposed DTC method are verified in the real-time experiment and also compared with the conventional DTC as well as the recently developed control methods.

The incorporations of palmitamide as a rubber chemical into carbon black-loaded styrene-butadiene rubber: cure rate index and torque properties

This study studied the effect of palmitamide as a new rubber chemical on the index of healing rate and torsion properties of carbon black (CB) (CB) charged styrene-butadiene rubber compounds. SBR was loaded with CB at a fixed load (thirty phr) and palmitamide was added to the CB-loaded SBR compound at doses varying from two to eight phr. The effect of palmitamide addition on the healing rate index and torsional properties of SBR CB loads were investigated. It was revealed that palmitamide caused an increase in the speed of the healing process in SBR containing CB. The greater the palmitamide dose, the higher the CRI. The increase in CRI is associated with the role of palmitamide as an additional accelerator for CB-loading SBR. The amine content of palmitamide increases CRI. It was also revealed that palmitamide lowers the minimum torque but increases the maximum torque as well as the torque difference by up to six palmitamide additions. The minimum torque reduction is due to the plasticizing effect of palmitamide. The increase in maximum torque and difference in torque is due to the increased intercalation process due to the action of palmitamide as an acting agent which increases CB dispersion.

When Do Stalled Stars Resume Spinning Down? Advancing Gyrochronology with Ruprecht 147

Abstract Recent measurements of rotation periods ( ) in the benchmark open clusters Praesepe (670 Myr), NGC 6811 (1 Gyr), and NGC 752 (1.4 Gyr) demonstrate that, after converging onto a tight sequence of slowly rotating stars in mass–period space, stars temporarily stop spinning down. These data also show that the duration of this epoch of stalled spin-down increases toward lower masses. To determine when stalled stars resume spinning down, we use data from the K2 mission and the Palomar Transient Factory to measure for 58 dwarf members of the 2.7 Gyr old cluster Ruprecht 147, 39 of which satisfy our criteria designed to remove short-period or near-equal-mass binaries. Combined with the Kepler data for the approximately coeval cluster NGC 6819 (30 stars with M ⋆ > 0.85 ), our new measurements more than double the number of ≈2.5 Gyr benchmark rotators and extend this sample down to ≈0.55 . The slowly rotating sequence for this joint sample appears relatively flat (22 ± 2 days) compared to sequences for younger clusters. This sequence also intersects the Kepler intermediate-period gap, demonstrating that this gap was not created by a lull in star formation. We calculate the time at which stars resume spinning down and find that 0.55 stars remain stalled for at least 1.3 Gyr. To accurately age-date low-mass stars in the field, gyrochronology formulae must be modified to account for this stalling timescale. Empirically tuning a core–envelope coupling model with open cluster data can account for most of the apparent stalling effect. However, alternative explanations, e.g., a temporary reduction in the magnetic braking torque, cannot yet be ruled out.

Impact of Selected Methods of Cogging Torque Reduction in Multipolar Permanent-Magnet Machines

This paper focuses on the matter of cogging torque reduction by combining various methods of cogging torque minimization. Due to the high costs of prototype construction, cogging torque is minimized during the design phase by using numerical methods, while computer simulations are used to find a magnetic circuit arrangement for which the cogging torque has the smallest possible value. Cogging torque occurs as a result of combined impact of the magnetic field of a permanent magnet located at rotor and stator with variable magnetic conductivity depending on an angle of rotation. It is a pulsating torque and occurs permanently during machine operation, impacting the operation of the entire device cooperating with the electric machine and causing vibrations, tension, and noise. It results in braking torque and subsequent power losses and leads to faster wear and tear of machine structural elements. High cogging torque values cause problems with rotational speed adjustment. In the case of electric generators used in wind power plants, it impedes the start-up of power plants at high wind speeds. Considering the above, the reduction of cogging torque in permanent-magnet machines is extremely important.

Optimal Design of Outer-Rotor Surface Mounted Permanent Magnet Synchronous Motor for Cogging Torque Reduction Using Territory Particle Swarm Optimization

In this paper, territory particle swarm optimization (TPSO) is proposed for the optimal design of surface mounted permanent magnet synchronous motor (SPMSM) for high altitude long endurance (HALE) unmanned aerial vehicle (UAV). The proposed algorithm exploits the concept of a territory to the particle swarm optimization (PSO) to solve the problem that the conventional PSO cannot find the multimodal solutions. Also, by combining the stochastic method, PSO, with the deterministic method, pattern search method, it is possible to find optimal solutions quickly and accurately. The superiority of the proposed algorithm is verified through comparison in the test functions with niching genetic algorithm, which is well known multimodal optimization algorithm. The TPSO is applied to the optimization design of outer-rotor SPM for HALE UAV, and the optimal design with reduced cogging torque has been derived.

Performance assessment of vegetable oil-based minimum quantity lubrication (MQL) in drilling

Metalworking fluids are widely used to increase productivity and quality of metal cutting. However, these metalworking fluids possesses the problems in terms of the effect on environment and health of the worker. Hence, various approaches to provide cooling and lubrication are explored such as mist cooling, high-pressure cooling, minimum quantity lubrication (MQL), nano fluids, solid lubricants, etc. In this regards, the present work exhibits the performance evaluation of vegetable-based minimum quantity lubrication (MQL) in drilling of aluminium alloy. This drilling tests have been performed in different cutting environments such as Dry, flood cooling, MQL with castor oil, MQL with sunflower oil with uncoated HSS twist drill. The effect of various drilling parameters have been analysed by measuring surface roughness, axial thrust, and torque produced. The comparison of results indicates effectiveness of the vegetable-based MQL in terms improved surface finish and reduction in axial thrust and torque during drilling.

Starting Torque Reduction of Direct Torque Control Based Synchronous Motor Using Simulated Annealing

The motion control of a container port on an industrial conveyor involves non-linear movement by varying the speed of the conveyor. The stability control of the conveyor system is in the starting current or starting torque of the synchronous motor. The starting performance of the motor requires rapid dynamics and precise regulation, hence the need of a direct control is becoming an urgent demand. A non-linear movement for the starting current of the motor can be effectively controlled through simulation. A synchronous motor is usually specified when constant speed and the power factor correction is required. However, subject to many loads, the starting current and starting torque heat up the fuse of the armature rotor and stator. Full state feedback control through simulation has been shown as not being able to stabilize a conveyor movement. Therefore, the need for direct control is important to stabilize the system. The starting current at a synchronous motor should be able to perform better, even for cases where the controlling parameter model was uncertain or changing over time. A reference of any controller model will be selected to stabilize the non-linear motion of the motor. Then the simulation studies will be performed to observe the performance with any controller on starting current of motor. A one objective simulated annealing will be used to optimize the system in decreasing a starting current synchronous motor. Keywords: A synchronous motor, Non linear, one objective simulated annealing, starting torque , parameter model

Design and Performance Assessment of a Small-Scale Ferrite-PM Flux Reversal Wind Generator

Currently, there is increasing research interest in harnessing wind energy for power generation by means of non-conventional electrical machines e.g., flux-reversal machines. The flux reversal machine is usually designed using scarce rare–earth permanent magnet material which may be unattractive in terms of machine cost. In this study, an attempt is made to re-design the flux reversal machine with non-rare-earth ferrite permanent magnet for wind energy applications. Because these machines possess high cogging torque, which results in vibration and noise, that are detrimental to the machine performance, especially at low speeds, a novel combined skewed and circumferential rotor pole pairing method is developed. The proposed cogging torque reduction method is implemented in 2-dimensional finite element analysis modeling and comparatively analyzed with other existing stand-alone methods viz., skewing, and rotor pole pairing. The results show that the proposed method led to 94.8% and 71% reduction in the cogging torque and torque ripple compared to the reference generator, respectively. However, the calculated torque density is reduced by 13%. Overall, the electromagnetic performance of the proposed ferrite PM machine exhibits desirable qualities as an alternative design for the direct drive wind generator.

Investigation of cogging torque reduction for a 6/10 hybrid axial field flux‐switching permanent magnet machine by harmonic field current injection

Hybrid axial field flux-switching permanent magnet (HAFFSPM) machine exhibits a high-cogging torque due to its doubly salient structure and flux focusing effect. In consideration of the armature and field windings are both equipped in the HAFFSPM machine, a cogging torque reduction method by the harmonic field current injection is proposed in this study. Initially, the mathematical model of the HAFFSPM machine is analysed. Moreover, the theoretical principle of the proposed method is investigated based on the analytical model of the machine. The amplitude and phase angle of the injected current are calculated according to the harmonic component of the cogging torque. The feasibility of the proposed method is analysed and validated by both the finite-element analysis method and experiments on the prototype. Finally, the comparison between the proposed method and several topology optimisation methods of the HAFFSPM machine is given to indicate the priority of the harmonic field current injection method on cogging torque reduction.

Migration of gap-opening planets in 3D stellar-irradiated accretion disks

Context. The origin of giant planets at moderate separations ≃1–10 au is still not fully understood because numerical studies of Type II migration in protoplanetary disks often predict a decay of the semi-major axis that is too fast. According to recent 2D simulations, inward migration of a gap-opening planet can be slowed down or even reversed if the outer gap edge becomes heated by irradiation from the central star, and puffed up. Aims. Here, we study how stellar irradiation reduces the disk-driven torque and affects migration in more realistic 3D disks. Methods. Using 3D hydrodynamic simulations with radiation transfer, we investigated the static torque acting on a single gap-opening planet embedded in a passively heated accretion disk. Results. Our simulations confirm that a temperature inversion is established at the irradiated outer gap edge and the local increase of the scale height reduces the magnitude of the negative outer Lindblad torque. However, the temperature excess is smaller than assumed in 2D simulations and the torque reduction only becomes prominent for specific parameters. For the viscosity α = 10−3, the total torque is reduced for planetary masses ranging from 0.1 to 0.7 Jupiter mass, with the strongest reduction being by a factor of − 0.17 (implying outward migration) for a Saturn-mass planet. For a Jupiter-mass planet, the torque reduction becomes stronger with increasing α (the torque is halved when α = 5 × 10−3). Conclusions. We conclude that planets that open moderately wide and deep gaps are subject to the largest torque modifications and their Type II migration can be stalled due to gap edge illumination. We then argue that the torque reduction can help to stabilize the orbits of giant planets forming at ≳ 1 au.

The Influence of Thermal Alterations on Prefrontal Cortex Activation and Neuromuscular Function during a Fatiguing Task

The purpose of this study was to examine prefrontal cortex (PFC) activation, neuromuscular function, and perceptual measures in response to a fatiguing task, following thermal alterations of an exercising arm. Nineteen healthy adults completed three experimental sessions. At baseline, participants performed maximum voluntary isometric contractions (MVIC) of the elbow flexors. Next, participants submerged their right arm in a water bath for 15 min. Cold (C), neutral (N), and hot (H) water temperatures were maintained at 8, 33, and 44 °C, respectively. Following water immersion, participants performed an isometric elbow flexion contraction, at 20% of their MVIC, for 5 min. Ratings of perceived exertion (RPE), muscular discomfort, and task demands were assessed. Functional near-infrared spectroscopy was used to measure activation (oxygenation) of the PFC during the fatiguing task. Reductions in MVIC torque at the end of the fatiguing task were greater for the H (25.7 ± 8.4%) and N (22.2 ± 9.6%) conditions, compared to the C condition (17.5 ± 8.9%, p < 0.05). The increase in oxygenation of the PFC was greater for the H (13.3 ± 4.9 μmol/L) and N (12.4 ± 4.4 μmol/L) conditions, compared to the C condition (10.3 ± 3.8 μmol/L, p < 0.001) at the end of the fatiguing task. The increase in RPE, muscular discomfort, and task demands were greater in the H condition compared to the N and C conditions (p < 0.01). These results indicate that precooling an exercising arm attenuates the rise in PFC activation, muscle fatigue, and psychological rating during a fatiguing task.

Analysis of Cogging Torque Reduction of IPMSM applying Skew Method

Background/Objectives: In a rotating machine such as Interior Permanent Magnet Synchronous Motor (IPMSM), which is widely used in industrial fields. The reluctance torque is generated by the difference when magnetic energy varies according to the relative position of the pole and slot in a slot shaped motor. The reluctance torque acts as a torque ripple in electrical equipment and causes noise and vibration. It generated by the influence of the slot in the permanent magnet device is called cogging torque, and a skew was applied as a method to reduce the cogging torque to analyze the characteristics of the motor. In this paper, we analyze the back electromotive force and torque characteristics of IPMSM motors applying 3-stage skew among various cogging torque reduction methods, and reduce torque ripple in the instantaneous and continuous sections of the motor through Finite Element Method (FEM). Findings: Therefore, in this paper, we discuss how to apply skew among many analysis methods for reducing cogging torque. It shows the procedure for reducing cogging torque by applying skew from the comparative model. Finally, it analyzes the characteristics of the existing model and the model to which the skew is applied, and indicates how much it has increased. Improvements/Applications: By applying a three-stage skew to the model applied in this paper, the effect of noise and vibration can be reduced through cogging torque reduction.

Effects of a Newly Developed Palm-Based Processing Aid and Curing Systems on the Physical Properties of Nitrile Rubber Composites

Researches on developing renewable and eco-friendly processing aid are still on-going in the effort of replacing conventional petroleum-based processing aid. In this study, the effects of a palm-based processing aid (Bio) and curing systems on the physical properties of nitrile rubber (NBR) composites were evaluated. Curing systems studied were conventional (CV), semi-efficient (SEV) and efficient (EV) curing systems. It was found that regardless of the curing systems, the addition of Bio reduced the delta torque, cure rate index, glass transition temperature and loss tangent of the NBR composites. Reduction of delta torque by Bio resulted in lower tensile modulus (M100) and higher elongation at break (EB) of composites. Hardness, swelling index and compression set were also higher with the incorporation of Bio. The effects of curing system were also prominent in which using CV cure system leads to higher M100 and hardness and lower EB and compression sets. Excellent aging properties are crucial as it predicts the properties of the composite during service. After accelerated aging, results revealed that the effects of curing systems were significant on the retention of M100 and compression set of NBR composites where the SEV cured composites showed the highest retention of M100 and the lower compression set values. NBR composite with Bio, using a semi-efficient curing system was found to have the best aging properties compared to other composites.

Short-term neuromuscular, morphological, and architectural responses to eccentric quasi-isometric muscle actions.

Eccentric quasi-isometric (EQI) contractions have been proposed as a novel training method for safely exposing the musculotendinous system to a large mechanical load/impulse, with few repetitions. However, understanding of this contraction type is rudimentary. We aimed to compare the acute effects of a single session of isotonic EQIs with isokinetic eccentric (ECC) contractions. Fifteen well-trained men performed a session of impulse-equated EQI and ECC knee extensions, with each limb randomly allocated to one contraction type. Immediately PRE, POST, 24/48/72h, and 7days post-exercise, regional soreness, quadriceps swelling, architecture, and echo intensity were evaluated. Peak concentric and isometric torque, rate of torque development (RTD), and angle-specific impulse were evaluated at each time point. There were substantial differences in the number of contractions (ECC: 100.8 ± 54; EQI: 3.85 ± 1.1) and peak torque (mean: ECC: 215 ± 54 Nm; EQI: 179 ± 28.5 Nm). Both conditions elicited similar responses in 21/53 evaluated variables. EQIs resulted in greater vastus intermedius swelling (7.1-8.8%, ES = 0.20-0.29), whereas ECC resulted in greater soreness at the distal and middle vastus lateralis and distal rectus femoris (16.5-30.4%, ES = 0.32-0.54) and larger echogenicity increases at the distal rectus femoris and lateral vastus intermedius (11.9-15.1%, ES = 0.26--0.54). Furthermore, ECC led to larger reductions in concentric (8.3-19.7%, ES = 0.45-0.62) and isometric (6.3-32.3%, ES = 0.18-0.70) torque and RTD at medium-long muscle lengths. A single session of EQIs resulted in less soreness and smaller reductions in peak torque and RTD versus impulse-equated ECC contractions, yet morphological shifts were largely similar. Long-term morphological, architectural, and neuromuscular adaptations to EQI training requires investigation.

Numerical analysis on replacement of integrated planet carrier at maximum torque reduction stage in industrial gearbox

Gearbox is used for the transmission purpose. The parameters like load, environmental effect, type of operation is affecting the carrier in planetary gearbox. The carrier employed in high torque involving stage will experience more forces, so those carriers are preferred with cast iron. But in industries, high torque industrial gearboxes are produced in large quantity so it leads to more investment and time consuming. To overcome that, we suggesting the carrier in the high torque gear box fabricated with structural steel. In this present study, numerical analysis on the casted and fabricated carrier was made. Furthermore, pressure and load are the input parameters selected for analysis. Total deformation, stress and fatigue life are assessed with NX – Nastran for every fatigue analysis. The various model modifications are produced and the analysis is performed using NX-Nastran software. The task is carried out using manual calculation and validation with the aid of kiss-software, and is carried out using SOLIDWORKS 2013, NX – NASTRAN software, through the aid of CAD modelling and final element analysis.

Effect of cyclic loading on the stability of screws placed in the locking plates used to bridge segmental bone defects.

The objective of this study was to evaluate the ex vivo effect of cyclic loading on the stability of screws placed in locking plates used to bridge segmental bone defects. The primary interface stability was assessed using peak reverse torque. Eighteen, 8‐hole stainless‐steel 4.5 mm locking plates and 4.0‐mm self‐tapping locking‐head screws were used to stabilize 40‐mm segmental defects in goat tibiae. Treatment groups included control constructs without cyclic loading (n = 6) and constructs tested to 5000 (n = 6) and 10,000 cycles (n = 6) of 600 N compressive axial loading. The insertion of all screws was standardized to 400 N‐cm insertion torque. Peak reverse torque was measured immediately after screw placement (control), or after the completion of the respective loading cycles. The difference between treatment groups was compared using univariate analysis of variance. The analysis revealed a significant difference in peak reverse torque of the screws among the treatment groups (p = .000). The mean reverse torque values equaled 343.5 ± 18.3 N‐cm for non‐cycled controls, 303.3 ± 25.9 and 296.0 ± 42.9 N‐cm after 5000 and 10,000 cycles, respectively. Among all treatment groups, screws placed in the distal bone segment tended to have lesser peak reverse torque reduction than those placed in the proximal segment and the difference was proportional to the number of cycles (p = .562; p = .255; p = .013 in control, and after 5000 and 10,000 cycles, respectively). Cyclic loading may have a negative effect on the primary stability of screws placed in locking plate constructs used to bridge segmental bone defects and could contribute to the risk of screw loosening.

Acute Static Stretching Results in Muscle-Specific Alterations amongst the Hamstring Muscles.

This study aimed to explore the acute effects of static stretching on the musculotendinous properties of two hamstring muscles. Twelve male volunteers underwent two testing sessions. One session was dedicated to the evaluation of the semitendinosus muscle before (PRE) and after (POST) static stretching (five sets of 30-s stretching), and the other session similarly explored the long head of biceps femoris muscle. In addition to the displacement of the myotendinous junction (MTJ), passive torque and maximal voluntary isometric torque (MVIT) were evaluated. MVIT (−8.3 ± 10.2%, p = 0.0036, d = 0.497) and passive torque (−28.4 ± 16.9%, p = 0.0003, d = 1.017) were significantly decreased POST stretching. PRE stretching, MTJ displacement was significantly greater for semitendinosus muscle than biceps femoris muscle (27.0 ± 5.2 vs. 18.6 ± 3.6, p = 0.0011, d = 1.975). After the stretching procedure, greater MTJ displacement relative changes were observed for biceps femoris muscle as compared to semitendinosus muscle (22.4 ± 31.6 vs. −8.4 ± 17.9, p = 0.0167, d = 1.252). Because of the smaller MTJ displacement PRE stretching and greater alteration POST stretching in biceps femoris muscles, the present study demonstrated muscle-specific acute responses of hamstring muscles during stretching. Although stretching acutely impairs torque production, the passive torque reduction and alteration of MTJ displacement might impact hamstring injury prevention.

Computation-Efficient Solution to Open-Phase Fault Tolerant Control of Dual Three-Phase Interior PMSMs With Maximized Torque and Minimized Ripple

For dual three-phase interior permanent magnet synchronous machines (DT-IPMSMs), open-phase fault (OPF) can result in significant average torque reduction and harmonics in the output torque and speed, which prevent the machines from a reliable and safe operation. Indeed, these adverse effects are mainly due to significant harmonics in the stator currents caused by OPF. This article investigates fault-tolerant control (FTC) of DT-IPMSM under OPF and proposes a computation-efficient FTC solution to maximize the average torque and minimize the fault-induced torque and speed ripples. In the proposed FTC, the open-phase model is first derived, and optimal stator currents are then derived to achieve maximized average torque and minimized fault-induced torque harmonics. The computation efficiency enables the proposed solution, the capability of FTC, under both the steady-state and transient conditions. Moreover, the proposed FTC can eliminate the harmonic current components in the torque contributing frame and, thus, reduce the harmonic losses, and nonlinear inductance maps are employed to consider magnetic saturation. The proposed FTC is compared with existing methods and evaluated with experiments on a laboratory DT-IPMSM under various operating conditions.

A New Technique to Reduce the Cogging Torque of Integral Slot Number in Permanent Magnet Synchronous Machine

This paper proposed a new cogging torque reduction technique of integral slot number in the permanent magnet synchronous machine (PMSM). The purpose of the proposed new technique simulated on the PMSM with 48 slot/6 pole structure. In the study, the magnet edge of the PMSM was slotted to minimize the cogging torque while the stator core has remained natural. Slotting in magnet edge is one of the techniques to reduce the cogging torque in PMSMs, which has been existed in the previous research. In the proposed structure, we employed the two steps of slotting in magnets edge as one of the cogging torque reduction techniques. In this paper, authors have investigated three permanent magnet synchronous machine with different magnet structure has been studied and compared. The proposed permanent magnet synchronous machine with employed two steps of slotting has shown to promise the best of cogging torque reduction. The performance of the permanent magnet synchronous machine studied has been computed and analyzed by finite element analysis. It is found that the smaller cross-section area of magnet pole results in the decrement of cogging torque and air gap normal flux density in the PMSM. The new slotting in the magnet edge reduces the magnet pole cross-section and the cogging torque. The cogging torque of the proposed structure could be reduced around 98.8 % compared with the initial structure. The two steps of slotting could reduce the cogging torque of integral slot number in permanent magnet synchronous machine significantly.