Torque Performance Research Articles

Multiobjective Optimization of the PMSM With the Same Number of Poles and Slots Considering Dynamic Response and Torque Performance

Multiobjective Optimization of the PMSM With the Same Number of Poles and Slots Considering Dynamic Response and Torque Performance

Design and Multi-Objective Optimization of an Asymmetric-Rotor Permanent-Magnet-Assisted Synchronous Reluctance Motor for Improved Torque Performance

Design and Multi-Objective Optimization of an Asymmetric-Rotor Permanent-Magnet-Assisted Synchronous Reluctance Motor for Improved Torque Performance

Development and Analysis of a Novel Bio-syncretic Parallel Hip Exoskeleton Based on Torque Requirements

Abstract This paper presents a novel bio-syncretic parallel hip exoskeleton (BsPH-Exo) to address the rehabilitation exercise needs of individuals with lower limb motor dysfunction. BsPH-Exo has six degrees of freedom and can generate all three kinds of rotations that the hip joint can naturally realize. BsPH-Exo effectively solves the problem of misalignment between human and exoskeleton joints, eliminating the need for patients to perform any alignment operations. Considering the varying maximum torque requirements for hip joint rehabilitation in different directions, the limbs of BsPH-Exo are specially arranged to ensure that the maximum torque provided by BsPH-Exo in each direction follows the same law as that of the required torque. As a result, BsPH-Exo exhibits excellent output torque performance, specifically in the flexion/extension direction. Moreover, BsPH-Exo demonstrates weak coupling characteristics in the flexion/extension direction and decoupling characteristics in the adduction/abduction direction, which reduces the difficulty in its control. Compared to currently available parallel hip exoskeletons, BsPH-Exo has several distinct advantages that make it particularly well-suited for rehabilitation applications.

Numerical Study on the Influence of Torque Performance Caused by Deflectors on Darrieus Wind Turbines

This paper investigates the effects on the torque performance caused by deflectors of the Darrieus turbine. Various deflectors were placed in front of the turbine and disrupted the wind flow before it came into contact with the turbine blades. Using numerical method, this study aims to find the deflector’s optimum geometric shape, offset distance, and dimension required for the turbine to produce the highest torque. This study utilizes flow simulation analysis to simulate the deflector effect on Darrieus turbine. The result of this study is the optimum deflector geometry and offset distance for producing highest turbine torque output. From the data gathered it is shown that a deflector with triangular cross-section with the size of turbine diameter placed 400 mm offset to the right of the turbine produces the best result. Turbine with this deflector configuration produces 1.24 Nm of torque, eight times higher than its non-deflector counterpart yields 0.14 Nm.

Rotor pole and stator tooth shaping in FSPM machines for torque performance optimization

Purpose This study aims to obtain the minimum torque ripple at the maximum average torque for Flux-switching permanent magnet (FSPM) machines. Design/methodology/approach This paper is about torque performance optimization of the FSPM machines. To achieve that, finite element analysis and genetic algorithm (GA) are used. Five different designs are simulated, optimized and compared on their air gap flux density, back electromotive force, cogging torque, average torque, torque density and torque ripple. Findings After the thousands of iterations, its proved that all proposed shaping techniques have potential for reducing torque ripple and cogging torque, with slightly reduced average torque. The best design is the joint stator and rotor shaping, Design V, which results in the lowest torque ripple and cogging torque. The techniques should be applicable to FSPMs with other stator slot/rotor pole number combinations. Originality/value In this paper, rotor pole shaping by notching, chamfering and generic shaping, stator tooth shaping and joint shaping techniques are investigated for 12 s/10p FSPM machines. Rotor and stator flanks are optimized separately and jointly, by using finite element analysis and GA for optimization to achieve maximum average torque and minimum torque ripple. Five different design is implemented and compared, respectively.

Influence of Pedal Interface During Pedaling With the Upper Versus Lower Limbs: A Pilot Analysis of Torque Performance and Muscle Synergies.

Pedaling is a physical exercise practiced with either the upper or the lower limbs. Muscle coordination during these exercises has been previously studied using electromyography and synergy analysis, and three to four synergies have been identified for the lower and upper limbs. The question of synergy adaptabilities has not been investigated during pedaling with the upper limbs, and the impact of various modalities is yet not known. This study investigates the effect of pedal type (either clipped/gripped or flat) on the torque performance and the synergy in both upper and lower limbs. Torques applied by six participants while pedaling at 30% of their maximal power have been recorded for both upper and lower limbs. Electromyographic data of 11 muscles on the upper limbs and 11 muscles on the lower limbs have been recorded and synergies extracted and compared between pedal types. Results showed that the torques were not modified by the pedal types for the lower limbs while a deep adaptation is observable for the upper limbs. Participants indeed used the additional holding possibility by pulling the pedals on top of the pushing action. Synergies were accordingly modified for upper limbs while they remain stable for the lower limbs. In both limbs, the synergies showed a good reproducibility even if larger variabilities were observed for the upper limbs. This pilot study highlights the adaptability of muscle synergies according to the condition of movement execution, especially observed for the upper limbs, and can bring some new insights for the rehabilitation exercises.

Research on Torque Performance of Marine Hybrid Excitation Synchronous Motors Based on PSO Optimization of Magnetic Permeability Structure

The rotor magnetic shunt structure hybrid excitation synchronous motor (RMS-HESM) has been widely used in marine propulsion due to its advantages of low loss and high efficiency. The objective of this paper is to improve the output torque capability of the hybrid excitation motor with a rotor magnetic shunt structure by conducting a multi-objective optimization design for the magnetic permeability structure. The first step involved establishing a mathematical analytical model of average torque and torque ripple based on the fundamental principle of motor magnetization. Next, the parameters of the magnetic permeability structure were designed and analyzed using the finite element simulation method. The impact of the variations in the parameters of the magnetic permeability structure on motor torque and no−load back electromotive force was examined. Additionally, a sensitivity analysis was performed on the design variables of the magnetic permeability structure, leading to the determination of optimization parameters based on the obtained results. The adaptive inertia weight-based particle swarm algorithm (PSO) was employed to conduct a multi-objective optimization design analysis. A comparative analysis on the average torque, torque ripple, and no−load back electromotive force of the motor before and after optimization was performed using the Maxwell and Workbench and Optislong joint simulation tools. This enhancement significantly improves the torque performance of the marine motor while simultaneously optimizing the no−load back electromotive force.

Comparison of Electromagnetic Performance in Interior Permanent Magnet Motors with Different Central and Bilateral Bridges

Studies on the central and bilateral bridges of interior permanent magnet (IPM) motors often focus on individual mechanical strength or electromagnetic performance, lacking comparative studies on the electromagnetic performance of motors with different central and bilateral bridges under the same mechanical strength. This paper designs three rotors with different central and bilateral bridges and compares the electromagnetic performance of the three motors. First, to ensure the safe operation of the three rotors at high speeds, the mechanical stress of each rotor has been analyzed using the finite-element method (FEM). Subsequently, the major electromagnetic performances of the three motors are analyzed and compared, including the air-gap flux density, back electromotive force (back-EMF), inductance, salience, torque, power, loss, efficiency, and demagnetization. The results indicate that the rotor without central bridges has the largest leakage flux and the lowest torque but exhibits minimal torque ripple. The rotor with narrower bilateral bridges has the highest torque and maximum torque ripple. The torque performance of the rotor with wider bilateral bridges lies between the two aforementioned motors, and it possesses the highest efficiency. In the end, by adjusting the dimensions of the permanent magnets, the torque of all three models increases, but the motor with narrower bilateral bridges still has the largest torque. These findings provide valuable references for rotor design.

Design and Multi-Objective Optimization for Improving Torque Performance of a Permanent Magnet-Assisted Synchronous Reluctance Motor

Permanent magnet-assisted synchronous reluctance motors (PMA-SynRMs) are widely used in various industries as a relatively inexpensive and high-performance energy conversion device. The model proposed in this article relies on a magnetic pole-biased permanent magnet synchronous reluctance motor with a magnetic focusing effect. Two types of models with Halbach array and magnetic focusing effect have been proposed, which increase excitation and make the internal magnetic circuit of the rotor more saturated, thereby achieving higher electromagnetic torque. Through finite element simulation analysis and verification, the motor characteristics of the basic and proposed permanent magnet-assisted synchronous reluctance motor were calculated, including the air gap flux density and back electromotive force (EMF) in no-load analysis, as well as the average torque, torque ripple, and efficiency in load analysis. In addition, multi-objective optimization was also conducted on the rotor topology structure of proposed model two, using the uniform Latin hypercube sampling method to uniformly sample the data samples and the Pearson correlation coefficients to perform a sensitivity analysis on the data. The pilOPT multi-objective autonomous optimization algorithm was used to perform multi-objective autonomous optimization on parameters with high correlation, and the best-found solution based on the Pareto front was selected. Compared with proposed model two, the average torque of the optimized model increased by 18.14%, the efficiency increased by 1.05% and the torque ripple decreased by 5.22%. Finally, the anti-demagnetization performance of the optimized model’s permanent magnet was analyzed.

Analysis of MW-Level Offshore Wind Turbine Generators with Dual Star–Delta Fractional-Slot Windings

This paper investigates the use of fractional-slot concentrated windings (FSCWs) in large-scale (MW level) offshore wind generators. It focuses specifically on a power rating of 3 MW and uses an existing direct-drive synchronous PM machine (DD-SPM) with 480s/160p and dual three-phase integer-slot winding (ISW) as a baseline. A multiple of the common 12s/10p FSCW machine is used that matches the electrical frequency of the ISW machine, yielding a 192s/160p dual three-phase machine. The hybrid star–delta connection has grown increasingly popular owing to its unique harmonic cancellation properties, which can help reduce rotor and PM eddy current losses in FSCW machines. In this paper, two dual three-phase star–delta-wound machines are scaled to 3 MW and included in the investigation. Specifically, a 384s/160p dual three-phase and dual star–delta winding machine, which is a multiplication of the 24s/10p machine, and a 192s/176p dual three-phase and dual star–delta winding machine, which is a multiplication of the 24s/22p machine, are used. These machines are investigated using finite element analysis (FEA) and compared on the basis of their air-gap flux density harmonics, open-circuit electro-motive force (EMF), torque performance, and losses and power. It is found that the proposed 384s/160p dual star–delta winding machine has the best electromagnetic performance of all, with a stator power that is 1.2% greater than that of the baseline ISW machine. However, this machine has a coil pitch of 2 and so loses the manufacturing and fault-tolerant advantage of having concentrated windings. If concentrated windings are desired, then the proposed 192s/176p dual star–delta winding machine is the best choice, with the stator power only 2.6% less than that of the baseline ISW machine, but unfortunately still has significant rotor and PM eddy current losses.

Research on the design of hydraulic heater and optimization of energy matching of internal combustion engine heated steam generator

A novel internal combustion engine heated steam generator (ICEHSG) and the energy-matching optimization method are proposed in this paper. In the ICEHSG, the energy generated by the internal combustion engine (ICE) of the vehicle is converted to thermal energy as the heating source of the steam generator. Firstly, the prototype model of the hydraulic heater (HH) of the ICEHSG is established, and the relevant structural parameters are optimized based on computational fluid dynamics (CFD). Secondly, the energy matching between HH and ICE is optimized based on the particle swarm algorithm with compression factors (CFPSO). Finally, the energy provided by the ICEHSG and the required energy of the steam generation process is optimized, and the analysis is combined with the actual engineering case. The simulation results show that when the inclination angle of the blade is 45°, the number of rotor and stator blades is 31–33, and the diameter of the circular circle is 386 mm, the torque performance and heating performance of the HH are optimal. Meanwhile, the maximum thermal power can be obtained when the liquid filling rate of the HH is 100%. After optimization, the maximum torque of the HH working with the ICE is increased by 8.07%. Compared with the traditional boiler steam generator, the ICEHSG system proposed in this paper can increase the thermal efficiency by 1.3%–2.7% and reduce the cost by 37%.

Value of different preoperative bone evaluation methods in predicting intraoperative screw insertion torque: a prospective clinical comparative trial

BACKGROUND CONTEXTEstablishing good screw-bone structural stability is conducive to reducing the risk of postoperative screw loosening. Screw insertion torque is an objective index for evaluating screw-bone structural stability. Therefore, accurate prediction of screw insertion torque can improve the preoperative evaluation of patients, optimize the surgical plan, and improve the surgical effect. At present, the correlation between different bone assessment methods and screw insertion torque is unclear. PURPOSEThe aim of this study was to evaluate the correlation between different bone assessment methods and screw insertion torque and to optimize the predictive performance of screw insertion torque through mathematical modeling combined with different radiology methods. DESIGNProspective cross-sectional study. PATIENT SAMPLESSeventy-seven patients with preoperatively available DXA, CT and MRI data who underwent spinal fixation surgeries between October 2022 and September 2023 and 357 sets of screw data were included in this analysis. OUTCOME MEASURESSpinal, vertebrae-specific and screw trajectory's BMD were measured preoperatively by different imaging modalities. Intraoperative screw insertion torque was measured using an electronic torque wrench. METHODSPearson linear correlation, scatter plots and univariate linear regression were used to evaluate the correlation between different bone evaluation methods and screw insertion torque. Different bone evaluation methods were fitted into the prediction model of screw torque and the related equations were obtained. RESULTSScrew insertion torque had the strongest positive correlation with the volumetric bone mineral density (vBMD) of the screw trajectory (Pedicle screw insertion torque (PSIT): R = 0.618, p<.001; Terminal screw insertion torque (TSIT): R = 0.735, p<.001). A weak negative correlation was found between the screw insertion torque and level specific vertebral bone quality (VBQ) (PSIT: R = -0.178, p=.001; TSIT: R = -0.147, p=.006). We also found that the PSIT was strongly correlated with the TSIT (R = 0.812, p<.001). CONCLUSIONSCompared to other bone quality assessment methods, screw trajectory vBMD may be better predict the magnitude of screw insertion torque. In addition, we further optimized preoperative assessments by constructing a mathematical model to better predict screw insertion torque. In conclusion, clinicians should select appropriate preoperative bone quality assessment methods, identify potential low-torque patients, optimize surgical plans, and ultimately improve screw insertion accuracy and reduce postoperative screw loosening rate.

A Novel Switching-Table-Based Direct Torque Control With Improved Current and Torque Steady-State Performance for Dual Three-Phase PMSM

A Novel Switching-Table-Based Direct Torque Control With Improved Current and Torque Steady-State Performance for Dual Three-Phase PMSM

Global joint position regulation of a class of torque-driven robot manipulators within actuators prescribed safe operating torque–speed area

This paper addresses the joint position regulation of a class of n degrees of freedom torque-driven robot manipulators under a novel practical motivated control objective: Simultaneous Regulation & Prescribed Safe Operating Area (SR&PSOA). More specifically, torque–speed characteristic safe limit functions associated to each actuator are taking into account to ensure that besides of global joint positioning, the requested torque control inputs to robot actuators remain inside user prescribed safe operating torque–speed areas, so avoiding thermal and physical actuator damages. A static smooth nonlinear controller is proposed to achieve global position regulation under prescribed speed-depending bound torque input. Numerical simulations and experimental results are included to illustrate the effectiveness of the proposed controller.

Torque Capacity Improvement of Flux-Switching PM Machines Based on Directional Stator Permeance Design

As one type of flux modulation machines, flux-switching permanent magnet (FSPM) machines present high sensitivity to airgap structures. Therefore, both stator/rotor teeth and slot/pole combinations have significant influences on machine performance. However, the relationships between the optimal stator structure and maximum torque capability of the FSPM machine are barely investigated. Therefore, this paper is devoted to proposing a directional stator permeance design approach to achieve the maximum torque of the FSPM machines under a given rotor, and reveal the corresponding stator structure. First, the relations between torque and air-gap permeance are presented based on a constructed torque contribution equation, where amplitudes and phase angles of the stator permeance harmonics are determined. Then, main permeance harmonics are directionally optimized to enlarge positive torque, while negative contributions are inversed to be positive. Especially, two FSPMs with 6-slot/19-pole and 6-slot/13-pole are chosen as design examples, and their optimal design processes and torque performances have been deeply analyzed, which verifies the effectiveness of the proposed design approach.

Effects of tribological and material properties of wire rope on the motion synchronization of a precision flexible transmission device

During the long-term service process of a precision flexible transmission device driven by a wire rope, the tribological and material properties of the rope changes and causes a motion synchronization degradation. In this paper, a finite element model and a transmission error model of the device are built with the considerations of the surface wear of the rope, the variations in the rope-pulley friction coefficient, elastic modulus and Poisson’s ratio of the rope material. The evolutions of transmission error, elongation, stress state, and the output torque of the device as well as the tension distribution along the rope are solved. The results show that the motion synchronization degradation results from the surface wear, the decrements in the friction coefficient and elastic modulus, and the increment in the Poisson’s ratio. The rope tension decreases in the wrapping section around the guide pulley, and increases in most other positions due to wear. An increment in the friction coefficient causes reduced tensions in the wrapping section around the active pulley and the free section between guide pulleys, and worsens the tension uniformity and output torque performance of the device. The maximum stress of the rope increases with increasing elastic modulus and decreasing Poisson’s ratio.

Field oriented control driver development based on BTS7960 for physiotherapy robot implementation

In conjunction with sustainable development goal 3 (SDG 3), it is important to develop a national electrical component for physiotherapy robot development. This study aimed to develop an open-loop field-oriented control (FOC) driver utilizing BTS7960. The driver utilized three BTS7960s that produce sinewave with variable angular frequency (ω). The research then compared the open-loop FOC driver with electronics speed controller (ESC) performance to drive a brushless DC (BLDC) motor with an initial rotation per minute (RPM) of 400, 500, and 600. The main observation was RPM reduction when the BLDC motor was subjected to loads of 20, 35, 50, 65, and 80 gr. The result showed that the open-loop FOC driver performed better, especially on an 80 gr load. For an initial RPM of 600, the RPM reduced to 100 when controlled with an open-loop FOC driver, but lesser when controlled using ESC. The open-loop FOC driver produces higher torque on the BLDC motor so it could rotate with less reduction compared to ESC, which is evident. The open-loop FOC driver can be easily developed using BTS7960 with a settling time of 4 seconds. However future studies should still consider close-loop FOC drivers to achieve higher torque performance and faster transient response for physiotherapy robot applications.

Analysis of low saliency ratio and torque characteristics of the fractional slot concentrated winding surface mounted motors

In recent years, fractional slot concentrated winding permanent magnet synchronous motors (FSCW PMSMs) have become a hotspot in the research field. Due to the unique inductance characteristics of the FSCW PMSM, a fast and accurate calculation of the d/q-axis inductance and saliency ratio is necessary. In this paper, a method is proposed to calculate the d/q-axis reactance of the FSCW SPMSM, which constructs the equivalent magnetic circuit model of the d/q-axis armature reaction flux separately, and the saliency ratio characteristics of the FSCW SPMSM were demonstrated. In addition, to meet the high requirements of the modern industries, especially in servo systems, accurate consideration of the effect of stator resistance on torque and electromagnetic performance is important and more applicable. According to the relationship between the vector parameter, the explicit expression of the d/q-axis currents that consider the stator resistance is obtained, and the prediction of load angle at maximum electromagnetic torque is achieved. Then, combined with the finite element method, the influence mechanism of stator resistance on the motor steady-state performance is revealed. Finally, the experimental data are compared with the calculation data, and the correctness of the models and analysis was verified.

Investigating balance-related gait patterns and their relationship with maximum torques generated by the hamstrings and quadriceps in older adults - Results from the Baltimore longitudinal study of aging

BackgroundBalance-related gait patterns in older adults can be objectively discerned through the examination of gait parameters, maximum leg torques, and their interconnections. ObjectiveTo investigate the correlation between leg muscle strength and balance during gait concerning functional performance in healthy older adults. MethodsParticipants included 117 adults aged 60-95 years were recruited from the Baltimore Longitudinal Study of Aging (BLSA). They underwent evaluations of gait, balance, and maximum isometric leg torque (for both hamstrings and quadriceps). Analyses examined the association between leg torque and functional performance among those with higher and lower balances. ResultsIndividuals with lower balance (n = 43) were older, more prone to experiencing a fear of falling, and exhibited lower functional performance (gait speeds and Generalized Gait Stability Scores (GGSS), ps < 0.001) compared to their counterparts with higher balance (n = 74). At a usual walking pace, the GGSS showed a positive association with concentric Quadriceps Maximum Torque (QMT) in participants with lower balance (p = 0.013). Conversely, it displayed a positive association with eccentric QMT in those with higher balance (p = 0.014). At a fast walking pace, only individuals with higher balance demonstrated a positive muscle torque association with both gait speed and GGSS, encompassing concentric and eccentric actions in both the quadriceps and hamstrings (ps < 0.050). ConclusionEvaluating muscle strength capacity in both concentric and eccentric phases during dynamic high-effort events, along with investigating their associations with gait performance, can be beneficial for identifying subtle gait deficits. This comprehensive approach may assist in the early detection of gait deterioration among healthy older adults, given the intricate muscle activations involved in lower body functional performance.

Analysis and reduction of electromagnetic vibration in integral-slot PM machine by functional magnet structure

It is significant to balances torque and vibration performance for the surface-mounted permanent magnet (PM) machines. This paper proposes a functional magnet structure to suppress the vibration response of integral-slot surface-mounted PM machines. At the same time, the torque ripple is also greatly reduced without sacrificing the average torque. Firstly, taking the 48-slot/8-pole PM machine as an example, the main sources of the air-gap radial force are analyzed based on the Maxwell stress equation. Thereby, the main PM flux density harmonic components that contribute to the radial force are pointed out. Secondly, the design method of different functional magnet structure is investigated. Then, the effects of different magnet shapes on the torque and vibration performances are compared. The result shows that the proposed sinusoidal+3rd-order harmonic injection functional magnet structure can effectively improve the vibration performance without sacrificing the average torque. Finally, the prototype of the 48-slot/8-pole PM with functional magnet structure is manufactured, and the experiments are carried out for validation.