Torque Performance Research Articles

Torque Measurement and Control for Electric-Assisted Bike Considering Different External Load Conditions

This paper proposes a novel torque measurement and control technique for cycling-assisted electric bikes (E-bikes) considering various external load conditions. For assisted E-bikes, the electromagnetic torque from the permanent magnet (PM) motor can be controlled to reduce the pedaling torque generated by the human rider. However, the overall cycling torque is affected by external loads, including the cyclist’s weight, wind resistance, rolling resistance, and the road slope. With knowledge of these external loads, the motor torque can be adaptively controlled for these riding conditions. In this paper, key E-bike riding parameters are analyzed to find a suitable assisted motor torque. Four different motor torque control methods are proposed to improve the E-bike’s dynamic response with minimal variation in acceleration. It is concluded that the wheel acceleration is important to determine the E-bike’s synergetic torque performance. A comprehensive E-bike simulation environment is developed with MATLAB/Simulink to evaluate these adaptive torque control methods. In this paper, an integrated E-bike sensor hardware system is built to verify the proposed adaptive torque control.

Design of multi‐phase permanent magnet synchronous motor with fractional‐slot windings for electromagnetic vibration reduction considering stator teeth modulation

AbstractA multi‐phase permanent magnet synchronous motor (PMSM) with fractional‐slot windings is proposed to reduce electromagnetic vibration and improve torque performance. Firstly, the analytical expression of electromagnetic force is derived, and the stator teeth modulation effect of electromagnetic force is introduced. The spatial order of the electromagnetic force and the stator teeth modulation are closely related to the slot‐pole combination of the PMSM. Then, three PMSMs with different slot‐pole combinations are presented, and they represent fractional‐slot concentrated winding, integral‐slot distributed winding and fractional‐slot distributed winding, respectively. Their torque performance and electromagnetic vibration performance are studied and compared considering stator teeth modulation. In addition, the multi‐phase winding technology is adopted to further improve the torque performance of the proposed PMSM. Finally, a 90s20p PMSM is manufactured, and the finite element method and experimental method are used to verify the proposed low vibration design method.

Particle Swarm Optimization of Electromagnetic Vibration of PMSM Using Surrogate Model

Intelligent algorithms and surrogate models are commonly used in electromagnetic design of electrical machines. But they are rarely employed for other single-physics or multi-physics designs, such as that for electromagnetic vibration suppression. On the other hand, it is uncommon in existing literatures to compare the performances of different surrogate models for optimization. In this paper, the accuracies of three surrogate models are compared for different optimization objectives, and a 15-input 7-output problem involving electromagnetic vibration is solved through particle swarm optimization. After optimization, the motor electromagnetic vibrations at all dominant frequencies are significantly reduced and the torque performance is improved. The optimization result is verified with both finite element simulation and experimental measurement.

A Novel Parallel-Excited Dual-PM Reluctance Machine With Enhanced Torque and Efficiency Performance

This paper presents a novel parallel-excited dual-PM reluctance machine (DPM-RM) with enhanced torque and efficiency performance. The key is to build an integrated magnetic field with two sets of PM excitation sources in both stator yoke and slot openings. Two excitation sources produce a parallel magnetic field, which contributes to a superimposed magnetic flux in the airgap, thus leading to strengthened flux variation, improved back-EMF and torque. Additionally, with a special slot/pole combination, biased component and even order harmonics in the phase magnetic flux are eliminated to make the phase flux linkage more sinusoidal. In the meantime, self-inductance variation is greatly suppressed with odd order harmonics of self-inductance removed, resulting in suppressed torque ripple. The prototype is manufactured, and experiments are carried out to verify the effectiveness of the machine design.

Rethinking the Design of Non-Salient Bearingless Permanent Magnet Machines

Bearingless motors are electric machines capable of simultaneously creating both torque and suspension forces. A detailed investigation into the underlying physics governing magnetic force creation in these machines is conducted in this paper, resulting in a newly derived analytic bearingless machine force model. Several key insights on designing bearingless machines for optimum force and torque performance are obtained from this investigation, including designing bearingless machines to be compatible with field-weakening and with conductive rotors. Validation for these findings is provided numerically, using optimization and FEA, and experimentally with hardware test results as well. The analytical foundations of bearingless machine operation developed in this paper makes bearingless machine design more intuitive and will pave the way for further innovation in this burgeoning field.

Research on magnetic field and temperature field of multi-phase SPMSM under winding fault

In order to quickly and accurately calculate fault-tolerant capability of multi-phase surface-mount permanent magnet synchronous motor (SPMSM) at condition of asymmetrical fault, based on subdomain model, an analytical model for multi-phase SPMSM with asymmetric fault is proposed to calculate magnetic field distribution. Firstly, air-gap flux density, no-load back electromotive force (EMF) and electromagnetic torque are obtained accurately. Then, in order to improve the fault-tolerant capability of multi-phase SPMSM, with the minimum phase current as optimization objective, a fault-tolerant control system under the condition of single-phase winding disconnection is established. The performance of electromagnetic torque and torque ripple are used as evaluation indicators. Finally, taking a 12-phase SPMSM prototype with 44-poles 48-slots as an example, the effectiveness of proposed model is proved by 2D finite element model (FEM) and experiment test.

Failure response of holed aluminum/glass hybrid composite tubes

It is known that aluminum/composite hybrid tubes of aluminum tube wrapped with a composite material on the outside can offer remarkable performance. This study systematically investigates the effect of stacking sequence on the torque capacity of holed aluminum/composite hybrid tubes. The stacked specimens manufactured by the filament winding method, [±452/Al], [90/±452/Al], and [±452/90/Al], are considered in experimental studies. The tubes were tested for torsional characteristics at a constant angular rotational speed. The experimental studies indicated that although monotonic crack propagation was observed in the aluminum tube with the damage starting from the hole wall at an angle of approximately 45° concerning the specimen axis, the damage in hybrid tubes containing a 90° layer occurs in two phases. This causes a step-like formation in the torque–angle curves. Although the ± 45° reinforcement has a profound effect on torque-carrying, it has been observed that the presence of the 90° composite on the aluminum tube in the reinforced tube improves the effectiveness (torque capacity and stiffness) of the subsequent reinforcement. Accordingly, it is understood that the hybrid structure increases the torque-carrying capacity up to 2.6 times compared to the aluminum tube, corresponding to a 20% increase in specific torque value. The stress components that play an important role in the deformation of the hole wall and damage formation processes have been successfully determined by the finite element method. It was found that there was a consistent relationship between the effect of the stacking sequence on the stress distribution and the experimental results. The results of the study are expected to be useful in terms of providing light and sufficient torque performance in case of possible hole-like discontinuity in-service conditions.

Design and Optimization of an Asymmetric Rotor IPM Motor with High Demagnetization Prevention Capability and Robust Torque Performance

In this paper, an asymmetric rotor interior permanent magnet (ARIPM) motor with high demagnetization prevention capability and robust torque performance is proposed. The key contribution of this paper lies in two aspects. On the one hand, a novel asymmetric rotor with a shifted magnet axis is proposed to improve the demagnetization prevention capability and torque density. In order to obtain a proper asymmetric rotor topology of the ARIPM motor, the multi-physical performances, especially the PM demagnetization characteristics of five types of PM arrangements, are analyzed. Furthermore, an asymmetric rotor with V- and VV-type PM arrangement is preliminarily designed, considering the multi-physical performance balance and the potentially high anti-demagnetization ability. On the other hand, it is found that the asymmetric rotor structure can not only improve the nominal value of motor performance but also can enhance the resistance to the influence of manufacturing uncertainties. Therefore, multi-objective optimization of the ARIPM motor with rotor notch design is carried out to obtain an optimal motor structure with both high nominal value and robustness of motor performances. By comparing the simulation results with those of a benchmark motor, the superiority and validity of the proposed ARIPM motor are confirmed. Experimental tests will be carried out in the future to further verify the effectiveness of the proposed motor.

Study on the influence of dual-winding optimization design on the torque and suspension performance of bearingless motor

Abstract The bearingless motor with dual-winding embedded in the stator can not only produce electromagnetic torque and can also produce suspension force to support the rotor suspension, and the design of the dual-winding will directly affect the torque and suspension performance of the motor. It is a complex problem of multi-objective optimization, multi-performance coupling, and multi-parameter collaborative optimization, which is great significance to improve the comprehensive performance of the motor. Firstly, in order to solve the problem of slot space ratio and turns design of dual-winding under the restriction of stator slot space and thermal loading, the calculation formulas of the electromagnetic torque and the suspension force are derived. The influence of dual-winding design on electromagnetic loading, thermal loading, torque and suspension performance are analyzed. The linear variation of electromagnetic torque with the slot space ratio of torque winding is obtained, and the influence of the dual-winding magnetic motive force on suspension force is clarified. Secondly, in order to obtain the dual-winding design scheme with the optimal torque and suspension performance, the performance parameters of the motor are calculated by finite element method and the influence of the slot space ratios of the torque winding on the torque and suspension performance is analyzed. Based on the coupling analysis of the electromagnetic torque and the suspension force in the case of different thermal loading distributions of dual-winding, the dual-winding optimal design of the bearingless motors is given. Finally, the suspension force of a prototype is tested by experiment.

Stall Torque Performance Analysis of a YASA Axial Flux Permanent Magnet Synchronous Machine

There is a trend to go towards low gear-ratio or even direct-drive actuators in novel robotic applications in which high-torque density electric motors are required. The Yokeless and Segmented Armature Axial Flux Permanent Magnet Synchronous Machine is therefore considered in this work. In these applications, the motors should be capable to deliver high torque at standstill for long periods of time. This can cause overheating of the motors due to a concentration of the losses in a single phase; hence, it becomes necessary to derate the motor torque. In this work the influence of the slot/pole combination, the addition of a thermal end-winding interconnection and the equivalent thermal conductivity of the winding body on the torque performance at standstill will be studied both experimentally via temperature measurements on a prototype stator, and via a calibrated 3D thermal Finite Element model. It was found that both a good choice of the slot/pole combination and the addition of a thermal end-winding interconnection have a significant influence on the torque performance at standstill, and allow up to 8% increase in torque at standstill in comparison to a reference design.

Synergistic Effect of J-Shape Airfoil on the Performance of Darrieus-Type Straight-Bladed Vertical Axis Wind Turbine

AbstractDarrieus-type straight-bladed vertical axis wind turbines (SB-VAWTs) are more appropriate for generating electricity than other VAWTs mostly suitable for regions having low to medium wind speed. The installation of SB-VAWTs faces start-up problems, which limits its applicability in low-wind speed environments. The start-up problem arises mainly due to the cross-sectional blade profile of the SB-VAWTs and is the crucial parameter used for blade design. To overcome this issue, the present investigation aims to study the influence of the J-shape airfoil with various opening ratios in the Darrieus-type SB-VAWTs in terms of starting torque and aerodynamic performance. The design of a J-shape airfoil is created by removing a portion toward the trailing edge of the conventional NACA 4415 airfoil on its upper or lower surface. This analysis displays a maximum power coefficient of 0.517, 0.512, 0.506, 0.498, and 0.488 when the Darrieus-type SB-VAWT utilizes upper cut J-shape airfoils with opening ratios of 0.8, 0.7, 0.6, 0.5, and 0.4, respectively, at the tip speed ratio (TSR) of 1.6. These values are higher than the power coefficient (0.486) of conventional NACA 4415 airfoil at the same TSR. The SB-VAWT depicts a lower performance while it employs the lower cut J-shape airfoils. Furthermore, the present study demonstrates that the power and torque coefficient of SB-VAWT improves by about 31% when the opening ratio of upper cut J-shape airfoil is varied from 0.1 to 0.8.

A new AC motor driven by travelling magnetic field excited on LC ladder circuit without its nonlinearity

In three-phase AC motors, three-phase AC voltage system is essential to generate a rotating magnetic field. Three- phase AC motors also require a three-phase inverter for variable speed and torque operation. In general, the number of switching devices used in three-phase inverter is not less than six and decreasing its number is difficult. This paper focuses on an LC ladder circuit consisting of linear inductors and capacitors. This paper presents a new operating method of the AC motor based on a propagating magnetic field. It is successfully excited by connecting one single-phase AC power supply to the end of the LC ladder circuit. The induction motor operated by the presented method produces torque as in general induction motors.

The optimal design and research of interior permanent magnet synchronous motors for electric vehicle applications

AbstractAn interior permanent magnet synchronous motor (IPMSM) with “VV—” shape rotor topology structure is proposed, and its performances are compared with “V” shape and “V—” shape rotor topology structure. The results show that the performances including output average torque, reluctance torque, torque ripple, cogging torque, iron loss of the IPMSM with “VV—” shape is better than the other two rotors. Firstly, the parameters which have great influence on the torque and the efficiency of the IPMSM are analyzed and optimized. The no‐load back electromotive force (EMF) of three different optimized rotor topology structures are analyzed and compared, the results show that the no‐load back EMF of the IPMSM with “VV—” shape topology structure has the lowest total harmonic distortion rate (THD). Secondly, the torque of the IPMSM with “VV—” shape under different current angles, current densities and speeds are analyzed and compared with the other two rotors. The results show that the torque performance of the IPMSM with “VV—” shape rotor topology structure is better than that of the other two. Finally, aiming at the problems that the torque ripple and cogging torque of the IPMSM with “VV—” shape rotor topology structure are greatly increased when the iron loss is reduced, This paper proposes to add a set of circular flux isolation holes between the second layer and the third layer of permanent magnets, and the position and diameter of this set of circular flux isolation holes are optimized and adjusted. The results show that the torque ripple and cogging torque of the IPMSM with the further optimized “VV—” shape rotor topology structure are greatly reduced, and the THD of no‐load back EMF is also further reduced, which has great significance to reduce vibration and noise, improve the control accuracy of the IPMSM.

An Enhanced Predictive Current Control Scheme for Common Mode Voltage Alleviation and Improvement of Torque Response of PMSM Drive

Predictive current control (PCC) is an effective control scheme with provisions to handle multiple objectives and nonlinear constraints. In the conventional PCC (CPCC) scheme, the application of a zero-voltage vector (ZVV) leads to the generation of large common-mode voltage (CMV), which gradually leads to bearing damage. However, disregarding ZVV can suppress CMV at the expense of large distortions in stator current. To avoid this, the present work deploys synthesized voltage vectors (SVVs) obtained from adjacent active vectors (AAVs) for permanent magnet synchronous motor (PMSM) drive control. In this article, two techniques are proposed for alleviating the CMV. Two AAVs are applied for a fixed duration in the first proposed method. Thus, the effect of neglection of ZVV can be circumvented with the application of two AAVs. In the second method, multivectors are applied to ensure CMV suppression and improvement of the steady-state torque response. Furthermore, an effective voltage vector (VV) preselection scheme using the complex-plane concept is introduced. Unlike the conventional CMV reduction schemes, the proposed VV-preselection evades tangent inverse angle determination and complex transformations. This offers the advantage of reduced computational burden with improved steady-state torque performance. The effectiveness of the proposed schemes is validated by comparing them with CPCC and existing literature.

Experimental analysis of hybrid VAWT and the effect of semi-cylindrical attachment to the trailing edge

Vertical axis wind turbines (VAWTs) work efficiently in low wind speed regions and varying wind directions like urban environments due to their omnidirectional capability. The current study examines experimentally the performance of the H-Darrieus VAWT having NACA 0018 airfoil by use of semi-cylindrical attachments at the trailing edge and hybridization using two bladed S-Savonius rotor with zero overlap conditions. The rotor's static torque and dynamic performances are investigated at a low wind speed of 4 m/s. The results show that the semi-cylindrical attachment increases the range of positive static torque. The static torque of Darrieus with attachment at 90° inside is more consistent, which enhances the starting capability of the Darrieus turbine with a static torque coefficient of 0.031, which is 29.7 % higher than a simple Darrieus turbine. The hybrid configuration shows maximum dynamic torque only at the 90° azimuthal position. The power coefficient of all configurations with attachments is lower than simple Darrieus due to drag created by attachments. The power coefficient value of 0.03 for hybrid configuration is the highest, with a wide range of tip speed ratio (TSR).

Effects of neurorehabilitation with and without dry needling technique on muscle thickness, reflex torque, spasticity and functional performance in chronic ischemic stroke patients with spastic upper extremity muscles: a blinded randomized sham-controlled clinical trial

Purpose Evaluation the effects of dry needling on sonographic, biomechanical and functional parameters of spastic upper extremity muscles. Methods Twenty-four patients (35–65 years) with spastic hand were randomly allocated into two equal groups: intervention and sham-controlled groups. The treatment protocol was 12-sessions neurorehabilitation for both groups and 4-sessions dry needling or sham-needling for the intervention group and sham-controlled group respectively on wrist and fingers flexor muscles. The outcomes were muscle thickness, spasticity, upper extremity motor function, hand dexterity and reflex torque which were assessed before, after the 12th session, and after one-month follow-up by a blinded assessor. Results The analysis showed that there was a significant reduction in muscle thickness, spasticity and reflex torque and a significant increment in motor function and dexterity in both groups after treatment (p < 0.01). However, these changes were significantly higher in the intervention group (p < 0.01) except for spasticity. Moreover, a significant improvement was seen in all outcomes measured one-month after the end of the treatment in the intervention group (p < 0.01). Conclusions Dry needling plus neurorehabilitation could decrease muscle thickness, spasticity and reflex torque and improve upper-extremity motor performance and dexterity in chronic stroke patients. These changes were lasted one-month after treatment.Trial Registration Number: IRCT20200904048609N1 IMPLICATION FOR REHABILITATION Upper extremity spasticity is one of the stroke consequences which interfere with motor function and dexterity of patient hand in activity of daily living Applying the dry needling accompanied with neurorehabilitation program in post-stroke patients with muscle spasticity can reduce the muscle thickness, spasticity and reflex torque and improve upper extremity functions

Torque analysis and stator windings influence research on negative-salient permanent magnet synchronous motor

Compared with the traditional motor, the negative-salient permanent magnet synchronous motor (NSPMSM) has the characteristics of wide-speed range, strong overload capacity and uneasily demagnetized permanent magnet. In this paper, a new rotor structure of NSPMSM is proposed by using magnetic bridge to increase the d-axis inductance (Ld) and W-type permanent magnet to decrease the q-axis inductance (Lq). Firstly, the electromagnetic torque performance of NSPMSM was analyzed from the parameters of permanent magnet (PM) thickness, magnetic bridge length, eccentricity distance and air-gap length using finite element method. At the same time, the electromagnetic torque ripple and cogging torque of the NSPMSM are further analyzed, which provides an effective basis for evaluating the optimal performance of the NSPMSM. Secondly, the effects of different stator slots and different winding layers on the air-gap magnetic flux density, electromagnetic torque, power and eddy current loss of PM of the NSPMSM were analyzed by finite element method under the condition of same rotor. The advantages and disadvantages of different windings are summarized, and the constant-power speed range of the NSPMSM is calculated, which provides the basis for the study of the flux weakening properties of the new motor. The results of theoretical analysis agree with those of simulation analysis, which verifies the effectiveness and feasibility of the new motor.

Research on the torque performance for two multi-pole bilayer magnetorheological fluid couplings

This paper studies on the permanent magnets configuration on the transmission torque of the multi-pole bilayer magnetorheological (MR) coupling. Based on the electromagnetic field theory, the magnetic circuit models of traditional permanent magnet array (TPMA) and Halbach permanent magnet array (HPMA) are established, and the magnetic flux density within the MR fluid working gaps has been derived in order to evaluate the merits of the designed MR coupling. A 3D FE magnetic-fluid analysis has been necessary following the initial conceptual analysis, in order to study the influence of key parameters on the transmission torque. The results show that the transmission torque of the MR coupling with Halbach permanent magnet array is 33.45% higher than that of the ordinary permanent magnet array, with a same structure size. For the MR coupling with Halbach permanent magnet array, the unilateral magnetic focusing effect is better with the increase of the residual flux density of the secondary magnetic pole as well as the radial length of magnetic pole. And the single side magnetic focusing effect is the best when the main magnetic pole is 15°. The influence of the magnetic pole angle on the transmission torque has been further studied.

A Torque-Enhanced Magnetic-Geared Machine with Dual-Series-Winding and Its Design Approach for Electric Vehicle Powertrain

Magnetic gear and magnetic-geared machine (MGM) are the potential solutions in electric vehicles (EVs) powertrains for inherent high efficiency and mechanical simplification. However, the torque density issue of the MGM greatly limits its industrial application. To enhance the torque performance of the MGM, a torque-enhanced magnetic-geared machine with dual-series-winding and its design approach are proposed. The key merits of the proposed design are to achieve a high space utilization with a dual-winding design, with no additional control topologies and power converters required. The auxiliary winding is supplemented and integrated with modulation rings. The relative position of the stator and armature winding are designed and rotated compared to the modulation rings with auxiliary winding, to ensure the auxiliary winding shares the excitation with the armature winding. Accordingly, simplifying the external control topologies. With the proposed design, the torque of the MGM can be significantly enhanced with a single three-phase driving. Theoretical analysis, parameters optimization and electromagnetic verification are given, demonstrating that the proposed machine can achieve an efficiency of 93.2%, generate a torque of 107.2 N·m, and reach a torque density of 10.81 N·m/kg.

Design to Reduce Modulated Vibration in Fractional-Slot Concentrated-Windings PM Machines Considering Slot–Pole Combination

The superior torque performance and unsatisfactory vibration are the inherent contradiction issue in fractional-slot concentrated-windings (FSCW) permanent magnet (PM) machines. This article aims to reduce the modulated vibration in FSCW PM machines while preserving their great torque performance. First, the contradictory relationship between the torque performance and the vibration of FSCW PM machines is revealed from the perspective of the slot–pole combination. Then, the radial force modulation of the FSCW PM machine is investigated from the aspects of spatial order and magnitude modulation. Subsequently, a new vibration reduction design methodology is presented, which combines the optimal slot opening coefficient and modified slot–pole combination. Finally, the prototype of a 12-slot/14-pole FSCW PM machine is manufactured, and several simulated and experimental verifications are carried out to validate the theoretical analysis.