Torque Variations Research Articles

Alleviation and control of chaotic oscillations in SMIB power systems using a modified-Whale optimization-based battery-STATCOM

BackgroundChaotic oscillations within the power system give rise to instability. While these oscillations may not have an immediate impact on the synchrony of the machine, they stimulate one of the oscillation modes, ultimately leading to voltage collapse and a loss of synchronism. ObjectiveThis paper introduces a modified Whale Optimization Algorithm (WOA)-based Battery-STATCOM (Static Synchronous Compensator) as a solution to mitigate chaotic oscillations within a Single Machine Infinite Bus (SMIB) system. MethodologyAn adaptable controller is implemented to manage the gate signal within the Battery-STATCOM. The AC-DC currents of this controller are optimally governed by two distinct WOA-tuned Proportional-Integral (PI) controllers. The battery storage unit serves as a robust voltage source, with the intelligent controller maintaining the DC-link voltage at the desired level. Test CasesAdditional disturbances, such as gradual variations in reference voltage and electromagnetic torque, are introduced to exacerbate chaotic oscillations. This is done to assess the controller's real-world performance under adverse conditions. Results and ConclusionUnder zero damping conditions, rotor parameters, including rise time, settling time, peak time, and overshoot, initially remain undefined due to uncontrolled oscillations. However, once the Battery-STATCOM is applied, these parameters are defined and achieve values (in seconds) of 0.90, 6.21, 1.71, and 21.10, respectively. After further optimization through the proposed modified WOA optimizer, the parameters reach values of 0.25, 1.01, 0.89, and 1.78, respectively. These results underscore the effectiveness of the proposed metaheuristic controller in suppressing overall chaotic oscillations within the power system.

Performance Analysis of 9, 11, 13, and 15 – Level Back-to-Back Connected Modular Multilevel Converters fed Doubly Fed Induction Machine

In this paper, back-to-back Modular Multilevel Converters are used to feed the Doubly Fed Induction Machine. The MMC with 9, 11, 13, and 15 – Level output voltages are generated and fed to the DFIM and the performance of the DFIM is analyzed, when the machine is working as Doubly Fed Induction Generator (DFIG) and when the machine is working as Doubly Fed Induction Motor. The performance of the DFIG is analyzed in terms of power factor at Grid Side Converter (GSC) for different levels of operation of MMC. The results show that the power factor is maintained near to unity power factor at grid side. The performance of the Doubly Fed Induction Motor is analyzed in terms of variation of the load torque being applied to motor. The results show that there is clear variation of the speed for two different load conditions. The work is carried out by using Typhoon HIL Real-Time Simulation platform, i.e., both Software and Hardware.

An improved time-varying mesh stiffness calculation method and dynamic characteristic analysis for helical gears under variable torque conditions

Based on the slice theory and numerical calculation methods, the time varying meshing stiffness (TVMS) calculation method of the gear pair was constructed for the helical gear pair of a electric continuously variable transmission (ECVT), and the TVMS of the helical gear were calculated under different constant and time-varying torque in this study. The obtained stiffness values were introduced into the established dynamics model of helical gear system, and the influence of changed TVMS, resulting from the variable speed and torque, on the nonlinear dynamic characteristics of gear pair was analyzed using the Runge-Kutta method. The results show that the proposed TVMS calculation method is very effective in computing the TVMS of helical gear pair under time-varying condition. The TVMS and dynamic transmission error (DTE) increase as the torque increase, and vice versa. Meanwhile, the system exhibits a diverse range of periodic, sub-harmonic, and chaotic behaviors at high speed and at low speed when torque is low, whereas not appear at steady high torque under low speed range. This study offers a method for gaining the TVMS of helical gear pair to analyze the dynamic characteristics of gear pair under actual working condition, and the influence of torque that change with the speed ratio on the dynamic performance of a gear system should be considered in the industrial applications.

Characteristics of the Linear Motor for Electrified High-Speed Maglev Transportation in the Rotational Motions Caused by Asymmetry Transverse Air-Gaps

The electromagnetic characteristics and running stability of the linear motor for electrified Maglev transportation under rotational motions caused by asymmetry transverse air-gaps are calculated and analyzed. Firstly, considering the end effect and the shape of the vehicle coils, the formulas of levitation and guidance currents, levitation and guidance forces, rolling torque, yawing torque, coupling stiffness between lateral and rolling direction, coupling stiffness between lateral and yawing direction and equivalent guidance stiffness are derived. Secondly, the variations of rolling torque, yawing torque, guidance force and levitation force with different lateral displacement, rolling angle and yawing angle are predicted. Then the two coupling stiffnesses and the equivalent guidance stiffness at different operating speeds are investigated. Finally, in order to verify the analysis results, not only the 3-D FEM model is established, but also the experiments are carried out. It shows that the combined levitation and guidance electrodynamic suspension (EDS) maglev train will roll and yaw, and its levitation height also changes after being disturbed laterally. In addition, the train will run more stably when being disturbed laterally as running speed increases.

Improved Federal Test Procedure (FTP75) driving cycle performance for PMSM‐fed hybrid electric vehicles using artificial neural network

SummaryThe sensorless speed control of permanent magnet synchronous motor (PMSM) is gaining popularity in hybrid electric vehicle (HEV) applications leading to its enhanced safety, reliability, and cost savings. Speed control using vector control for PMSM‐fed HEV requires the speed encoder. When the speed sensor information fails, the inverter must ensure power delivery to the PMSM continuously by estimating the speed; this mode of operation is referred as limp‐home mode in HEV. In this paper, a speed sensorless scheme has been proposed for PMSM‐based HEV during limp‐home mode operation. This paper presents a model reference adaptive system (MRAS) speed estimator based on an adaptive neural network controller (NNC) for speed estimation of PMSM. In the HEV application, in case of speed/position encoder failure, the speed of the PMSM can be estimated by stator flux using stator current.The proposed method employs stator currents in the reference model to eliminate the DC drift problem. Furthermore, the NNC is employed in the adaptation mechanism to improve the Federal Test Procedure (FTP75) driving cycle performance. The performance of the proposed control scheme has been validated with dSPACE 1104 R & D rapid development controller using vector control for the PMSM during variable speed and torque, including the zero‐speed applications

Variable Flux Direct Torque Control System of Switched Reluctance Motor

Direct Torque Control (DTC) strategy is very suitable for controlling Switched Reluctance Motors (SRM) due to its advantages of the simple control structure and fast system response, etc. This paper first analyzes the principle of DTC and establishes the DTC model of three-phase 6/4 SRM by Matlab/Simulink. In this paper, a three-closed-loop variable flux DTC system with velocity as the given quantity is constructed to solve the problem that the stator current of constant flux DTC is too large when the motor is in a steady state. The simulation results show that the variable flux DTC system has a better inhibition effect on the stator current and torque ripple of SRM than the conventional DTC system.

Toward an optimal twisting-sliding mode control of a three-phase PMSM for electric vehicles

This paper deals with an optimal twisting sliding mode controller (OT-SMC) for the operation of a three phase permanent magnet synchronous machine (PMSM) in an electric vehicle (EV). In order to drive these vehicles, optimal performance is needed with robust control against real-time disturbances such as the variable load torque, uncertainties such as the parameters variation and speed variations between medium, low, and high speed as well as good performance characteristics for enhanced drive quality and longer battery time. Several conventional techniques have been applied to PMSM but they suffer from the problem of uncertainties and disturbances due to the PI regulator. A hybrid approach comprising of a robust nonlinear and optimal controller to achieve these objectives is attempted for driving electrical vehicles. This advanced hybrid controller obtained after the merger of sliding mode control (SMC) and a linear quadratic controller (LQR) is found to outperform existing controllers due to their superb performance characteristics. Furthermore, SMC is designed based on the exponential reaching law for the twisting sliding mode control (T-SMC) in order to ensure stability of the system while reducing the chattering, accelerating the rate of convergence with higher accuracy of the control performance, and the LQR is developed using the steady-state error method (N-LQR) in order to obtaining better performance characteristics. In addition, the hybridization between a twisting SMC and an optimal LQR is characterized by stabilizing and minimizing the oscillations in the permanent regime thus optimizing the system’s performance. Extensive simulation results illustrate the effectiveness and validity of the proposed control for achieving the highest performance of the PMSM.

Investigations on the wave performance of Savonius turbine operating under initial phase-locked strategy

Savonius hydrokinetic turbines (SHTs), categorized as emerging cyclic-type wave energy converters (WECs), have demonstrated notable potential in achieving elevated energy conversion efficiency and consistent power output. This performance is particularly observed when operating under the initial phase-locked strategy (IPLS), marking a significant advancement in the realm of wave energy harvesting. However, a thorough exploration of the influences stemming from wave conditions and turbine design remains an area that warrants further investigation for advancing the performance of SHT-WECs under the proper operational strategy. This study undertakes an exhaustive analysis of geometric parameters, encompassing turbine diameter, blade number, and thickness. An experiment-validated numerical model based on the unsteady two-phase Reynolds-averaged Navier–Stokes equations is adopted in the research. Comprehensive investigations include analyses of flow fields around the turbine, pressure distributions on blade surfaces, and dynamic torque variations. These analyses serve to elucidate the variation rules of hydrodynamic characteristics and their influential mechanisms. The results highlight the notable impact of the proposed “relative-short wavelength impact” on the performance of SHT-WECs operating under IPLS conditions. Notably, no significant impact is observed when the relative wavelength exceeds 17. Optimal performance is achieved with the thinnest and two-bladed turbine configuration. Moreover, optimizing the turbine diameter significantly enhances SHT-WEC conversion efficiency, with the attained maximum value reaching approximately 18.6%. This study offers a concise guideline for designing turbine diameters in alignment with specific wave conditions.

An Improved Integral Sliding Mode Control for PMSM Drives Based on New Variable Rate Reaching Law With Adaptive Reduced-Order PI Observer

This paper focuses on speed control in a permanent-magnet synchronous motor (PMSM). To promote the speed tracking performance and anti-disturbance property of PMSM speed regulation system against various unknown disturbances, such as parameter mismatch, load torque variation, friction force, and so on, an improved integral sliding mode control (IISMC) method based on a new variable rate reaching law (NVRRL) and an adaptive reduced-order proportional integral observer (AROPIO) is proposed. The NVRRL method can reduce chattering, and convergence time of the system state at the same time compared to the existing sliding mode reaching law. An anti-windup sliding mode surface is proposed to overcome the overshoot problem of the integral sliding mode surface when the reference speed is large and rises in steps or large ramps. To further improve the system tracking accuracy and anti-disturbance ability, an AROPIO is used to estimate lumped disturbances and provides feedforward compensation for the IISMC. The simulation and experimental results show that the proposed IISMC+AROPIO method not only achieves high speed tracking accuracy and fast convergence speed but also achieves strong anti-interference ability.

The immediate effect of multidirectional elastic tape on the passive mechanical properties of the ankle joint

ABSTRACTThis study examined the immediate effects of multidirectional elastic tape (MET) on passive ankle joint torque in healthy adults. A randomised crossover trial evaluated four tape conditions (no-tape-NT, low-tension-LT, medium-tension-MT, and high-tension-HT) at two angular speeds on peak dorsiflexion torque, low- (stiffness 1) and high-torque stiffness (stiffness 2), area under the loading curve (AUC) and hysteresis. Twenty-two adults completed the study (17 females; mean (SD): age 26.0 (6.9) years, height 1.7 (0.1) m, body mass 71.1 (20.2) kg. There was no significant condition-by-speed interaction for any ankle torque variable. There was a significant main effect of condition on peak dorsiflexion torque, stiffness 1, and AUC, but not stiffness 2 or hysteresis. Post-hoc tests revealed that peak dorsiflexion torque, stiffness 1 and AUC were significantly lower in the NT condition, compared to the three taped conditions, and between the LT and HT conditions, though the effect sizes were considered small. MET applied with increasing levels of pre-tension, led to a small and incremental increase in stretch resistance and elastic energy stored (range 5.5% to 12.5%) during passive ankle dorsiflexion. Importantly, effect sizes were small and may not translate to measurable improvements in muscle-tendon unit performance during dynamic exercise.

Experimental investigation of a real-time singularity-based fault diagnosis method for five-phase PMSG-based tidal current applications

This paper presents a novel real-time singularity-based fault diagnosis method for tidal current applications, specifically utilizing a five-phase permanent magnet synchronous generator with trapezoidal back electromotive forces. The proposed method incorporates an innovative orthogonal signal generator through a second-order filter, enabling the extraction of detectable singularity signatures from phase current signals. The principle of the method is elucidated through step-by-step design procedures, outlining the indicator enhancement approach and adaptive thresholds employed for enhanced robustness and adaptability. Fault detection is performed based on the improved fault indicators and an adaptive threshold law, followed by immediate fault localization that is achieved via twice average operations of the phase currents. To demonstrate the effectiveness and efficiency of the proposed method, a comparative study is carried out with a classical mean current vector-based fault diagnosis method. A small-scale experimental platform emulating a tidal current application is established for a comprehensive evaluation of both methods. The experimental results highlight the superior fault diagnosis performance of the proposed method, particularly in detecting single and multiple open circuit faults in phases or switches, while exhibiting enhanced robustness against variations in torque and speed. The simplicity of implementation and rapid detection mechanism are principal merits for the proposed method.

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.

Data-Driven FMPC Based Dynamic Coordination Control Strategy for Power-Split Hybrid Electric Bus

Since no engine clutch exists in the power-split system of the hybrid electric bus, the torque variations of the power sources (i.e., the engine, motor, and generator) are easy to cause system shock during mode switching. To yield a better control effect, the model predictive control (MPC) based dynamic coordination control strategy (DCCS) is considered as an effective solution to guarantee the drivability and reliability of the system. However, the existing MPC-based DCCS still have the challenge of model accuracy and computational complexity. Therefore, to solve the problem, a data-driven Fast-MPC(FMPC) based DCCS is proposed for a power-split hybrid electric bus in this paper. Firstly, to ensure the accuracy of the engine dynamic model, a piecewise data fitting method is proposed by analyzing the historical data of the engine. Then, considering the high dimension of the control model (based on the dynamics model of the power-split system), a fast solving method for the quadratic optimization problem of MPC is proposed with respect to the proper assumption and simplification. Finally, to verify the effectiveness of the proposed control strategy, offline simulation and hardware-in-the-loop (HIL) simulation experiments are carried out. Simulation results show that good driving comfort and real-time performance have been achieved. This research is expected to promote the application of MPC in the DCCS and further improve the dynamic performance of the power-split system.

Numerical Simulation of Torque Variation During Paste Mixing and Kneading

In the production process of aluminum electrolytic carbon anode, the kneading process is to fully mix asphalt and powder to obtain the best paste, because the kneading process is completed in a high-temperature kneading machine, there is no suitable automatic real-time judgment method for the uniformity of paste. Real-time online monitoring based on the viscoelastic change of paste during kneading is a potential method to judge the uniformity of paste. In this paper, the Discrete Element Method numerical simulation is used to study the variation law of stirring torque in the mixing and kneading wet mixing process, mainly examining the effect of viscosity on stirring torque. The results showed that the mixing and kneading torque varied periodically and the total torque of the stirrer was positively correlated with the viscosity.

Research on the Prediction Method of Braking Rotation Angle for Remote-Controlled Excavator.

To calculate, analyze, and predict the rotation angle during the deceleration and braking process of large remote-controlled excavators, this article established a spatial coordinate system based on a simplified model of a hydraulic excavator's upper structure. Using the D-H parameter method, a mathematical model of the working device's center of gravity and its rotational inertia was established. Based on the characteristics of the excavator's hydraulic system and the relationship between brake torque variations, a prediction model was developed to forecast the stopping position (brake rotary angle) of the excavator's bucket after braking. Subsequently, the predicted results were validated using simulation and compared with existing experimental data to assess the accuracy of the model. The findings demonstrate that the predictive model exhibited high precision with minimal error. The utilization of this model enabled effective forecasting of the excavator's braking position changes, providing a theoretical foundation for the intelligent remote control of excavators.

Learning effect on an isokinetic knee strength test protocol among male adolescent athletes.

Learning effect occurs when the best performance is not achieved at the earliest trial of a repeated protocol of evaluation. The present study examined, within testing session, the intra-individual variation in an isokinetic strength protocol composed of five reciprocal concentric and eccentric contractions of knee extensors (KE) and knee flexors (KF) among male adolescent swimmers. Additionally, test-retest reliability was determined as intra-individual mean differences between two consecutive testing sessions. The sample included 38 swimmers aged 10.1-13.3 years. A subsample (n = 17) completed a second visit. Isokinetic dynamometry was used to assess concentric and eccentric contractions of KE and KF at an angular velocity of 60°.s-1. The protocol included three preliminary repetitions that were not retained for analysis, a 60-second interval, and five reciprocal maximal concentric contractions (cc). The preceding sequence was repeated for eccentric contractions (ecc) of KE and KF. Multilevel regression confirmed intra-individual and inter-individual levels as significant sources of variance in peak torque (PT) values. Intra-class correlation (ICC) fluctuated between 0.582 and 0.834 and, in general, a substantial percentage of participants need more than three repetitions to attain their best PT: KEcc (36.8%), KEecc (23.7%), KFcc (39.5%), KFecc (18.4%). For the subsample of 17 swimmers who completed a second testing session, intra-individual mean differences of the best PT were trivial or small. In summary, the validity of shorter protocols may be compromised if swimmers do not attain their best peak torque in the first few attempts, and the reliability of a 5-repetition protocol seemed acceptable.

Longitudinal assessment of strength and body composition in a mouse model of chronic alcohol-related myopathy.

Excessive, chronic alcohol consumption can result in muscle atrophy and weakness (i.e., alcoholic myopathy) that impairs the quality of life. However, the precise mechanisms responsible for ethanol's detrimental impact on skeletal muscle have not been fully elucidated, in part due because the time course of disease development and progression are not well established. Therefore, we examined muscle strength and body composition longitudinally using an established preclinical mouse model of chronic alcoholic myopathy. To establish a time course of chronic alcoholic myopathy, we fed High Drinking in the Dark (HDID) female mice (n = 7) 20% ethanol for ~32 weeks (following a 2-week ethanol ramping period). We assessed in vivo isometric contractility of the left ankle dorsiflexor and lean mass via NMR every 4 weeks. Outcomes were compared with age-matched control HDID mice that did not consume ethanol (n = 8). At study completion, mice who consumed ethanol were 12% weaker than control mice (p = 0.015). Compared to baseline, consuming ethanol resulted in an acute transient reduction in dorsiflexion torque at Week 4 (p = 0.032) that was followed by a second, more sustained reduction at Week 20 (p < 0.001). Changes in lean mass paralleled those of dorsiflexor torque, with ~40% of the variance in dorsiflexor torque being explained by the variance in lean mass of the ethanol group (p < 0.001). Dorsiflexor torque normalized to lean mass (mN·m/g lean mass) did not differ between the ethanol and control groups from Weeks 4 to 32 (p ≥ 0.498). These results indicate that reductions in muscle mass and strength due to chronic, excessive ethanol intake are dynamic, not necessarily linear, processes. Moreover, the findings confirm that ethanol-induced weakness is primarily driven by muscle atrophy (i.e., loss of muscle quantity). Future studies should consider how chronic alcoholic myopathy develops and progresses rather than identifying changes after it has been diagnosed.

Flow past a sphere translating along the axis of a rotating fluid: revisiting numerically Maxworthy's experiments

We compute the flow induced by the steady translation of a rigid sphere along the axis of a large cylindrical container filled with a low-viscosity fluid set in rigid-body rotation, the sphere being constrained to spin at the same rate as the undisturbed fluid. The parameter range covered by the simulations is similar to that explored experimentally by Maxworthy (J. Fluid Mech., vol. 40, 1970, pp. 453–479). We describe the salient features of the flow, especially the internal characteristics of the Taylor columns that form ahead of and behind the body and the inertial wave pattern, and determine the drag and torque acting on the sphere. Torque variations are found to obey two markedly different laws under rapid- and slow-rotation conditions. The corresponding scaling laws are predicted by examining the dominant balances governing the axial vorticity distribution in the body vicinity. Results for the drag agree well with the semi-empirical law proposed for inertialess regimes by Tanzosh &amp; Stone (J. Fluid Mech., vol. 275, 1994, pp. 225–256). This law is found to apply even in regimes where inertial effects are large, provided that rotation effects are also large enough. Influence of axial confinement is shown to increase dramatically the drag in rapidly rotating configurations, and the container length has to be approximately a thousand times larger than the sphere for this influence to become negligibly small. The reported simulations establish that this confinement effect is at the origin of the long-standing discrepancy existing between Maxworthy's results and theoretical predictions.

Nonlinear speed-tracking control with overcurrent protection for uncertain permanent magnet synchronous motor systems

For the speed-tracking control of permanent magnet synchronous motor (PMSM) systems, fast dynamic response and high reference speed require a large transient current to provide sufficient electromagnetic torque. However, the excessive transient current may damage the drive circuit and threaten the system safety. Besides, it is also important to pay attention to the influence of multiple disturbances including system parameter uncertainties and unknown load torque variation. To solve these problems, we propose a nonlinear speed-tracking control approach for uncertain PMSM systems. More specifically, based on the cascade control structure and by introducing auxiliary smooth function, we first develop a nonlinear current-constrained controller (CCC) to guarantee the speed tracking, disturbance rejection, and overcurrent protection simultaneously. In order to improve the robustness of the desired performances, we further implement extended state observer (ESO) techniques to propose an ESO-based CCC (ESO-CCC). Finally, comparative experiments are implemented in a 5.5 kW PMSM platform to verify the performance of the proposed two controllers.

Natural Gas/Hydrogen blends for heavy-duty spark ignition engines: Performance and emissions analysis

In view of the strong interest in the adoption of hydrogen as an alternative fuel for internal combustion engines, the authors present the results of an experimental activity aimed at evaluating the effect of hydrogen use on performance and emissions of a heavy-duty (HD) spark ignition engine.The engine, installed on a test bench and working with compressed natural gas (CNG) in its standard version, has been fed with blends of CNG and H2, at various percentages (15% and 25% of H2 by volume) and tested in steady-state and transient driving conditions. The analysis in steady state was performed in two working modes: at the same combustion barycentre and at the same nitrogen oxides (NOx) emissions of the pure CNG case, by means of proper spark advance calibrations.A detailed combustion and emissions analysis were performed, highlighting a coherent response of the engine to the replacement of CNG with H2. The NOx increment tendency is easily counteracted by reduced SA settings, while total hydrocarbons and carbon oxides emissions reduction were measured when the blends were burnt. Consistent carbon dioxide emission mitigation was revealed, mainly in transient conditions, operated at the same ECU calibration of the pure CNG case.The main novelty of the work is in providing an in-depth study of the engine behaviour to hydrogen addition in transient condition. The response of engine management system to different fuels when rapid speed and torque variations occur, were evaluated. In this sense, the study offers detailed information on the feasibility of the use of hydro methane in existing engine architecture; such mixtures can represent, in the next future, a probable fuel option in view of the oncoming decarbonization process.Moreover, new insights on particle emission burning hydro-methane are presented. The results of engine-out PN emissions along a transient cycle revealed a correlation between particle emissions spikes with specific phases of the driving cycle and a trend in PN reduction in case of hydrogen addition.