Search Results (406)

Modular multilevel converters (MMCs) are attractive for medium- and high-power motor drive applications; however, low-speed motor operation can cause significant submodule (SM) capacitor voltage ripple. In conventional carrier phase-shifted pulse-width modulation (CPS-PWM), the carrier phase displacement is usually fixed. This fixed setting does not account for the longer capacitor charging and discharging intervals that occur as a motor’s electrical frequency decreases. To address this issue, this paper develops a dynamic carrier phase-shift control strategy for MMCs under low-frequency motor drive electrical operating conditions. The proposed strategy relates the carrier phase-shift angle to the motor operating frequency through a piecewise function. A larger phase-shift angle is adopted in the low-frequency region, whereas the angle gradually returns to the conventional CPS-PWM value as the frequency increases. The strategy is implemented in the PWM generation stage through an equivalent carrier delay update, without modifying the MMC power circuit. Comparative MATLAB/Simulink simulations over the frequency range of 0.5–10 Hz are carried out to evaluate the capacitor voltage ripple, output current total harmonic distortion (THD), upper-arm current, and circulating current. The results indicate that the proposed scheme can effectively reduce the peak-to-peak capacitor voltage ripple at low frequencies while maintaining comparable AC-side output current quality and acceptable internal current behavior within the investigated converter-side electrical model. Full article

In applications with a wide constant power speed range, the use of conventional permanent magnet machines is complicated by their uncontrolled magnetic flux, increased losses at high speeds, increased inverter current, and dangerous open circuit back EMF. For this reason, synchronous machines without magnets and with a field winding on the rotor are increasingly being used in traction applications. However, due to high electrical losses in the field winding, rotor cooling becomes a critical issue. An alternative is to use hybrid excited machines, which retain the advantages of electrically excited machines while significantly reducing rotor losses. This paper presents a comparison between a conventional electrically excited machine and a novel hybrid excited machine for traction applications with a wide constant power speed range of 9.3:1 (4200 to 450 rpm, mechanical power 23.6 kW). Both machines have the same external dimensions and were optimized using the same optimization algorithm. It is shown that the hybrid excited machine provides a reduction in rotor losses by 2.0–3.25 times depending on load conditions. Its total loss is also reduced, although its cost of active materials increased by a factor of 1.6 due to the use of permanent magnets. Full article

This study investigated the effects of high-definition transcranial alternating current stimulation (HD-tACS) on cognitive–motor dual-task performance and upper-limb multi-joint motor control. Sixteen right-handed healthy male participants completed a double-blind, randomized crossover experiment involving active tACS and sham tACS conditions separated by a one-week washout interval. A 4 × 1 HD-tACS montage was applied over the left dorsolateral prefrontal cortex at 5 Hz for 20 min. Participants performed a synchronous cognitive–motor dual-task paradigm that combined an N-back working memory task with an upper-limb throwing task under different task difficulty levels. Task performance outcomes included accuracy, reaction time, release velocity, peak velocity, movement duration, and dual-task cost. Upper-limb motor control outcomes included elbow and wrist joint range of motion, peak angular velocity, and peak joint flexion and extension moments. Accuracy showed a significant Stimulation × Time interaction. Under active stimulation, adjusted accuracy increased by 5.4 percentage points in N1 and 10.1 percentage points in N2, whereas the corresponding changes under sham stimulation were not significant. Reaction time, release velocity, peak velocity, and movement duration showed no significant stimulation-related changes. Release-velocity DTC also showed a significant Stimulation × Time interaction across N1 and N2. Under active stimulation, the signed DTC shifted upward, indicating a smaller release-velocity decrement relative to N0. The task-specific follow-up was significant for N2 but not N1; however, the Stimulation × Time × Task interaction was not significant. Most upper-limb kinematic and kinetic outcomes showed no significant stimulation-related changes. Active HD-tACS was associated with higher accuracy and a favorable shift in release-velocity DTC, while most motor, kinematic, and kinetic outcomes were unchanged. The effects were limited to selected behavioral outcomes and did not differ significantly between N1 and N2. Full article

Permanent magnet synchronous motors (PMSMs) are widely used in AC drive systems, and their control performance depends strongly on accurate motor parameters. Conventional proportional-integral model reference adaptive system (PI-MRAS) observers use fixed adaptation gains, resulting in a trade-off between rapid convergence and low steady-state fluctuation. To address this limitation, this paper proposes a fuzzy proportional integral (Fuzzy-PI)-tuned MRAS observer for the simultaneous online identification of stator resistance (Rs) and stator inductance (Ls). The parameter-error dynamics are formulated from the PMSM model, and the adaptation laws are derived using Popov hyperstability theory. A fuzzy tuner uses the absolute identification error and its rate of change to schedule the proportional and integral gains online, thereby accelerating transient error convergence when the identification error is large and reducing estimation oscillations during steady-state operation. The method is evaluated through simulation and laboratory experiments involving rated operation, speed variation, parameter perturbation, and load disturbance. Under the investigated conditions, the identification errors of Rs and Ls are 3.8% and 0.18%, respectively. Compared with the conventional PI-MRAS, the reported Rs identification error decreases from 8.1% to 3.8% and the Ls identification error decreases from 0.91% to 0.18%. The results demonstrate an improved identification accuracy and disturbance recovery within the tested operating range. The implementation on an Infineon TC233 platform also demonstrates real-time feasibility, while broader validation under temperature variation, magnetic saturation, inverter nonlinearity, and measurement noise remains necessary. Full article

Physical performance can be understood as a continuum throughout the life course, ranging from peak athletic ability in early life to the preservation of mobility and functional independence in old age. This narrative review explores whether the biological and genetic pathways involved in athletic performance might also modulate the risk of geriatric motor dysfunctions (GMDs), a conceptual umbrella proposed here for sarcopenia, dynapenia, lower-limb weakness and the motor component of physical frailty. The available evidence suggests a convergence between performance and motor decline in mechanisms such as mitochondrial function and mitophagy, anabolic–catabolic balance, oxidative stress and low-grade chronic inflammation, neuromuscular integrity, satellite cell function, mechanotransduction, myokine-mediated signalling, and the gut–muscle axis. Although classic candidate genes such as ACTN3, ACE and PPARGC1A have been useful for formulating mechanistic hypotheses, genome-wide association studies support a highly polygenic architecture for strength, lean mass, muscle weakness and frailty. These effects are strongly modulated by the exposome, particularly by physical activity, nutrition and comorbidities. Overall, the relationship appears consistent with predominantly beneficial pleiotropy, although context-dependent effects cannot be ruled out. Genetics may influence functional reserve and decline trajectories, but exercise, particularly strength and power training, along with adequate nutrition and the management of comorbidities, remain the primary strategies for preventing or delaying sarcopenia, frailty and lower-limb weakness. Full article

This study focuses on the synthesis of Co_0.5Cu_0.5Fe₂O₄ mixed ferrites supported on nanoporous carbon materials. The carbon supports were derived from two mixtures: a mixture of spent motor oil and pine wood chips (designated as AC-A), and a mixture of spent motor oil and crushed coal obtained from the Chukurovo mine (designated as AC-B). Additionally, two types of carbon components—nanodiamond and graphene oxide—were used for the synthesis of nanosized ceria-based hybrid nanocomposites. The results revealed that the active phase deposited on the carbon supports consists of a complex mixture of finely dispersed ferrite nanoparticles as well as small CeO₂ crystallites in the case of hybrid nanocomposites. The dispersion and phase composition of the deposited copper–cobalt ferrites depends on the textural properties of the carbon supports. Among the investigated materials, the graphene oxide-modified composites exhibited the highest catalytic activity at 670 K, achieving a methanol conversion of 90%. Full article

Dielectric Barrier Discharge (DBD) plasma actuators have shown considerable potential for aerodynamic flow control over fixed wings and helicopter rotors. However, their application to small unmanned aerial vehicle (UAV) propellers operating at high rotational speeds remains largely unexplored. This study experimentally investigates the effectiveness of leading-edge AC-DBD plasma actuators in improving the aerodynamic performance of rotating UAV propellers under hovering conditions. A custom-built experimental test stand was developed to measure thrust, rotational speed, and motor power consumption while supplying high voltage to the rotating blades through high-speed slip rings. A series of 3D-printed propellers with different blade pitch angles was tested at rotational speeds up to 4000 rpm. The results showed negligible performance changes for low-pitch propellers, whereas significant improvements were observed under separated-flow conditions. At nearly constant rotational speed and thrust, plasma actuation reduced the propeller power coefficient by up to 7.66%, resulting in a maximum 9.42% increase in Figure of Merit (FoM). The greatest benefits were obtained for intermediate blade pitch angles, while no measurable improvement was observed under severe separation conditions. These findings demonstrate that plasma actuation is most effective within an intermediate separated-flow regime and highlight its potential as a lightweight active flow-control technology for electrically powered UAVs. Full article

In AC motor field-oriented control systems, employing a single DC-bus current sensor with a phase-shifting strategy can effectively reduce system complexity and hardware costs. The vector-symmetry-based phase shift (VSPS) strategy has been shown to offer advantages in extending the linear modulation range and reducing the total harmonic distortion (THD) of phase currents. However, the harmonic suppression mechanism and the effective operating region of this method remain unclear. To fill this theoretical gap, this article develops a time-domain current ripple model for the VSPS method, analyzes the relationship between ripple distribution and vector symmetry, and reveals that VSPS reduces the root-mean-square value of the current ripple through improved PWM waveform symmetry. Furthermore, the boundary conditions under which VSPS can effectively reduce THD over a range of modulation indices are derived. Simulation results validate the correctness of the theoretical model. Experimental results show that the variation trend in the THD difference between VSPS and conventional phase shift compensation with modulation index agrees with the theoretical predictions, although the numerical improvement is relatively small. This work provides a theoretical basis and practical guidance for the engineering application of the VSPS method. Full article

This paper presents a battery-aware control framework for a single-phase integrated battery charger (IBC) for electric vehicles, in which the traction system is reused as part of the charging hardware. The proposed charger consists of a stator-assisted bridgeless totem-pole power-factor-correction AC–DC stage and a bidirectional buck–boost DC–DC stage connected to a 48 kWh, 400 V lithium-ion battery pack. The battery pack is modeled using a lookup-table-based equivalent circuit model with state-of-charge- and temperature-dependent open-circuit voltage and impedance parameters. A conventional double-loop PI controller is used as the baseline, while the proposed strategy combines nonlinear model predictive control, an extended Kalman filter, and lookup-table-based battery parameterization to regulate charging current under electrical and thermal constraints. The system is evaluated under 7 kW, 230 V/32 A and 22 kW, 230 V/96 A charging cases using average-model simulations, switching-model transient simulations, and finite element thermal assessment of the induction motor stator. The average-model results show stable charging from 20% to 80% SOC, with charging times of approximately 275 min at 7 kW and 90 min at 22 kW. The EKF provides bounded battery state estimation, with maximum SOC estimation errors of approximately 1.3% and 2.0% for the 7 kW and 22 kW cases, respectively, while the core-temperature estimation error converges close to zero. The switching-model results confirm feasible duty-command behavior, bounded battery-current tracking error, and a representative DC-link ripple of approximately 8 Vpp. During grid-voltage reduction, the charging current is reduced to keep the grid-current envelope within the intended limit. FEM results show that charging-only motor temperatures remain low, reaching approximately 27.39 °C at 7 kW and 38.82–38.85 °C at 22 kW. The most critical charging-related thermal case occurs at 22 kW after one hour of full-load motor operation with a 40 °C initial condition, reaching approximately 92.32 °C. Overall, these simulation-based findings support the feasibility of the proposed NMPC–EKF–LUT framework as a battery-aware supervisory control strategy for single-phase IBC operation. The proposed controller improves constraint-aware, battery state-based decision-making, while switching ripple and motor thermal response are mainly governed by the power stage, feasible current trajectory, and initial thermal condition. Full article

The bearingless induction motor (BIM) relies on accurate displacement feedback to maintain stable magnetic suspension, but sensor faults, degradation, and noise can distort feedback and induce transients during branch switching. This paper proposes a confidence-fusion-based fault-tolerant displacement measurement method for the BIM suspension feedback chain. A four-channel asymmetric redundant sensor configuration is developed, and channel state evaluation functions are constructed from sampling-difference terms and geometric-consistency residuals. A decreasing Sigmoid mapping with first-order smoothing generates continuous confidence coefficients to represent channel health. Combined with discrete fault flags of the primary channels, four reconstruction branches, AB, BC, AC, and CD, are adaptively weighted to obtain the reconstructed displacement, which is connected to the original suspension controller through a smooth feedback access mechanism. A MATLAB/Simulink closed-loop suspension model is used to evaluate the method under fault-free operation, an abrupt fault of primary channel A, simultaneous and sequential faults of primary channels A and B, abrupt and gradual degradation, constant bias, intermittent signal dropouts, and noise disturbance of primary channel B. Results show that the method identifies abnormal primary channels, redistributes reconstruction weights according to sensor conditions, and maintains a fallback path through the CD branch under dual-primary-channel failure. Under channel-B degradation, the confidence coefficient tracks the deterioration and supports the subsequent AB-to-AC branch transfer, whereas under noise disturbance, the fault flag remains inactive and unnecessary branch switching is avoided. The method improves feedback continuity without changing the main suspension controller. Full article

Parkinson’s disease (PD) is characterized by progressive dopaminergic neurodegeneration driven by oxidative stress, mitochondrial dysfunction, synaptic loss, and impaired neurotrophic signaling; however, the role of integrin α5β1 in neuronal vulnerability remains unclear. Here, the data show that rotenone-induced stress reduces integrin α5 expression in a dose- and time-dependent manner, leading to increased ROS accumulation, glutathione imbalance, synaptic degeneration, senescence-like β-gal activity, and apoptosis, whereas integrin α5 knockdown further exacerbates these deficits, supporting a protective role of α5β1. In contrast, treatment with the fibronectin-derived α5β1-activating peptide Ac-PHSRN-NH₂ restores integrin signaling by engaging the FAK–PI3K–AKT/ERK cascade and NRF2-mediated antioxidant responses, thereby reducing oxidative stress, suppressing cell death, and improving redox homeostasis. Moreover, PHSRN enhances NGF and BDNF levels, preserves synaptic integrity, and promotes dopaminergic neuronal activity and dopamine release. Consistently, in MPTP-lesioned mice, PHSRN preserves nigral TH-positive neurons, reduces apoptosis, restores neurotrophic support, and improves motor function. Collectively, these findings identify integrin α5β1 as a critical protective axis and support PHSRN as a potential disease-modifying therapeutic strategy for PD. Full article

Flat-wire windings have been widely used in high-power-density electric vehicle motors because of their high slot fill factor and high efficiency. However, conventional flat-wire conductors usually have relatively large cross-sectional dimensions, which may lead to significant AC winding losses under high-frequency operation due to the combined effects of the rotor magnetic field and the armature-reaction field. To address this issue, this paper proposes a multilayer thin flat-wire continuous-wave winding and its end-winding transposition method. The parallel multilayer thin flat-wire structure effectively suppresses AC losses by reducing the characteristic dimension of each conductor, while the end-winding transposition method reduces or even eliminates circulating-current losses among parallel strands without compromising slot utilization. An analytical calculation method is established to investigate the AC loss characteristics of the multilayer thin flat-wire winding, and the main influencing factors of winding losses are analyzed. To address the circulating-current loss issue, the loss suppression effect of the transposition method is quantitatively evaluated, and an intermittent transposition method with both effective circulating-current suppression and fewer end-winding crossovers is proposed. Finally, the proposed method is validated by finite-element analysis (FEA) and prototype experiments. The results show that the proposed winding can significantly reduce AC losses over a wide speed range, providing a low loss and manufacturable winding design solution for high-power-density electric vehicle traction motors. Full article

Symmetrical resistance training induces corticospinal and cortical network plasticity; however, the neural consequences of asymmetrical resistance training (offset loading or OL) remain unclear. In this preliminary study, fourteen healthy adults completed eighteen supervised upper-extremity training sessions over a 6-week intervention period. Participants were allocated to either an offset loading (OL) intervention group (n = 8) or a conventional symmetrical resistance training active control group (AC; n = 6). Electroencephalography (EEG) recordings were acquired during motor task performance at baseline, 3 weeks, and 6 weeks. Directed functional connectivity among predefined cortical regions was quantified, and longitudinal changes were assessed using Friedman tests with false-discovery-rate correction for multiple comparisons. Significant changes in the OL group were observed involving two cortical pathways after correction for multiple testing. Connectivity from the right parietal cortex to the right sensorimotor cortex increased over time (Friedman χ² = 8.00, q = 0.037), with post hoc analyses showing a significant increase between the midpoint and post-training assessments (q = 0.047; effect size r = 0.894). No significant longitudinal changes in cortical connectivity were identified in the AC group. Six weeks of OL training was associated with selective strengthening of directed connectivity within prefrontal-to-sensorimotor and parietal-to-sensorimotor cortical pathways. In contrast, conventional symmetrical resistance training was not associated with detectable changes in connectivity. These findings suggest that asymmetrical loading may induce task-specific reorganization of cortical networks involved in sensorimotor processing and motor control. Full article

This study proposes a printed circuit board (PCB) stator pattern for alleviating the trade-off between DC copper loss and AC winding loss in a slotless axial flux permanent magnet motor (AFPM). The proposed pattern has a structure in which the width of the effective conductor region directly exposed to time-varying magnetic flux is reduced, and two additional conductors with the same width are placed within the available axial space and then connected in parallel through vias. Three-dimensional finite element analysis was performed while varying the effective conductor width ratio from 0.3 to 0.8, and an additional refined sweep was conducted in the range of $\alpha$ = 0.5–0.6, where the minimum total winding loss appeared in the initial sweep. Under the rated operating condition, the minimum total winding loss was obtained at $\alpha =0.53$ based on the refined sweep results. Under this condition, the phase resistance, DC copper loss, AC winding loss, and total winding loss were reduced by 11.82%, 12.1%, 15.09%, and 12.48%, respectively. As a result, the efficiency increased from 81.53% to 83.5%, while the back electromotive force (BEMF), torque, and output were nearly unchanged. In addition, the AC winding loss distribution decreased in both the coil region closest to the magnets and the coil region farthest from the magnets. These results demonstrate that the proposed pattern is an effective design method for improving the winding loss characteristics of slotless PCB AFPM without meaningful degradation of the fundamental electromagnetic performance. Full article

The AC rotary head, serving as a dual-axis direct-drive rotary actuation unit in five-axis CNC machine tools, integrates torque motors for A- and C-axis actuation, and its structural static and dynamic characteristics directly govern the actuation accuracy, dynamic response, and stability of the electromechanical system. Its complex spatial pose variations further complicate performance prediction. To overcome the difficulty of existing local optimization methods in balancing stiffness-mass matching for such complex actuation assemblies, this paper proposes a static and dynamic performance optimization method based on stiffness-mass matching. First, a pose-dependent semi-analytical dynamic model is established using dynamic condensation and component mode synthesis (CMS) to reveal performance distribution laws across the workspace and identify weak poses. Then, Sobol’ sensitivity analysis identifies key joints and structural components, and the NSGA-II algorithm optimizes their stiffness-mass matching. Finally, a surrogate model performs dimensional parameter optimization targeting the optimized matrices. Results show that the first-order natural frequency increases by 10.5%, translational static stiffness in the X and Y directions improves by over 20%, and other directions by 4.2–18.6%. The proposed method effectively enhances global static and dynamic performance, providing theoretical guidance for the structural design of direct-drive rotary actuators in electromechanical actuation systems. Full article