Thermal analysis of an electromagnetic linear actuator

In this study, a type of direct-drive gearshift system integrated into a motor-transmission coupled drive system is introduced. It used two electromagnetic linear actuators (ELAs) to perform gearshift events. The adoption of ELAs simplifies the architecture of the gearshift system and has the potential to further optimize gearshift performance. However, a number of nonlinearities in the gearshift system should be investigated in order to enhance the performance of the direct-drive gearshift system. An active disturbance rejection control (ADRC) method was selected as the principal shifting control method due to the simple methodology and strong reliability. The nonlinear characteristics of the electromagnetic force produced by the ELA were subsequently reduced using the inverse system method (ISM) technique. The ADRC approach also incorporated an acceleration feedforward module to enhance the precision of displacement control. The extended state observer (ESO) module used a nonlinear function in place of the original function to improve the ability to reject disturbances. Comparative simulations and experiments were carried out between the ADRC method and improved ADRC (IADRC) method. The outcomes demonstrate the effectiveness of the designed control method. The shift force fluctuates less, and the shift jerk decreases noticeably during the synchronization procedure. In conclusion, combined with the optimized IADRC method, the direct-drive gearshift system equipped with ELAs shows remarkable gearshift performance, and it has the potential to be widely used in motor−transmission coupled drive systems for EVs.

Linear electromagnetic actuators (LEAs), operated by electromagnetic action, are widely used in various applications, such as switches and solenoid valves. Since it operates on the principle of electromagnetic attraction, it is very sensitive to magnetic field. LEA may fail under the impact of disturbing magnetic field (DMF), thus threatens the stability of the whole system. As the magnetic field around tokamak is very strong, it is of great importance to evaluate the behavior of LEAs under DMF. This article presents the analysis of two different types of LEAs in DMFs. Based on the finite element method, the influences of DMF on the two LEAs are analyzed, and both the opening and closing processes are considered. Analyses show that the piston-type LEA may fail to act under DMF, while the plate-type LEA may malfunction even it is not energized. Based on the analysis, the failure mechanism is revealed, and the failure thresholds of the two LEAs are also quantified. The experimental verifications are carried out, which are in good agreement with the simulation results. The analysis model and the main conclusions presented in this article are of great significance to guide the antimagnetic field design of LEAs and ensure their reliable operations in tokamakxs.

Extended state observer-based time-optimal control for fast and precise point-to-point motions driven by a novel electromagnetic linear actuator

The formation of wrinkles, one of the aspects of aging skin, results as a consequence of a degenerated dermis. The aged protein network, muscle contractions and gravitation result in wrinkling of the skin. Currently, in the cosmetic industry, treatments for skin rejuvenation are rapidly evolving. Only a few techniques are used to counteract the aging dermis. One of the most promising areas is non-ablative laser techniques. These techniques have clinically been tested. However, the physiological background remains to be established. It is hypothesized that laser induced heat in the skin causes a heat shock and a subsequent heat shock response by the dermal fibroblasts. This heat shock response is said to stimulate, through heat shock proteins, the collagen synthesis by these cells. Subsequently, the laser has next to the thermal effect also a photochemical effect, where the photons are absorbed by cytochrome-c proteins, located on the cell membranes of the fibroblasts, and by doing so enhance the oxidative phosphorylation process, which in turn would result in a positively stimulated metabolism of the cell resulting in synthesizing more proteins, such as collagen. The present thesis focuses on the influence of the thermal effect on the collagen production of human dermal fibroblasts in culture and in ex-vivo skin. A model was developed that describes the interaction of laser light with skin resulting in the generation of heat. This model was combined with a transport model to describe the distribution of this heat through the skin. The model was used to determine the optimal laser conditions for heating and to describe the temperature distribution in the skin as a function of time. To investigate the response of human skin to heat shocks, the initial research was performed on cell cultures. Here, human dermal fibroblasts were cultured and exposed to heat shocks of 45°C and 60°C, respectively, and with pulse duration of 2 seconds. The results of this study showed that these heat shocks enhanced the collagen type I synthesis. Subsequently, a study was performed with heat shocks of 45°C and 60°C that were applied for 2, 4, 8, 10 and 16 seconds. The conclusion from this study is that 8 to 10 second pulses at 45°C are the maximum exposure time range at which the collagen type I synthesis is optimal. In addition, viable ex-vivo human skin samples were immersed into heated PBS of 45°C and 60°C. The 45°C heat shock does not create damage at all, while the 60°C heat shock shows initial damage around the cells in the skin. It was demonstrated that procollagen type I as well as type III were upregulated by both 45°C and 60°C heat shocks. Subsequently, a pilot study of a laser induced heat shock on ex-vivo skin study was performed. The results of this research demonstrated that the 45°C laser induced heat shocked did not damage the skin samples. The 60°C laser induced heat shock, on the other hand, demonstrated the presence of hsp27 in the area of the cells, and indication of early damage. The gene expression results revealed that the 45°C heat shocks upregulated procollagen type I. In conclusion, it has been shown in this thesis that a heat shock of 45°C applied to fibroblasts or in ex-vivo skin results in upregulation of in collagen heat shock gene expression. Furthermore, the cell studies showed the relevance of the combination of time and temperature; an optimal exposure time range of 8 to 10 seconds at 45°C to achieve the highest amount of collagen type I was found. Also the harmful nature of a 60°C heat shock was revealed. Showing that collagen synthesis can be enhanced by the 45°C heat shock is another step towards understanding the physiological pathways that lead to skin rejuvenation.

Conventional manual transmissions suffer from deterioration due to wear and reduced responsiveness. Therefore, a linear electromagnetic actuator (LEA) for gear shifting has been developed. Since the LEA is a direct drive, it prevents deterioration due to wear and has high responsiveness. In addition, this LEA has a high holding force by detent force at three points. In this paper, sensorless position estimation is performed to simplify the system. Since one coil is not energized during driving in this LEA, so the back-EMF of the unenergized phase can be measured. We propose a sensorless position estimation method that focuses on the variation of the magnetic flux linkage characteristics in the position change. The simulation results show that the sensorless position control is possible.

Conventional electromagnetic linear actuators(ELA) have difficulty in balancing efficiency, response and accuracy, so a novel compound ELA is researched, featuring a coaxial integrated design of moving coil and moving iron actuators that switch between co-drive mode and separate drive mode based on service environment. In order to further enhance the comprehensive performance of the actuator and improve its adaptability to extreme working conditions, a multi-objective hierarchical optimization strategy was proposed based on NSGA-II algorithm by analyzing its structural principle, magnetic circuit characteristics and electromagnetic force characteristics. The moving coil actuator, as the main driving component, and the moving iron actuator, as the auxiliary driving component, are selected as the first and second layer optimization objects for multi-objective optimization design. Results indicate that the actuator achieves starting forces of 587.6N and 191.4N under cooperative drive mode and separate drive mode, respectively. Following optimization, these forces increased by approximately 2.2% and 22.4%, while the mover mass was reduced by about 7.2%. The actuator's thrust density, response speed, and structural compactness were effectively enhanced. The proposed approach can be used to solve the complex multi-objective optimization tasks in ELA designing.

This paper presents the research on a problem which is difficult to implement in the actual magnetization process of Electromagnetic Linear Actuator (ELA)'s permanent magnets radially magnetized. Given magnetic field symmetry and assembly feasibility, it creatively puts forward four parallel magnetized-permanent magnets joint schemes (PM-PMs Joint Schemes) of the ELA. On the basis of mathematical modeling and simulating calculation, further study on the comparison of magnetic field effects and ELA's performance in different joint schemes is accomplished. Then, through the Analytic Hierarchy Process(AHP), 8 parallel magnetized-permanent magnets joint model (8 PM-PMs Joint Model) is determined as the best choice after optimizing selection. Further, the 8 PM-PMs Joint Scheme is trial-produced and its air gap flux density and electromagnetic force are also tested. Compared with simulating calculation, the maximum error from test result is within 4.3%, verifying the accuracy of mathematic model and simulating calculation.

With the ANSYS Workbench software,the 3D fluid model of the impeller for the centrifugal compressor is set up,whose design flow is 3.2kg/s,rotating speed is 32473r/min,pressure ratio is 3.8,and then with the method of CFD,the k-ε two equations model is selected as the turbulence model,in the condition of design speed,the fluid region of the impeller is simulated under eight different flow rate,the aerodynamic load of the impeller blade and its distribution is acquired under different flow rate,the results showed that the location of the largest aerodynamic load is in the blade that near the outlet of impeller,under the design flow rate condition,the largest aerodynamic load is 0.1969MPa,the aerodynamic load increases with the flow rate decreases.

Lattice vibrations are the microscopic mechanism responsible for a large, if not dominant, contribution to heat transport in crystalline insulators. These vibrations are described in terms of phonons, collective excitations (or quasiparticles) in the form of waves of atomic displacements inside a crystal. Phonons are traditionally considered to be the quasiparticles responsible for carrying heat through the material. Heat transport is considered as a flux of a phonon gas, diffusing from hot areas (high phonon densities) to cold areas (low phonon densities) in an attempt to reestablish equilibrium, with phonon collisions being the source of heat flux dissipation. However, as dimensionality is reduced, the motion of phonons stimulated by temperature perturbations becomes correlated and this gas-like picture of thermal transport in terms of phonons becomes invalid. In this Thesis, we lay out an interpretation of thermal transport in 2D materials based on the Boltzmann transport equation in the form of collective excitations of phonons. These collective phonon excitations give raise to complex phenomena, such as high thermal conductivities, that are otherwise unexplained. As another example, collective excitations, at variance with conventional diffusive transport, can induce wave-like heat propagation, or second sound. This had been found only in a few exotic materials at cryogenic temperatures, but is present instead routinely in 2D materials at room temperature. The correlated-phonon description of heat transfer can be rationalised by introducing a new collective excitation, called 'relaxon', which is defined as the eigenstate of the collision operator. Whereas only oversimplifying assumptions endow phonons with well defined relaxation times (the average interval of time between collisions), relaxons have always well defined relaxation times and permit an exact description of thermal transport. The complex dynamic of heat transport in 2D is thus greatly simplified and a kinetic gas theory of thermal transport still applies, provided that the gas is not constituted by phonons, but by relaxons. Our work on thermal transport is part of a larger effort, aiming at the creation of a database of numerically computed properties of materials. The high-throughput production of simulated properties is a challenging task, since it necessitates the understanding of a physical model, but it also needs to face a myriad of technicalities and problems that hinder the execution of a large number of calculations. In order to allow the creation of computational materials databases, we developed AiiDA, an open-source automated interactive infrastructure and database for computational science. This platform tackles the problems of creation, management, analysis and sharing of data and simulations, summarized in the pillars of Automation, Data, Environment and Sharing. Automation is achieved by management of remote computational resources and the encoding of workflows, that allows the execution of complex sequences of calculations. The tight coupling between automation and data storage, handled by the platform, enables full reproducibility of the results and a suitable database design allows for efficient data analysis tools. Sharing of scientific knowledge is addressed by providing tools for distribution of data and of the underlying workflows that generated them, creating an ecosystem for computational materials science.

While linear actuators have many applications, the majority of them are rigid and straight, limiting their applications and the work environment. This article presents a novel design for an electromagnetic flexible linear actuator (FLA) that can overcome such restrictions, as well as a computationally efficient model that predicts the output force based on the input current and the actuator shape. The FLA design is of a 3D-printable stator, easy-to-manufacture, and assemble with off-the-shelf components, modular, scalable, and easy to maintain. It can bend and take any arbitrary shape with reasonable curvature based on the dimensions of the motor. This facilitates the integration of the FLA in industry. The presented novel mathematical model fills the gap in the research area of the nonstraight actuator models. The model is derived by decomposing the actuator into noncoaxial coils and magnets. Through cascading the forces generated between each coil and the magnets, the output force of the actuator is calculated. The output of the model is validated experimentally by comparing its results to the actuator's force at different bending angles, planar, and in 3D space.

Performance of flange is characterized by its strength. A number of analytical and experimental studies have been conducted to study this characteristic of flange in pipeline under internal pressure loading. Very few researchers have studied the companion flange which is used in assembly of Universal Drive shaft. A companion flanges can be supplied as an individual component or as assemblies with universal drive shafts. It allows connection of a flange yoke to another type of connection, for proper torque transmission. In the present work Structural analysis on the flange was performed to obtain the areas of maximum stress under the given boundary conditions. The present study also reports the comparison of experimental and modeling results. It is observed that the deformation is reduced by 3.2% through modeling study and 3% through Experimental study. It is also observed that AISI 204 material is better than SAE 1141 material. Keywords: UTM, ANSYS Workbench, CREO 2.0, Companion flange

In advanced gas turbines, the turbine blade operated temperature is for above the melting point of blade material. A sophisticated cooling scheme must be developed for continuous safe operation of gas turbines with high performance. Several methods have been suggested for the cooling of blades and one such technique is to have radial holes to pass high velocity cooling air along the blade span. In the present work to examine the heat transfer analysis of gas turbine with four different models consisting of blade with without holes and blades with varying number of holes (5, 9&13) were analysed The analysis is carried out using commercial CFD software FLUENT (a turbulence realizable k-є model with enhanced wall treatment) has been used. On evaluating the graphs drawn for total heat transfer rate and temperature distribution, the blade with 13 holes is considered as optimum. Steady state thermal and structural analysis is carried out using ANSYS software with different blade materials of Chromium steel and Inconel718. While comparing these materials Inconel718 is better thermal properties and induced stresses are lesser than the Chromium steel.

This paper proposes a novel planar electromagnetic-actuated positioning stage. The stage is suspended by the monolithic parallel flexure mechanism, which motion comes from the deformation of the flexure. A linear electromagnetic actuator which consists of a near-uniform magnetic field and four coils is designed and implementation to provide the propelling force for 3-DOF motions. In order to suppress the vibration of the flexure suspension mechanism, an eddy current damper is designed and integrated with the electromagnetic actuator. The non-contact damper is more advanced than the contact damper used in our previous researches. The design traveling range is 3mm × 3mm in planar motion. The experimental results show the vibration of the flexure mechanism could be suppressed by the designed eddy current damper. The results also show the regulation and tracking performance by a well-designed robust adaptive sliding mode controller, which can overcome the disturbance and modeling uncertainty and guarantee a satisfactory performance.

Model-based approach to fault detection of the linear electromagnetic actuators is proposed and validated in the framework of the electromagnetic actuator in the bistable valve operation. The forward uncertainty propagation for the nonlinear mathematical model is performed to determine the probability of faultless operation under aleatoric and epistemic uncertainties. A basic technique is then proposed to make a decision on occurred fault.

Due to the motion control system of electromagnetic linear actuator (EMLA) is a nonlinear system with poor controllability, single control strategy has been difficult to meet the requirements of its control. A compound control strategy based on inverse system control (ISC) and proportional-integral (PI) is designed in this paper. Switching between two algorithms, which is based on the fuzzy rules, prevents the control algorithm to jitter and jump. System model is build under Matlab/Simulink to do simulation analysis. The designed controller is integrated into the system simulation model and the system software of digital signal processor (DSP) controller. Simulation and test results show that the compound control strategy using fuzzy switching rules achieves the smooth transition of two control algorithms, and the goal of any position location, and continuous adjustment in 0~4mm lift. Positioning accuracy is up to ± 0.02mm, while the response time is less than 10ms.