Optimization analysis of Electromagnetic Linear Actuator's radial array permanent magnets

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.

This article presents a new electromagnetic linear actuator applied in the electromagnetic-driven valve train. To clarify the actuator’s temperature rise and heat distribution, a heat transfer mode...

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.

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.

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

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.

Fracture behavior of superconductor REBCO tapes with multiple edge cracks under electromagnetic force

This paper investigates the influence of different magnetization patterns on the performances of the surface-mounted permanent magnet synchronous machines (SMPMSMs). Three magnetization patterns are employed, which are radial, parallel, and ideal Halbach magnetizations. These magnetization patterns are applied to 9-slot/10-pole and 15-slot/4-pole permanent magnet (PM) machines. The PM machines are designed and simulated by using Opera 2D finite element. The performances of three PM motors, such as airgap flux density, phase back-EMF, and cogging torque, are evaluated under the influence of different magnetization patterns. The total harmonic distortion of phase back-EMF (THDv) for the motors are investigated. The PM motors with ideal Halbach magnetization provide the lowest cogging torque and the lowest total harmonic distortion of phase back-EMF. Besides that, the optimum setting of the magnet pole-arc can reduce the total harmonic distortion of phase back-EMF and achieve lower cogging torque. The optimum magnet pole-arc produced by radial magnetization in 9-slot/10-pole motor is 24.8° mech., with cogging torque of 0.45 Nm, and THDv of 2.69 %. Meanwhile, the optimum magnet pole-arc produced by parallel magnetization in 9-slot/10-pole motor is 26.0° mech., with cogging torque of 0.41 Nm, and THDv of 2.00 %.

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.

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.

In the light of electromagnetic motor driving system, electromagnetic con-version characteristics and structural principle were described. Electromagnetic drive and hybrid-driven method were proposed; the mathematical models describing the two drive systems which have adopted the magnetic circuit analysis method were established, starting with a discussion on how the drive system affects the electromagnetic force and air-gap magnetic flux density. Under the same conditions, the electromagnetic drive and hybrid-driven model was respectively simulated to reveal the impact on the electromagnetic force and air-gap magnetic flux density due to the different driving mode. Variation of the electromagnetic force with increasing coil current of two types of drive systems under motor speed control is studied preliminary. The results shown that compared to pure electromagnetic drive system, the hybrid drive system electromagnetic force raised from 2198N to 4097N, the airgap magnetic flux density increased from 1.048T to 1.393T; the electromagnetic characteristics of the magnetically driven motor are improved effectively.

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.

In this research work a new and simple calculation model for the analysis of the salient pole PM machines taking into account the stator slotting effect is presented. The approach to analyze the air-gap flux density based on the new model is to determine the air-gap magnetomotive force (MMF) and the flux path permeance function. The air-gap MMF for different rotor topologies is described with the well known Fourier series function, however, the flux path permeance function taking into account the stator slotting is determined using a simple magnetic reluctance network. Using the new model the air-gap flux density distribution for a PM machine is calculated. FE methods are used to prove the accuracy of the new model. Also, the effect of magnet volume (magnet length and width) in the air-gap flux density is investigated.

A novel 6-degree-of-freedom parallel platform and its motion control based on a modified active disturbance rejection controller are presented in this article. Structure and mathematical model of a novel electromagnetic linear actuator are analyzed, which is the main component of the novel 6-degree-of-freedom parallel platform. Kinematics-based control method of the 6-degree-of-freedom parallel platform is adopted, and the modified active disturbance rejection controller is used to track each desired trajectory accurately in spite of disturbances. Comparative simulations and experimental results demonstrate the effectiveness of the modified active disturbance rejection controller, and this novel 6-degree-of-freedom parallel platform can be driven to realize the given motion well.