Thrust Ripple Research Articles

A Slotted Double-Primaries Permanent Magnet Synchronous Linear Motor With a Low Thrust Ripple

A Slotted Double-Primaries Permanent Magnet Synchronous Linear Motor With a Low Thrust Ripple

Discrete Space Vector Modulation-Based MPCC With Inductance Identification for Thrust Ripple Suppression in Linear Induction Machine

Discrete Space Vector Modulation-Based MPCC With Inductance Identification for Thrust Ripple Suppression in Linear Induction Machine

Thrust ripple suppression analysis of moving-magnet-type linear synchronous motor based on independent coil

In this paper, a novel thrust ripple suppression method for multi-secondary permanent magnet synchronous linear motor based on independent coil structure is proposed. Independent coil structure can realize independent power supply for each coil by changing the driving mode of the coils. Combined with the new power supply strategy, the detent and electromagnetic force fluctuation can be suppressed. Firstly, the cogging and end force of moving-magnet-type linear motor are separated by periodic and vector boundary conditions and harmonic analysis is carried out. An analytical model of air gap magnetic field based on virtual magnetic poles is established to solve the back EMF and electromagnetic force fluctuation of the motor. The generation mechanism and harmonic of electromagnetic force fluctuation are analyzed. A multi-secondary PMLSM based on independent coil is proposed, the principle of suppressing motor thrust ripple is expounded, and the coupling effect between modules is analyzed. Finally, a zero-crossing power supply strategy is proposed. The simulation and experimental results show that multi-secondary independent coil PMLSM can effectively suppress the detent and electromagnetic force fluctuation.

PR Internal Mode Extended State Observer-Based Iterative Learning Control for Thrust Ripple Suppression of PMLSM Drives

PR Internal Mode Extended State Observer-Based Iterative Learning Control for Thrust Ripple Suppression of PMLSM Drives

Thrust Ripple Suppression Strategy for Precision Machining Platform by Using Predicted Current Sliding Control

Thrust Ripple Suppression Strategy for Precision Machining Platform by Using Predicted Current Sliding Control

Optimization of dual-function suspension structures using particle swarm optimization approaches

The suspension system integrating both vibration control and energy harvesting capabilities is denoted as Dual-function Suspension (DFS). The principal objectives for DFS encompass lightweight structure, high output force, extensive adjustability in damping, and minimized energy consumption. In pursuit of optimizing the linear motor and magnetorheological damper (MRD) amalgamated into the DFS, a multi-objective Particle Swarm Optimization (PSO) algorithm is conceived, emphasizing primary and secondary objectives to enhance the holistic performance of the DFS. A comprehensive mathematical model of the DFS is established, and subsequent to this modeling, the structural parameters of DFS are meticulously analyzed. Drawing upon the insights from this analysis, primary and supplementary optimization objectives are delineated, employing PSO for the refinement of the DFS structure. Following this, the Pareto solution set, derived from the optimization process, is judiciously selected utilizing fuzzy theorem principles. The outcomes reveal that, under the constraints of unaltered suspension packaging dimensions and overall energy consumption, the optimized suspension system manifests a 50% augmentation in output force, a 30% expansion in adjustable damping range, and a 39% reduction in thrust ripple compared to its pre-optimized state.

Control Strategies of Thrust Ripple Suppression for Electromagnetic Microgravity Facility

This paper presents an innovative solution that is able to suppress the thrust ripple in a high-power asynchronous linear induction motor (LIM) used in a microgravity experiment facility electromagnetic launch (MEFEL) system. By addressing the crucial need for low levels of thrust ripple in MEFEL applications, we propose a dynamic model-based adaptive controller (MAC) and an enhanced quasi-proportional-resonant (PR) controller. The MAC is designed to compensate for the inherent impedance asymmetry of the linear motor. The PR controller minimizes thrust ripple by eliminating harmonics within the current loop. A comparative analysis indicates that both MAC and PR control are effective in reducing harmonics, suppressing the thrust ripple, and maintaining system stability. Computer simulations show a noteworthy 75% reduction in the thrust ripple and a decrease in the negative current. Partial tests on the MEFEL device validate the practical efficacy of the proposed control methods, emphasizing the method’s ability to enhance the quality of microgravity in real-world scenarios significantly.

Relegated Thrust Ripples for Linear Induction Motors Based-Four Voltage Vectors Finite-Set Predictive Control and Model Reference Adaptive System

—These days, there are extensive signifies to the evolution of newfound control procedures like model predictive control. The finite-state predictive thrust control (FSPTC) for LIMs is still not deftly addressed by scholars and limited research was acted to exploit the FSPTC for LIM drive systems. Therefore, the current study proposes a novel finite-state predictive thrust control (NFSPTC) for linear induction motors (LIMs) with reduced numbers of voltage vectors (VVs) in the prediction phase. The NFSPTC utilizes the conventional direct thrust control (DTC) concept to reduce the required VVs from eight to only four which consist of two active vectors and two zero vectors. Decreasing the number of predicted VVs leads to a significant reduction in computational time. Moreover, the weighting factor is removed to reduce the effort in selecting the best weighting factor. Since the LIM drive system can be succeeded by developing a sensorless speed estimation, the linear speed is estimated depending on the model reference adaptive system (MRAS) before using actual sensors; thus, low cost can be attained. The suggested control approach is validated by simulation proofs based on a 3-kW arc machine. The gained findings clarified the effectiveness of the proposed four VVs control over the eight VVs procedure in dipping the thrust ripple. Besides, using the four VVs control under variable speed and fixed thrust load, the execution time was decreased by 50%. Furthermore, the proposed control procedures ensued in maintaining the primary flux linkage constant alongside succeeding a glowing-tracking speed profile throughout the tackled speed and thrust load variations.”

Ramming Mechanism Based on Permanent Magnet Synchronous Linear Motor

To overcome the drawbacks of the traditional ramming mechanism, such as complicated maintenance and low reliability, an artillery ramming mechanism is proposed in this study based on the principle of a double primary tubular permanent magnet synchronous linear motor. First, a subdomain model is proposed for this mechanism, which significantly simplifies the programming difficulty by solving through coordinate transformation. In comparison to the finite element method, the analytical method considers the flux barrier and end effects, resulting in high calculation accuracy. Then, considering the uncertain factors in the machining process, an interval uncertainty optimization model considering robustness is established using the interval order and interval probability degree method, which is further solved via interval nesting optimization. Compared with the initial structure, the average thrust and thrust density of the optimized structure are increased by 32.7% and 12.4%, respectively, with almost constant thrust ripple. Finally, a prototype and control platform are developed to verify the validity of our work and superiority of the proposed structure through experiments involving electromagnetic parameters and comparative experiments.

Mover structure optimization and performance improvement for halbach consequent-pole PM synchronous linear motors with flux barrier

Aiming at the problems of large thrust ripple, low thrust density and magnetic leakage in the structure of Halbach consequent-pole PM synchronous linear motor, this paper proposes a flux barrier Halbach Consequent-Pole PM Synchronous Linear Motors (BHCP-PMSLM) by using the combination of unequal height PMs and air flux barrier. Firstly, after analyzing the structural magnetic leakage by the magnetic circuit method, the new motor structure proposed by adding an air flux barrier is used to suppress the magnetic leakage and to determine the structural shape of the air flux barrier. Secondly, the GA-ELM-GA algorithm was used to optimize the structural parameters of the motor with the optimization objectives of increasing thrust and reducing thrust ripple, the optimum motor structure parameters are obtained. Then, calculation and comparison of the electromagnetic characteristics of the new structure with three conventional PM synchronous linear motors with non-salient (NS-PMSLM) and Halbach consequent-pole (HCP-PMSLM). From the comparison results, the proposed structure has advantages, so the prototype was machined and experimented. The experimental results show that the optimization algorithm is effective, and the new structure increases the PM utilization by 41.1% and 7.4%, the thrust density by 5.3% and 12.1%, and the thrust fluctuation by 21% less than HCP-PMLSM compared to the conventional non-salient poles and Halbach consequent-pole.

Proposal and Optim al Design of an Air-cored Linear Synchronous Motor with Bézier-track Armature to Suppress the Thrust Ripple

Proposal and Optim al Design of an Air-cored Linear Synchronous Motor with Bézier-track Armature to Suppress the Thrust Ripple

Consequent pole flux modulated linear actuator under winding chang and field oriented control driving conditions for long track and multi-track agricultural robot

The electromagnetic performance improvement of a double saliency (DS) flux modulated (FM)- permanent magnet linear synchronous motors (PMLSM) for agricultural robots is proposed in this work by minimizing the effect of cross-coupling. To understand the effect of the cross-coupling on the electromagnetic performance, a dq axes model of the DS FM-PMLSM is developed and analyzed under different driving conditions. Based on the result obtained, winding modification schemes are proposed to minimize the thrust ripple and improve the zero torque control. The modified models are studied using finite element analysis (FEA) and the model with the best performance is selected for prototyping. The prototype is then tested and the results are validated against the electromagnetic performance obtained using the FEA. This research targeted the development of a low-cost linear actuator for a sapling grower gantry robot that can be used by farmers around the world.

Optimization Design of Thrust Characteristics of Switched Flux Linear Motor

AbstractThe structure of permanent magnet flux‐switching linear motor (PMFSLM) with permanent magnet and coil as short primary mover and slotted core as long secondary stator can solve the problem of high cost in the long‐stroke transportation field, but PMFSLM has the phenomenon of top magnetic flux leakage. The permanent magnet on the mover side of U‐shaped permanent magnet flux‐switching linear motor (UPM‐FSLM) is arranged in a U shape, which improves the utilization rate of the permanent magnet of the motor. In order to reduce the edge effect and suppress the thrust ripple, based on the size parameters of PMFSLM prototype, a UPM‐FSLM with arc‐shaped assistant permanent magnet teeth structure is proposed, its specific structure and operation mechanism are introduced; In order to obtain the optimal thrust characteristics, the Taguchi method is used to screen the arc‐shaped assistant permanent magnets teeth sensitive parameters, and then the NSGA II algorithm based on the response surface method is used for comprehensive multi‐objective optimization. The results show that compared with PMFSLM, the average thrust of the optimized motor is increased by 16.09%, and the thrust ripple is reduced by 91.78%. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Novel Virtual Winding Current Controller for Suppression of Linear Permanent Magnet Machine Electromagnetic Thrust Ripple

Thrust force ripple, including no-load detent force and electromagnetic thrust ripple, worsens the precision of linear permanent magnet machine (LPMM) control system. Asymmetrical current injection algorithm has been proposed for the suppression of electromagnetic thrust ripple, and the key point of the algorithm is positive- and negative-sequence (PNS) current closed-loop control. To achieve better steady-state and dynamic performance, a novel high-bandwidth current controller is proposed in this paper. A dual three-phase control system composed of three-phase virtual winding and the three-phase LPMM is introduced. According to the dual three-phase topology, PNS components are decoupled by a novel coordinate transformation, and the proposed controller avoids the use of filters or sophisticated algorithms for extraction of PNS currents. Experimental results based on a linear vernier permanent magnet machine (LVPMM) are presented. It verifies that the asymmetrical current control strategy based on the novel PNS current controller reduces electromagnetic thrust ripple by more than 60% compared with symmetrical three-phase current control.

Modified modeling and internal model control method of thrust ripples in PMLSMs for ultraprecision air-bearing linear feed systems

With the aim of attenuating thrust ripples in ultraprecision air-bearing linear feed systems, a simple and effective internal model control (IMC) system is herein presented based on a modified modeling and identification method of permanent magnet linear synchronous motors (PMLSMs). First, flux linkage equations were used to describe the volt–ampere characteristics of PMLSMs and provide a thrust expression in a differential form based on the principle of virtual work. Then, an analytical formula was obtained through derivation based on the condition of field-oriented control. On this basis, an IMC compensator was designed using an inverse model to attenuate nonlinear thrust effects, and an extended Kalman filter (EKF) was adopted to estimate the actual current in an analog linear amplifier. The boundedness of the nonlinear system was analyzed based on the convergence condition; furthermore, the stability of the proposed IMC compensator with EKF could be guaranteed. Then, an accurate model and thrust parameters were obtained using an identification experiment on an air-bearing linear platform driven by a linear analog amplifier. To demonstrate the coupling effect of current on thrust and confirm the effectiveness of the proposed method, both simulations and experiments were performed at a uniform velocity under extra loads of different weights; then, an extended state observer (ESO) was introduced as a comparative method. Finally, the results of the following error indicated that the proposed method demonstrated improved performance in terms of overcoming the influence of nonlinearity and that it results in smooth velocities in steady states.

Thrust Ripple Suppression Based on Negative Current Control for Short-Primary Low-Speed Large LIM Under Transient Operation

End effect of linear induction motor (LIM) leads to magnetic asymmetry and thrust ripple, which seriously restricts the performance and application of LIM. Existing methods for thrust ripple modeling and compensating have mostly focused on the steady state, which suffer from poor transient performance. Moreover, the influence of asymmetric currents on output thrust is not considered. In this paper, the thrust ripple characteristics and impact factors of a low-speed large LIM with negligible dynamic longitudinal end effect are analyzed in details, firstly. Then, a data-driven extracting and modeling method for transient thrust ripple is proposed. The non-stationary time-varying thrust ripple signal is extracted through wavelet decomposition and reconstruction, the polynomial parameters of thrust ripple model are trained off-line by particle swarm optimization algorithm. Finally, an improved suppressing scheme for transient thrust ripple is proposed, considering the decoupling and feedback control of positive and negative currents, based on the dynamic model of six-phase LIM. Full-scale experimental results have fully demonstrated the accuracy of proposed data-driven transient thrust ripple model is more than 90%. During the high-thrust operating stage, the axial vibration acceleration level of LIM within 100Hz is reduced by more than 12dB, with the adoption of improved control scheme.

Force Ripple Reduction of a Fractional Pole Pair Complementary Modularized Variable Reluctance Linear Machine for Long Stroke Application

Variable reluctance linear machine (VRLM), which takes advantages of magnet free, simple structure and low cost, is one of the emerging candidates for long stroke application. However, due to the abundant harmonics in the air gap, the conventional modular linear machine suffered from thrust ripple which leads to vibration and acoustic noise problem. The thrust force ripple in VRLM is mainly caused by higher-order harmonics in the induced voltage and detent force. To furtherly suppress the odd-order harmonics in the induced voltage and detent force, a fractional pole- pair unequal module arrangement (FP-UMA) design, in which the distances of adjacent modularized mover segments are not equal, is proposed to VRLM and collaborated with complementary structure in this paper. The key is that the modularized movers are artificially designed to be unequally distributed regarding to spatial distribution to eliminate the odd-order harmonics in the induced voltage along with the thrust ripples they caused based on the quantitative analysis on the thrust ripple components. It is revealed that, with the proposed FP-UMA design, the thrust ripple ratio of the machine has been effectively relieved from 4.6% to 2.2% under copper loss of 450W. Further, some design guidelines for the proposed machine, such as position offset of modularized mover Δμ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m2</sub> , DC loss ratio <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> and slot pole combinations are discussed. In addition, the feasibility of the proposed design method is evaluated by finite element method as well as experiments.

Magnetic Field Analysis and Thrust Optimization of Arc Permanent Magnet Synchronous Motor Combined With Linear Mover and Arc Stator

The intelligent annular transmission system driven by permanent magnet synchronous linear motor (PMSLM) is composed of linear and arc segments. When the mover enters the arc segment from the straight segment, the coupling area between the primary and secondary becomes smaller. It results in that the average thrust decreases and the thrust ripple increases. This phenomenon affects the control accuracy and operation reliability. This paper focuses on the research on the arc permanent magnet synchronous motor (A-PMSM) in the arc segment of the annular transmission system. The equivalent magnetic network model of A-PMSM is established. The air-gap coefficient is used to compare the slot effect of arc primary structure with that of straight primary structure. The influence of arc radius and radial width on the slot effect of A-PMSM with linear mover is obtained. The structure of magnetic pole, the radial width of secondary and the slot width are optimized by the combination of hierarchical optimization and orthogonal optimization. The A-PMSM's performance of thrust is optimized, which provides experience for the design of the motor in the annular transmission system.

Integrated thrust ripple identification and compensation for linear servo system using an MP algorithm

Generally there are two methods for the thrust ripple modeling: one is to identify the eigenvalues and the model parameters of thrust ripple sequentially under rigorous operating conditions; another is to treat thrust ripple as a general and inaccurate disturbance. To get rid of the constraints and further enhance the tracking accuracy of the linear servo system, a novel integrated identification and compensation scheme using an improved matching pursuit algorithm is proposed in this paper. First, the dynamics of the linear motor is formulated, and the cause of thrust ripple is analyzed. Then, a time–frequency atomic library of thrust ripple is constructed with the consideration of the frequency characteristics of position command, and meanwhile, the two optimal atoms are obtained successively by maximizing the inner product for the thrust ripple reconstruction. Based on the above, the eigenvalues and model parameters of thrust ripple can be simultaneously identified in an online manner. Finally, the feedforward compensation component is devised by the identification results to suppress thrust ripple. In order to verify the superiority of the proposed scheme, simulations and experiments are conducted compared with the conventional methods.

Electromagnetic analysis and detent force minimization of a linear vernier motor

This paper proposes a new dual-sided linear permanent magnet vernier motor (LPMVM). The advantages of high thrust density, low thrust ripple, positive force elimination and structural stability are introduced in detail. The double-sided structure and toroidal winding proved the novelty of the machine tool, which is suitable for high definition digital control machine tools. Firstly, the basic structure and working principle of the engine are introduced. Through theoretical analysis, the expressions of electromagnetic thrust and detent force are derived. Thirdly, basic characteristics of permanent magnetic magnet flux coupling, backless electromotive force, detent force and electromagnetic drive are analyzed by using a a simplified three-phase model with symmetric boundary in 3-D finite element analysis. Finally, the thrust density and the detent force of the designed motor are calculated and analyzed. The results show that the designed motor is superior to the linear permanent magnet synchronous motor.