Permanent Magnet Linear Synchronous Motor Research Articles

Research on Magnetic Field Simulation of Cylindrical Linear Synchronous Motor

In order to obtain the influence of different structures and frequencies on the thrust of cylindrical permanent magnet linear synchronous motor, the transient simulation of magnetic field of cylindrical permanent magnet linear synchronous motor is carried out by using Ansoft software, and the correctness of the simulation is verified by experiments. Through simulation, the characteristics of the linear motor under different voltage frequency, air gap size, and permanent magnet width and its influence on the linear motor thrust are obtained.

Design and performance analysis of permanent magnet linear synchronous motor

In order to effectively control the vibration transmitted from the ground to the precision equipment, permanent magnet linear synchronous motor (PMLSM) can be effectively applied in the active vibration absorber systems due to its good characteristics. The design of a PMLSM is very important because of the special requirements of the damping system on the response speed, working temperature, working bandwidth and installation size of the PMLSM. In this paper, the multi-objective design problem of the PMLSM in vibration damping system is proposed. Based on the equivalent magnetic circuit analysis of the PML SM’s air gap magnetic field, the performance and design of the PMLSM are effectively analyzed in combination with the design objectives. The design and performance of the prototype meet the design requirements.

Position Sensorless Control System of Permanent Magnet Synchronous Linear Motor Based on Sliding Mode Observer with an Improved Phase-Locked Loop

In this paper, position sensorless control system of permanent magnet synchronous linear motor (PMSLM) based on sliding mode observer (SMO) with an improved phase-locked loop (PLL) is studied. Firstly, according to the mathematical model, a SMO is designed for sensorless control PMSLM drive. Thereafter, an improved PLL is proposed to tackle the imperfection of data overflow existed in the traditional PLL. The designed SMO incorporating with the improved PLL can be effectively suppress the pulsation of the estimated position and hence the chattering of the derived electrical angular velocity. At last, simulated and experimental results are presented to verify the effectiveness and feasibility of the position sensorless control system.

Characteristics Analysis of Double-Sided Permanent Magnet Linear Synchronous Motor with Three-Phase Toroidal Windings

This paper proposes three-phase 120° phase belt toroidal windings (120°-TW) and are applied in a double-sided permanent magnet linear synchronous motor (DSPMLSM), in which the incoming ends of all coils are on the same side and have the same incoming direction. First, the structure of the proposed motor is introduced and its operation principle is analyzed by describing the variation in the armature magnet field versus time. Second, based on the similar volume, magnetic load and electrical load, the initial parameters of the DSPMLSM with different winding arrangements are presented. Then, the finite-element models (FEMs) of the DSPMLSM with 120°-TW (120°-TWDSPMLSM) and traditional toroidal windings (TTW) are established to analyze the distribution of magnetic field, back electromotive force (back-EMF), detent force, thrust, efficiency and so on. Besides, the primary optimization of the detent force is designed. Finally, the results show that the thrust density and efficiency of the 120°-TWDSPMLSM is higher than that of DSPMLSM with TTW (TTWDSPMLSM).

Multi-Kernel Neural Network Sliding Mode Control for Permanent Magnet Linear Synchronous Motors

In this paper, a multi-kernel neural network sliding mode control (MNNSMC) method is proposed to enhance the position tracking performance and disturbance suppression capability of permanent magnet linear synchronous motors (PMLSMs). The designed MNNSMC strategy consists of two parts, a sliding mode control with a dynamic boundary layer and a multi-kernel neural network (MNN). In the former, the dynamic boundary layer is utilized to guarantee that the sliding mode variable converges to the sliding manifold asymptotically. In the latter, disturbances are introduced into the design of kernel functions to further approximate and compensate for the internal and external disturbances, such as parameter variations, positioning force, friction, and un-modeled nonlinearities of PMLSMs. The stability of the proposed MNNSMC strategy is analyzed and proved based on Lyapunov Theorem. Experiments are conducted on a PMLSM servo drive system to validate the effectiveness of the presented MNNSMC method, and results show that the proposed scheme has significant improvement on the position tracking performance, disturbance suppression capability, and robustness of the PMLSM system compared with an existing method.

Suppression of Thrust Fluctuation of a New Ironless Tubular Permanent Magnet Synchronous Linear Motor Based on the Halbach Array

The air gap magnetic field (AGMF) is the key factor in determining the ironless tubular permanent magnet synchronous linear motor (ITPMSLM). The distortion of its waveform causes thrust fluctuation during the operation of the motor, resulting in poor machining accuracy of the machine tool. To solve this problem, this paper proposes a new chamfered permanent magnet structure (CPMS) to improve its performance. First, the equivalent magnetic charge method is used to analyze the AGMF, and the analytical expressions of the no‐load back EMF and thrust of the new motor are obtained. Second, the AGMF of six kinds of CPMS is analyzed by the Fourier coefficient. Taking the minimum harmonic distortion rate as the optimization objective, the CPMS that makes the AGMF waveform reach the best sinusoidal property is obtained and the no‐load back EMF and thrust of the new motor are analyzed. Then, the new motor is compared with the ITPMSLM of rectangle permanent magnet structures (RPMS). Finally, according to the CPMS, the test prototype is built and tested under different working conditions. The research results show that when the outer circumference is 45ochamfered, the ratio of permanent magnet thicknessh2to the chamfered thicknessh1is 0.8; the sinusoidal property of AGMF is the best, and this structure can effectively reduce the motor thrust fluctuation rates to less than 0.01%, which verifies the effectiveness of the CPMS in improving the sinusoidal property in the AGMF and restraining the thrust fluctuation of the ITPMLSM.

Extended State Observer-Based IMC-PID Tracking Control of PMLSM Servo Systems

Servo systems driven by a permanent magnet linear synchronous motor (PMLSM) are often affected by uncertain disturbances, such as magnetic resistance, friction, and external disturbances, which increase tracking errors and reduce motion accuracy. Traditional control methods may have difficulty to achieve satisfactory control performance in terms of tracking accuracy and disturbance rejection. In this paper, we propose an internal model control PID method based on a model linear extended state observer, which is termed as IMC-PID-MLESO method. With this method, the nominal model parameters of the PMLSM servo system are obtained via system identification. The model linear extended state observer (MLESO), with known parameter information, is designed to improve the estimation accuracy for the system states and total unknown uncertainties. As the uncertainties are compensated in the feedback control law, the PMLSM servo system model is transformed into a known nominal model. Based on the nominal model, the IMC-PID feedback controller is designed to ensure satisfactory performance on disturbance rejection and tracking error reduction. Simulation and experimental results show that the IMC-PID-MLESO method can effectively improve the position tracking accuracy of the PMLSM servo system and rapidly suppress the system disturbance.

Absolute Position Acquisition for Linear Synchronous Motor With Passive Mover

The winding segmented permanent magnet linear synchronous motor has restrictions on the last absolute position acquisition when the power goes from off to on, and the traditional absolute position acquisition systems depend on complex battery and calibration systems. Therefore, a true absolute magnetic encoder based on the Vernier principle with error rejection and decoding technology is studied in this paper. First, the output signal of the magnetic encoder with noise was subjected to the adaptive ellipse parameter correction algorithm with recursive least squares (RLS), and the source output signal predicted and reconstructed. Furthermore, the RLS was optimized by the speed weighting factor and the forgetting factor to reduce the computational pressure and the iterative process. Second, one improved double second-order generalized integrator(DSOGI) decoding technology was investigated by extracting and separating the symmetric-positive sequence components in the unbalanced signal, and, using the phase-locked loop technique for tracking calculation, accurate speed and angle obtained. The adaptive ellipse parameter fitting algorithm effectively reduced the problem of overshoot and steady-state error of the DSOGI, which provides a practical and theoretical basis for the future application of the magnetic encoder. This trajectory arrangement not only avoids the influence of accumulated error on the accuracy of encoder, but it also solves the contradiction between high resolution and small volume, and the advantages over the special decoding chip IC-Haus were also verified by comprehensive experimental results.

VECTOR CONTROL OF PERMANENT MAGNET SYNCHRONOUS LINEAR MOTOR BASED ON IMPROVED BP NEURAL NETWORK

The permanent magnet synchronous linear motor has the character-istics of nonlinearity, coupling, load disturbance and time-varyingparameters, which lead to low precision of speed tracking controlof the linear motor.

Improved Analytical Modeling of a Novel Ironless Linear Synchronous Machine With Asymmetrical Double-Layer Winding Topology

The Ironless Permanent Magnet Linear Synchronous Motor (ILPMLSM) with nonoverlapping windings is widely used in precise applications due to its simple structure, low thrust ripple, and fast response, while the disadvantage is low thrust density. The novel asymmetrical double-layer winding ILPMLSM with quasi-Halbach magnets can improve the thrust density while keeping simple structure. However, the double-layer windings are asymmetric and the primary has finite length. To solve the problem of this asymmetry and investigate its influences on electromagnetic characteristics, an improved 2-D analytical model is proposed, which introduces “virtual periodic primary” and solves the magnetic field of each winding layer. By the results of finite element and experiments, the proposed analytical model is verified. Moreover, the analytical model requires less computation time, which is helpful for optimizing design of this motor.

Disturbance attenuation and response time improvement of permanent magnet synchronous linear motor by using robust predictive resonant current control

Disturbance attenuation and response time improvement of permanent magnet synchronous linear motor by using robust predictive resonant current control

Integrating time-optimal motion profiles with position control for a high-speed permanent magnet linear synchronous motor planar motion stage

This note addresses the high-speed, high-precision point-to-point motion control of an air-bearing planar stage. The custom-designed stage uses four air-bearings to levitate the stage for the high-speed frictionless operation. Because of the floating nature, the controller for the system needs to overcome the nonlinear free-moving dynamics of the stage and achieve the required performance. To fulfill this purpose, we propose a unique integrated control structure that allows both velocity and reference position inputs. With the proposed structure and the weighting design, it is possible to use the H∞ chain scattering description (H∞-CSD) synthesis for the control parameters. The single structure is used for both the point-to-point movement and the high precision positioning. The reference velocity input enables the long-stroke time-optimal velocity profile injection. The controller converges to the popular PDF control when the stage comes close to the target position. The H∞ specifications enable a robust performance against the load uncertainty. The control undergoes no switching and is thus free from the undesirable chattering. The experimental results show that the proposed control achieves an ultrahigh precision control of 20 nm within 200 ms for a 9-kg stage with 20-mm x, y motion ranges.

Co-simulation of self-adjusting fuzzy PI controller for the robot with two-axes system

This paper presents the co-simulation of the self-adjusting fuzzy PI controller to control a two-axes system. Each axis was driven by a permanent magnet linear synchronous motor (PMLSM). The position and speed controller used the fuzzy PI algorithm with parameters adjusted by a radial basis function neural network (RBFNN). The vector control was applied to the decoupled effect of the PMLSM. The field programmable gate array (FPGA) was used to control both axes of the system. The very high-speed integrated circuit-hardware description language (VHDL) was developed in the Quartus II software environment, provided by Altera, to analyze and synthesize designs. Firstly, the mathematical model of PMLSM and fuzzy PI was introduced. Secondly, the RBFNN adjusted the knowledge base of the fuzzy PI. Thirdly, the motion trajectory was introduced for testing the control algorithm. Fourthly, the implementation of the controller based on FPGA with the FSM method and the structure of co-simulation between Matlab/Simulink and ModelSim were set up. Finally, discussion about the results proved the effectiveness of the control system, determining the exact position and trajectory of the XY axis system. This research was successful in implementing a two-motor controller within one chip.

A Single- and Multi-objective Optimization Algorithm for Electromagnetic Devices Assisted by Adaptive Kriging Based on Parallel Infilling Strategy

A computationally efficient surrogate model is suggested to approximate the objective and constraint function values, which replace expensive evaluation of the objective and constraint function values in numerical simulation-based optimization. Kriging surrogate model has been widely used in surrogate-based design optimization (SBDO) to replace the highly nonlinear black-box functions. In this paper, a novel adaptive Kriging model based on parallel infilling strategy is proposed to improve both the numerical accuracy and efficiency of the SBDO methods. The parallel infilling strategy consists of two parts: local sampling and globaluthor sampling. In the local sampling, new additional sampling points are generated only within a limited region that is determined according to the optimal point at the last iteration, while in global sampling they are generated based on the fitting error estimation in the whole region. The effectiveness of the proposed algorithm is verified through applications to analytical functions. Then the algorithm is applied to the multi-objective optimal design of an ironless permanent magnet synchronous linear motor.

Model of a Permanent Magnet Synchronous Linear Motor for an Urban Transport Electric Vehicle

Model of a Permanent Magnet Synchronous Linear Motor for an Urban Transport Electric Vehicle

Feedback Linearization Based Robust Control for Linear Permanent Magnet Synchronous Motors

In this study, we designed a feedback linearization control strategy for linear permanent magnet synchronous motors (LPMSMs) as well as a robust control mechanism. First, the highly nonlinear system was transformed into an exact linear system by the feedback linearization technique. Then, we designed a robust controller to mitigate the impact of system parameter disturbances on system performance. This novel robust feedback controller can be applied to electromagnetic force, speed and position control loops in linear motors, correct the errors created by uncertainty factors in the entire system in real time, and set the system’s settling time based on the application environment of the plant. Finally, we performed simulations and experiments using a PC-based motor control system, which demonstrated that the proposed robust feedback controller can achieve good performance in the controlled system with robust anti-disturbance control.

PMLSM Nonlinear Integral Sliding Mode Control Based on Gain Time- Varying Reaching Law

Background: The permanent magnet synchronous linear motor is a strongly coupled, nonlinear system. It has been applied in many fields, especially in the field of machining lathes and rail transportation. In order to ensure the permanent magnet synchronous linear motor has good dynamic performance and robustness, sliding mode control is gradually applied to the control system of permanent magnet synchronous linear motor. However, in the traditional sliding mode control, the convergence speed is slow, and the robust performance is poor when the sliding surface is not reached. Objective: The main purpose of this paper is to improve the dynamic performance and robustness of the permanent magnet synchronous linear motor during the process of approaching the sliding surface. Methods: Firstly, the type of nonlinear curve with "small error reduction, large error saturation" is introduced to design a nonlinear integral speed controller with global robustness. Secondly, the gain rate time-varying reaching law is introduced to reduce "chattering". Finally, using a symbolic tangent function instead of a sign function in designing a sliding mode observer reduces fluctuations in load observations. Results: Finally, the correctness and effectiveness of the control method are proved by simulation. Conclusion: The results of the simulation show that the nonlinear integral sliding mode controller based on gain time-varying reaching law is shown to have good global robustness and dynamic performance.

Pulsating Magnetic Field of Permanent Magnet Linear Synchronous Motor and Its Influence on Detent Force

For permanent magnet linear synchronous motor (PMLSM), the end effect not only changes the distribution of the end magnetic field, but also causes the pulsating magnetic field in the air gap between the primary and the secondary components. In this paper, the existence of the pulsating magnetic field is proved and the characteristics of the pulsating magnetic field are analyzed through the finite element analysis. On the base of that, the influence of the pulsating magnetic field on the detent force is studied, of which the result shows that the pulsating magnetic field generates the pulsating magnetic force, which is a part of the detent force. The amplitude of the pulsating magnetic force is closely related to the length of the primary component. By adjusting the length of the primary component, the pulsating magnetic field can be effectively suppressed. Moreover, the results of simulation and theoretical analysis prove that with the increase of primary component length, the influence of pulsating magnetic field is becoming weaker and weaker. Finally, a prototype is made to test the detent force characteristics, which verifies the research theory in this article.

Robust Optimization of PMLSM Based on a New Filled Function Algorithm With a Sigma Level Stability Convergence Criterion

Traditional design optimization methods for permanent magnet linear synchronous motor (PMLSM) always pursuit the optimal result without considering the influence of uncertainties (manufacturing errors, use wear, etc.), which will result in big fluctuations for the stability of motor thrust performance. This article proposes a new filled function algorithm (NFFA) to improve the stability of PMLSM. It searches for the structure parameters that not only lay in the smooth area of thrust ripple distribution but also satisfy the thrust ripple constraints under the effect of uncertainties. First, an analytical model of thrust ripple is established for the next-step optimization. Second, a sigma level stability criterion is proposed, which will be used to judge the robustness of optimal thrust ripple under uncertainties, and a new global robust algorithm NFFA is studied to realize the stability of thrust ripple by managing the sigma level stability criterion as the convergence criterion of traditional filled function optimization algorithm (TFFA). Third, the NFFA is used to optimize the thrust ripple of PMLSM based on the analytical model. The optimization results are proven to be stable and superior compared with other methods, such as TFFA, Taguchi robust optimization method, and design for six sigma method. Finally, the experiments confirm the feasibility and validity of the proposed method.

Modified complementary sliding mode control with disturbance compensation for permanent magnet linear synchronous motor servo system

In this study, a modified complementary sliding mode control (MCSMC) method based on a disturbance force observer with mass identification (DFOB-MI) applicable to the permanent magnet linear synchronous motor is proposed to achieve high-performance servo control fields. MCSMC is an improvement on the complementary sliding mode control (CSMC) method, which incorporates an approach angle into the saturation function. MCSMC allows for asymptotic convergence of the position tracking errors and guarantees the global robustness of the system. In addition, compared to hybrid control strategies combining neural networks with CSMC, the MCSMC method has a simpler structure and faster response. However, in practical applications, the mass variation of the mover has a significant impact on system performance. To achieve better dynamic and static characteristics, a disturbance force observer capable of identifying the mass variation based on model reference adaptive identification theory is proposed. DFOB-MI can identify the mass of the mover and provide information on the disturbance caused by the change of the load. Thus, the compensation current is calculated to reduce the disturbance and realise compensation. The more accurate tracking performance and stronger robustness of the proposed control scheme compared to conventional approaches have been confirmed through comparative experimental studies.