Permanent Magnet Linear Synchronous Motor Research Articles

Flatness‐based control in successive loops for mechatronic motion transmission systems

AbstractMechatronic systems with nonlinear dynamics are met in motion transmission applications for vehicles and robots. In this article, the control problem for the nonlinear dynamics of mechatronic motion transmission systems is solved with the use of a flatness‐based control approach which is implemented in successive loops. The state‐space model of these systems is separated into a series of subsystems, which are connected between them in cascading loops. Each one of these subsystems can be viewed independently as a differentially flat system, and control about it can be performed with inversion of its dynamics as in the case of input–output linearized flat systems. In this chain of subsystems, the state variables of the subsequent ( )‐th subsystem become virtual control inputs for the preceding ‐th subsystem and so on. In turn, exogenous control inputs are applied to the last subsystem and are computed by tracing backwards the virtual control inputs of the preceding subsystems. The whole control method is implemented in successive loops, and its global stability properties are also proven through Lyapunov stability analysis. The validity of the control method is confirmed in the following two case studies: (a) control of a permanent magnet linear synchronous motor (PMLSM)‐actuated vehicle's clutch and (ii) control of a multi‐Degrees of Freedom (multi‐DOF) flexible joint robot.

Thermal analysis of permanent magnet synchronous linear motor accounting for three-phase current unbalance

Three-phase current unbalance is a common winding fault of the motor, which will bring local overheating, cause security risks and economic losses, accurate temperature rise calculation and thermal flux characteristics analysis of the motor working in three-phase current unbalance are necessary and challenging. However, little research has been conducted on the thermal characteristics and analysis methods for the permanent magnet synchronous linear motor (PMSLM) working in three-phase current unbalance. To address this problem, a multilayer composite flat wall model contained heat source of the primary is proposed firstly to analysis the heat transfer characteristics of the PMSLM caused by three-phase current unbalance qualitatively. Then, the heat transfer and temperature distribution characteristics of the PMSLM are obtained by calculating the fluid-thermal coupling model of the PMSLM directly. What's more, the effect of current grade on heat transfer is analyzed by comparing the heat transfer characteristics of the PMSLM working in four different three-phase current balance cases. Finally, the qualitative analysis and fluid-thermal analysis results are verified experimentally with a PMSLM adopting four different three-phase current unbalance conditions. Thermal analysis of the PMSLM working in three-phase current unbalance makes it is possible to prevent local heat accumulation and avoid unexpected interruptions for the redundant motor system and the fault tolerant motor system.

Analysis and Optimization Design of U-Shaped Ironless Permanent Magnet Linear Synchronous Motor

The working speed of the U-shaped ironless permanent magnet linear synchronous motor is determined by the frequency and pole pitch. When the motor’s working speed is required to be constant, different combinations of frequency and pole pitch can be chosen. This article mainly discusses the influence of the pole pitch on the motor performance when other parameters are kept constant. First, the magnetic field of the motor permanent magnet is analyzed using the equivalent magnetizing current method to discuss the relationship between the pole pitch and the motor air gap magnetic field. Then, the finite element method is used to analyze the influence of the pole pitch on the motor air gap magnetic field, transverse edge effect, and electromagnetic thrust considering the saturation effect of the magnetic yoke. The research shows that under the conditions of constant motor basic structural parameters and speed, and the same amount of permanent magnet material, both the air gap magnetic density and the motor thrust line density have maximum values as the pole pitch changes. The research results have certain guiding significance for the design of this type of motor.

Primary component segmental design to suppress the normal force ripple for the permanent magnet linear synchronous motor

AbstractThere is not only thrust but also normal force between the primary and secondary components for the single‐side flat plate permanent magnet linear synchronous motor (PMLSM). The normal force will fluctuate periodically, which will cause friction perturbation and finally affect the positioning accuracy of linear feed system. For the single‐side flat plate PMLSM, the variation law of normal force ripple under the coupling effect of multiple effects is studied, and the method of primary component segmental design to suppress it is proposed. Firstly, the influence of the cogging effect, the end effect and the armature reaction on the normal force ripple is analysed. Meanwhile the mathematical model of normal force ripple is established. Secondly, the PMLSM with segmental primary component is introduced and its suppression mechanism to the normal force ripple is expounded. On this basis, a scheme combining the non‐integer pole slot matching with the primary component segmental design is proposed to further suppress the normal force ripple. Finally, an 18‐slot 96/5‐pole prototype is taken as an example to carry out the finite element simulation and experimental test, of which the results verify the research theory in this paper.

Magnetic Field Distortion Analysis and Suppression for the Minimum Unit Winding Segmented Moving-Magnet Linear Motor

Segmented power supply is frequently utilized for long-stroke moving-magnet linear synchronous motors to lessen the issue of large loss and heating brought on by long-stroke power supply. However, the driving mode of partial excitation in segmented power supply brings some problems, such as unbalanced parameters of three-phase, the transient inductance of winding changing with secondary position, and distortion of armature reaction magnetic field. This paper proposes a new topology with the minimum unit winding segmented to solve the problems of unbalanced inductance parameters and distortion of armature reaction magnetic field in winding segmented permanent magnet linear synchronous motors (WS-PMLSM). An analytical model of inductance distortion in the end coils of a moving-magnet PMLSM is established and compared with the non-end coil inductance to summarize the mechanism of inductance unbalance in WS-PMLSM. Based on the model of winding transient inductance changing with secondary position, the changing law of transient inductance is expounded. An analytical method of the air gap magnetic field based on virtual winding is proposed, and the formation mechanism of magnetic field distortion caused by partial excitation is revealed. Aiming at the topology of the minimum unit winding segmented moving-magnet PMLSM, an optimized drive strategy of n+3 is proposed.

Air gap flux density measurement of PMSLM based on TMR sensing external stray magnetic field and CNN-LSTM

This paper presents a new non-invasive air gap flux density measurement method for permanent magnet synchronous linear motor (PMSLM) using tunneling magnetoresistance (TMR) sensor and convolutional neural networks-long short-term memory (CNN-LSTM) regression modeling. First, the analytical and finite element models of the air gap magnetic field of PMSLM are established as the data basis. Second, TMR sensor is used to measure the external stray magnetic density. Gramian Angular Field method combined with image similarity matching technology are used to obtain the optimal measurement position of the TMR sensor. Then, a new deep learning regression method as CNN-LSTM is introduced to establish a high-precision mapping model to realize non-invasive high-precision measurement of the air gap magnetic density by “substituting external to internal.” Finally, PMSLM prototype experimental platform with TMR sensor hardware acquisition circuit is built. Comparison confirmatory experiments with Gauss meter can verify the effectiveness and superiority of the proposed method.

Temperature field analysis and cooling structure optimization of permanent magnet linear synchronous motor

A water-cooled permanent magnet linear synchronous motor was designed, and the investigation focused on the temperature distribution of motor and the optimization of the cooling structure to address its electromagnetic thermal effects. Firstly, the electromagnetic model of the motor was employed to calculate losses using finite element analysis. Subsequently, the motor's temperature distribution under various operating conditions was determined through electromagnetic-thermal coupling analysis, with prototype measurements validating the predicted outcomes. Secondly, the study placed emphasis on the impact of different water-cooled structure parameters on the motor's cooling performance, resulting in a 69 % reduction in the maximum temperature of the motor module after the cooling system was applied. Building on this, cooling structure parameters underwent optimization and design via the response surface optimization method, which achieved a reduction of 0.617 K in the motor's maximum temperature. The analysis findings revealed a substantial improvement in the motor's thrust performance by a factor of 3.08 when the water flow rate reached 1 m/s. This research can serve as a fundamental reference for the design of water cooling structures for permanent magnet linear synchronous motors.

The Speed Control of PMLSM with Discontinuous Driving Coils Based on Multi-loop DOB Model

A permanent magnet linear synchronous motor (PMLSM) with discontinuous driving coils potentially applied in the underground pipeline freight delivery system is introduced in this article. Firstly, the detailed structure of the PMLSM with discontinuous driving coils is designed and presented, and the dynamic models of the PMLSM during three different processes are developed. In addition, based on the proportional-integral (PI) and the adaptive disturbance observer (DOB), a multi-loop control strategy is designed for the PMLSM with discontinuous driving coils. The critical performances of PMLSM, such as the speed precision and anti-disturbance ability, are testified in the experiment, and the results validate that the multi-loop control model with adaptive DOB used in the PMLSM with discontinuous driving coils has better speed precision than the PI+PI model by suppressing the detent force.

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.

Vector Control Simulation of Permanent Magnet Synchronous Linear Motor

Compared with rotating motor, linear motor can “directly” obtain linear motion, which eliminates the intermediate transformation link and can directly drive the equipment requiring linear motion. It is applicable to rotating motor mature control strategy can be better for linear motor control research. Its development and application of linear motor has great significance. In this thesis, starting from the weakening characteristics of permanent magnet synchronous linear motor, through the MATLAB simulation and comparative analysis of different control signals (SPWM and SVPWM) of vector control strategy, the conclusion that vector control strategy can effectively control ideal linear motor is obtained, which lays a foundation for further improving the control strategy to control non-ideal linear motor.

Simultaneous Reduction of Normal- and Tangential-Direction Force Ripples in Permanent-Magnet Linear Synchronous Motors

Simultaneous Reduction of Normal- and Tangential-Direction Force Ripples in Permanent-Magnet Linear Synchronous Motors

Virtual position predictive control with system delay observer to improve PMLSM position tracking accuracy

AbstractTo improve the position tracking accuracy of permanent magnet linear synchronous motors (PMLSM), this paper introduces a virtual position predictive control (VPPC) with a system delay observer (SDO). Un‐like conventional position predictive control (CPPC), which ignores the complexity of prediction models and velocity adjustments, the proposed VPPC combines a simplified position model with an active variable speed control. This design accelerates mover response and increases maximum reference speeds through active adjustments to better estimate the predicted output. Since the prediction period in CPPC often misaligns with the system delay, resulting in additional prediction errors, this paper further explores the relationship between predictive periods and system delay. Based on this analysis and a unified modelling concept, an SDO is included to observe and compensate for system delay, correcting the prediction period and optimising the control model. Experimental results on a PMLSM platform confirm the superior position tracking performance of the VPPC with SDO compared to conventional controllers.

Fixed-Time Sliding Mode Control for Linear Motor Traction Systems with Prescribed Performance

In this research, we propose a fixed-time sliding mode controller using a prescribed performance control approach to address the speed tracking problem in linear motor traction systems, which are powered by high-power permanent magnet linear synchronous motors (PMLSMs). Initially, to tackle the issue of the convergence time and dynamic response associated with traditional finite-time sliding mode controllers, we introduce a fixed-time sliding mode controller. This controller guarantees that the system state converges to the origin within a specified upper time limit. Subsequently, to enhance the dynamic response of the PMLSM and minimize speed errors, we integrate the prescribed performance control strategy with a fixed-time sliding mode controller. This effectively limits the motor’s speed error within the predefined function boundaries, reduces system overshoo, and mitigates system jitter to a certain degree. Finally, simulation results are presented to validate that the proposed control strategy significantly enhances precision of speed tracking in PMLSMs.

A Novel Control Method for Permanent Magnet Synchronous Linear Motor Based on Model Predictive Control and Extended State Observer

Permanent magnet synchronous linear motor (PMSLM) is widely used to meet the requirement of high dynamic accuracy positioning, such as in machine tools and devices of semiconductor manufacturing. A new 2-DOF control structure is proposed in this paper to improve the dynamic performance of the positioning servo system with PMSLM. Aiming at the position tracking performance, a control algorithm based on the model predictive control (MPC) is developed with position and speed as the feedback state variables. In addition, an extended state observer (ESO) is designed for the rejection of various disturbances, which are not involved in the control model and are regarded as the lumped disturbance to be estimated and compensated by the ESO. The experimental results show that, compared with the commonly used PPI controller (proportional position controller and proportional–integral speed controller), the proposed method enhances the position bandwidth and servo stiffness effectively.

Design and utilization of thrust fluctuation of slotted-tubular permanent magnet linear motor: Mechatronics for low-frequency vibration forming machine

Usually, the conventional low-frequency vibration forming machine has a main transmission mechanism as the driving source to provide forming force and an auxiliary mechanism as the vibration source to generate vibration force. The transmission chain is long and the structure is complex and bloated, which affects the forming process and product quality. This paper presents a novel mechatronics idea of low-frequency vibration forming machine, which uses a slotted tubular permanent magnet synchronous linear motor (slotted-TPMLM) as both the driving source and the vibration source. The key is that the slotted-TPMLM provides sufficient forming force accompanied with a certain low-frequency vibration force. Consequently, this paper focuses on the thrust fluctuation caused by the structure. Firstly, the effect of end force and the influence of cogging force are discussed in detail through Fourier analyses, especially the stator adjustment length and pole-slot combination. Then, the slotted-TPMLM is designed, manufactured, and tested. The results show that the slotted-TPMLM can provide a certain low-frequency vibration force (low frequency of 4.8 Hz at 100 mm/s and 48 Hz at 1000 mm/s), which meets the technical requirements. Consequently, the feasibility of the novel mechatronics idea of a low-frequency vibration forming machine has been verified. This research will contribute to the field of linear motors and metal forming machines.

Heat Transfer Performance Improvement of Permanent Magnet Synchronous Linear Motor Based on Embedded Staggered Double Channel Water-cooling Structure

Heat Transfer Performance Improvement of Permanent Magnet Synchronous Linear Motor Based on Embedded Staggered Double Channel Water-cooling Structure

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

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.

Parameter Identification of Permanent Magnet Synchronous Motor with Dynamic Forgetting Factor Based on H∞ Filtering Algorithm

To address system parameter changes during permanent magnet synchronous motor (PMSM) operation, an H∞ filtering algorithm with a dynamic forgetting factor is proposed for online identification of motor resistance and inductance. First, a standard linear discrete PMSM parameter identification model is established; then, the discrete H∞ filtering algorithm is derived using game theory reducing state and measurement noise influence. A cost function is defined, solving extremes values of different terms. A dynamic forgetting factor is introduced to the weighted combination of initial and current measurement noise covariance matrices, eliminating identification issues from different initial values. On this basis, a dynamic forgetting factor is added to weigh the combination of the initial measurement noise covariance matrix and the current measurement noise covariance matrix, which eliminates the influence of the discrimination error caused by the different initial values. Finally, the identification model is built in MATLAB/Simulink for simulation analysis to verify the feasibility of the proposed algorithm. The simulation results show the proposed H∞ filtering algorithm rapidly and accurately identifies resistance and inductance values with significantly improved robustness. The forgetting factor enables quick stable recognition even with poor initial values, enhancing PMSM control performance.

Non-cascaded finite time control of PMSLM based on super-twisting observer

A novel control strategy based on finite time control and super-twisting observer is proposed to improve the control performance and robustness for permanent magnet synchronous linear motor (PMSLM) drive system. First of all, the velocity-current single loop control which called non-cascade structure control is proposed by the finite time control, then the response velocity of the PMSLM drive system can be improved. Secondly, to improve the disturbance rejection performance, a super-twisting observer is designed to feedforward the load. Furthermore, the strictly convergence of the proposed control strategy is implemented. Finally, comparative simulations and experiments are designed on PI control, sliding mode control, and the proposed control method. Results demonstrate that the proposed method has better robustness and control performance.