Linear Variable Reluctance Motor Research Articles

Design and Analysis of a Magnetless Linear Variable Reluctance Motor With Modular Mover Units for Electric Propulsion

This paper proposes a magnetless linear variable reluctance motor (MLVRM) with modular mover units (MMUs) for electric propulsion. The proposed MLVRM adopts a doubly-salient structure with two sets of windings on mover, namely the ac armature windings, the dc field windings. In space, the two sets of windings are naturally isolated from each other due to the iron-core structure of the mover. Consequently, the space conflicts between the two sets of windings can be eliminated. To improve the force production capability, high-temperature superconducting (HTS) windings injected with large current are employed in the dc windings. The focus of this paper is to elaborate the method to adopt MMUs with equal clearance to suppress force ripple without weakening the back electromotive force (EMF). This paper also introduces the structure, working principle and choice of key parameters for the proposed MLVRM in detail. Moreover, MLVRMs with different number of MMUs are compared to MLVRM with only one MMU by finite element method (FEM) to verify the proposed method to suppress force ripple. The results show that the force ripple decreases significantly from 24.75% to 12.59% when the MLVRM adopts two MMUs.

Nonlinear Analytic Modeling for Novel Linear Variable Reluctance Motors

Nonlinear Analytic Modeling for Novel Linear Variable Reluctance Motors

Design, Simulation and Performance of a Four Phases Linear Variable Reluctance Motor

Design, Simulation and Performance of a Four Phases Linear Variable Reluctance Motor

Development of a Segmented Linear Variable Flux Reluctance Motor with DC-Field Coil

This paper proposes a new type of linear motor based on the concept of variable flux reluctance motor (VFRM). By adopting segmented primary stator, the segmented linear VFRM (SLVFRM) can eliminate asymmetry between phases due to end-effect. Meanwhile, multi-phase SLVFRM of any number of phases can be obtained by adjusting number of segments directly. The stator/mover tooth pitch combination and segments arrangement rules are also illustrated. An optimized 3-phase SLVFRM is analyzed by finite element analysis, with focus on characteristics such as cogging force, back-EMF and winding inductances. Further, both brushless AC (BLAC) and brushless DC (BLDC) drive for SLVFRM are investigated. Besides much smaller force ripple, BLDC drive can obtain higher average force at same RMS current due to trapezoidal back-EMF. The force characteristicwith variousAC and DC currents and current angles are also investigated in the paper, and it shows that SLVFRM has negligible reluctance force while keeping the same AC and DC currents is optimal for maximum efficiency operation under a fixed copper loss.

Adaptive Integral Sliding-Mode Position Control of a Coupled-Phase Linear Variable Reluctance Motor for High-Precision Applications

Key factors limiting the greater use of linear motors are motor cost and complexity of controls. This paper develops an adaptive sliding-mode position control of a coupled-phase linear variable reluctance (LVR) motor for high-precision applications. With several distinct features, the LVR motor can be considered a strong candidate for high-performance linear motion applications due to its simple structure, compactness, and low cost with no permanent magnet. The adaptive position controller based on sliding-mode control is considered because of its simple structure and robustness against uncertain perturbations and external disturbances. The designed controller consists of the following: 1) an inner force control loop based on the sinusoidal flux model for simplicity and computational efficiency and 2) an outer position control based on the adaptive sliding-mode control to enhance the system robustness and to achieve high accuracy for high-precision applications. The LVR motor prototype was constructed for laboratory test, and the controller is implemented on a real-time DSP-based controller card. The comparative experimental results clearly show that the proposed controller is suitable for controlling the LVR motor system for high-accuracy applications and effective for reducing the chattering.

Position Control of a Linear Variable Reluctance Motor with Magnetically Coupled Phases

The objective of this paper is to design and implement a direct-drive position control based on a simplified sinusoidal flux model for a linear variable reluctance motor. The motor under consideration is a three-phase linear reluctance motor with strong magnetic coupling between phases that has the advantages of simple structure, compactness and low cost with no permanent magnet. The experimental results show overall good performance indicating that the developed system can be considered as a strong candidate for high precision manufacturing automation applications.

A Global Sliding-Mode Control Scheme with Adjustable Robustness for A Linear Variable Reluctance Motor.

A novel global sliding-mode control (GSMC) scheme with adjustable robustness is presented in this article. The proposed scheme offers a switching function together with unperturbed system dynamics to weigh the contribution from SMC such that all of the closed-loop poles can be located within predefined regions to provide design flexibility, and the robustness of system can thus be adjusted. By this scheme, the maximal control effort and chattering level can be reduced according to designer's specifications directly. Since the switching function can initially be made to equal to zero, the adjustable performance during the entire response can be guaranteed, and the reaching condition is thus lifted. The efficacy of this scheme is demonstrated via successful implementation on a linear variable reluctance motor (LVRM) servo system. Both simulation and experimental studies further demonstrate its feasibility and effectiveness.

TOWARD THE DESIGN AND IMPLEMENTATION OF A GLOBAL SLIDING-MODE CONTROL SCHEME WITH INPUT CONSTRAINT

A global sliding-mode control (GSMC) scheme with input constraint is presented in this article. The scheme offers a measure to weigh the contribution between GSMC and the nominal dynamics so that the chattering level and the maximal control effort can be reduced based on an online tuning of the weight on GSMC. A moving sliding function is adopted on the control design, the input can thus be confined within a predefined boundary during transient period, while a robust performance can be guaranteed in the steady state. The efficacy of this scheme is further validated via implementation on a linear variable reluctance motor (LVRM) servo system. Both simulation and experimental studies further demonstrate its feasibility and effectiveness.