J. F. Pan

An Asymmetric Linear Switched Reluctance Motor

A novel double-sided electric asymmetric linear switched reluctance motor (LSRM) is proposed in this paper. The features of the proposed linear machine are that mover teeth and stators are not exactly identical according to the axis of the moving platform. This machine structure ensures that the alleviation of motor saturation magnetization effect and a higher thrust force output can be derived from the asymmetric LSRM. A thorough magnetic analysis is carried out for performance prediction of the machine, and results are compared to a symmetric LSRM counterpart. Both theoretical and finite-element methods results prove the priority of the asymmetric LSRM with higher force-to-volume ratio and better acceleration performance. Experimental results from the machine prototype validate the design of an asymmetric LSRM with yoke length of 12 mm.

An Improved Force Distribution Function for Linear Switched Reluctance Motor on Force Ripple Minimization With Nonlinear Inductance Modeling

An improved force distribution function (FDF) of linear switched reluctance motors (LSRMs) based on nonlinear inductance modeling for force ripple minimization and smooth speed operation is proposed. Nonlinear inductance profile is divided into three segments with a K factor that depicts current effect on inductance of the LSRM. Speed controller based on the proposed FDF and the nonlinear inductance model is constructed. Both simulation and experimental results verify the proposed FDF with the nonlinear inductance modeling effectively reduce force ripples with uniform speed response.

On the Voltage Ripple Reduction Control of the Linear Switched Reluctance Generator for Wave Energy Utilization

This paper discusses about the voltage output ripple reduction and error minimization for the direct-drive, linear switched reluctance generator (LSRG)-based wave power generation system. First, the concept of the LSRG-based wave power generation system is studied. According to the characteristics of the LSRG, the suitable drive circuit dedicated to proper current excitation and generation is established. Second, the reasons that cause voltage output ripples are investigated. To reduce the remarkable ripples from phase current commutations, a current distribution function (CDF) is proposed based on the minimized copper loss principle. Third, the dual-loop control strategy with current and voltage as the inner and outer loop is constructed, implemented with the proposed CDF. Theoretical bases of the control strategy are derived. The simulation results prove that the proposed control algorithm is capable of voltage ripple suppression and error reduction within the range of ±0.5 V over the entire operation speed for wave energy extraction, validated by experimental verification.

Nonlinear Modeling of the Inverse Force Function for the Planar Switched Reluctance Motor Using Sparse Least Squares Support Vector Machines

In the advanced manufacturing industry, planar switched reluctance motors (PSRMs) have proved to be a promising candidate due to their advantages of high precision, low cost, low heat loss, and ease of manufacture. However, their inverse force function, which provides vital phase current command for precise motion, is highly nonlinear and hard to be accurately modeled. This paper proposes a novel inverse force function using sparse least squares support vector machines (LS-SVMs) to achieve nonlinear modeling for precise motion of a PSRM. The required training and testing sets of sparse LS-SVMs are first obtained from experimental measurement. A sparse LS-SVMs regression is further developed using training set to accurately model the inverse force function. Accordingly, the function is tested via the testing set to assess its feasibility. Finally, the proposed approach is applied to the PSRM system with dSPACE controller for trajectory tracking, and its effectiveness and superior performance are verified through experimental results.

Optimization Design of the Planar Switched Reluctance Motor on Electromagnetic Force Ripple Minimization

In planar switched reluctance motors (PSRMs), the electromagnetic force ripple minimization is important to reduce the noise and vibration for high-precision motions. In this paper, an improved PSRM by optimization design for minimization of the electromagnetic force ripple is proposed. The structure, principle, and mathematical model of the PSRM are clarified. Based on Ansoft Maxwell, optimization design of the PSRM is performed by improved structure with smaller pole pitch and incremental number of mover poles. Experiments of the improved PSRM are implemented based on dSPACE. The experimental results verify that the improved PSRM effectively reduces electromagnetic force ripple with planar trajectory tracking.

Performance Analysis and Decoupling Control of an Integrated Rotary–Linear Machine With Coupled Magnetic Paths

An integrated rotary-linear machine based on switched reluctance principle is investigated. The characteristics of the motor are analyzed by finite-element methods, with particular emphasis on the coupled magnetic paths. Results from numerical calculation are verified by the hardware experiment. The simple yet effective decoupling algorithm for the independent position control of both rotary and linear axes is proposed. Implemented with the proportional-integral-differential algorithm, the motor is capable of high-precision rotary and linear position tracking with the steady error within 0.3 ° and 10 μm, respectively.

Core Loss Analysis for the Planar Switched Reluctance Motor

Core loss is one of the key factors for performance evaluation of switched reluctance machines. In this paper, core loss analysis of the planar switched reluctance motor (PSRM) is calculated based on the 3-D time-stepping finite element methods. The numerical analysis for the computation of the core loss is discussed, also its transient and average core loss in the mover and the stator are calculated. The corresponding experiments of measurement loss for a PSRM prototype are conducted and the results validate the accuracy from the numerical analysis. It can be concluded that core loss dominates around the corner of the mover and stator cores.

An adaptive control method for the linear switched reluctance motor based on DSP

The linear switched reluctance motor (LSRM) is a new kind of direct-drive actuator, however, it is very difficult to build an exact theoretic model for the LSRM. In this paper, an indirect self-tuner is proposed for position control of the LSRM by combining the recursive least squares (RLS) estimator with the minimum-degree pole placement method (MDPP) for controller design. Control system construction and operation based on one single Digital Signal Processor (DSP) are also established. Experimental results demonstrate the control scheme with on-line least-square parameter identification has a better performance than PID controller on modifying steady-error variances between each operation side in square-wave tracking. Experimental results prove that the control algorithm considering disturbances has smaller steady-state error compared with PID control algorithm.

Design and Analysis of a Novel Transverse-Flux Tubular Linear Machine With Gear-Shaped Teeth Structure

A transverse-flux tubular linear machine with novel gear-shaped teeth for high force density is proposed. The teeth can be formed by silicon steel laminations or permanent magnets for a tubular linear switched reluctance or tubular linear hybrid motor. With the unique improved teeth structure and short magnetic circulation paths, larger propulsion force output can be obtained with reduced mover weight and volume. Simulation based on finite element method (FEM) verifies the validity of the proposed machine design. The proposed machines are compared with other transverse-flux linear machines. Results show that the proposed tubular motors exhibit better output performance with a higher force-to-volume ratio.

High-precision control of LSRM based X-Y table for industrial applications.

The design of an X-Y table applying direct-drive linear switched reluctance motor (LSRM) principle is proposed in this paper. The proposed X-Y table has the characteristics of low cost, simple and stable mechanical structure. After the design procedure is introduced, an adaptive position control method based on online parameter identification and pole-placement regulation scheme is developed for the X-Y table. Experimental results prove the feasibility and its priority over a traditional PID controller with better dynamic response, static performance and robustness to disturbances. It is expected that the novel two-dimensional direct-drive system find its applications in high-precision manufacture area.