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Electromagnetic levitation system is the core component of maglev trains, and the performance of its control loop directly affects the stability, safety and riding comfort. After a long time of operation, the control loop performance of the electromagnetic levitation system will be reduced from its initial condition, due to changes in external environment, actuator failure, etc. Therefore, monitoring and evaluating the control loop performance is of great significance to ensure a smooth operation of the maglev train. In this paper, the concept and framework of control loop performance evaluation are introduced to the electromagnetic levitation system for the first time; and then the fundamental for control loop performance evaluation based on data-driven methods is presented; with the operational data of commercial maglev train, performances of different evaluation methods are tested and compared. In addition, by taking advantages of the geometrical significance of covariance matrix, evaluation results of the control loop performance can be visualized in a compact and intuitive fashion.

In this paper, the electromagnetic levitation ball system is taken as the research object. The electromagnetic levitation ball controller combined with fuzzy control algorithm and conventional PID control algorithm is designed. Firstly, the basic principle of the electromagnetic levitation ball system is analyzed and the mathematical model is established. Then Based on the classical PID control model and fuzzy control algorithm, fuzzy inference of PID controller feedback parameters is realized to realize dynamic adjustment of feedback parameters of the PID controller. And the control algorithm is implanted into the DSP controller, then the loading and the unloading experiments are carried out. The experimental results show that the levitation controller has good static performance and better dynamic performance and robustness than conventional PID controller.

This paper describes about the basic understanding procedure undertaken in building the electromagnetic levitation mini-model using E-I design topology. Simulation was done on the E-I core design using COMSOL software to study the distribution of the magnetic flux and flux leakages. Two types of E-core design were proposed and the rectangular shape gives the better output because of less flux leakages around the core. Besides that, the process of generating pulses using H-bridge to energize the coil winding on the E-core is also explained. From the simulation result, the test jig was assembled based on the parameter used in the simulation. The test jig was then placed at the SCML-02 to test for its levitation performance. The PID-controller in LabView software was employed together with the H-bridge PWM type to produce its modulated signals. With this design, the magnetic levitation is succeeded up to 5 mm separation between the E-core and I-core.

The electromagnetic suspension control system is a complex open-loop unstable system. The system has problems such as unmodeled dynamic characteristics, uncertain external interference, and sensor noise. In order to make the controller designed under the influence of uncertain factors in the system, The system can still keep the system stable. In this paper, a robust electromagnetic levitation control algorithm is designed based on mixed sensitivity. Simulation results show that the algorithm can still maintain the system's expectations in the presence of model uncertainty or external interference Performance.

This research work presents the modified cascade control scheme using the Fuzzy Tuner. The proposed control structure is implemented for the Electromagnetic Levitation System (EMLS). This EMLS is a group of the highly nonlinear, unstable and electromechanically coupled system. The conventional cascade control with PID and PI controllers as primary and secondary loops is one of the widely used control approaches for the EMLS. However, the constant gains of the conventional cascade control structure may not provide the proper stabilization of the levitating object in the presence of the nonlinearities and the payload disturbances. Hence, Fuzzy Tuner is incorporated for the automatic tuning of the controller gains based on the ITAE criterion. Additionally, the nonlinear estimator is hybridized with the scheme to provide an online estimate of the vertical velocity of the EMLS. Also, the feed-forward compensator is introduced to compress the effect of the variation of the operating conditions. The experimental hardware is utilized to perform the stabilizing control and tracking control operations. The vertical payload disturbance in the range of 0-40 % is considered to check the efficacy of the proposed modified cascade controller.

The development of educative prototypes of industrial control techniques has increased in the past few years, since its importance lies in their low cost compared to real systems. This study presents the design, modeling, and implementation of a magnetic levitator. The complete system is formed by amplifiers, an optoelectronic sensor, a coil used as an electromagnet, and a metallic sphere used as an object to levitate. The information from the sensor is used to feed the proportional-integral-derivative (pid) controller, and with this regulate the incoming current that flows through the coil by means of a power amplifier with the objective of maintaining the metallic sphere at the balance point. The pid controller is designed based on dominating poles in a closed loop (s=−4 ± j4) being ±180°, assuring that the zeros contribute to the same angle. The proposed system levitates a metallic sphere with an inertial mass of 24.75 g and a diameter of 12 mm to a distance of 4mm.

In this paper, a digital controller is applied to distance control of the Magnetic Levitation System (MLS). The characteristics of the magnetic levitation are very nonlinear. This is a prime reason for the difficulty of controlling the magnetic levitation. Conventional control is normally not appropriate for this kind of application. Hence, a robust digital controller of the magnetic levitation using a combination of Proportional-Integral (PI) and Approximated 2 Degree of Freedom (A2DOF) controller method for keeping the level of magnetic ball with sudden change of setpoint is proposed. The simulation using MATLAB/Simulink and experimental results are shown. It demonstrates that the proposed digital controller of which gain parameters are determined by the proposed method satisfies the given specifications.

In contactless electromagnetic levitation technology, one of the main challenges is that the amount of power delivered to the load depends significantly on parameters of the transformer and therefore is very sensitive to system impedance variations. In this paper, a systematic design procedure based on virtual impedance control strategy is proposed to obtain high transfer efficiency and achieve maximum power transfer. A contactless electromagnetic levitation melting system was used to validate the proposed method. Both theoretical analysis and simulation results indicate the effectiveness of the proposed structure.

The main advantage of Electromagnetic Levitation Melting system (ELM) is to solve the pollution problem in metal melting process. This paper provides an analysis of the system large-signal behavior for modeling the dynamics of ELM that can be used for control design. Moreover, the high frequencies utilized by wireless ELM have posed a challenge for simulation software in the form of long simulation times. In order to reduce simulation time, it is proposed to replace the analysis of the high-frequency-electrical-signals by only the envelope-signals and still get all the information on the system dynamics. A larger than 92% decrease in simulation time is observed. Experimental results are presented to validate the analysis and the simulation results.

The traditional control strategies for electromagnetic levitation systems (EMLS) are the voltage or current control strategies based on linearization models at the equilibrium, but their effectiveness and efficiency of response are not satisfactory especially when load varies strongly. As a large amount of overshoot occurs, the adjustment time is intolerable long. A load adaptive control strategy based on a mass observer, which is able to apply the signals of current and air gap between electromagnets and tracks to predict the mass of load, is proposed in this paper. The mass can modify the Proportion Integration Differentiation (PID) parameters associated with the changed operating point. Via the comparison between simulation and experimental results, it is verified that the load adaptive control strategy performs more accurately and efficiently than traditional PID control strategies and fuzzy PID control.

It is proposed in this paper the design of a contactless electromagnetic levitation and electrostatic driven rotation control system for a micro mirror. The design can levitate an aluminum micro rotor with 3.3mm diameter and $8 \mu\mathrm{m}$ thickness. Using electromagnetic force and electrostatic force, the rotor can be levitated to $100\mu\mathrm{m}$ height with 20MHz frequency and 0.5A p-p input current and driven to rotate around the vertical axis within the range of ±180°. The control system design is presented using detection and control circuit, and the levitation and rotation figures are also presented. The square wave response experiment is carried out to show its feasibility.

This paper presents derivation and experimental validation of levitation melting system electro-mechanical model. It was shown that the work load may be perceived as time-varying inductance-resistance combination from the electrical point of view. Expressions linking the values electrical side variables with their mechanical counterparts are developed, forming a unified dynamics representation. Experimental prototype is used as an example throughout the paper, allowing validation and fine tuning of the model subsystems. Analytical and experimental results are shown to be in close agreement, verifying the proposed modeling approach.

Recent years, high quality thin steel plate is used for many industrial products. A production line of thin steel plate includes a transport system utilizing the friction force induced by contact. However, the deteriorates of surface quality from contact with rollers is a problem. As a solution to this problem, non-contact conveyance systems applying electromagnetic levitation technology have been proposed. From the previous study, control horizontal displacement of thin steel plate using electromagnet. Using horizontal displacement control, we confirmed improvement performance of magnetic levitation system. By using an electromagnet installed horizontally direction, a vertical force to support the steel plate and a horizontal force to suppress elastic vibration act on the steel plate. Focusing on these forces, we have proposed a magnetic levitation system for a steel plate with simultaneous horizontal positioning control and vertical non-contact support using a horizontal electromagnet. In this study, we carried out levitation experiment using magnetic levitation system. We verify levitating characteristic of thin steel plate.

This paper proposes an effective control solution to achieve stabilizing control and tracking control with robustness against high valued disturbances in the area of Electromagnetic Levitation System (EMLS). EMLS is an open-loop unstable and nonlinear test bench with input and state types of nonlinearities presents in the current control mode. Fuzzy-PID controller is designed and implement based on ITAE performance criterion to achieve satisfactory transient as well as steady state performance from EMLS. Pre-filter structure is added to smooth the system performance as well as to reduce the transient overshoot problem. The simulation results and different integral errors like ISE, ITAE and ISTE are presented to validate the effectiveness of the proposed research work under different initial conditions, various trajectories and different disturbances.

This paper presents the design of position and current controllers for an electromagnetic levitation platform. The system will be linearized and modelled. A PID controller for the position (gap levitation and roll) and a PI controller for the current will be designed. Simulation results will be presented for the following input signals: a step reference and a sinusoidal reference. Some experimental results will also be presented.

In this paper a unique combination of sensorless electromagnetic levitation stabilized by zero power control is experimentally demonstrated. The sensorless method includes high frequency voltage injection to electromagnetic coil by a switching amplifier and measurement of the resulting current-ripple slopes. Inductance is estimated from a weighted contri­bution of both (positive/negative) slopes from which air gap is calculated. Zero power control forces average current to approach zero and consequently duty ratio to 0.5, which is an optimal case for least dynamic noise in the gap detection. Furthermore, since sensorless methods are often influenced by magnetic circuit modeling errors, instead of absolute and exact air gap, rather a proportional signal to air gap is estimated which has a possible offset. Zero power control being a reference current tracking control, thus does not require absolute information of air gap. These mutually enhancing characteristics show that such combination has potential of a simple, robust and low cost magnetically levitated carrier in industrial environment.

This paper presents the analysis of feedback linearization based optimal controller design for ElectroMagnetic Levitation (EML) system, which is a class of nonlinear and unstable system. Using feedback linearization method, nonlinear model is first converted into controllable linearized model in large operating range under certain conditions. Using linearized model, optimal controller is designed for stabilizing and tracking control of EML system. Feedback linearization based optimal controller shows kind of smooth, stabilizing and tracking response under different trajectories and bounded load variations due to variation of parameters. Simulation results and conditions under which mentioned approach is applicable are presented to validate the contribution in the paper.

This paper simulates the melting process and liquid titanium droplet formation in electromagnetic levitation melting (EML) process by using the finite element method. The modelling of the physical EML process involves the coupling of electromagnetic, thermal, and fluid flow fields. The bidirectional interactions of different fields are also consided. The electrical parameters, such as frequency, current, and number of turns of the excitation coils, which might affect the size of droplet, are studied. The arbitrary Lagrangian-Eulerian formulation is employed to model the deformation of metal sample during the melting process. The results show that the method adopted in this paper could dynamically predict the melting process, and size of the droplet could be controlled by modifying the electrical parameters.