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2D Simulation of a magnetic levitation system used in semi-high-speed maglev train

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Wednesday, July 28, 2021
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08:00 PM
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02:00 PM
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Introduction 

Magnetic levitation is a method by which an object is suspended in the air with no support other than magnetic fields. The fields are used to reverse or counteract the gravitational pull and any other counter accelerations. 

It is a highly advanced technology and has various uses. The common point in all applications is the lack of contact and thus no wear and friction. This increases efficiency, reduces maintenance costs, and increases the product lifespan. 

Magnetic levitation technology can be used as an efficient technology in various industries. Many countries are attracted to maglev systems, and many systems have been proposed in different parts of the world. 

Magnetic Levitation

Figure 1 – Magnetic Levitation 
 

Mainly, there are two types of magnetic levitation: Electromagnetic suspension (EMS) and electrodynamics suspension (EDS). Electromagnetic levitation type uses the attractive force between the magnets present on the bottom of the train and the guideway to lift the train. The magnets on the left and right sides of the train are used to eliminate any lateral displacement. This method is easier to implement, and it works even for zero speed. 

In this application note, a proposed electromagnetic levitation system model in a semi-high-speed maglev train is analyzed using EMWorks2D [1]. EMWorks2D is a 2D electromagnetic simulation software provided by EMWorks. 

The proposed model consists of a Type F rail, levitation electromagnets, and guidance electromagnets [1]. The levitation magnets are used to lift off the vehicle from the ground to a specific position in the free space, while the guidance magnets are used to center the vehicle above the rail and eliminate any lateral displacement. The ferromagnetic components are made of steel 1010, while the windings are made of copper. 

The studied electromagnetic levitation system [1]

Figure 2- The studied electromagnetic levitation system [1] 

The illustrated magnetic levitation system represents a planar symmetry; hence it can be solved under the 2D assumption, especially at the earliest design stage. Later, the 2D simulation results can be verified and confirmed with 3D simulation. This helps to reduce time-to-market and increase productivity.? Figures 3a) and 3b) show respectively 3D and 2D CAD models built inside SOLIDWORKS. The 2D model is extracted from the 3D original geometry automatically using the 2D Simplification feature of EMWorks2D. EMWorks2D is fully integrated inside SOLIDWORKS which is one of most powerful CAD tools. In addition to the great capabilities in CAD, SOLIDWORKS ensures a flexible co-existence between 2-dimensional and 3-dimensional geometries and EMWorks2D profits of this. 

CAD models of the presented magnetic levitation system, a) 3D model, b) 2D model [1]

Figure 3 - CAD models of the presented magnetic levitation system, a) 3D model, b) 2D model [1] 

2D electromagnetic simulation of a magnetic levitation system 

Static magnetic simulations are performed using the Magnetostatic module of EMWorks2D. Parametric sweep feature is used to compute the magnetic fields, levitation force, and guidance forces versus different parameters like airgap length, applied current, etc. The levitation winding has 250 turns, while the guidance winding has 180 turns. The applied current is 15A and 7A respectively. Studying both levitation and guidance forces is particularly important to build an efficient and stable maglev system. 

The figures below show the magnetic field results versus vertical airgap. It can be noticed that the magnetic field increases when the air gap decreases. The field results can be animated versus the parametric variable using EMWorks2D. Figure 6 contains an animation of the magnetic flux versus the Y position of the levitation magnet. 

2D model with the variable airgap

Figure 4 - 2D model with the variable airgap 
 
Magnetic flux results at different airgap, a) 2 mm, b) 20 mm
Figure 5 - Magnetic flux results at different airgap, a) 2 mm, b) 20 mm 
 
Animation of magnetic field versus Y position
Figure 6 - Animation of magnetic field versus Y position 
 

Figure 7 shows the force results versus airgap. The force decreases exponentially with the airgap. It has a peak value of 15 kN at 2 mm, while it is lower than 2 kN with an air gap smaller than 7 mm. 
 

Force results versus airgap computed using a parametric study of EMWorks2D, a) force curve, b) design scenarios page of EMWorks2D

Figure 7 - Force results versus airgap computed using a parametric study of EMWorks2D, a) force curve, b) design scenarios page of EMWorks2D. 

Figure 8 contains a comparison between force results versus current at different airgap lengths. The force increases with the current and decreases with the air gap. 
 

Force results versus current at different airgap distances

Figure 8 - Force results versus current at different airgap distances 
 

In this section, the lateral position of the rail is varied (Figure 9) and both levitation and guidance forces are measured. The lateral position of the rail impacts the stability of a maglev system. The rail should be maintained in an aligned position to maximize the levitation force and reduce the losses. 

2D model with lateral deviation

Figure 9 - 2D model with lateral deviation 
 

Figures 10a) and 10b) show the magnetic flux results at a maximum lateral deviation and an airgap of 10 mm. Figure 10b contains a superimposed plot of the 2D field plot with a cross-section view of the 3D model. 
 

Magnetic field results, a) plot on the 2D model, b) plot on the 3D model

Figure 10 - Magnetic field results, a) plot on the 2D model, b) plot on the 3D model 
 

An animation of the magnetic field versus x position is shown in Figure 11. It can be seen that the airgap flux density decreases versus lateral displacement.

animation plot of the magnetic field versus lateral deviation

Figure 11 - animation plot of the magnetic field versus lateral deviation 
 

Figures 12a) and 12b) show respectively the guidance and levitation forces versus deviation. The lateral force, which should be maintained at low values, increases with the lateral deviation. Unlike lateral force, the levitation force decreases with the x position. 
 

 Magnetic forces versus lateral deviation, a) guidance force, b) levitation force

Figure 12 - Magnetic forces versus lateral deviation, a) guidance force, b) levitation force 
 

Inductances of the electromagnets winding are computed and shown in the figures below. They represent maximum values at the aligned position and start to decrease with the deviation in the x position. 
 

Inductances results, a) levitation coil, b) guidance coil

Figure 13 - Inductances results, a) levitation coil, b) guidance coil 
 

Optimizing the levitation force 

Using SolidWorks multi-configurations feature, the levitation force is evaluated versus 3 different configurations. This feature of SolidWorks helps to test different CAD geometry and topology within the same model. 

Below is shown the three simulated configurations; the original configuration (figure 14a), a second configuration with two added magnets in lateral positions (Figure 14b), and a third configuration with one added magnet at the bottom of the ferromagnetic core that has two coils instead of one coil (Figure 14c). 

Figures 15a) and 15b) show SolidWorks multi-configuration page and EMWorks studies tree, respectively. 
 

simulated configurations, a) original design, b) design 2, c) design 3

Figure 14 - simulated configurations, a) original design, b) design 2, c) design 3 
 
a) Multi-Configurations feature page, b) EMWorks2D tree with multi-configurations
Figure 15 - a) Multi-Configurations feature page, b) EMWorks2D tree with multi-configurations 
 

The magnetic field results for different configurations are plotted in Figure 16, while the force results are illustrated in Figure 17. It shows that the third configuration, with two adjacent coils, gives the highest force among the studied cases which can be considered as a well-optimized system. 
 

Magnetic flux results, a) original design, b) design 2, c) design 3

Figure 16 - Magnetic flux results, a) original design, b) design 2, c) design 3 

 Comparison of the three configurations in terms of the levitation force
Figure 17- Comparison of the three configurations in terms of the levitation force. 

Summary 

EMWorks2D was used to study and simulate an electromagnetic levitation system. Magnetic fields, winding parameters, different magnetic forces were computed versus several design variables. These kinds of simulations help to build and create more innovative and efficient magnetic levitation systems that can be used in many applications, especially in transportation. The 2D simulation showed a great capability to handle such applications by increasing the design iterations and hence the productivity. 

Reference

[1]: Min Kim, Jae-Hoon Jeong, Jaewon Lim†, Chang-Hyun Kim and Mooncheol Won. Design and Control of Levitation and Guidance Systems for a Semi-High-Speed Maglev Train. J Electr Eng Technol.2017; 12(1): 117-125