Hyperloop linear induction motor
QuickField simulation example
Linear induction motor for the hyperloop train is simulated. Motor is powered by the variable frequency drive. Motor starts at zero speed. For each specific speed of motion the frequency is attenuated to get the maximal thrust force value.
All dimensions are taken from the Linear Induction Motor (LIM) for Hyperloop Pod Prototypes master thesis by Christopher Timperio (ETH Zurich, Institute of Electromagnetic Fields).
Problem Type
Plane-parallel problem of AC magnetics.
Geometry
Z-length is 55 mm. Slot dimensions are 13*125 mm.
Given
Rail is made of Aluminum 6061-T6 with electrical resistivity of ρ = 2.857e-8 Ohm*m
Number of conductors in the slot is 25, current is 140 A (r.m.s).
Magnetic permeability of steel core is 1000.
Task
Calculate the thrust force as a function of the frequency and the velocity.
Solution
We do not draw each individual conductor in the slot, instead we draw a large block and specify the total current value and zero electrical conductivity. In this case the current density is uniformly distributed across the conductor cross-section.
Stator produces a moving sinusoidal wave of the magnetic field. The speed of the wave is vsync = frequency * stator length. To take into account the motion of the stator along the rail the following assumptions are made:
A set of parametric problems with different electrical conductivity of the rail is automatically generated and simulated with the help of the LabelMover parametric tool.
Results
Maximal thrust force value is 4.8 kN.
1. When the stator speed is equal to the speed of the magnetic field wave there is no eddy current induced in the rail. This can be modeled by specifying zero rail conductivity.
2. At zero stator speed the material properties are specified as is.
3. In general case at non-zero speed the stator and rail can be modeled as motionless, for the rail the attenuated value of electrical resistivity ρ / slip is specified, where slip = 1 - ( speed / vsync ).
Magnetic flux density and current density distribution in the rail of the hyperloop linear induction motor at zero speed and frequency of 60 Hz. The thrust force acting on the rail is fx = -60 N (on the stator acts the force with the same magnitude, directed to the right).
