Modeling and optimal design of relative position detection sensor for high speed maglev train

The long stator track for high speed maglev train has a special tooth-slot structure. The relative position detection sensor obtains precise relative position information for the operation control system by detecting the changing coil inductance reflecting the long stator tooth-slot structure. The aluminum windings are inlaid in the stator slots, and the magnetic field due to the sensor coils induces eddy current in them, which would change the magnetic field distribution and have a significant influence on the sensor. In this paper, the multipole theory (MT) is adopted to build the analytical electromagnetic model of the sensor. Based on the electromagnetic model, the influence of the eddy current induced in the windings on the coil inductance is studied. The DC offset formula of differential voltage owing to the slight inductance difference of the coils is derived. The influence of the eddy current on the DC offset is analyzed, based on which, a method of no-load voltage compensation and an optimal sensor excitation frequency is proposed to improve the accuracy of the sensor.

► The electromagnetic model considering the eddy current is built up analytically.
► The eddy current induced in the windings has influence on the coil inductance.
► The DC offset formula of differential signal due to the coils difference is derived.
► With an optimal frequency, the no-load voltage compensation can minimize the DC offset.