Estimation of Airgap Length in Magnetically Levitated Systems

In this paper, a new technique for estimation of airgap length in magnetically levitated systems (MagLev) is introduced. The proposed method makes use of the embedded airgap information in the inductance of an active phase in a hybrid MagLev system. Terminal measurements are used along with the phase voltage equation to estimate airgap length by the virtue of an existing one-to-one correspondence between inductance and airgap length. Sensitivity analysis will be carried out to illustrate the impact of changes in MagLev's geometry and current sensor resolution on the accuracy of the proposed method. Based on experimental results, it will be shown that the proposed sensorless method performs well both at standstill and moving conditions.