Levitation-guidance stabilization of superconducting maglev through LSM currents
This paper presents a modeling and simulation of a superconducting maglev vehicle with a levitation and guidance assist method we have proposed. The assist system stabilizes and assists the vehicle operation so that the vehicle does not need to depend on the mechanical wheels as much as possible at low speeds. By controlling the LSM armature currents, the auxiliary levitation and guidance forces are provided. The results show that the assist system produces appropriate levitation and guidance forces, establishing the reference levitation height and a sufficient guidance at low speeds even against the disturbance force of lateral wind.
Robust uncertainty compensation in MagLev by using extended state observer
The magnetic levitation (MagLev) system control is one of the most complex problems due to open-loop instability, nonlinear dynamics and uncertain parameters. The 3rd order differential model of MagLev is linearized by using input-output linearization. The control law is designed using feedback linearization (FL) augmented by uncertainty estimates. The states and uncertainties are estimated using extended state observer (ESO). This paper addresses the issue of robustification of FL control law against the uncertainty and nonlinear perturbation by using ESO. The stability of overall system is assured and is dependent on the pole placement. The results demonstrate the efficacy of extended state observer for estimating wide range of uncertainty in a highly nonlinear plant, when maximum information of MagLev system is unknown.
Analysis of a Superconducting Linear Synchronous Motor Propulsion in terms of dq variables
The paper deals with the analysis of a superconducting linear synchronous motor propulsion of a maglev vehicle of Japan Railway. A dq-axis analysis is made with taking account of the space harmonic fields that the superconducting magnets (SCMs) produce. The relative angle, which is an electrical angle between the three-phase axis and the dq axis, used as a variable of a dq transformation matrix is readily determined by observing the fundamental component of the flux linkages of the LSM windings by formulating in Fourier series expression. The propulsion force is formulated in terms of both three-phase and dq0 variables. The calculated results are shown for the two types of LSM winding configuration, i. e., the configuration of 120-degree coil pitch with single layer and the configuration of 240-degree coil pitch with double layers. The propulsion force coefficient, which is defined as a ratio of the propulsion force to the armature current in q-axis, can fluctuate with time according to the configuration of the LSM windings. And the coefficient is shown to have fluctuations even for the 240-degree coil pitch configuration due to the difference between the positions of the two winding layers. It is suggested that selecting the number of poles of SCMs as an even number may be the effective measure to flatten the pulsated propulsion force coefficient.