Study On Suspension Control Based On Magnetic Flux Feedback

Suspension control is the key technology of maglev vehicle research. Adopting current feedback suspension control algorithm, the stable region of control parameters are narrow, overshoot is great and unable to make the closed-loop system bandwidth narrow. But flux feedback control can solve these problems well. The dissertation concentrate on flux feedback in maglev suspension application, covering the electromagnetic field analysis, the numerical model of single magnet establishment, controller designing, parameter optimization, simulation, magnetic field measurement and experiment.Firstly, the dissertation has analyzed the relationship between electromagnetic force and air gap, and obtained fitting formula of force and flux density using computed results. In single magnet modeling, from the air gap magnetic-flux density, single magnet linear model which take the flux density as the state variable is obtained, and used the fitting formula which the magnetic field analysis had obtained to revise the model parameters.Next, consulting current feedback control, the flux feedback control algorithm is designed. This algorithm has two loops, the inner loop is flux feedback loop, the outer one is air gap feedback loop; the outer loop uses PID controller whose output is expected flux density, the inner uses the proportional or PI controller whose output is the magnet control voltage. In order to compare performance of current feedback control with flux feedback control, the PID parameters optimization algorithm is designed based on genetic algorithm. Under the same closed-loop system bandwidth request, the PID parameters of two kinds of control algorithms are optimized. Then based on non-linear simulation model of single magnet, the dynamic performances of two kinds of control algorithms under optimized parameters have been compared. In order to realize flux feedback control, the request of air gap flux density measurement is studied. Using the 3D magnetic field analysis software, how and where to install the magnetic field sensors have been discussed. Then two magnetic fields measuring methods have been chosen: the Hall effects measurement and the electromagnetic induction method. In order to realize magnetic field measurement, the amplifier and filter have been designed.Finally, single magnet and bogie suspension experiments have been carried out. Also two kinds of control algorithms effect has been compared. The experiments confirmed that flux feedback control has a wide parameter stable region and satisfying dynamic performance.