Acquisition of a permanent magnet linear synchronous motor´s electrical parameters and dead beat current control considering saturation

A dead beat current control for a short stator permanent magnet linear synchronous motor (PMLSM) requires accurate knowledge of its electrical parameters. This paper presents a method to acquire simultaneously saturation and position dependent self- and mutual differential inductances as characteristic diagrams at standstill. The combination of two current transients provides at the crossing of the current trajectories four independent electric equations to calculate four independent differential inductances. The method does not require a special measurement setup, except that the mover has to be fixed and is robust against voltage errors induced by the inverter´s nonlinear characteristics. By combining the characteristic diagrams for evenly distributed positions within two pole pitches, the mover fixed inductances are extracted. Remaining inductances contain stator fixed and higher order saliencies. While a dead beat controller relies on a state invariant model, the given controller is adapted to the operating point and features an additional integral branch. This makes the controller robust against parameter variation during the sampling intervals, at minimum deviation of the ideal dead beat characteristic. The achieved inductance characteristics and the control performance of the controller, adapted to the measured inductances, are presented.