Enhanced disturbance rejection due to highly dynamic parameter-adaptive control of saturated PM linear motor

Linear motors´ comparably low inertia leads to large acceleration and speed. Consequently they are favourably employed in certain machine tools applications. Due to low inertia highly dynamic control is required to guarantee good disturbance rejection. Nevertheless cascaded control is still the predominant control structure. The decisive dynamic of the subordinate thrust control has to be designed as fast as possible. On the other hand highly magnetic utilisation leads to nonlinear system characteristics. An accurate flux model that depends, due to saturation and unbalance, on the exciting currents and the position allows the design of highly dynamic parameter adaptive thrust control in contrast to standard PI control. The required flux model can be acquired by numerical methods or by measurement. The achievable dynamic stiffness towards disturbing load forces is to be compared for the highly dynamic deadbeat and standard PI thrust control as subordinate control loop in the cascaded position control.