Bias Linearization and Decoupling for Active Magnetic Bearing: A Generalized Theory

The mathematical basis for bias linearization of active magnetic bearings is developed. The approach generalizes prior ad-hoc methods of linearizing the relationship between actuator force and electromagnet current. Growing from the properties of a fundamental representation for the current-force relationships, conditions are determined under which linearization may be possible. A numerical optimization problem is posed whose solution provides a linearization scheme which maximizes the available force capacity of the bearing. A corollary result is a method for obtaining coil-fault tolerance without adding coils to existing actuators. Several paper examples are presented to illustrate linearization of asymmetric bearings and those with failed coils.