Fault tolerant control of magnetic bearings with force invariance

A magnetic bearing even with multiple coil failure can produce the same decoupled magnetic forces as those before failure if the lemaining coil currents are properly redistributed This faulttolerant, force invariance control can be achieved with simply leplacing the distribution matrix with the appiopnate one shortly after coils fail, without modifying feedback control law The distribution gain matrix that satisfies the necessary constraint conditions of decoupling linearized magnetic foices is determined with the Lagrange Multiplier optimization method