Magnetic displacement and velocity sensor for robust control of active magnetic bearings

This paper introduces a novel magnetic distance sensor, based on compensating current transformers, which combines a direct measuring of displacement and rotor movement velocity in one unit. The velocity signal is used as an auxiliary control variable and involves significant improvements. An external differentiation of the displacement signal is not necessary, thus it reduces the noise level in the control loop. Due to the simple structure and functionality the sensor is robust and economically producible. It can be used in magnetic bearings as well for oscillation monitoring in electrical drives. To verify the theoretical and simulated calculations a test rig was installed and the experimental results are presented.