Design and Analysis of a PCB Integrated Differential Current Slope Sensor with Ferrite Support for High dV/dt Operations

Self-sensing control of electrical machines often relies on a real-time inductance profile evaluation of the magnetic circuit. In the case of active magnetic bearings, the rotor position can be detected by inductance deviations of an eccentrically levitating rotor by a measurement of the coil’s current slopes. In this study, a novel PCB integrated differential current slope sensor with ferrite support is aspired. A differential evaluation of opposing coils inside a single sensor enables a high sensitivity by a cancellation of inductance offsets. The main requirements of the sensor include high bandwidth, low distortions and low output noise. Special attention is also paid to the suppression of capacitive couplings due to fast voltage change rates of power inverters. Finally, measurements will show the performance of the designed sensor.