Noise Analysis of Current Sensor for Medium Voltage Power Converter Enabled by Silicon-Carbide MOSFETs

Abstract

New semiconductor devices based on wide bandgap materials are emerging in medium voltage power electronic converter applications, presenting new opportunities to the industry relying on semiconductor devices. SiC MOSFETs with blocking voltages of 10 kV (and above) is a promising technology, however, their fast switching transitions result in increased output voltage slew rate (dv/dt), which poses challenges to the applicability of the SiC MOSFET technology. This paper examines the impact of the increased dv/dt on the applicability of an off-the-shelf closed loop hall-effect current sensor when utilized in a medium voltage SiC MOSFET based power electronics converter. Analysis of the capacitive couplings in the current sensor is presented along with an experimental determination of the parasitic capacitance between its primary conductor and secondary winding. Experimental measurements have identified two distinct noise components in the current sensor measurement path due to: 1) capacitive coupling between the primary conductor and secondary winding, and 2) an inferred capacitive coupling into the active circuitry of the current sensor.