In-situ measurement for drain current of SiC-MOSFET using optical-probe current sensor with half-open loop magnetic yoke

Abstract

In recent years, the switching frequency of power converters has increased significantly with the widespread adoption of wide-bandgap power semiconductors. Conventional sensors, such as current transformers and Rogowski coils, are limited by their size and frequency bandwidth, making accurate current measurement difficult. The optical probe current sensor developed by the authors is effective for high-frequency current measurements due to its compact sensor head and wide bandwidth (DC to 150 MHz). Although this sensor can measure magnetic fields in narrow spaces, measuring wideband current in wide conductors like busbars or copper traces remains challenging due to skin and proximity effects. In this study, we improved the frequency response of the sensor by integrating it with a half-open loop magnetic yoke that homogenizes the magnetic field around the conductor. Finally, we report the in-situ measurement results of the drain current flowing through a SiC-MOSFET during a double-pulse test using the proposed sensor.