Assessment of State-of-the-Art Current Sensors for Fast Switching

Wide-bandgap power devices enable switching times in the range of several nanoseconds. This poses high requirements on current sensors: Ideally, they should offer high bandwidth, negligible insertion inductance, and galvanic isolation, but common sensors exhibit deficiencies in at least one of these aspects. In this study, state-of-the-art inductive and resistive current sensors are experimentally compared to standard sensors and evaluated regarding their capability of resolving nanosecond switching transients. Double pulse tests demonstrate their capabilities but also reveal vital differences and limits regarding captured waveforms, current slopes, and switching energies. LTspice simulations are used to validate the results.