Tunable Isolated Gate Driver Supply for Automated Switching Loss Measurement of Power Field Effect Transistors

The switching losses of power Field Effect Transistors (FETs) such as Silicon IGBTs, MOSFETs, SiC MOSFETs, GaN HEMTs and Diamond FETs are highly dependent on the gate driver currents. These currents are typically set by gate resistors. However, it is then difficult to change the switching speeds, especially during the characterization of switching losses, and integrate such changes in automated design of experiments. In this work, we report a simple circuit to add margining (trimming) capability to any isolated gate driver DC/DC supply, which can be changed online and controlled by a supervisor through an isolated bidirectional series communication. This technique allows 1024 different positive gate voltage levels, which can then be used for characterization of switching losses. The driving voltages can be adjusted online and the effect on switching speeds is demonstrated experimentally by double pulse tests.