Double Pulse Testing

The Standard Method for Measuring Switching Parameters

Minimizing switching losses continues to be a major challenge for power device engineers working on SiC and GaN devices. The standard test method for measuring switching parameters and evaluating the dynamic behavior of Si, SiC, and GaN MOSFETs and IGBTs is the double pulse Test (DPT). Double pulse testing can be used to measure energy loss during device turn-on and turn-off, as well as reverse recovery parameters.

How to Generate Gate Drive Signals for a Double Pulse Test

The easiest way to generate the gate drive signals to perform a double pulse test is to use an arbitrary waveform generator (AFG). An AFG may be used to generate the gate drive signal to perform a double pulse test. The Tektronix AFG31000 has a built-in double pulse test application to create the pulses with varying pulse widths.

Equipment set up for conducting a double pulse test.

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Double Pulse Test with the AFG31000

Measure Reverse Recovery

Reverse recovery time of the diode is a measure of the switching speed in the diode and thus affects the switching losses in the converter design. Reverse recovery current occurs during the turn-on of the second pulse. As shown in the diagram, the diode is conducting in a forward condition during phase 2. As the low side MOSFET turns on again, the diode should immediately switch to a reverse blocking condition; however, the diode will conduct in a reverse condition for a short period of time, which is known as the reverse recovery current. This reverse recovery current is translated into energy losses, which directly impact the efficiency of the power converter.

Double pulse test circuit.