The Importance of Double Pulse Testing for Designing Today’s Power Converters
The field of power electronics is rapidly transitioning from the use of silicon semiconductor materials to wide bandgap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN). One of the most common applications of GaN and SiC semiconductors is to enable smaller, faster and more efficient designs of power converters.
Power converters operate at multiple stages throughout the power delivery chain, and, because no conversion is 100% efficient, some power loss occurs at each step. A typical converter would have an efficiency of about 85% to 95%, meaning that 5% to 15% of the input power is dissipated within the converter, mostly as waste heat.
Wide Bandgap Device Test Solution
A significant portion of this loss is dissipated in switching devices such as MOSFETs. And the preferred test method to measure the switching parameters of MOSFETs is the “Double Pulse Test” method.
Tektronix’ Wide Bandgap Double Pulse Test Solution was recently shown at Applied Power Electronics Conference (APEC). The core of that solution is the Wide Bandgap Double Pulse Test application (Opt. WBG-DPT) which runs on the 5 Series B MSO oscilloscope. (It is also available on the 4 Series and 6 Series MSOs.) Here’s a brief look at the simplicity that solution brings.
Test Automation for MOSFET Device Characteristics
The demonstration at APEC focused on measuring the switching characteristics on the high-side MOSFET and the reverse recovery on the low side. The double pulse testing application automates switching, timing, and diode reverse recovery measurements. A Tektronix High Voltage Differential THDP probe on the low side measures the voltage while an IsoVu™ TIVP probe measures the current. For further detail on how, see an earlier blog.
Other elements of the demonstration system were a Tektronix AFG31000 Arbitrary Waveform Generator to generate the pulse to turn on the MOSFETs, a Keithley 2470 Source Measure Unit to generate the high voltage for the VDS. And for powering the gate drivers a Keithley 2280S Precision Power Supply was used.
For an in-depth look, we’ve created a couple of applications notes for both double pulse testing with an oscilloscope and a full-featured stand-alone arbitrary function generator as well as double pulse testing where the AFG that is part of the oscilloscope is used. You’ll find these application notes, videos and product information on our Wide Bandgap Double Pulse Reference Solution page.