Troubleshooting - Wolfspeed SPEEDVAL KIT HALF-BRIDGE MOD-MB-HB-0900V-40A User Manual

10. TROUBLESHOOTING

1. No gate pulses.
Check the PWM selection jumper position (J1 &J2). If supplying PWM pulses with an external
function generator, the jumpers need to be in the "BNC" position. If using one of the optional
control cards, both jumpers should be in the "CTRLR" position. Refer to section 5.7 for a picture of
the jumpers in the correct positions.
2. Distorted current waveforms when performing double pulse tests (switching energy).
The power daughter cards are shipped ready for high-power testing. Before performing double
pulse tests, the board must be modified. There are two modifications (high-resistance shunt and
current transformer) to choose from to take accurate double pulse measurements. Refer to section
6 for details. Figure 52 shows the waveforms with the power daughter card in its stock
configuration, which has been optimized for high-power testing. The fast switching speeds of SiC
devices can create noise and ringing in the measurement circuit. With low-resistance shunts, the
signal-to-noise ratio is relatively low, so parasitics in the measurement circuit significantly change
the measured waveform causing excessive peaks and ringing.
Figure 53 shows the waveforms with the power daughter cards modified for double pulse
measurements. The current waveform is much cleaner, and the ringing is less pronounced,
allowing for more accurate double pulse measurements.
F
IGURE
PRD-06829 REV. 1, December 2022
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OWER AUGHTER ARD
SpeedVal Kit™ Half-Bridge User Guide
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AVEFORMS PTIMIZED FOR
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OWER ESTING
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