Oszillations in phase shifted bridge

Designing with GaN FETs and ICs
1

Dear Team,
I use EPC 23101 and EPC2302 for a phase shifted full bridge.
It works great, but when leg A switches on, I get some oszillation with about 120Mhz, when leg B follows (now energy is transferred), there were virtually no oszillation. Same when leg A switches off.
Any idea to damp this oszillations a little bit?
Tried C from SW to ground, no effect on frequency or amplitude.

Thanks for helping.

With best regards

Gerhard

2

Hello Gerhard,
you could try and slow down the device a little bit. In our EPC9170 KIT – 2 kW 48 V/14 V Bi-directional Power Module Evaluation Board (epc-co.com) which uses the same parts, the switching speed can be tuned with the resistors circled in red below:

image
image1114×761 102 KB