I am developing a 3000 Watt dc/dc converter, 48 Volt nominal input, 200 Volt output. A planar transfromer has been implemented with a four-turn primary and a 22-turn secondary (although the secondary turns need to go up on re-spin). There is no shim inductor (although I can add one). the leakage inductance is about 500nH, the resonant frequency is about 925KHz.
I am noting excessive ringing on the primary waveforms at the resonant frequency, as shown in the scope plot below (hopefully it uploaded correctly).
The plot shows operation with a 50 Volt input and an 870 Watt load. Channel 1 is the A Upper gate drive signal from the 2895; Ch2 is the primary current as measured by a current transformer. Ch3 is also the primary current, as measured by a TCP2020 current probe. Ch4 is the primary voltage (bridge output).
Note the ringing at what I believe is the resonant frequency. Channel 4 shows a peak of 73 Volts, and Channel 3 shows a 34.4 Amp peak-to-peak ripple.
From what I understand there should be some resonant component to the voltage and current waveforms, but this seems excessive. Are these waveforms typical for this converter toplogy? If not any idea what I can do to resolve this issue? I believe the ringing and current magnitude are causing excessive power dissipation in my primary and secondary windings, as they are getting quite hot.
Thanks in advance for any assistance.
