Graham Gunderson's Energy conference presentation Most impressive and mysterious

[verpies]

But with the transformer action dropping the voltage to about 12-20 VAC, what is the value then? ?  The transformer is not 1/1!  Transfer is in the mw range.

I was more concerned about the Gate Leakage from the MOSFETs that are AFTER the transformer.

AFAIK these MOSFETs form the synchronous rectifier and the secondary/output 1μs interrupter circuit.

[TinselKoala]

I couldn't find anything under the part number on Spokane1's diagram, C2M002510D. Neither the Cree website nor DigiKey lists anything with that part number that I could find. However, the nearest thing I could find is the C2M0025120D mosfet, 1200V 90A 34mOhm Rdson. Only 69 dollars and 80 cents _each_, from DigiKey. Data sheet attached:

[verpies]

2.7nF gate capacitance ...OUCH!

...but only 15pf reverse transfer capacitance (w/o transconductance multiplier).

[Spokane1]

I was more concerned about the Gate Leakage from the MOSFETs that are AFTER the transformer.

AFAIK these MOSFETs form the synchronous rectifier and the secondary/output 1μs interrupter circuit.

Dear verpies,

What kind of leakage takes place if the MOSFETS are constantly on? In order to pass energy through a parasitic Miller capacitance don't we have to have AC present? In this circuit the MOSFETS are on for 20 uS  (50 k cps) and then are briefly shut off for 5 to 1000 nS (I don't know the exact timing).  Wouldn't this very narrow duty factor have a tendency to reduce the kinds of losses you are addressing?

Spokane1

[Spokane1]

I couldn't find anything under the part number on Spokane1's diagram, C2M002510D. Neither the Cree website nor DigiKey lists anything with that part number that I could find. However, the nearest thing I could find is the C2M0025120D mosfet, 1200V 90A 34mOhm Rdson. Only 69 dollars and 80 cents _each_, from DigiKey. Data sheet attached:

Dear TK,

Thanks for pointing  this out. I shall make corrections on the next revision.

Let me know if you can see anything else that needs improvement.

Spokane1