Transcript HV_SYSTEM_DESIGN_AND_ISSUES

HV SYSTEM DESIGN AND ISSUES
Lubomir Dimitrov
YEAR OF
DELIVERRING
NUMBER OF
CRATES
NUMBER OF
IRF1310
BURNINGS
2002 (2003)
2 PPP
2004
7
1
2005
9 + 2 (HF)
2
2006
4 + 1 (HF)
2007
2
REMARK
IRF3415 USED
2008
2
2009
3
2010
6
SAME PS
This type of electronics was out of my ROI until 2004 when I took the
responsibility to service them.
Next year two burnings in the same PS happened and I realized that there was a
reliability issue.
I studied that module carefully and find that everything is corresponding at what I read
in the books.
Then followed two years with no one problem and when I decided that it was just bad
coincidence the reality was back.
As a result we have
2 PS 3 times burned
3 PS 2 times burned
2 PS once burned
What I tried till now?
In 2008 (Sep) I modified the RC group in primary winding (R27, C18) in order to
reduce drain overshots.
Four PS was modified, 3 of them failed again.
In couple of PS I cut the copper supplying the converter and solder thin wire.
Two of them failed and the thin wires burned
One saved the transistors, the another didn’t.
More facts
No one PPP PS burned till now /at least I’ve never repaired one of them/. That’s why I
mounted yesterday IRF3415 transistors on the 3 times burned modules.
No one HF PS burned till now. They are as almost as twice loaded than the others. So
the load is not the reason of burning /maybe/.
Have I any suggestion how to solve the problem – Not for now.
How then to proceed.
The resettable fuses (SHURTER PFMF.150.2) on all PS /already mounted on 5/. They
will separate the 40 V DC-DC in case of failure and the crate will remain
communicable. And maybe the FET transistors will be saved.
Two PS – one never failed and second failed at least twice to be carefully investigated
and compared. To hope any difference will be found.
Last version of firmware
The voltage threshold around set value is implemented. If the output voltage goes below
or above the threshold the bad voltage bit will be set. The threshold value can be
changed by implemented new instruction in the control messages protocol. The default
value is 8 bits.