Hi All,
Is there a good analog EE in the house? I finished converting a
Porsche 914 to an electric vehicle a few weeks ago and the first
thing to die was the DC-DC converter that transfers charge between
the main 144V pack to the 12V accessory battery. I took the unit
apart and found a push-pull switching power supply with shorted out
FETs. After replacing the FETs, the unit shorted again under a 20
amp current load. I replaced the FETs again and captured several
waveforms of the internal nodes.
The schematic and datasheets for the CCPower unit are here:
http://914ev.blogspot.com/2007/09/initial-ccpower-schematic.html
The oscilloscope waveforms are here:
http://914ev.blogspot.com/2007/09/debugging-dc-dc-waveforms.html
The main 144V battery pack can range anywhere from 120V to 170V
based on charging and regenerative braking. Again, the unit dies and
shorts the FETs when pulling a significant current out the 12V side of
about 20amps.
I'm still commuting in the vehicle, but I need to charge the 12V accessory
battery every night along with the main pack (argh!). Any suggestions for
how to fix this would be most welcome. Thanks for your time!
Cheers,
Tim
http://914ev.blogspot.com/
____________________________________________________________________________________
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_______________________________________________
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Is there a good analog EE in the house? I finished converting a
Porsche 914 to an electric vehicle a few weeks ago and the first
thing to die was the DC-DC converter that transfers charge between
the main 144V pack to the 12V accessory battery. I took the unit
apart and found a push-pull switching power supply with shorted out
FETs. After replacing the FETs, the unit shorted again under a 20
amp current load. I replaced the FETs again and captured several
waveforms of the internal nodes.
The schematic and datasheets for the CCPower unit are here:
http://914ev.blogspot.com/2007/09/initial-ccpower-schematic.html
The oscilloscope waveforms are here:
http://914ev.blogspot.com/2007/09/debugging-dc-dc-waveforms.html
The main 144V battery pack can range anywhere from 120V to 170V
based on charging and regenerative braking. Again, the unit dies and
shorts the FETs when pulling a significant current out the 12V side of
about 20amps.
I'm still commuting in the vehicle, but I need to charge the 12V accessory
battery every night along with the main pack (argh!). Any suggestions for
how to fix this would be most welcome. Thanks for your time!
Cheers,
Tim
http://914ev.blogspot.com/
____________________________________________________________________________________
Sick sense of humor? Visit Yahoo! TV's
Comedy with an Edge to see what's on, when.
http://tv.yahoo.com/collections/222
_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev