Hi Wayne, Good to hear that a simple diode indeed takes care of your problem!
Thermal paste only helps to fill the voids that otherwise air would leave, improving the passage of heat from one surface to the next. This means that the next surface must be conducting heat - putting paste between the diode and a plastic insulator is not going to give any heatsinking. What many electronics designs do is either bolt the diode directly on a metal block/heatsink and insulate that assembly from chassis (and touching) or put an insulating layer between diode and heatsink, then use thermal pads, or the oldfashioned mica and thermal grease to allow the heat from the diode to flow via the heat conducting, electrically insulating, layer into the heatsink. The direct contact method usually has better thermal behavior, but you need to insulate a larger assembly. Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: [email protected] Private: http://www.cvandewater.com Skype: cor_van_de_water XoIP: +31877841130 Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 -----Original Message----- From: [email protected] on behalf of Wayne Krauth Sent: Sat 8/3/2013 6:18 AM To: [email protected] Subject: Re: [EVDL] Blown output fuse (was: First time PFC charger setupquestion) Hi Cor, I had a 400V 30A diode on hand and have added it in series with the charger output. It solved the problem of blowing the fuse, and the car has now been through 2 discharge / charge cycles with no problems. I do need to put in a bigger diode, but this one confirms a fix. To use a larger diode like the one you suggested, I would mount it nearby the charger on an existing aluminum panel, using a piece of mylar to electrically insulate it from the aluminum and nylon screws & nuts to secure it, also use some thermal paste to conduct the heat away. Or would you recommend further isolation from the chassis? Thanks, Wayne Krauth Cor van de Water wrote > Wayne, > The reason is simple and has been discussed a couple times on this list. > The fuse blows, because the controller is causing a large ripple current > and the output caps of your charger are trying to smooth that ripple, > leading to large ripple current through the output fuse. > In theory, removing the output caps would solve this problem, > but it might be simpler and in practice more likely to give > good results to add a diode to the output of the charger, so it > can only send current into the pack and not allow the > controller to use the output caps for smoothing the controller ripple. > > (It is even possible that the controller causes the charger caps to blow > and so destroy the charger without you even being plugged in, simply > from the ripple that the controller produces and the charger caps > are being subjected to - the resulting ripple current is probably well > beyond their rating, so you could be damaging those caps while driving. > > I have two Schottky diodes that are heatsink-mountable (watch out - the > mounting is also the electrical connection, so make sure to mount them > on an isolated base) > These are 200A, 400V so should be plenty for your charger output. > Reason I can't use them is that these are half of a dual diode package > and I have blown one diode, the other is still fine, my applicatoin > needs both to sustain 400A, so just give me your address and I will > ship a diode to you. The blown half is a dead short, so your > multimeter will tell you which half is good and which is bad. > > Here is a new one on Ebay (403CNQ400): > http://www.ebay.com/itm/230918736569 > > Cor van de Water > Chief Scientist > Proxim Wireless Corporation http://www.proxim.com > Email: > CWater@ > Private: http://www.cvandewater.info > Skype: cor_van_de_water Tel: +1 408 383 7626 > > > -----Original Message----- > From: > [email protected] > [mailto: > [email protected] > ] On > Behalf Of Wayne Krauth > Sent: Tuesday, July 30, 2013 12:51 PM > To: > [email protected] > Subject: [EVDL] Blown output fuse (was: First time PFC charger > setupquestion) > > The output fuse on my PFC30 appears to be occasionally blowing while I > am > driving. The car completes its charge cycle ok, and can top up the > pack > if the car has not been used after charging, so I know it's ok before > driving. > > If it is driven with motor & battery currents limited to 400A or 500A, > there > is usually no problem. If the current limits are increased to 700A or > more, and that current is used during the drive, then the charger output > fuse *might* be blown when I next try to charge. > > One time I heard the fuse pop when starting to turn up the charger > current, > so the fuse was not blown until charge time. > > I have also checked the fuse after a drive but before plugging in the > charger, and have found it to be blown. > > At first I thought that maybe there is a HV isolation fault between the > traction pack and the car frame. A voltmeter from chassis to voltage > points > in the pack shows HV DC, but the voltage quickly drops to zero (well > under a > minute). I presume that this is a capacitive charge that discharges > through the voltmeter. Is this behavior expected or does it indicate > a > problem? > > The traction pack has six 40V batteries, and is connected directly to > the > charger, motor controller, and DC/DC. Should I use a diode between the > traction pack and the charger? Or a inrush current limiter? > > Looking for suggestions on how to determine the source of the blown fuse > problem. > > Thanks, > > Wayne Krauth > evalbum.com/3567 > > > > -- > View this message in context: > http://electric-vehicle-discussion-list.413529.n4.nabble.com/First-time- > PFC-charger-setup-question-tp4656968p4664498.html > Sent from the Electric Vehicle Discussion List mailing list archive at > Nabble.com. > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA > (http://groups.yahoo.com/group/NEDRA) > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA > (http://groups.yahoo.com/group/NEDRA) -- View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/First-time-PFC-charger-setup-question-tp4656968p4664556.html Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com. _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
