Greetings all - just found this site while searching for "boost pfc" and noticed that Winfield Hill has posted here before so I figure the site can't be all that bad ;)
I'm just throwing this out as a sort of curiosity-type question. I have designed quite a few switchmode power supplies over the years but nothing even approaching this power level (600W is the previous maximum). A friend of a friend has one of 492 electric chevy S-10 pickups, and the onboard charger has lost its magic smoke. Frankly, the design of this charger/motor drive pretty much blows, ihmo, so I'm toying around with the idea of whipping up something new. "Toying" because there is little financial motivation for doing this. However, it is an interesting project and that is motivation enough, sometimes.
There are two banks of batteries in the pack, each containing 26 12V/42Ah batteries. The manufacturer, Genesis, recommends charging them at the 0.4C rate up to a maximum of 2.4V/cell (with -20mV/C of compensation). As this comes out to a rather onerous 6.3kW, I'll either have to go with a less- ambitious charge rate or force the guy to unplug the range every time he needs to plug in (or, of course, have a dedicated 40A. circuit installed). As of now he does have a 240V/20A circuit for this purpose which, if we adhere to the NEC, gives us *just* enough continuous amperage to charge each bank at
0.25C (10.5A) . This means both banks can be sequentially charged in about 8 hours, which is tolerable.A linear and/or design using 60Hz magnetics is totally out of the question - you won't be able to move the thing around without a forklift. The next simplest thing I can imagine, then, is to use the output of a boost PFC more or less directly. This has some serious safety issues, but it ain't like I'm going to be submitting it for UL approval any time soon. So, these are the various factors/ideas I am contemplating:
quasi-resonant (soft) switching; ZVS or ZCS? IGBTs or advanced MOSFETs Boost PFC + full-bridge or some combo to provide isolation
Current mode control is a natural, here. Voltage regulation needs to be accurate but there's no need for a lot of loop bandwidth (ie - fast transient response not required). Ideas welcome!
-Jeff