Tom is correct, the Sep-ex system is very dependant on the end application (A series system is too, but much more acceptable to errors). A well designed Sep-ex system tries to match the variable load it will encounter for the application. I think that is the reason Sep-ex is not used for the majority of general purpose applications. It is definately better for a defined application such as a golf cart that has a predefined mass and operating range. Try putting the sep-ex system in an on road EV that can vary from 2500-5000 lbs, has a variable torque ratio based on the transmision (if it has one) and things can look bad. A sepex system designed for an application is cost competitive and superior to a series system. How do you make this work for an EV market? It's very difficult. You have to depend on the operator to program in the appropriate parameters for their application. This is assuming the motor is the same. If you have several different sepex motors it gets even more complicated. So the bottom line is series is a Wal Mart solution. If you have an educated consumer that knows motor/torque/gearing relationships the sepex is better. Unfortunately this leads to increased customer support that cuts into the profit considerably for the general market. The NEV and golf cart market are huge, they will benefit considerably from this technology, but I don't see it happening for the hobbiest. Rod
Thomas Shay wrote: > ----- Original Message ----- > From: "Rod Hower" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Tuesday, October 01, 2002 9:13 AM > Subject: RE: SepEx Motors and Controllers for EVs > > > >>I've read about the advantages of sep-ex and don't really understand why >>higher voltage systems aren't available. Would it be possible to have >>Warfield or NetGain rewind a series motor for high voltage sep-ex? >>Wouldn't building a high voltage sep-ex controller from scratch be much >>easier than a similar voltage series controller? > > > Things are a bit more complicated than that. A sepex motor needs > interpoles so just rewinding a series motor wouldn't do the > job except of course for a motor like a Kostov which has interpoles > already. > > A good sepex controller is much more complicated than a series > motor controller, not simpler. It needs a section similar to > the series motor controller to control the sepex motor's armature > current. Another section is needed for the sepex motor's field > current. The field conrol section should provide high field current > for good starting torque and for regeneration, weakening the field > current for high speeds, and reversal of the field current to reverse > the motor. It also needs to be programmable to allow setting it > up for each application and user's preferences. A good example > of a sepex controller is the Curtis model 1274 described at: > http://www.curtisinst.com/Uploads/DataSheets/ACFEFE5.pdf > A higher voltage, higher current version of the 1274 and a > compatible motor could be a great sepex setup for EVs. > > A feature of any good sepex controller that distiguishes it from > a simple series motor controller is programmability. My Curtis > 1231C has three adjustment pots which I've never touched. > A sepex controller needs adjustments > to set up field control, regeneration, speed control, etc. The > Curtis 1274 and other sepex controllers connect to a seperate > handheld programmer module or to a computer to set up the > controller to suit the application and the user's preferences. > > Tom Shay > >
