Re: regen on a heavy EV (range ~ lbs)

["Peter VanDerWal" <peter_v@primenet.com>]

>> Lee - give us a circuit diagram of your PWM / contactor 192V controller
>> where the PWM controller only sees 96V or tell me why I'm wrong.
>
>         _______________________
>        |                 M+   _|_
>       _|_ +                 /     \
>      _____  96v            |       | motor
>        |  -       diode     \ ___ /
>        |___________|/|_________|
>        |      B+   |\|   M-    |
>       _|_ +                  |_|
>      _____  96v           --||_  transistor
>        |  -                  | |
>        |_________________B-____|
>


Ok I'm trying to figure out what happens when we run the controller at 95%
duty cycle (mostly on).

The motor sees almost 192V when the FETs are on and when they switch off the
inductance of the motor wants to continue to see 192V correct?

The only path for that voltage is thru the diode and top battery,  I can't
figure out if the diode ends up seeing 192V or not.  If it does then it goes
pop right?

If the diode doesn't go pop, then the motor demands 192V from 96V worth of
batteries correct? The current's gotta flow.  It seems to me that the motor
will, in effect, act like another 96V power source connected up (in reverse
polarity) to the battery.

When you add that to the pack imbalance problems at low duty cycle (and the
fact that at ANY duty cycle the motor demands more voltage from the top
batteries than they produce)...it seems to me like you're going to end up
murdering your pack pretty quick.

Then again, I might just be looking at this wrong.