I should think that a simple resistor network would allow a variable minimum voltage offset above zero. This would provide an adjustable minimum voltage into the controller when the throttle was fully released.
I had a quick look at the Lyen controller parameters and I didn't see anything offhand that you could use to set a minimum rpm. The GM software may have something (i thought I had it on file). It's worth taking a look there first.
Doesn't having an active motor in the loop violate the intent of the race though?
Jeff
Thanks for the idea, that sounds like it could work. For our situation, there is only energy storage allowed in capacitors, and they would have to start at empty. This way, any energy we are putting in to reduce the freewheeling resistance would have to first be generated by our rider. So an active motor would only be using the energy from the rider, and with any losses, the bike without the motor has the advantage.
However, the race we are designing our vehicle for, (
ASME HPV Challenge) is all about making vehicles that are practical, meaning they have to be able to maneuver sharp turns, come to complete full stops at stop signs, carry "groceries", etc. (Instead of just going really fast in a straight line)
If a big enough portion of the energy lost when braking for stop signs and turns can be re-used, then the constant additional power to run the motor at a "speed matching" level (closer to a freewheel) will likely be worth the implementation.
That leads to another question: How exactly does the regenerative function work? Does it regenerate regardless of whether the electric brake is engaged?
If pedalling against the resistance is indeed charging the capacitors by "regenerative braking", what kinda of efficiency can we expect? (Does the fact that we are using capacitors instead of batteries increase the energy stored from ~15% to above 50%?)
