[Oeva-list] reprogramming the drive inverter to mitigate roll back

Paul Wallace ianaudio at aracnet.com
Mon Aug 27 20:06:24 PDT 2012


Last time I wrote, I was struggling with the AC inverter accelerator and brake pot programming parameters in the simple state machine mode.  I was contemplating radically changing the programming to put in a creep function, but that would eliminate pedal up regen and coasting.

Today, I rethought the programming and then set the brake pot to a very narrow band to get to max regen, after measuring the pedal free play before the mechanical brakes engage.  I've got about 75% of max regen now before the mechanical brakes come on with any force.  I also moved all the throttle position parameters down towards the pedal up stop so that the pedal up regen area is very small and likewise the coasting space.

Now when I release the brake, I can move to the accelerator smoothly and take up the drive line slack while the inertia of the truck is essentially holding it in place before gravity can take over.  I've tested this on several local hills and I seem to be able to make the move without much effort or clanging of the drive line.

Now I want to increase the max regen value and also the accelerator torque ramp rate.  I'm not getting head snapping acceleration yet, and may never considering the weight of the truck and the motor I'm using.  The AC drive is soooooo much better than my old DC truck, except in the acceleration.  More parameter programming may at least partially solve the problem.

My design goal is to put my wife in the truck and find out if she can drive it.  The power steering is a big step in that direction.  If I've got the inverter programming under control, I may be most of the way there.

Paul Wallace
'94 USElectricar S10 coming back from the dead




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