View Single Post
Old 10-15-2014, 12:00 AM   #1207 (permalink)
Master EcoModder
Join Date: Sep 2010
Location: Saskatoon, canada
Posts: 1,488

Ford Prefect - '18 Ford F150 XLT XTR

Tess - '22 Tesla Y LR
Thanks: 749
Thanked 565 Times in 447 Posts
Originally Posted by MPaulHolmes View Post
A change I just made that actually worked really well was to only update the new PWM when Vd and Vq clamp difference is zero. I mean, why change the 3 pwms if you know they will change Id and Iq in a discontinuous way in the wrong direction? it didnt work to use zero when updating PWMs regardless of clamping value.
Cool. Don't update the output if it doesn't make sense ... who'd have thought?

I was able to go as low as -25 instead of -100 after each violation. much below 25 caused overcurrent trips.
Will the constant have something to do with the processor speed? I'm not comfortable with hard-coding constants since a brief problem with video games on the original PC (8088 @ 4.77 Mhz) ... made my games run too fast to play on a clone (8088-2 @ 8 Mhz) ... but perhaps I'm paranoid!

So, what we can do is,, in a test mode, lock the rotor, tune the PI loops for Id and Iq (ebrake on), and then in neutral, let it run through all rotor time constants for a sec each or so and the highest rpm candidate wins. the time can be so short that the rpms are very small. like less than 100. Then we have every characteristic we need. easy peasy! save those values, and you are done.
Sounds like an easy calibration procedure. With the motors that people are likely to drive with this large controller, a limited amount of power sounds like a good idea. The test would be messed up if the motor over-powers the brakes, right? How many amps (perhaps a percentage of rated current?) would you need for the locked rotor test?
  Reply With Quote