Re: Another homebrew AC-controller
OK i may have a good procedure on how to setup the motor - inverter to best efficiency. It worked for me at least and since i figured it out more by accident i want to share it here.
After first motor run setup next parameters important ones in bold
boost calculate cca 15V boost at first to overcome motor winding resistance at start
fweak calculate it acc. to johannes equasion, in general something around 130Hz works unless motor is industry specific
fslipmin either calculate it like Johannes showed or set it so that you can take off without motor jittering
fslipmax just set it 2x fslipmin initially
ampmin 5 i set it at this and try to set fslipmin. I later reduce it if neccesary.
fmin 0.5 or 0.25 it is slip resolution. I have minslip 3Hz and at such high minimal freq. motor doesnt work good, so i set it lower.
brknompeda -25 i reduce braking only for initial setup
brknom 35 throttle braking action in %
brkmax 10 throttle pedal braking torque set low initially
brkrampstr 25 Hz ramp for braking at low rpm set high only initially
Now comes the tuning part.
First you want to find a flat surface - a parking lot etc. so you can drive and stop without checking traffic. Change only one parameter at a time and save settings that work!
1. set fslipmin so that you feel car taking off smoothly and try to change it by +/-0,1Hz and check differences in starting. Save when satisfied.
2. lower boost value in 100pts untill motor jitters at start. Then return it to last good value.
3. try lowering ampmin in 0,1 increments and observe throttle travel. When throttle is not just smooth but becomes sluggish return some previous increments untill throttle reaction is acceptable.
4. change fweak value in +/-10Hz increments from starting point and observe torque in starting. This value is very dependent on battery voltage and is very subjective.
Now you find a hill or ramp and set car on it. You want to hold car in position on slope just using throttle pedal. If there parameters are not good motor will jump or will feel sluggish
1. add boost if motor is oscillating if it is smooth reduce it in 100pt increments untill you get oscillation. Then return to last good value
2. reduce/increase ampmin in 0,25 increments untill you get oscilation in motor and return last good value
Now set the car into a hill to set fslipmax. Warning full throttle will be used. Be sure there is no other traffic!
Set fslipmax to chosen value (guess it at 2xfslipmin if you have no other way) and try to take off with full throttle.
If car feels sluggish with full throttle you have to add more slip.
If motor starts to jitter there is too much slip. Try to reduce it in 0.1Hz increments.
When you feel satisfied with settings save them and go on setting regen and braking effect.
Hope this procedure helped you. It certainly was succesful for me. My car can now drive at 130km/h highway speed without motor overheating and i get enough torque at start to drive comfortable in city traffic. Best of both worlds!
Last edited by arber333; 06-08-2016 at 02:10 AM.