Q&A Forum
Hello!
At last I got my hardware working with little stupid mistakes and now I am starting to test it. I got few questions.
First of all I have problems when measuring power (power runs/sweep runs). Dyno is starting to brake too late. If I put start run at: 2000 rpm, then it barely starts to brake at 2800-3000rpm. If I put even lower - 1500rpm, it still starts to brake at more than at 2500 rpm. How about stop sweep rpm? Do I need to put this over redline or little before redline?
The best my system seems to work with PIDs Kp-0.23; Ki-0.1;Kd-0.
Next thing is that my measured power is really low. As I understand these are readings from wheels, not flywheel.
It starts to give only normal numbers if I enable loss correction about 25%. How do you measure power on flywheel?
From retarder (Telma) datasheet I see that it has 1.82kgm² inertia. Can I put it straight in software or better measure it? Then I can get power on flywheel?
This is what I get on my best dyno run.
Still measuring power little bit lower than 3000rpm. But really would be nice to see lower end. at least from 2000rpm.
Hope to see some answers.
Hi Edgars, as i said, i dont use power sweep on my hub dyno, looks like power sweep should be the best choice for hub dyno but not, just the only 2 times i tried to use didnt work properly to me, right now with load control not sure if Will Works good too. i always used RPM Curve, im sure with the latest versión with more info tracking im sure there is a way to improve any setup of each dyno but since mine Works very good i Will keep it as it. maybe forward with some free time i Will try to test load control mode maybe .
Try in Rpm curve mode . Also it's very important to calculate MOI, forget inertia of your brakes, calculate MOI you Will get it, my brakes have 2.92kgm2 but after to calculate MOI, i was 9.8, with the newest software versión that ask for each brake/roller in the case you use 2 rollers/brakes, then just divide and you are done.
Your closed loop PID is wrong.
Have a read on the instructions again.
Set KP first with everything else 0.
You want it to steady state hold with out rpm changing.
Next set Ki, you want this so steady state catches the RPM at the point you want instead of over shooting it (You have this wrong)
Only set Kd if brake is coming on too hard and fast.
Then watch the video and set your MOI.
Runs should be accurate now.
Now play with noise filtering to remove spikes from graph.
Hi guys are u powering the retarder with analog out put im having trouble getting the brake to apply early enough pwr readings etc seem fine but engine basically free revs for first 1000rpm of run its a eddy roller dyno
You have to configure PID control.
thanks walter so basically folow bmgjets instructions above