Q&A Forum
Hi,
Have you any suggest to gearing the Motor? Is not possible increase velocity by software or stepper driver?
Hi,
So you are getting closer to a good setup. It is still about 1.5 seconds from no brake to full brake, which is slow. If you are below 0.5 seconds, best to have below 0.5 seconds. You may add a gearing.
Anyway, with slow valve control you need low Kp and Ki. It will still work but it means the regulator will be less able to adjust to sudden changes.
Indeed any setup without Ki will have a static error, only Ki can fix that. You are on the right track, you can experiment a bit more with Kp and Ki, but better to increase the speed of the valve control.
Hi, today I have made some test with 400 pulse/rev and 1200 steps from 0% to 100% brake. I have reduce the stroke of the valve at about 3 turns, but the System is yet instable, I think I must find the correct value of kp and ki value. With kp 0.3 and ki 0 The System is instable. With kp 0.1 ki 0 System is quite stable but with some errors. Could you suggest me a good brake curve to set pid controller? Thanks a lot
Eric
Hi, I use 36v 5a external supplier for nema 34 engine. Look stepper online.com, have a lot of stepper Engines. I choose high torque nema 34 Motor because vmp valve have the resisteance of spring. With normal flow valve is necessary less torque..
Hi eric91 , what external Supply Voltage are you using to the nema 34 stepper motor ?
I see that the MS_driver ST_M5045 can control a Vdc - 24V to 50Volts ,
I'm going to use this 4.5Nm Nema 34 1 Axis Stepper Motor & Driver ( https://www.ebay.com.au/itm/112373699571 ) or Stepper Kit 4.0Nm(566oz.in) Nema 24 Stepper Motor & Driver ( https://www.ebay.com.au/itm/172864922496 ) , I haven't yet decide which of the two but one has feedback ( for future upgrade potential !) or even maybe smaller unit 3.0Nm Nema 23 Stepper Motor & Driver ( https://www.ebay.com.au/itm/171994207870 ) .
What size Nema stepper motor will do the job ? Don't know yet ?
Bye
My stepper driver have minimum 400 pulse/rev. I will try with 400pulse/rev, but valve from fully open to fully closed have almost 10 turns, 4000 steps. 2000 steps/second is the Maximum speed allowed?
PS i have nema 34 stepper motor.
Sorry for banal request, but it's my first experience with stepper motors.
Eric91,
That's a lot of steps!! It will not work like you have set it up. You have 9700 steps between 0 brake and 100% brake, and max 2000 steps per second. So it is going to take about 5 seconds for the valve to go from 0 to 100% brake. That's way too slow.
Can you configure your stepper controller to use 200 steps per rev, or is this set by your stepper motor? I would consider swapping out the motor if that is not possible. Also see if you can get a higher gearing such that the stepper does not need to go so many revs from min to max brake.
Great, let us know how the testing is going and where you buy the valves!
Hi , Plenty vendors sell V-grooved ball valves , haven't place a order with any at this stage.
https://www.bray.com/ball-valves/control-valves/advanced-v-control
https://whatisneedlerollerpin.com/2VULport+hollow+SS316-SS304+balls.htm
Don't know of any European suppliers that are closer to you.
I will be for the experimentation purposes modifying a standard ball valve at work , turning and grinding spherical shapes with V grooves. Also cylindrical valve arrangement with a V groove is much easier to turn on a lathe/grind and mount into a housing.
I also thinking along the lines of a pintal orifice design a bit more work in concept.
At this stage my H&F GB4 dyno has a V-groove cylindrical valve arrangement similar to one of your websites pictures you posted on http://yourdyno.com/brakeabsorber-dynos/
Bye
The problem could be cause by vmp 12 valve that is not suitable for this scope?
I have set the brake curve Like in photo but the rpm is not stabile at 10000rpm and rpm keep going up and finally the brake Force goes up and kill of the engine brutally. Seems Like that the stepper Motor is not so rapid to control the brake valve (vmp 12 hydraulic valve) .
The setting of stepper Motor is Like in photo. In a stepper driving I have set 800 pulse/rev.
Hi jostein, to set the kp and ki parameters with stepper Motor, which brake curve do you suggest me?
Great, let us know how the testing is going and where you buy the valves!
Love the valve on this G490EH , which is basically the same dyno I have a Heenan&Froude GB4 but have different range of operating speed/torque
https://www.youtube.com/watch?v=mG2Q48l2V7A
A very nice compact and neat valve and stepper motor that can be seen in the video bottom left hand corner
Hi , I'm hoping to experiment with different V ball valve ( and other shape ball valve configuration ) and see what flow characteristics can be accomplished with them.
Spherical balls as opposed to cylindrical valves you have pictured on you forum and website.
Thanks