AC Motor Choice

[Turn]

Arno,

From my research, I believe the TECO inverter may be a better choice: http://dealerselectric.com/item.asp?PID=4708

I have not personally tried either, however, just offering an alternative. Good luck!

[Riton]

It is interesting to have the possibility to connect a load resistor on the drive.
This load resistance absorbs the current in the drive generated by the engine which is driven by its load.

The inertia of the load generator and create an effect appears in the current drive, which causes set error on the drive

[Arno]

I believe the TECO inverter may be a better choice: http://dealerselectric.com/item.asp?PID=4708

Hello There,

Thank you very much for your suggestion.
I will look at this and definitely need to evaluate the different products out there before purchasing 4 of them.

Still sorting out some mechanicals Maths right now, on torque needed for the platform, then will update this as I decide on the motors and final gearboxes choices.
Thanks for the feedback.
Cordially,
Arno

[Arno]

The inertia of the load generator and create an effect appears in the current drive, which causes set error on the drive

Hello Riton,

Could you please explain a little more in detail what the issue is?
Will this create problems long terms, or it this simply an annoyance but does not interferre with X-sim otherwise?

I understand that the resistor may also help with reducing the inertia and is interesting for dynamic applications like ours.

Cordially,
Arno

[Riton]

I speak of an electrical resistance that connects to the inverter.
there is no problem with xsim.
Just in case the simulator falls down, the simulator because of its weight and inertia may drop faster than the motor leads.
it then turns the motor into a generator, and that in due to the frequency safe.
can to prevent this decrease drive speed and / or reduce the inertia.
But there are frequency converter with the possibility of connecting a load resistor.
This is a conventional circuit for this kind of problems.
Français:
je parle d'une résistance électrique qui se connecte sur le variateur de fréquence.
il n'y a pas de problème avec Xsim.
Simplement, dans le cas ou le simulateur descend vers le bas, le simulateur à cause de son poids et de l'inertie risque de descendre plus vite que le moteur ne l'entraine.
ça transforme alors le moteur en générateur, et cela à pour cause de mettre le variateur de fréquence en sécurité.
on peut pour éviter ça baisser la vitesse du variateur et/ou limiter l'inertie.
Mais il existe des variateur de fréquence avec la possibilité de connecter une résistance de charge.
C'est un montage classique pour ce genre de problèmes.

[Arno]

Thank you Riton for the detailed explanation.
Merci Riton pour l'information détaillée.

Cordially,
Arno

[Arno]

Well, here I am back.
Was traveling for a while.

After reviewing many options, it has become clear that the gearbox that I had purchased is too weak.
670 lbs.in is not quite enough for this application, and I am looking at getting gearboxes that are closer to 80:1 ratio with about 2000 lbs.in of output torque.
This will give me an output speed of about 22rpm, which I can bring slightly down to work for this application by reducing the motor speed a little bit.

I have also looked further into the VFD choices, and I am likely to get an Hitachi WJ200 series.
High starting torque and good reputation.

I will hopefully have purchased a final gearbox and motor this week, so that I can do some testing over the holidays.
Now I just have to get an AMC644USB board fabricated to get the testing started.

More to come soon...
Happy Holidays to all!
Arno

[Arno]

Some updates...

Over the last couple of weeks, I have purchased a gearbox from Worldwide Electric.
The specs are quite impressive I think.
80:1 Ratio, which gives about 22rpm on the gearbox output.
Max Power input is 1.4HP and max Torque output is 2500 lbs.in.

I also purchased an Hitachi VFD, model WJ200.

Here is a quick little video I took this morning.
The motor is only 0.25HP, this is for simple application testing.
http://youtu.be/OXn3fnWkuBA

The VFD was not setup, and the speed goes from 0 to 1750rpm, back to 0 with a slow speed ramp.
For the final product, the motor should go from 0 to full speed in a fraction of a second.

When I put all my upper body weight on the end of the wooden cam, I can barely stop the motor.
I imagine that with a motor a bit more powerful, I should be able to lift quite a bit of weight...

The can is only there for a scale representation, this motor-gearbox is quite big.
I will be back next week with more updates hopefully,

Cheers,
Arno

[Arno]

New Video posted this morning:
http://youtu.be/XuNdwhE1IpI

Test platform with the same motor as above.
I was able to lift 60 pounds easily at about 22rpm on the gearbox output.

Later, modifying the VFD for quick acceleration, and another video to follow...

Arno

[Arno]

Last videos for today...

First, acceleration and deceleration settings changed to 0.01s in the VFD.
It does make a big difference...

Not loaded here:
https://www.youtube.com/watch?v=1BqKPF6zVro

60lbs load here:
https://www.youtube.com/watch?v=Gv1YuqPhYTQ

Finally, I felt that this would not be complete without at least 100lbs on the platform.
Tested with 105lbs.
https://www.youtube.com/watch?v=BSnEkWvvQAQ
Not too long, the platform was meant as a simple test bed, and I would hate for that big bucket of bricks to come down crashing on the ground...

All in all, this motor and gearbox combination have showed me that this should be a pretty good choice for a 4dof.
The gearbox can take up to 1.3HP motor, so there is some room there...

I am likely going to upgrade to the bigger MicroMax motor, of 0.5HP.
This will allow for some expansion if needed.

More tests coming up, in a few weeks.
Arno