powerful stepper /brushless motors up to 12Krpm 750+W

[Simon]

like i say we hacked this motor off a fan and then gave it some heavy gearing to drive. It come with a built in controller so no chance of changing it as that is not meant to be and ultimately we don't want to keep cutting motors off of fans we want a motor that is bought as a motor.

[G7PSK]

If you are mechanical engineers its most likely that you have compressed air service. So what about an air motor, they have high speed and are available in quite high powers Ingersoll Rand do up to 30KW) and they wont have any emi problems.

http://www.ingersollrandproducts.com/eu-en/products/air-motors

http://www.pneumatictoolservices.co.uk/industrial_air_motors.htm

[Simon]

except most automotive vehicles don't have compressed air.

[Paul Moir]

That would have been helpful to know several pages ago.

I give up.

[Ton]

Best I have found is this, maybe share the burden between two ?

400W 24V 14011RPM @ no load

http://www.peromatic.ch/d/produktelinien/moog/bldc_motoren/bn34hs.pdf
reseller of Moog.com motors
http://www.moog.com/literature/MCG/bnhsseries.pdf

Most BLDC motor manufactors stop their standard line around 400W, especialy on the high RPM line

but dont think they are cheep 

you could check http://www.maxonmotor.com
their EC line look fine, but stop at 250W 24V 10400RPM (EC = electronically commutated)

so a search after "electronically commutated motor" might find something, but now I am off to bed

good luck

[codeboy2k]

...must never fail

You've lost already.

If you're a mechanical engineer (did I read correctly? ) then you should know that moving parts will fail.

Your best defense against this :
(a) a time-limited lifespan where it is guaranteed not to fail because you've done the math on the wear and tear already, or;
(b) a maintenance program with specified replacements that is strictly adhered to in order to get more life out of the moving parts. 

When you say it must not fail, then if it does fail is someone likely to die? or be hurt? I read about automotive something earlier on...

By the way.. that Wikipedia page that says brushless DC motors are like steppers... I really want to edit that out. Brushless DC motors rotate continuously, are never stepped.  They may be used in a closed loop feedback as part of a servomotor system, but this does not make them "steppers" just because the feedback loop allows them to be "stepped".  They actually make really, really good servo motors because they are mostly RPM linear with voltage and torque linear with applied current, so if you know the torque you need to move a mass X meters, it's easy to calculate the drive requirements. If your bed or pickup has a load cell on it you can feedback the mass to the motor controller and it can apply needed torque to move a changing load with constant velocity.  This makes BLDC motors in servo loops really good for robotic arms on factory floors.

[strangelovemd12]

Can't you just post a picture of the current setup, or describe what mechanical action needs preforming?  Three pages of teasing out what you are trying to accomplish is driving me crazy.  So far it sounds like you just need to add a .15 duty starter to your current rig to overcome static load.

At the very least , fill in the blanks:
Available Voltage: 24v
Available Start Current*:
Available Run Current*:
Final Shaft Speed: 10k-12kr/m
Ramp-up Time (max/min):
Starting Torque:
Static Load (y/n):
Average Run Time**:
Max Run Time**:

*   Is 750w your max power supply output?  Because measuring the actual mechanical requirements of a motor as a function of it's input current doesn't really work.
** "Continuous" can mean a lot of things.

Also wouldn't hurt to know about the thermal properties of the space the motor would occupy.  And the motor itself will fail at some point, never mind the chain of electronics/mechanics on either side of it.  The closest you'll get to non-fail is a highly redundant system.  You probably don't want to do this whole thing in triplicate.

In other words, take a picture of the current setup.

[Simon]

That would have been helpful to know several pages ago.

I give up.

To know what ? about no compressed air ? that was an offshoot and never part of the discussion

[Simon]

Can't you just post a picture of the current setup, or describe what mechanical action needs preforming?  Three pages of teasing out what you are trying to accomplish is driving me crazy.  So far it sounds like you just need to add a .15 duty starter to your current rig to overcome static load.

At the very least , fill in the blanks:
Available Voltage: 24v
Available Start Current*:
Available Run Current*:
Final Shaft Speed: 10k-12kr/m
Ramp-up Time (max/min):
Starting Torque:
Static Load (y/n):
Average Run Time**:
Max Run Time**:

*   Is 750w your max power supply output?  Because measuring the actual mechanical requirements of a motor as a function of it's input current doesn't really work.
** "Continuous" can mean a lot of things.

Also wouldn't hurt to know about the thermal properties of the space the motor would occupy.  And the motor itself will fail at some point, never mind the chain of electronics/mechanics on either side of it.  The closest you'll get to non-fail is a highly redundant system.  You probably don't want to do this whole thing in triplicate.

In other words, take a picture of the current setup.

Unfortunately being a work project I can't tell all or post any pictures, sorry about that. The load is another fan but heavier than the original plastic fan on the motor which i think is upsetting the controller. Apparently "bolting 2 together" has not helped as they load share and we get the same speed as before and the same power and infact it's like having only one motor I'm told. I'm the electronics geek around although we usually subcontract electronics design and manufacture but I help with general specifications and making sure we are all on the same page. As a company we are mechanical only really with basic electrical knowledge but for me being the "local anorak"

"At the very least , fill in the blanks:
Available Voltage: 24v
Available Start Current*: battery - big ones so for our purpose unlimited
Available Run Current*: as above
Final Shaft Speed: 10k-12kr/m we are currently getting around 9000rpm but I'm told we are looking towards 10000-11000
Ramp-up Time (max/min): that's very secondary at this point, current setup is not quick anyway
Starting Torque: no idea but the load turns freely
Static Load (y/n): not sure what that means but don't know
Average Run Time**: no idea - as long as needed
Max Run Time** as above

[Kremmen]

Basically you have 2 alternatives:
1) A brush DC motor. Somewhere in the world a motor exists that can do what you need, if only someone can find it.
2) A "brushless DC" motor, i.e. in fact an electrically commutated 3 phase AC motor, either a BLDC or PMSM. The power output will be no issue but max RPM will be, and the input voltage is also quite a challenge.

Pros and cons as i see them:
A brush DC motor is a no-brainer to control so the electronics will be easy. If the numbers match you can let it run directly from the battery after the initial start&acceleration.
The downside is that it has a mechanical commutator with carbon brushes that require regular maintenance. The intervals can be long(ish) but they will be there. Other than that and properly applied such a motor can be quite reliable however.

A brushless motor has 1 moving part, making it essentially indestructible. So the only maintenance is related to bearing life which probably exceeds the lifetinme of the rest of the application with a comfortable margin.
The downside is that industrial quality BLDC motors with the required output power combined with this low supply voltage are few and far between. And you will not get 12 kRPM out of one so prepare to set up a gearbox.

Basically that's it. An induction motor would be the #1 candidate for this app, but lacking an AC/line voltage supply it is apparently not an option.
A stepper was never an option for many reasons that have already been pointed out.

I at least don't know of anything alse that could work.

[Simon]

A stepper is not what I was after but I was unsure basically the 3 phase motor with electronic comutation is what I'm after. i will have words and explain that for the power/speed a voltage increase is a must.

but to give an idea of how possible it is to get the power at this voltage I can quote the current motor we are using that is 750W off 24V and we have used a bosch fan in the past that if the dogs privates in commercial fans and will pull 48A at 12V (it was designed for high end audi's but we have used them often where power is required and locked them into max speed rather than used a controller).

I think the limiting factor is the speed here, we need more voltage for that or gearing. I personally would recomend a brushed motor unless lifetime and emi is a problem. At this point I need more details as I'm not heavily incolved in this project I've just pocked my finger in having seen them try to do it the hard way because they don't seem to know any better (as if I know much more which I don't but when dealing with electrical things i tuirn to electronic solutions before i look at mechanical ones where as they know mechanics so start making bits of metal to solve the problem first).

[poorchava]

There are two fundamental differences: steppers have thing inside what I can only describe as a circular bumpy spring washer which makes the motor "snap" to certain angles, BLDC motors don't have that. The second thing is that steppers have many more poles than BLDC's do.

I think for a stepper you can try A4989. It's specced up to 500W, but it's a N-MOS controller, and all the power elements are external, so in practice the limit may be much higher.

[Simon]

Right, I've done some convincing and explained that even if we get a custom solution they will be just bumping up the voltage and then driving as motor so now my fixes are 750W and up to 12Krpm and we shall see what voltage we need.

So spindle motor may do it.

Any people good at doing off the shelf DC/DC inverters ?

[ovnr]

Kelly Controls does some acceptable, fairly reliable motor controllers. Make sure you stay inside the maximum frequency range; they give up when you get too close to it.

[G7PSK]

except most automotive vehicles don't have compressed air.

Sorry I was under the delusion that this was some form of test rig. 

These people might have what you are looking for.
http://www.transmotec.com/brushless-dc-motors/no-gear/B86-Series.aspx?gclid=COvar5P1ibsCFZLKtAodyjAAew

http://yzkg.en.alibaba.com/product/413397031-201032127/KG315_high_power_brushless_DC_hub_electric_motor.html

http://www.adlee.com/brushless_dc_motors_with_dc_driver.htm

[Simon]

No it's to go in a vehicle, we are using a testing rig now so that we have things to bolt it all to but it will be vehicle kit. I'll take a look at those suppliers thank you, I'm also open to coupling 2 motors together.

[Kremmen]

[...]
Any people good at doing off the shelf DC/DC inverters ?

Technically that would be a boost converter then. Boosters take an input voltage and produce an equal or higher output voltage, up to something like max ~8 times the input voltage. Doubling or tripling the input voltage should be quite feasible.
One thing that makes this application easier is that you don't need galvanic isolation between input and output. That said it is still the case that implementing a proper production quality SMPS is no task for a novice. If you want i can do a quick check on what kind of efficiency you can expect from a converter like this. Offhand it could be between 80-90%.

[Simon]

anything like that would need to be bought off the shelf or designed for us. I don't do electronic design for the company other than mess with things and poke sticks at the subcontractors work.

[Kremmen]

anything like that would need to be bought off the shelf or designed for us. I don't do electronic design for the company other than mess with things and poke sticks at the subcontractors work.

My sentiment exactly I would not recommend you to try this, but wanted to mention it just to let you think about the feasibility of such a solution. I have no idea if you could locate a true off the shelf, standard device that can do this. Someone will make it for you certainly, but the price is a good question and certainly depends on the length of the production run and other variables.

[Simon]

Well most brushless motors and higher power stepper motors seem to work of fairly standardized higher voltages and 24v is fairly standard so i'm hoping that there is an off the shelf DC booster out there. I mean even 110V is quite common on motors and that coincides with mains voltage as does 220V. We could use a spindle cnc motor if we get the speed.

[oldway]

I remember that such high power and high speed brushless motors are used for flywheel energy storage.

[Kremmen]

Well most brushless motors and higher power stepper motors seem to work of fairly standardized higher voltages and 24v is fairly standard so i'm hoping that there is an off the shelf DC booster out there. I mean even 110V is quite common on motors and that coincides with mains voltage as does 220V. We could use a spindle cnc motor if we get the speed.

24V to 110-120V or 220V inverters should be findable without too much trouble.
You will certainly get the speed with a spindle motor, but there might be other issues. At least be careful of the motors with very high power density because they tend to be liquid cooled. Also at those power densities probably not very long life in continuous use unless you pay through the nose.

[Simon]

Well i have spoken to one supplier who is suggesting water cooling which is not a problem for us as we are primarily a heat exchanger manufacturer.

[Kremmen]

OK that should make things considerably easier then. Just include the cooling system in your reliability loop since failure there will kill the motor quite fast.

[strangelovemd12]

Unfortunately being a work project I can't tell all or post any pictures, sorry about

The downside of  a proprietary, private system is that you can't find much help for it in a forum, you have to actually know what you are doing.

The load is another fan but heavier than the original plastic fan on the motor which i think is upsetting the controller.

Taking off some plastic blades and replacing them with heavier metal ones sounds safe.

Apparently "bolting 2 together" has not helped as they load share and we get the same speed as before and the same power and infact it's like having only one motor I'm told. I'm the electronics geek around although we usually subcontract electronics design and manufacture but I help with general specifications and making sure we are all on the same page. As a company we are mechanical only really with basic electrical knowledge but for me being the "local anorak"

I guess we all have to trust that the mechanical know-how floating around your place is enough to keep this thing from turning into a bloodbath.  Spinning a fan up to 12krpm is not a trivial thing.  Even at a foot in diameter a 12krpm fan has tips moving at twice the speed of sound.

Available Start Current*: battery - big ones so for our purpose unlimited
Available Run Current*: as above

What?  Are they just some big car batteries with impressive CCAs?  Presumably they are lead-acid.  Are they deep cycle?  What do you need their service life to be?  How are they recharged?  Do you intended to run the fan while charging them?  All of these factors (and more) are important. 

Average Run Time**: no idea - as long as needed
Max Run Time** as above

Jesus Christ on a cracker.  Do you mean you guys might run it all the way through a single work day, or similarly short period of time?  Are you trying to run it for months on end?  And when it fails, what are the implications of it not running?

Final Shaft Speed: 10k-12kr/m we are currently getting around 9000rpm but I'm told we are looking towards 10000-11000

Why?  Because that is what will provide the airflow you need with the current blades?  Can those blades be run at those speeds?  Saying you need a "10krpm fan" is like saying you need a "48 pin MCU", it's verging on meaningless unless you provide a whole bunch of context.  (Same goes for the wattage rating frankly)

Starting Torque: no idea but the load turns freely

Well yeah, you can't put a brake on it if you want it to start.  You mentioned you had troubled getting it started with the current motor.  We need to know how much torque is required to start it.  Easily tested with a torque wrench.

Static Load (y/n): not sure what that means but don't know

It just means whether or not the load demands on the motor change.  Since we are apparently looking at a can, it would be a constant/static load.


I think what you really want is a fan.  Places sell them, go buy one.  You seem to be stuck on this avenue of tweaking this and that to boost your current system, and I think it's the wrong approach.  Define the airflow characteristics you need the device to accomplish, then find a fan that meets them.  My money is on it being faster and cheaper, and all the smart money is on it being a hell of a lot safer.