Industrial Motors

There is no such thing as a <...3 phase DC motor...>. Only AC has phases.

All manner of DC motors are powered from batteries, ranging in size from the vibrate-wobblers in mobile telephones to toys to golf carts to articulated trucks/lorries to railway rolling stock. All these could be described as <...portable...>.

Thanks for getting back to me all the information the better it really means a lot! One of my old tradesman got back to me on the specific details of the motors that were used in the place I served my apprenticeship and it was indeed a 3 phase induction motor. Like I said I'm mechanical biased so my electrical knowledge is very, very limited. Basically I'm working on a design project for my degree now and I'm wondering if industrial high RPM motors (round about the 3000 RPM mark) could be powered by rechargeable batteries to allow units to be portable.
Craig.

AC motors (single- or 3-phase) can be battery-powered using an electrical device called an inverter. As the wording suggests, high-powered motors need a lot of power, so large (and heavy) batteries would be needed for running for extended periods.

John,
But in theory it is possible to run an industrial high RPM induction motor on batteries?
Craig.

That's what I implied.

You don't need no stinkin' theory, all you need is an inverter and 3 phase converter....

Most AC motors will run on MSW inverters with an efficiency reduction of about 20% owing to the harmonic content. However, they may be quite noisy. A series LC filter tuned to the fundamental frequency may help....wikipedia

Correct.

Yale AC electric forklifts had them for over 10 years.

https://en.wikipedia.org/wiki/British_Rail_Class_379#BEMU_trial

https://en.wikipedia.org/wiki/British_Rail_BEMU

There is no theoretical limit to the speed of a series-wound DC traction motor. That is why wheel-slip detection is needed in order to prevent the thing accelerating to the point where catastrophic self-disassembly takes place.

Folks,
Just to be clear the motor I'm talking about would actually be something along the lines of an industrial induction motor (operating around 3000 RPM) used to rotate a variable displacement hydraulic pump, sorry for the initial confusion. I'm not looking for prices or if it would economically possible. I'm just wondering if it WOULD be possible to run a motor of similar capacity on a rechargeable battery rather than being wired into the grid. I hope I've now made my idea a little bit more transparent.
Craig.

The particular application dictates the selection of the pump, the motor, the selection of the power source and the connection between the two. Anything is <...possible...>, however there are tried and tested examples of good practice that are worth following.

The query seeks only a yes/no answer to the <...WOULD...>. Without the forum knowing more about the application it is difficult for any reader to comment further, and as such detail has been withheld:

<unsubscribes>

Guys,
The motor that's in question would be operating a variable displacement hydraulic pump that supplies high pressure fluid to rotating, lifting and linear equipment.
Craig.

How big you wanna' go?

HYDRAULIC PUMP, BATTERY OPERATED

GREENLEE| ZORO #: G7029321| MFR #: EHP700LU11 Reservoir Capacity (Gal.): 0.20 Maximum Pressure: 10,000 psi Application: Utility

Check this...

http://www.allair.com/downloads/files/enerpac/_elec_pumps_e327_us.pdf

http://www.directindustry.com/prod/holger-clasen/product-52922-975885.html

https://www.enerpac.com/en/industrial-tools/hydraulic-pumps-and-valves/electric-hydraulic-pumps

It would probably be more economical to spin the motor shaft thereby causing it to become a generator

No, the theoretical speed limit with a DC motor is when the back EMF from the motor matches the DC voltage applied to that motor. This is why DC motors are used for speed control on mechanical loads like a LP record platter or commuter train.

Now if one had a truly infinite voltage source like an ideal current source then an infinite velocity is possible, well except for those pesky effects from relativity.

I don't think the speed of a series wound dc motor is unlimited. The equilibrium speed is when the back emf (plus IR drop) equals the applied voltage. The back emf is proportional to flux x speed. Flux is proportional to current, which is proportional to mechanical load. So less mechanical load, less current, higher speed at equilibrium.

If a motor is designed to run under a mechanical load, unloaded it will spin at a much higher rpm than it was designed for.

We are saying the same thing unless your double negative leading sentence is intended to be an emphatic double negative. In English a double negative leads to confusion.

Yes, agreed! (meant to reply #7, my bad)

You consider 'unlimited' to be negative? Sounds quite positive to me.

Is it the 'un-' that makes it negative to you? If so, what about:

Unbenumb

Unharmed

Unspoiled

Under appreciated

Unflappable

Unfettered

Uncommon

Unbroken

Unique

Unctuous

?

Unnecessary.

Of you the question was unasked. Your response is ungenial.

There are several responses I have written specifically to you that remain unanswered. If you feel that you don't wish to respond to me, that is your decisions, but why go out of the way to respond to my comment in a discussion you aren't part of, just to claim it wasn't needed?

Go back in your hovel, no one walked on your lawn, you old curmudgen.

Attempting to demean and belittle other members just makes you look unintelligent and it makes you look uncouth!

An inspection of the rules indicates that you cannot un-invite someone from responding to your unwarranted and unnecessary drivel.

You must lead an unhappy life!

Oh, I apologize, I did noy mean to offend, I thought a hovel was the customary housimg of all curmudgens. How presumptive of me.

Still, no one stepped on your lawn.

If you feel the desire to respond, there is a backlog of far more interesting topic with questions posed to you.

Or if you prefer this tedious stuffm devoid of value, I guess you can respond here.

Actually, there are three phase brushless DC motors. The windings are grouped in three phases that are alternately driven with DC or PWM current. They are slightly more efficient than an induction motor.

Any motor can be driven from DC batteries with the right drive electronics.

I'm not sure what you mean by a 3 phase DC motor

You can run a DC motor off of 3 phase via a DC drive but you still only send out DC= and DC - on the A1 and A2 armature leads and F+ F- fie;d leads.

https://www.digikey.com/en/articles/techzone/2017/jan/why-and-how-to-sinusoidally-control-three-phase-brushless-dc-motors

My terminology was wrong, the pumps were ran by induction motors at about 3000 RPM.

It depends on the size (power) of the motor, the kWh level of the battery bank, and the maximum power level output of the three-phase inverter required to run the 3 phase motor.

There is no such thing as 3 phase DC motor.

There are Brush Less DC motors (BLDC) where dedicated motor circuitry instead of brushes handle the commutation. ManBy of these are three phase in design. All use permanent magnets for the rotor field that do the dual pubose of sensing rotor position and producing torque for motion by the rotor.

Any electric forklift or scissors lift is an example. Why does AC need to be involved?

A gas or diesel generator would be a better solution than batteries which would require a grid for charging.

What we need to know is the requirement of the machine that would be run hydraulically, then we could choose a pump, and then size the motor....anything can be designed and built, it's just a question of practicality and cost...

https://www.engineering.com/ElectronicsDesign/ElectronicsDesignArticles/ArticleID/9252/Batteries-Are-the-New-Peaker-Plants.aspx

Hello,

Because my inspiration came from hydraulic power packs that supplied fluid power to equipment such as: rolling mills, hydraulic double acting actuators, hydraulic shears and various types of lifting equipment that’s what I was aiming for. Pretty much I worked in a steel alloy and steel manufacturing plant and it was similar industries I felt could benefit from the product.

Cheers,

Craig.

cab12,

Welcome to the forum and hang in there. As you read and study, you will learn the normal uses of all the abbreviations, words and terms used in electricity and power. As others have pointed out, DC means direct current, which is either on or off. AC means alternating current, which varies in amplitude from a positive peak through zero to a negative peak, then through zero back to a positive peak, normally following a sinusoidal wave form. One can impose three AC wave forms onto a graph with their zero points offset by one third from each other and you now have 3 phase AC power.

Back to your question: Yes, it is possible. Challenges in doing so would include: 1) Having enough energy stored in the batteries, to power the motor so it can complete its job; 2) Keeping the weight and size small enough (in other words the energy density high enough) so portability is a realized; and 3) Doing this within any cost and time limits.

You have asked us a question. Now is time for you to really do your homework and study the various fields that your question "plays" in.

--JMM

Yes.

I'm amazed that after at least 37 posts, no one has mentioned the Tesla car.

Of course all 3-phase motors are AC. Ignoring that detail, the Tesla fits the OP perfectly. It uses an inverter to provide power to its 3Ø motor(s) from the battery pack.

Dkwarner,

This was my thinking completely! If Tesla can run a super car on a rechargable battery surely there’s battery power available to run an industrial sized motor that’s connected to a hydraulic pump.

Cheers,

Craig.

In case it wasn't clear, part of my point was that the Tesla car does indeed use a 3-phase motor driven by an inverter. Many other electric vehicles use one or another form of DC motor, brushed or brushless. I haven't yet heard whether the Tesla Semi-truck uses the same type of motor(s).

Scared off another one with internal bickering...

Yep. Neither 'scared', nor 'off'.