# AC industrial motors?



## brian_ (Feb 7, 2017)

Brady93 said:


> The scrap yard has hundreds of AC synchronous, single and three phase motors.


Are you sure they are synchronous? That seems unlikely... could they be asynchronous (induction) motors, which are extremely common?



Brady93 said:


> How suitable are these AC motors from the junkyard? From what I've read, a lot more power can be pulled from these motors with the right controller.


Exceeding the normal ratings on motors is normally based on running them at higher speed and voltage. Three-phase AC motors are all likely to be designed to run at about the highest voltage that a home builder is likely to want to try, so pushing them harder without rewinding for a lower voltage seems unlikely.


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## Brady93 (Sep 16, 2019)

Hey Brian,

Yes, some of them are definately Synchronous, it says on the data plate. Are these somehow better than the other motors? 

Thanks


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## Brady93 (Sep 16, 2019)

Thinking out loud here, can I get a scrap induction motor, machine out the guts off the rotor and fit permanent magnets? 

Maybe I could just machine a whole new dedicated centre to support the magnets? 

I've seen people do it on the internet, but I have no idea what kind of results to expect with regards to power and efficiency. 

From a mechanical standpoint, I have no issues machining a rotor, bonding and supporting the magnets properly and balancing the rotor. This is relatively easy for me. 

However, knowing very little about motor design I don't know what side effects this may raise? 

My idea of converting to permanent magnets is to potentially simplify the controller side. 

I've been heavily involved with RC airplanes, drones etc... So that type of ESC and motor type is familiar territory for me. 

I'd ideally like to keep my motor solution under $500 AUD / $400US. 

Thanks!


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## kennybobby (Aug 10, 2012)

Yes you could replace an AC induction rotor with permanent magnets, the stator windings would work in both cases.

The controller for a variable frequency AC induction or AC synchronous motor, and a 3-phase brushless permanent magnet motor would be nearly identical. 

The only difference would be in the manner and type of feedback sensor used to detect rotor position for commutation.


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## Emyr (Oct 27, 2016)

Brady93 said:


> Thinking out loud here, can I get a scrap induction motor, machine out the guts off the rotor and fit permanent magnets?


Induction motors normally have a "squirrel cage" rotor, you wouldn't have much to mount the magnets to, and the metal used for the cage rotor probably wouldn't be helpful in a permanent magnet motor.


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## brian_ (Feb 7, 2017)

Brady93 said:


> Yes, some of them are definately Synchronous, it says on the data plate. Are these somehow better than the other motors?


Synchronous means that the rotor must have either permanent magnets, or a powered winding. Permanent magnets seem unlikely in an industrial motor which is large enough to be useful, but maybe. A powered winding means slip rings and brushes to get the power to it; that would typically be considered undesirable and is very rarely used in EVs (although Renault seems to like them).

Is synchronous better? A permanent magnet synchronous motor has an efficiency advantage, although it's not a big difference.


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## brian_ (Feb 7, 2017)

Brady93 said:


> Thinking out loud here, can I get a scrap induction motor, machine out the guts off the rotor and fit permanent magnets?





kennybobby said:


> Yes you could replace an AC induction rotor with permanent magnets, the stator windings would work in both cases.


Yes, in fact BorgWarner (formerly Remy) offers both types of rotor for their HVH series of 3-phase EV motors... although I believe that the induction rotor is rarely chosen.



Brady93 said:


> Maybe I could just machine a whole new dedicated centre to support the magnets?
> 
> I've seen people do it on the internet, but I have no idea what kind of results to expect with regards to power and efficiency.
> 
> ...





Emyr said:


> Induction motors normally have a "squirrel cage" rotor, you wouldn't have much to mount the magnets to, and the metal used for the cage rotor probably wouldn't be helpful in a permanent magnet motor.


I agree with Emyr.

A rotor is not normally a solid hunk of iron (or steel). It is built up of laminations of steel sheet, to control the magnetic flux direction. While the construction of a rotor with permanent magnets is fundamentally straightforward, it's not an easy DIY thing, particularly with interior (rather than surface-mounted) magnets, which are inserted into slots formed in the stamped laminations.




Brady93 said:


> My idea of converting to permanent magnets is to potentially simplify the controller side.





kennybobby said:


> The controller for a variable frequency AC induction or AC synchronous motor, and a 3-phase brushless permanent magnet motor would be nearly identical.
> 
> The only difference would be in the manner and type of feedback sensor used to detect rotor position for commutation.


Well, that and the control logic, which manages slip speed in an induction motor and phase in a synchronous motor. The same controller can do both, but it needs to know which one it is controlling.


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## Brady93 (Sep 16, 2019)

Is a synchronous motor as it is suitable for an EV conversion? Assuming I found one powerful enough...


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## major (Apr 4, 2008)

Brady93 said:


> Is a synchronous motor as it is suitable for an EV conversion? Assuming I found one powerful enough...


Hi Brady93,

That's like asking if a DC motor, or induction motor as it is, is suitable for an EV conversion. Answer is maybe. It depends on the particular details of the motor and of the application. Also on knowledge and skills of the conversion designer and installer.

Finding a suitable controller, tuning it, and fashioning a battery for it will likely be troublesome to say the least compared to a DC motor. 

Good luck,

major


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## Brady93 (Sep 16, 2019)

Thanks Major,

I shall keep researching and hunting, and report back with further questions as needed. 😃 

Thanks for the input so far everyone. 😃😃


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## Eddie49 (Dec 6, 2018)

This previous thread describes an EV conversion with an industrial AC motor and using a Variable Frequency Drive ( VFD ) as a controller:

https://www.diyelectriccar.com/foru...ersion-vw-polo-ac-industrial-motor-78701.html


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## MRMOPARMAN1 (Feb 1, 2019)

I cant help with the electrical side of things, im a complete noob in that regard.

Mechanically though, i dont think using a solid shaft from motor to diff and having the motor swing with the axle would be a great idea. It will probably put thrust loads through the motor, which would be less than ideal.
A common driveshaft is usually the go like you mentioned. 

Its common in 4wding circles to 'divorce' the transfer case and remotely mounting it on the chassis. By doing this you could keep drive to the front diff, and even low range etc. You could run the motor in the trans tunnel or engine bay with a driveshaft to the transfer case, which would eliminate any weird angles/loads/nvh etc. You could mount the transfer where it usually sits so you dont have to modify driveshafts or alter driveline angles. 

Having said that, if you dont actually intend on using the 4wd, or need the extra grip of the fwd, id recommend you run, it in rwd only, as the front diff and transfer will reduce the total efficiency of the package.


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## Brady93 (Sep 16, 2019)

Thanks! 

I was only thinking about that unslung weight this morning. I definitely like your idea of basically replacing the gearbox with a motor and leaving the transfer behind. The gearbox I have leaves itself open to this option, as it seperates forward of the transfer. The gearbox mount also attaches to the transfer, further reducing the work needed as it's already in place. 

I also have a blown gearbox sitting here that has a good transfer on it that I could modify on the bench to accept a motor. 

I know that unslung weight is not good, I guess my thoughts were; How much unslung weight before it is noticeably creating issues. 

The EV Facebook page had a photo pop up this morning of a ford 9 inch diff with a motor mounted directly on it. It looked nice, it also looked heavy. 

I am also a bit in the dark with the electrical side of things. I've done some basic electrical courses, but I have no in depth working knowledge, I'm hoping to get there though. 

That link to the VW Polo build is interesting. I'm going to continue researching the option to fit a large industrial AC induction motor, in the mean time I'll keep an eye out for any motors that may be suitable. 

I noticed there's a heap of AC induction motor controllers at the recyclers. I'm assuming they came off grid power and won't accept a DC battery input. But are they of any value as parts to build/modify a controller? Or could they be converted to accept a DC input?

My suspicion is NO, due to the unique requirements of an EV, but but I thought I'd ask anyway. 😎😎😎

Thanks for the input guys, I very much appreciate learning from this forum and the people on it.


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## Brady93 (Sep 16, 2019)

I went past a shut down metal recyclers today and decided to poke my head in. Sure enough there was an older gent kicking around that owned the yard. 

I found two identical electric forklifts, unfortunately they are the smaller stand on type with three wheels. 

So immediately I sprung to action, made an offer and bought the drive and lift motors out of both for cheap. I also got two identical 36 volt Curtis speed controllers, some large relay banks etc... 

I originally went in there to find a large AC three phase motor. I found four large ones between 20 and 30kw, one in particular looked good and had a flanged face with a decent output shaft. I almost bought it, but decided to see what I can do with the forklift DC motors first. 

I am however doubtful these forklift motors are strong enough to run my ute/pickup, even with two of them. 

The motors are Raymond 24 volt model no: B94-4003 

The forklift itself ran a 24 volt battery, so is it reasonable to assume the curtis controllers can deliver more power with a 36 volt battery? Or will the controller just deliver less amps at 36 volt to net the same watt output? 

The lift motors also look good, but small. I'll keep them aside for something else. 

Is there any chance these Raymond motors might move my 1200kg (2400lb?? ) ute/pickup around? 

What if I found another two identical motors, to give a total of four? The yard owner said he sees a few of these lifts around, so there must be more kicking around. 

If all else fails, maybe these Raymond motors could go into an old motorcycle we have here with no engine. 

Cheers
Brady


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## aeroscott (Jan 5, 2008)

see Damien Maguire on youtube or this forum


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## aeroscott (Jan 5, 2008)

or jackbauier on this forum


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## cts_casemod (Aug 23, 2012)

I used an induction motor for my conversion and it run fairly well as a city run around. Folks in the US seem to be able to get hold of DC motors still, but for most everyone else that's a very tough market - at least in the power levels required to comfortably move a car.


Those with deep pockets use custom permanent magnet or brushed motors that provide very good performance, but for the rest of us it will suffer in highway/motorway.


Low end torque should always be good. I used a 3rd gear 90% of the time on mine.



You need to have a few things in mind, such as the voltage of the motor. Typically you need a motor that can be wired as 208VAC or lower. This requires a 350V+ battery pack and adds to the complexity of the battery management system.



There are commercial packages using induction motors that run at lower voltages (144-250VDC) with matched inverters for EV use. I started with a variable frequency drive and found it unsuitable - the ideal controller employs torque control with a custom FOC or slip control. In both cases the best performance requires a motor encoder to be added to your motor shaft. Cooling may or may not be required. Mine had provision for active cooling but was never used - the motor peaked at 60KW with continuous output around 15KW and it worked fairly well just gathering air moving into the engine bay

I used an off the shelf induction motor re-wired for 208V and a 409V battery pack - The design of the inverter was quite involved and was the hardest part. If you search around you'll see other people that have done similar and there should be some open source inverter designs around the microchip dsPIC and the ST STMF103.

In theory synchronous motors can also be used, together with hall sensors or even sensor less - Control would be easier too. You can get started with a car alternator (watch suitable conversions on YouTube) to understand what's involved. They are essentially a permanent magnet motor, with the disadvantage that you need to provide power to the field. This can be useful for field weakening, but requires careful design of the inverter. Without field weakening it should be fairly easy, as long as the field is powered at the same power at all times, but will result in a slightly smaller efficiency.


Also not to forget the typical hybrid car approach - where you replace the tiny battery on board with a larger one and add a suitable charger to make it plug in. This allows good range and backup as a normal car whenever needed. I would follow this route if starting again - rather than re-inventing the wheel.


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## Brady93 (Sep 16, 2019)

I'm not familiar with the Prius, but there's plenty around here. Do they have a suitable electric motor I could utilise? Or are they intergrated into something they can't be removed from (electrically or mechanically)? 

Did you use a commercial AC industrial motor or a dedicated EV AC motor like those on the EVwest website? 

I would like to buy a good sized AC induction motor cheap, and build a controller myself off some existing plans to keep costs capped. Is that a bad idea though?


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## brian_ (Feb 7, 2017)

Brady93 said:


> I'm not familiar with the Prius, but there's plenty around here. Do they have a suitable electric motor I could utilise? Or are they intergrated into something they can't be removed from (electrically or mechanically)?


Any hybrid of this power-split type (which includes all Toyota hybrids except the Corolla, and most Ford and GM hybrids) has two motors. Except in rare cases they are permanent magnet synchronous motors. They are integrated into the transmission or transaxle, so to use them separately would require building a custom housing - I've never heard of anyone doing that.

The HVH motors from BorgWarner (formerly Remy) are available as cores because they were originally designed to be components of the "two mode" hybrid transmissions from GM, BMW, and Chrysler. They are available as complete motors in housings from BorgWarner (the original Remy design) and from Cascadia Motion (now a BorgWarner division, incorporating AM Racing and their HVH motor package), but most other motors used in OEM hybrids (including Toyota) do not have housings like this available.


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## Brady93 (Sep 16, 2019)

All very interesting! Thanks. 

Another question, what's the difference between an automotive AC motor and an industrial AC induction motor? 

Obviously the housings are different to suit different applications, but what else differentiates the two types? 

Thanks
Brady


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## major (Apr 4, 2008)

Most OEM EV motors are synchronous using permanent magnets (PM) in the rotor. They are designed and wound for higher frequency meaning higher RPM. Most employ active cooling systems.

major


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