AC industrial motors?

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!

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.

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.

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

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.