[catphish]

I am coming at this project from a slightly different starting point to many others. My skills are primarily in software and electronics. Consequently, I have started my project at the electrical end rather than the mechanical end.

I will follow the guide on how to write this post.

Your skill level with auto mechanics and fabrication

Essentially none (yet). I can replace parts if they attach with bolts, I can measure and drill holes accurately, I have some experience with CAD and 3D printing. I have no skills in welding. I understand a lot of learning is going to be required in this area and very much hope I can acquire these skills as I need them.

The range you are hoping to get what level of performance you are hoping to get

I am largely unconcerned with this. If I can get a range of a couple of miles for testing I will be happy. My goal right now is not necessarily a useful vehicle, but an exercise in learning the process and testing my electronics.

How much money you are willing to put into your project

An absolute minimum. As above, I have very low expectations for my initial build and consequently intend to spend very little. I intend to take my time and buy things as and when I need them.

What parts you've already considered, if any.

I have recently acquired a 30kW 3-phase 2-pole motor in a 160L aluminium frame. I hope to use this with my DIY inverter (already built) running at 288V. This will produce 15kW, but could potentially be upgraded to 30kW+ in the future by either rewinding or adding a voltage converter to my inverter.

What else?

I believe that I will likely use the existing flywheel, clutch and gearbox setup from the donor vehicle.

I am comfortable with the electrical requirements including my DIY inverter, fuses, circuit breakers, contactors, precharging, DC to DC 12v battery charging, and now just about got my head around high voltage battery charging and balancing.

First question

The biggest issue I have at this stage is that I have not chosen a vehicle. I need something with an engine bay large enough to accommodate the fairly large 160L motor frame, but still light enough to be viable as a low power electric vehicle. It seems that a vehicle with a reasonably large longitudinal engine and a rear wheel drive is going to be the answer, but many of these are large heavy cars. I'd appreciate any specific suggestions, or general advice on the types of vehicle to consider.

For quick reference, the motor is approx 13 inch diameter, and 18 inches long (excluding shafts, 4 inch front, 2 inch rear).

I am hoping for a little hand-holding with the mechanical aspects, particularly getting the motor mounted in the engine bay correctly, which is currently the biggest gap in my understanding of the process. This image of Johannes's engine bay roughly sums up what I'm aiming for. It can be seen that space is tight in terms of the size of the motor. http://johanneshuebner.com/quickcms/files/DSCF4013.jpg?t=1501541381435 so I don't want to get this wrong.

Thanks all for the excellent pointers from folks here so far!

Edit: sprocketman has kindly sent me a picture of a BMW 3-series bay which has plenty of place and a longitudinal mount, so this seems like the type of vehicle I may want to start looking at.

 

[catphish]

Thanks for the pointers. Trucks are indeed not very popular here. Almost all vehicles (particularly low cost ones) are compact FF hatchbacks. Those that aren't are far too heavy to be suitable for a moderately low power conversion.

I measured up the engine bay of a VW Golf today and it looks like the motor *may* fit in this vehicle (it will be very very close taking into account the need for an adapter plate). In the interests of getting on, getting my hands dirty and learning something, I'm going to go ahead and get a cheap Golf, pull the engine out and see what happens.

I am thinking that if there is sufficient space between the gearbox and the end of the engine bay, great, I will go ahead and install the motor directly to the bell housing, utilizing the existing gearbox, flywheel and clutch.

If it does not fit, I see 2 options:

1) Buy a slightly smaller motor (160M 132L housing instead of 160L). Johannes's motor is a 132, but I can't find anything with a decent power output in this form factor.

2) Remove the gearbox and install something else, perhaps a chain driven diff, allowing more control over placement of the motor and switching to direct drive.

Neither of these options are ideal and I am mostly regretting my decision to buy a large motor without considering space, but I am learning

 

[catphish]

Hey cat,

I wouldn't let a early part purchase ruin or encumber your whole project. Cut your losses so to speak. 2-pole motors are rarely used, if ever, for EVs. Look for a 4-po!e. Also try a 15kw model planing to run twice frequency and reconnect winding nodes for half voltage. You'll get same power and more torque for a lot smaller motor.

major

Thanks for the encouragement!

This is exactly what I am thinking now. 132L 4-pole 11kW should be easily available, and I hope to be able to rewire windings in parallel for half voltage (sill 200V bit better than 400).

 

[catphish]

fwiw, for example the ac24ls was (still is) a 4kw motor (@1760 rpm), they rewound it for a lower voltage (so you can run it at higher than 60hz) and are listing a peak power of 47kw, and 20kw continuous.

That's impressive. I've definitely overspec'd with my motor then!

I've also since realised that despite being rated at 30kW, it's really only a 15kW continuous motor, rated 30kW at 60% duty cycle, so going down to 11kW is really not much of a loss. Perhaps I could consider going even smaller to begin with, particularly if I go with an even smaller vehicle, which was my original plan.

I think I came into this with no idea just how under-rated these industrial motors were.

Thanks again!

 

[catphish]

I was trying to make sense " rewire windings in parallel"
Each phase is in series 4 coil sets (4 pole motor)

I understand you're the expert on this! My hope is that I can take the 4 coil sets and wire then in 2S2P instead of 4S, thus halving the total voltage required, but keeping the current in each coil the same. I believe may people do this, avoiding the need for a full re-wind. Does this make sense?

Of course this requires that the motor is wound with 2 separate windings per phase instead of one continuous winding, but I understand many are. Again, you're the expert here

There's a long thread about this process here: http://forums.aeva.asn.au/viewtopic.php?t=1237 and several people have recommended this as the best way to run a 400V 4-pole motor.

 

[catphish]

My car has arrived. http://imgur.com/a/S7zvv

The space in the engine bay measures 520mm. This is enough for a 132L, almost certainly not for the 160L. I will source a replacement motor and upgrade to 4-pole. I will try to find a 11kW 132L with 6 windings, otherwise will have to find someone to do me a low voltage rewind.

 

[catphish]

this may or may not help, fwiw this part has to be pretty accurate.

http://www.evwest.com/catalog/product_info.php?products_id=116

I'll definitely need one of those. I'd like to have a go at designing and machining my own, but handy to know there's an off-the-shelf design if I get stuck. I wonder if that bolt pattern matches IEC B4 motor facepate, will look it up.