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Discussion Starter · #1 · (Edited)
Oldtimer conversion: Renault R4

Hi everyone,

as spring is sort of dawning on us, I'm planning my first ever EV conversion. I admit not havng planned in a disciplined fashion, a lot of stuff is trying out and taking chances. So first, the car:




It's a Renault R4 which happens to lurk about in a friends garage. First chance I take. It looks like a lot of space and little weight.

Second is the drive system. It is supposed to start out as a low power (maximum 20kW) high voltage (500V) AC system. I really don't like thick wires and other large high current components, thats why.

And here comes the second chance I take: the motor will be a standard squirrel cage induction motor with forced air cooling and rewound to [email protected] With special bearings it should be able to spin up to 9000rpm.

The inverter will be my homebrew device described here http://www.diyelectriccar.com/forums/showthread.php/another-homebrew-ac-controller-45909.html

It runs software developed by the Tumanako project.

The BMS shall also be sourced from the Tumanako project.

The batteries will most likely be Thundersky or similar LiFeyPo4 cells. I am planning to use 155 40AH cells.

The charger is supposed to be integrated with the inverter. The idea isn't entirely new and I like sharing the IGBTs for two purposes.

I haven't thought about the auxilary components like pumps, DC-DC converters and so on.

This project isn't about building a road legal car as fast as possible. It's about being in control of the key components and gaining experience.

So, any comments about the details already posted?

/Johannes
 

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Johannes,

good luck with that conversion, I'll be watching closely, as my route is Industrial ACIM too (but rather with an industrial VFD).

Regards,


Huub
 

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Discussion Starter · #3 ·
I think this one is interesting for the industrial motor fans:

http://rc-autopilot.de/wiki/index.php/Opel_Corsa_Project

He hasn't even rewound the motor or added forced cooling. Also he just spins up to 3000rpm.

I'm thinking to increase my DC voltage even more with smaller batteries to be able to spin a bit higher than that at full torque.

/Johannes
 

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Discussion Starter · #4 ·
Besides planning and setting up my workshop I actually made some hardware progress:


This is the first out of 13 cell blocks. Each cell block will be monitored with an LTC6803 battery monitoring IC. It monitores 12 voltages and 2 temperatures.
The device communicates via SPI. So I will build a number of hubs, that will collect the data and provide it via RS485. Finally, the data will be evaluated by a standard PC software which can display bar graphs etc.
The LTC6803 also has shunt switches for each cell to allow passive balancing during charging.
 

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Discussion Starter · #5 ·
Now the remaining 144 TS cells have arrived.
When charging 12 of them they almost reached 100% simultaneously with very little need for balancing.

Also the motor has arrived. It is about the size of a 7,5kW motor and weighs 66kg. It is speced at 120Hz though, with a nominal output power of 18,5 kW at 3560 rpm.

My home-made inverter reved it up nicely but soon my tiny cables melted ;-)
 

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Discussion Starter · #6 ·
Meanwhile the car has arrived and we pulled motor and transmission from it.

We have made the drawings for the adapter plates and the shaft connector which will be fabricated this week.

Unfortunatly while pulling the motor I was so busy that I couldn't be bothered to take any pictures.

When the transmission and motor come back to my workshop I will take some pics.

One question arose: the motor has an IP55 rating. Is that ok for sitting in an engine bay?

I'm planning to put some of the TS batteries in the engine compartment as well, how much water-proofing will I have to do?

/Johannes
 

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One question arose: the motor has an IP55 rating. Is that ok for sitting in an engine bay?
/Johannes
Here is the explanation for IP (Ingress Protection) http://www.protectingpeople.co.uk/fire_tech/ip_explained.htm
IP55 is protection from dust and protection from water from a nozzle. That is pretty tightly sealed, and a lot better sealed then a DC motor would be.

I think the average DC motor would be IP20 what with air vents over the fan and brush ring.:D
 

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Discussion Starter · #8 ·
Here is the explanation for IP (Ingress Protection) http://www.protectingpeople.co.uk/fire_tech/ip_explained.htm
IP55 is protection from dust and protection from water from a nozzle. That is pretty tightly sealed, and a lot better sealed then a DC motor would be.

I think the average DC motor would be IP20 what with air vents over the fan and brush ring.:D
Yeah good point :)
How do these motors cope with driving in heavy rain, possibly behind another car?
 

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Discussion Starter · #10 ·
We've gotten around to putting the motor in the car

Here it is supposed to be:



Here comes the motor+transmission:



And now it's all in:



Drive shafts are not mounted yet, had to solve some issues with the speed sensor first. That should happen next week. We will be able to do the first test-crawl with the 24-cell pack.

Unfortunatly we had to remove the motors fan because it wouldn't fit otherwise. I hope it won't overheat. Subject to test.
 

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It looks like your cell connection straps are made from some clamps. It isn't a good idea to use some unknown zinc plated steel for electrical connections. It is quite possible to pick a metal with only 15% of the conductivity of the same size in copper.
 

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Discussion Starter · #13 · (Edited)
Some more progress made:



9 12-cell battery packs easily fit in the trunk. We will build a wooden box around it.

Also the final motor mounts have been welded together and are fixed to the motor with a total of 10 M10 screws. The motor sits on rubber brackets:


I have also replaced the three single wires to the motor with a single shielded cable. It's only 6mm² but according to DIN thats ok for 43A continous. Thanks to the high voltage thats the full load current. I've found some nice waterproof bushing that contacts the shield.

I've also added contactor control to my inverter as well as a precharge resistor. When the inverter is powered on, the precharge relais closes. When the voltage reaches a certain treshold, the main contactor is closed.
 

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Discussion Starter · #14 ·
First test drive done!

Hi everyone!

Last night we did the first test run with the Renault!
http://youtu.be/jCyK6MCE66o

It drove smoothly but the inverter shut down when accelerating a bit more.

Anyway, the home-build, home-programmed inverter moved the car. I'm really quite happy about it and will go bug-hunting now.

Cheers,
Johannes

Getting ready to test-drive. The laptop is only there to modify parameters and restart on fault:


Made it out of the garage

 

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Discussion Starter · #16 ·
Yeah, how about it :)

There will be some kind of shelf for the remaining batteries.

Today I did another test run in V/f mode. I.e. theres no more slip control, the pot plainly controls the inverter frequency. That way I could accelerate up to 30 km/h and might have illegaly taken it on the road.
I learned a lesson how sensitive the motor reacts to wrong V/f settings. I found that above 1 Hz I don't need any boost voltage. Must be down to the low ohmic resistance of the stator.

I didn't succeed in testing with 4,4 kHz because the scaling factors are all set up for 8,8 kHz and thus my V/f parameters were off again.

Finally a cable of my usb-uart converter came off and I decided to quit the experiment for today.

Oh and I definitly need to route the reverse/forward switch into the cockpit. Getting under the bonnet every time I want to change direction really is disturbing :(
 

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Johannes> so you are basically transplanting that kiwi software on completely different driving board and different igbt/mosfet power stage which is designed by yourself (as followed in you homebrew AC controller thread)? That's some advantureous approach indeed.

You might consider ditching the stock ACIM cooling fan completely for ever and just add low voltage PC/electronics or automotive fan over there. It's more efficient and less noisy, the aussie guys are doing it for some time with ok results.
 

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Discussion Starter · #18 ·
Johannes> so you are basically transplanting that kiwi software on completely different driving board and different igbt/mosfet power stage which is designed by yourself (as followed in you homebrew AC controller thread)? That's some advantureous approach indeed.
Well basically it was me who contributed the first V/f software to the project. So it's not a black box to me. Running it on a different controller board is no rocket science either, just need to change some gpios.
I guess my self-designed power stage is the biggest adventure. I'm rather into computer science and the strange paths of current in power electronics offend me very much ;)
Right now I'm running the software on an Olimex board which will replace my box of many wires which you can see to the left of the power stage.

You might consider ditching the stock ACIM cooling fan completely for ever and just add low voltage PC/electronics or automotive fan over there. It's more efficient and less noisy, the aussie guys are doing it for some time with ok results.
Yes, I guess that cooling method is more reliable on low motor revs anyway. I'll read out the temp sensor within the motor and until it doesn't show alarming values I won't add any cooling at all. The motor runs at 1% slip nominal, so it is on the efficient side.
 

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Thanks for the prompt reply.

I'm wondering what is your strategy then for making it street legal especiallly in TUV-Germany, lolz? I gather It's either individual electromagnetic compliance test for the entire vehicle, which runs into thousands of EUR or producing papers for each individual component as been certified by its manufacturer/dealer in Europe. That latter "easy" option would also incl. your new controller..
 

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Discussion Starter · #20 ·
Thanks for the prompt reply.

I'm wondering what is your strategy then for making it street legal especiallly in TUV-Germany, lolz? I gather It's either individual electromagnetic compliance test for the entire vehicle, which runs into thousands of EUR or producing papers for each individual component as been certified by its manufacturer/dealer in Europe. That latter "easy" option would also incl. your new controller..
Don't remind me... We'll take it to the TÜV as soon as we have things cleaned up and ask them about things to change. I will have to go though a compliance test, maybe working at an inverter company helps...

I did another test run today with a frequency ramp behind the slip control. This prevents spikes to cause frequency jumps which result in instant over-current. It runs smoothly now above 10km/h, below that it still tends to oscillate and sometimes trip from over-current.
 
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