Richo's AC BMW E30

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Richo
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Richo's AC BMW E30

Post by Richo » Sat, 15 Aug 2009, 22:30

I am building a BMW 318i E30 1986 electric car.

Requirements:
I want it to have good acceleration - better than the ICE.
It needs to have a range of more than 44km to travel to work and home.
I don't want the gearbox anymore so Direct drive is a must.
It needs to keep all 5 seats to take the family around on weekends.
So the weight should be the same or less than original.
To Recharge from renewable energy whenever possible.

Status:
BMW E30 Vehicle bought
Minor repairs done to car
Car test driven
Car weighed
Electric Motor bought and is ready to drop in
Controller partially designed
Most Controller components ordered
Waiting for free time to work on it...
Plans changed!
Car and eV parts sold
Last edited by Richo on Tue, 29 Dec 2009, 12:35, edited 1 time in total.
So the short answer is NO but the long answer is YES.
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Richo's AC BMW E30

Post by Richo » Sun, 16 Aug 2009, 00:57

Once I decided to convert a car to electric I started looking at the smallest/lightest cars around.
I was originally going to convert a Daihatsu Sirion.
So I went to a wrecker with a pad, pen and measuring tape.
I wanted to know all the spaces available for motor and batteries.
By the time I left I was very unhappy.
Smaller does mean less requirements but also means less space to put everything.
I gave up on the Sirion and decided to look at Rear wheel drive cars.

After going through a number of possibilities I decided on the BMW E30 318i.
It took a number of months before I found one that I liked.

It was unregistered, motor was ok and ran.
But the body is in good condition with only a minor dent and almost no rust.
The gearbox however is clunky which is why it was a good price.

The paint is a bit flakey with the clear coat coming off.
The sun roof had been replaced and is a different colour.
So the car will be repainted in BMW Orient Blue.
Last edited by Richo on Sat, 15 Aug 2009, 18:57, edited 1 time in total.
So the short answer is NO but the long answer is YES.
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Post by Richo » Sun, 16 Aug 2009, 01:00

Here is a picture of it when it arrived home on the car trailer.

Image
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Richo's AC BMW E30

Post by Richo » Sun, 16 Aug 2009, 03:13

The original manufacturer specifications of the car are:

1.8L fuel injected SOHC inline petrol motor.
77kW@5800RPM
145Nm@4500RPM
MAX RPM 6200RPM
Max Cont RPM 6000RPM
6.0L/100km@90kph

GearBox:
1st 3.72
2nd 2.02
3rd 1.32
4th 1.00
5th 0.81
rev 3.45
Final Drive 4.10:1

Wheels:
195/65 HR 14

Body:
Length 4325mm
Width 1645mm
Height 1380mm
Wheelbase 2570mm
Ground Clearance 123mm
Curb weight 1030kg
GVM 1490kg
Front load limit 765kg
Rear load limit 845kg

Performance:
Top Speed 186km/hr
0-50kph 3.3sec
0-80kph 7.4sec
0-100kph 11.2sec
0-120kph 16.2sec
80-120kph in 4th 13.5sec

Coefficient of drag 0.385
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Post by acmotor » Sun, 16 Aug 2009, 03:44

What top speed (I thinking legal) do you plan to work to ?
i.e. with direct drive, what RPM range and what's the diff ratio/tyre circ.
Will it be a BEV ? Above picture looks like a new idea hybrid (trailer for long distance runs Image )

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Post by coulomb » Sun, 16 Aug 2009, 04:40

Richo wrote: Smaller does mean less requirements but also means less space to put everything.
I gave up on the Sirion and decided to look at Rear wheel drive cars.

Yes, I've often thought that the smallest cars would actually be harder to convert than the medium to larger ones. The hassle is that simple internal combustion engines (without turbo etc) are so damned compact, and batteries aren't particularly compact.

Of course, since you wanted direct drive, that limits you somewhat to rear wheel drive vehicles, or front wheel drive where you can fit a conventional differential in place of the original transaxle.
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Post by Richo » Sun, 16 Aug 2009, 04:46

My estimate is it should be able to get to 150km/hr on a cool still day.
I drive to Fremantle and 1/2 of the trip is under 60km/hr.
On a normal day I would be lucky to get to 75km/hr.
So Top speed is not much of an issue for my use.
But will be able to get on the Freeway with no issue and run at 100km/hr until flat.
It's 3571RPM for 100km/hr.

Yes it will be a pure plug-in BEV.
The series hybrid range extender was only a rental for half the day Image
So the short answer is NO but the long answer is YES.
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Post by Richo » Sun, 16 Aug 2009, 04:52

I would have kept the gearbox in a FWD.
Currently there is no real easy solution for a FWD without the original gearbox.
Most of the places in the Sirion had about a hand width room.
There was just small little pockets here and there.
So a battery box would be more like little 10 battery boxes scattered over the car.
Power cable running every where just to connect it together.
Bah - maybe another day I might reconsider it.
So the short answer is NO but the long answer is YES.
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Post by Richo » Sun, 16 Aug 2009, 05:26

Deciding on the correct motor for an electric car is tricky.
Especially since I wanted more power and acceleration than the original ICE.
Also because it will have no gearbox and run the motor direct to the diff via the tailshaft it needs quite a bit of torque.
So after numerous calculations my options were an 11" Series DC motor or about 22kW AC induction motor.
At this point I decided an Industrial AC motor would be cheaper than a series DC motor.
So AC it was.

I hunted high and low for a 22kW Aluminium Industrial AC Induction motor.
A lot of responses I got back from suppliers "sorry they are rare as hens teeth".
Then the ones that would get one in for me were approx $3500+GST+Shipping.
Eventually I found an 18kW ABB motor on sale cheap from a liquidator from some company in the US that had gone down during the financial crisis of late '08.
Looking at some on line shipping quotes it would be around $600 to freight it Australia.
So I decided to buy the motor.
Then I organsied the shipping.
And to my horror the $600 was just the Australian leg of the journey.
It had to be picked up, trucked part the way accros the US to a depot via a third party shipping agent before it could get to a boat that was going to Australia.
Then there was the boat which got it finally to Fremantle.
All up it cost $1700 shipping it to Australia.

BUT before I would use it I needed to change it's specifications.
So a rewind was ordered locally to change it from 400V to 220V in Class H windings.
That's another $800+GST.

So now I have an AC motor that cost $3000 at my door ready to go.
It worked out a bit cheaper than if I ordered from a local supplier.
So the short answer is NO but the long answer is YES.
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Post by Richo » Sun, 16 Aug 2009, 05:32

Here it is fresh from popping the lid.
Image

And here comparing size and power against an Oatley 500W DC motor vs ABB 100kW peak Brushless AC motor.
Image
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Post by acmotor » Sun, 16 Aug 2009, 05:46

It warms my heart ! Image ABB. Is it 38 or 42mm shaft ?

Not certain of the relevance of the Oatley motor though ??? Image

Who did the rewind ? and is it 220V star or delta ?
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Post by Richo » Sun, 16 Aug 2009, 05:55

The motor specifications are:
Manufacturer: ABB
Nominal Power: 18.5kW @ 50Hz @ 1460RPM
Model number: ABB M2AA 180M
Part number: 3GAA 182 111 - ADB
Weight: 110.00 kg
Nominal Torque: 121Nm
Pull Out Torque: 3.5 x Tn (423Nm)
Efficiency: 91.5% at 75% nominal load.
Mounting: Foot mounted only
Voltage: 3 Phase 400Vac Delta

But now it is rewound:
Rewind Voltage: 3 Phase 220Vac Delta
Power: 33kW Continuous, 115kW Peak @ 91Hz @ 2654 RPM (used on 400Vac in Delta)
Other specifications remain the approx same.

Compare this to the original ICE of 77kW peak. Image
The electric motor should have a noticable improvement in performance.
And NO Gears Image
Last edited by Richo on Sat, 15 Aug 2009, 20:19, edited 1 time in total.
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Post by Richo » Sun, 16 Aug 2009, 06:05

Mmmm the shaft should be 48mm according to ABB.
But I have not measured to confirm.

Well imagine 200 oatley motors to produce 100kW...

The rewind was done by "Global rewinds"
They are my local rewinders on the way home from work.
Other quotes were the same except others were charging more for the class H.
They had no problems - went in - got rewound - came out.
They were quite interested when I told them I would be using it in a car.
Still he told me I should have got the motor local - bad me Image

EDIT:
Measured the output shaft and it is 48mm in diameter as per ABB specs.
Last edited by Richo on Sun, 16 Aug 2009, 13:40, edited 1 time in total.
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Post by acmotor » Sun, 16 Aug 2009, 06:13

Just playing with the numbers...

91/50 x 18.5 = 33.67kW or thereabouts continuous.
at 400/220 x 50Hz = 90.9Hz but you will have a tad over 400V ?
1500 x 91/50 = 2730RPM sync speed less 40RPM slip at 121Nm = 2690RPM
2730 - 3.5 x 40 = 2590 RPM (or a bit less) at pullout.

peak power at ~ 2590RPM = 2 x pi x 121 x 3.5 x 2590 / 60 = 114.863kW (approx) Image

Now you'll have to change that to 120kW controller in your signature !!
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Post by Richo » Sun, 16 Aug 2009, 06:23

Yeah unfortunately the prototype controller will probably be the limiting factor.
As I initially designed it for 100kW.
Not too hard to upgrade later though.

100kW on the BMW is plenty anyway Image
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Post by Richo » Sun, 16 Aug 2009, 06:33

At this stage I will probably construct an engine mount similar in design to Red Suzi.
But I would like to do a test on the BMW before I pull out the ICE.
This is to determine the running efficiency of the vehicle.
It should allow me see the kW required at every speed.
And so I can accurately predict the Joules required for a daily run.
Which helps to estimate the size of the battery pack.

I'm not saying my calculations from manufacturer data is wrong.
I just like to be sure Image

Also as the motor does not fit in the tunnel and I have no gearbox.
The tailshft will be too short to directly attach to the motor.
So I will need to pull the front section of the tailshaft (it's a 2 piece) to have it lengthened.
The tailshaft has a spider coupling at the end
so an adaptor plate will be made up to attach the other half of the spider coupling to the motor.
Image

Last edited by Richo on Sat, 15 Aug 2009, 20:44, edited 1 time in total.
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Post by Richo » Sun, 16 Aug 2009, 06:42

I have to say if you have never played with a big industrial AC motor
Turning the rotor is super easy and smooth as.
I can see the BMW coasting halfway to work Image
Try that on a permanent magnet motor Image
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Post by acmotor » Sun, 16 Aug 2009, 08:48

What will be the current limit on your controller ?

Neat tail shaft arrangement.
My Rodeo has similar centre bearing as does Mal's electrolux.
The flexi coupling is an additional on the BEeMA. Nice.

Battery type not locked in yet ? Hi rate low Ah Lithium to stay within 1000kg ?
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Post by Tritium_James » Sun, 16 Aug 2009, 14:53

Richo, just for future reference (!!!) to ship 115kg in a 70x70x50 (?) box from some random town I picked in the USA to our office in Brisbane, via FedEx air freight, door-to-door, would be $1414.

Controllers are really rated in kVA. So if you want to get 115kW (mechanical) out of the motor, you have to account for the power factor and motor efficiency, both of which might not be quite fantastic if you're running to higher frequencies. So I'd say if you want full power out of the motor, you'd probably want a controller in the 115 / 0.8 / 0.8 = 180kVA region.

Oh, and a permanent magnet motor will spin for ages too, if it's brushless (no brush friction) and ironless (no cogging). Not many like that around, though! Our solarcar hub motor would spin for several minutes just with a good hard shove with your hand.

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Post by vince » Sun, 16 Aug 2009, 17:31

Richo;What can you tell us about your controller?

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Post by acmotor » Sun, 16 Aug 2009, 20:22

Tritium_James wrote:
.......... Controllers are really rated in kVA..........


Actually, VFDs are rated in current first, kVA second and kW third.

Current First, since that is what matters to the switching devices (IGBTs etc) and heat generated in controller. (independent of voltage)
Many VFDs are sold on current rating only. e.g Delta and PDL.

kVA is second because of the range of volatges that most VFDs can operate from. As TJ noted, this is the more complete definition since it allows for pf and voltage. But I would add that not stating A and V leaves things a bit open.

It is common to market industrial VFDs in kW rating since that is what customers want to know e.g. 30kW VFD for a 30kW motor (pf, and voltage having already been allowed for i.e. less technical for consumer).

So after that waffle, if Richo's controller were presented as 100kW I would be thinking it was (100kW / pf) kVA in line with TJ's note.
Maybe 100/.85 = 117kVA ?? What say you Richo ? Image
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Post by Tritium_James » Sun, 16 Aug 2009, 20:34

The reason those VFDs can be sold on current only is because the voltage is known - you're operating them from the AC grid. It's a bit more complex for an EV, where the voltage could be anything.

Heat generated in the controller isn't just proportional to current - switching losses are proportional to both current and voltage. They're quite likely to be similar to conduction losses, so operating voltage is definitely a factor when it comes to losses.

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Post by acmotor » Sun, 16 Aug 2009, 21:10

Well.... e.g. PDL UE140 sold as a 140A drive (referred to as 75kW for people who don't want to know more ! but not as xkVA anywhere in the specs)
There is no mention of kVA and note the rather broad input voltage range. Current determines the final kVA / kW.
BTW, I have one of these PDLs.

2.1 ELITE UE-140 SPECIFICATIONS
INPUT
Input frequency range 48 to 62Hz
Input current < output current
Input displacement factor > 0.99
Input current THD < 40%
Power loss ride through > 2 seconds at nominal
voltage
Input voltage 3 phase AC 230 to 480V

OUTPUT
Output voltage to motor
Microdrive Elite Series 0 to VIN -3V @ 100% load
Ultradrive Elite Series 0 to VIN -15V @ 100% load
Current overload capability 150% for 30 secs (when hot)
at 50°C at nominal rating
150% for 60 secs (when hot)
at 40°C at nominal rating
Frequency range
Closed Loop Mode 0 to ±100Hz
Open Loop Mode 0 to ± 100Hz
V/Hz Mode 0 to ± 400Hz
Efficiency (full load, 50Hz) >97%
Suit motor rated kW typically 50 to 150% of Elite
Series nominal rating (75kW for UE140)
Suit motor rated voltages 5 to 500Vac
Suit motor rated frequencies 10 to 400Hz
Modulation method Space vector modulation
Modulation frequency Up to 16kHz

So this drive can deliver somewhere between 45 and 75kW nominal mechanical from a motor depending on operating voltage. This is what end user wants to know.

Yes to switching losses being related to voltage, but a distant second to switching losses related to current. The only other reference I see in VFD manuals is switching losses related to the selectable switching frequency. Higher frequency = more loss.

Maybe it is safer to quote Amps AND volts with a VFD then you don't get into trouble with users wanting kW when they don't have the amps ?

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Post by Richo » Sun, 16 Aug 2009, 21:57

Tritium_James wrote: To ship 115kg in a 70x70x50 (?) box from some random town I picked in the USA to our office in Brisbane, via FedEx air freight, door-to-door, would be $1414.

Well I live and learn.
I got 3 quotes which included air vs sea for each.
Only one air freight came back cheaper but was still more expensive than sea on other quotes.
Tritium_James wrote: Oh, and a permanent magnet motor will spin for ages too, if it's brushless (no brush friction) and ironless (no cogging). Not many like that around, though!

Ah true.
I was more thinking of that stiff cogging effect on normal brushless PMM.
vince wrote:What can you tell us about your controller?

Hold on - I'll get there Image
acmotor wrote: What will be the current limit on your controller ?
Battery type not locked in yet ? Hi rate low Ah Lithium to stay within 1000kg ?

I would think the current limit will be around the 275A mark.
But obviously if it's getting too hot I'll have to reduce that.
I may also include some destructive testing to make sure Image Image
At the end of the day if it's not good enough I'll redesign.

Since the batteries are the biggest single cost I'll leave them to last.
But at the moment I am leaning towards cylindrical High C low Ah LiFePO4 as you suggest.
My range is quite short so I don't need a big pack.
But I want the power so High rate cells are a must.
Hopefully this should keep the weight down too.
acmotor wrote:So after that waffle, if Richo's controller were presented as 100kW I would be thinking it was (100kW / pf) kVA in line with TJ's note.
Maybe 100/.85 = 117kVA ?? What say you Richo ? Image

Actually only 110kVA Image
I should have got some bigger IGBT's.
But these will do for a start.
You're both right.
I should not just say kW as it is a bit meaningless without other data.
So the short answer is NO but the long answer is YES.
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