AC motor/controller sources

Do you own or use a EV. Then this is a good place to discuss things.
MalcolmB
Posts: 423
Joined: Sat Jun 23, 2007 8:07 pm

AC motor/controller sources

Postby MalcolmB » Wed Jun 04, 2008 9:39 am

I've started looking around for suitable AC motor/controller combinations for a car conversion. These have been coming down in price lately. As I understand it the main benefits of AC motors over the usual DC series motors are lower weight, a flatter torque curve, better overall efficiency across the speed range and no brushes to wear. Disadvantages include higher cost and a greater need to match the controller precisely to the motor.

Thought it would be useful to gather information about suppliers here, so if you know of any please add them to the list, especially if available in the UK :)

Electric Motorsports http://www.electricmotorsport.com/store ... uction.php
offer a choice of four AC motors and two Curtis controllers, with power output ranging from 13.5 to 34..5 kW and prices (motor and controller) from $2500 to $3200. They quoted me an approximate price of $150 for shipping and said they have a 96V combination coming soon.

Green Motorsport
http://www.greenmotorsport.com/green_mo ... 26796.html
have just started offering a water-cooled motor/controller package, with a peak output of 27.5 kW, again with the Curtis controller. They say they can also supply larger motors. I don't have prices yet.

Metric Mind
http://www.metricmind.com/index1.htm
offer a range of high-end motors and controllers with one-hour outputs ranging from 8 to 64 kW. Some prices are listed on the site.

bobc
Posts: 107
Joined: Thu Dec 20, 2007 1:11 pm
Location: Knutsford

Postby bobc » Wed Jun 04, 2008 10:36 pm

Interesting links Malcolm - the last one in particular gives plenty of information & tries hard to "sell" the AC solution.
I was interested to see that all the motor options were liquid cooled. I note that nobody seems to have used my system & gotten a standard industrial motor rewound to reduce the terminal voltage. This got me a custom motor for the price of a rewind (recycling a scrapped industrial motor) - MUCH less than the motor costs in the links! I intend to get that motor into work over the next few weeks to do some electrical tests (I need to know suitable magnetisation current & some equivalent circuit data). We have a big variac so I should be able to get the data I need from 50Hz measurements.
There are 2 flavours of AC machines: induction motors and permanent magnet synchronous motors (or the practically identical "brushless DC"). Although these two can be driven by the same inverter hardware, the control is quite different, and so are the driving characteristics. You can get fantastic power density and efficiency from the PMS motors but they need a fancy(er) controller & they don't have the safe wide high speed range (field weakening operation) that you get from induction motors. The links above all refer to induction motor drives.

User avatar
retepsnikrep
Posts: 1387
Joined: Sat May 26, 2007 4:50 pm
Location: North Yorkshire England
Contact:

Postby retepsnikrep » Thu Jun 05, 2008 4:44 am

http://www.electricmotorsport.com/store ... uction.php

I think these prices are very good value especially if you could get it into the country without paying horrendous duty vat etc :shock:

The motor is also tiny and a featherweight compared to my AC motor which weighed at least 100lbs.

Curtis controller is well respected and allows coasting :)

I would think the 84v 1236 300A model will be enough for most small car conversions. 8)
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

MalcolmB
Posts: 423
Joined: Sat Jun 23, 2007 8:07 pm

Postby MalcolmB » Thu Jun 05, 2008 8:02 am

Bob
I think a lot of people would use your approach if they had the know-how to do it. Personally I've no idea which industrial motors would be suitable or how to specify a rewind. Are there any motor specialist who do this sort of thing regularly? I'd imagine it would make a nice little business for someone who has the knowledge and equipment needed.

Interesting you mention brushless DC motors (what is the difference between those and synchronous PM motors?). These seem to be used in some smaller EVs, but I've not found anything over about 10 kW yet. The two that spring to mind are the Mars motor ("brushless Etek") http://marselectricllc.com/burnishermotor.html
and the Plettenberg Predator http://www.plettenberg-motoren.com/UK/M ... /Motor.htm
11 kW peak from a 1.5 kg motor!

Peter
I've not seen the coasting feature mentioned for the Curtis before. They usually mention regen, but I'm still not sure how useful that would be. Do you think the higher powered AC motor from Electric Motorsports would be suitable for driving a vehicle weighing around 700 kg total without the need for a gearbox, or would it still be advisable to retain it even with an AC motor?

bobc
Posts: 107
Joined: Thu Dec 20, 2007 1:11 pm
Location: Knutsford

Postby bobc » Fri Jun 06, 2008 12:28 am

PMS motor has a sinusoidal mmf distribution around the airgap whereas with brushless DC it's trapezoidal. In the inverter the PMS motor expects to be given sinewaves which are a wee bit trickier to make than the trapezoidal voltage for a BLDC. In the BLDC case it is usual to open circuit the "slopey" one of the 3 phases (to make the trapezoids) transiently, during which time its back emf can be measured to achieve sensorless control. Generally though the sensorless control schemes are still a research topic & commercial systems still use shaft encoder feedback of some description. The PMS system with sinusoidal drive waveforms has no torque harmonics so it's quieter (audible noise not electrical).
That's the situation how I understand it - my job is induction motor drive hardware so I'm pretty hazy on the permanent magnet stuff.
There's a company advertising "in wheel" motors - these have to be PMS or BLDC - & I think they get e.g. 80kW from a 4" cube (!!!!). They mitigate the unsprung weight issues by discarding the brake rotor/caliper & rely entirely on regen braking (also !!!!!) I sort of find it hard to see that washing with DVLA, but I guess it's possible

bobc
Posts: 107
Joined: Thu Dec 20, 2007 1:11 pm
Location: Knutsford

Postby bobc » Fri Jun 13, 2008 12:17 pm

Tests on rewound motor, looking at off load power loss and motor current 3rd harmonic, both of these jump up at 60Vrms(line-line) so that gives me 2 independent pointers at a suitable magnetisation current. Windings resistance, per phase, is 37 milliohm (star connection). That should be enough for me to work out a suitable way to control the motor.
Bob

User avatar
timpootle
Posts: 1361
Joined: Wed Mar 14, 2007 12:13 pm
Location: Chorlton-cum-Hardy, UK

Postby timpootle » Fri Jun 13, 2008 1:48 pm

Wow- I'm impressed.

Work are sending me on a 4 week course (starting Monday) on aircraft electrics. By August I might understand this!

Keep up the posts, Bob. I am fascinated.
Tim Crumpton

User avatar
PHEV
Posts: 123
Joined: Wed Mar 26, 2008 5:50 pm
Location: Peacehaven/Brighton

Postby PHEV » Sat Jun 14, 2008 4:53 pm

Greenmotorsport are coming on well with thier AC motor, testing is going well, and they are taking preorders for the first run..

16kg motor @ 50HP. I've put my name down for 1!
*Mazda MX-5, 300KW peak, 300v 20KW/h lipo pack, Soliton 1000A controller. 1100KG.
*Ducati SS twin Agni 80HP peak.
*Aprilia RS motorcycle, 500A controller, Cedric's AgniMotor, 96v 6kw/h LiPo pack, 130kg, 90mph.
www.jozztek.com

MalcolmB
Posts: 423
Joined: Sat Jun 23, 2007 8:07 pm

Postby MalcolmB » Sat Jun 14, 2008 5:48 pm

Look forward to hearing more about that Jozzer! Can you tell us how much?
Is it for another bike or are you planning something bigger this time?

User avatar
PHEV
Posts: 123
Joined: Wed Mar 26, 2008 5:50 pm
Location: Peacehaven/Brighton

Postby PHEV » Sun Jun 15, 2008 10:41 am

I don't think they had a finished price yet...around £1500 was mentioned, and the controller is expensive too I know. At least i'll have a couple of months to save up for it :lol:

I'm thinking of doing a longer range tourer....I'm looking for a Ducati ST2 as a doner. If I can't find one, I may be "forced" to test it in the little aprilia though :twisted:

Green motorsport are just an hour away from me, they've invited me up to see one in action...i'll try and get up there week after next and check it out.
*Mazda MX-5, 300KW peak, 300v 20KW/h lipo pack, Soliton 1000A controller. 1100KG.
*Ducati SS twin Agni 80HP peak.
*Aprilia RS motorcycle, 500A controller, Cedric's AgniMotor, 96v 6kw/h LiPo pack, 130kg, 90mph.
www.jozztek.com


Return to “Cars,Vans and other road vehicles”

Who is online

Users browsing this forum: No registered users and 5 guests