# AC motor supplier in NZ?



## Hadleigh Reid (Jul 22, 2008)

Hello,

Anyone know of any AC motor and inverter suppliers for conversion in NZ?


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## Jens Rekker (Oct 26, 2007)

Hi

If you are going with an AC induction motor then that's easily obtained in NZ. You could buy an industrial 3 phase 415V 11kW induction motor new or second hand. Second hand is probably OK, just put new bearing into it and test the windings.

The more difficult item is the controller for an AC induction motor. I have heard of Danfos or Micro-Drive controllers being used behind a 3-phase high current inverter to drive the induction motor. It is helpful for your battery pack to be pitched at the higher voltages; typically in the 220V to 500V range. Commonly lots of smaller Ah batteries or lithium cylindrical battery packs are used.

To get a packaged AC motor, controller and inverter set-up tailored for EV's you are probably limited to importing from Metric Mind in California or the old Solectria kit from EVParts in Oregon. Save up your dollars though. AC systems are hideously expensive - say $25,000 of the Metric Mind setup and $14,000 for the lower powered Solectria package.


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## Hemon Dey (Jul 31, 2008)

Hi Jens,

Is 11kW powerful enough? Both Metric Mind and Azure Dynamics (previously Solectria) have motors that are more powerful even for the low power range. Also aren't the typical mains voltage controllers designed for fixed frequency operation?

Regards,
Hemon 



Jens Rekker said:


> Hi
> 
> If you are going with an AC induction motor then that's easily obtained in NZ. You could buy an industrial 3 phase 415V 11kW induction motor new or second hand. Second hand is probably OK, just put new bearing into it and test the windings.
> 
> ...


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## Jens Rekker (Oct 26, 2007)

Hi

Don't forget that the 11 kW is three-phase, i.e. the current carried in three cycles so the power is RMS based.

Tuarn Brown went 11 kW for his AC Suzuki conversion:
http://www.evalbum.com/1149

Mal went 15 kW for his Hilux conversion (under-way):
http://a4x4kiwi.blogspot.com/
(don't be confused by the "a4x4kiwi", Mal is actually in Sydney).

Even the comparable DC motors are around 19 kW and 25 kW, respectively (e.g. ADC 6.7-inch and 9-inch motors).

Industrial AC 3-phase induction motors were originally developed for fixed frequency use. In the 1980's advances in solid state AC tech lead to many induction motors being fitted with veriable speed controller that chopped and modulated the supply frequency to the motor leads. The controllers were readily wired between the supply circuit and the motor leads. This tech was taken further in the 1990's and it is these units the Tuarn and Mal are using for their AC conversions.

The Metric Mind and Azure Dynamics both state the power ratings differently to the industrial motors above and concern higher performance systems.

I have done a DC conversion in my own case, but I acknowledge the cost-effectiveness and elegance of the AC system that Tuarn has applied to his conversion. Mal is following Tuarn's lead. I hope similar packages are used in conversions more widely.


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## Hemon Dey (Jul 31, 2008)

I like the sound of AC (brushless DC or induction) because it is fully sealed and has a more flat torque curve up to the rated RPM, then a linear torque dropoff there after, and can much more easily be made regenerative (usually a function built into the AC controller). 

However the controllers are more difficult to design, hence the hefty price tag. Azure's controller is cheaper than Metric Mind's - but still quite expensive, especially so for us EVers in kiwiana wrt shipping.

Jens, out of interest what DC motor did you use in the end? And what controller?

Regards,
Hemon 




Jens Rekker said:


> Hi
> 
> Don't forget that the 11 kW is three-phase, i.e. the current carried in three cycles so the power is RMS based.
> 
> ...


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## Jens Rekker (Oct 26, 2007)

Hi

I used a "bog-standard" Curtis - ADC set-up. The units were old and slightly experimental at the time of manufacturing; a 144V / 500A version of the Curtis 1221 controller and an ADC XP-1263A motor. They were superceded by the Curtis 1231C and the ADC FB 9-inch motor, respectively. But the overall build was a very standard series DC set up at 144V using 24 x 6V Trojan T105's. very simple, no finese and relatively inexpensive (or as much as conversions can be cheap and still get certified under the NZ guidelines).

An AC conversion is a much less conventional prospect. I imagine it will take a far bit of planning and research. I would follow Mal's blog and read up on the AC discussion within the Australian EV Association website. Alternatively there are discussion groups based in the states with threads following AC technology.


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## Hadleigh Reid (Jul 22, 2008)

Thanks for that guys. Ive since been thinking that instead of spending $30k NZD on a flast AC motor and converter im gonna go for a WarP 11" DC motor. Looks like the Curtis 1231c-8601 controller's the most appropriate and affordable. Do these still 'whine'? Drops the motor and controller to under $10k i rekon, hopefully will enable me to get lithium!


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## Jens Rekker (Oct 26, 2007)

Hey Hadleigh

You've got a healthy budget in mind!

It depends how much performance you are after. If you're talking about a WarP11 (an 11-inch Netgain DC series motor), then you are probably thinking you want good performance. In general, the 9-inch motors are up for most applications and the 11-inch motors are for performance. The bottleneck to high performance will be the controller and battery pack.

The Curtis is a wonderful pile of power electronics, but it is not a performance package. The 1231C is limited to 500A (ie 72 kW peak). A higher current or even higher voltage controller will provide performance current. The obvious candidate is a Zila 1000A controller, but they are effectively unavailable due to the waiting list. There other high current options but you need to dig hard for them or get lucky with an old DCP or Auburn.

The next bottleneck is battery pack. In the lead-acid range, the flooded deep cycle bats are the longest lived and have the best range. But the Absorbed Glass Mat (AGM) lead-acid batteries such as Optimas or Orbitals give the best performance in terms of delivering high currents without too much voltage sag. It comes down to internal resistance and an obscure but important effect called 'Peukart'. Best of all, a high performance lithium iron phosphate or lithium polymer battery pack gives best battery performance at high current draw.

Next, you need to match the motor, controller, battery pack and the weight of all this with the donor car. In general, it is best to choose your donor car; set goals for performance and range before selecting the gear that will deliver it for you.

Back on the subject of AC motors and controllers, I was wanting to point out that there is an alternative to the really expensive (but high quality) AC kits from MetricMind and Azure Dynamics. That is the use of a Variable Frequency Drive (VFD) from industrial applications. The VFD technology includes rectifying three phase power to DC in the industrial setting, before inverting it for ultra-flexible frequency control of an AC three phase induction motor. Because EV converters are already working with high current DC from our batteries, the VFD units are an effective means of inverting and controlling the speed of an AC induction motor powering an EV. That's the approach the Tuarn Brown and Mal are using.


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## Hadleigh Reid (Jul 22, 2008)

Thanks again. Im hoping to keep it below $25k, all adds up though! Looks like ill need to have a look around


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## linz (May 18, 2008)

As I understand it, regen braking is more common and easier on AC systems than DC. But whats the situation with regen and DC and is it possible on the standard controllers available? As said in another thread NZ is a hilly country and regen could be quite a benefit, has anyone done the range improvement calculations with any NZ cities in mind?


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## Hemon Dey (Jul 31, 2008)

Most of the DC controllers out there are series DC, where the field windings are in series with the drive circuit. This means that when you stop the controller, the field windings also die - hence you have just a bunch of non-energised windings turning around another bunch of windings. This makes it not really viable to do regen, unless the field winding is switched out of the loop and separately excited during braking. 

Brushless DC and Brushed PMDC motors are the easiest to implement regen in, because the rotor that is spinning is a permanent magnet, not a coil of wire that needs to be energised. DC motors that have separately excited field windings is possible to implement regen, though these aren't as powerful as series DC. All these require a charge pump (or boost converter) setup to increase the votlage of the back emf of the motor as it starts to slow down because the speed of the slowing down motor doesn't generate a voltage high enough to charge the battery. From what I've read, the regen complexity constitutes a lot of effort but for diminishing returns because the amount of energy that is able to be recaptured doesn't always justify the expense. However a lot of Brushless DC (or 3 phase AC induction) controllers have the ability to regen built into the topology of the circuit - though it pays to remember that AC controllers are complex beasts of their own. 

The issue with a slowing down motor can be also be side stepped to some extent using gearing ... when slowing down you also shift down in gears to keep the motor speed high enough that regen still works. This is probably a simpler way rather than having switching electronics to do that job. Because most of the conversions done will retain the gearbox, and most of them also retain the clutch - this would seem the easier and more intuitive way of doing "engine" braking. However you still need to have an AC motor or separately excited DC motor to implement this. You could also play around with the idea of switching out the field winding in a series DC setup, and energise it only during regen - note that this take energy out of the pack, to get energy back into the pack (low regen efficiency).

Incidently, I was reading last night a novel idea of using a CVT transmission in an electric car, here. The motor is controlled by a contactor controller (very rudimentary) but is turned on so that is revs up to the most efficient RPM for it (which would be 3000-5000 rpm depending on the motor). The job of the CVT is to smoothly transfer the energy fromthe motor to the wheels, and as you press more on the accelerator the car picks up speed by changing up. When you lift the foot off the pedal the CVT gets a signal to shift down again, thereby maintaining the motor speed as constant as possible over the speed range of the slowing car ... this enables the regen circuit to work without complex electronics, and technically easier to implement. It was designed before the days of complex power electronic controllers however and is a bit old school, but still novel I think.

Regards,
Hemon 

ps: sorry it got a bit technical there ... just ignore me if I'm ranting like a mad scientist


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## Jens Rekker (Oct 26, 2007)

Hi

I think Brushless DC motors (a.k.a. BLDC) with their relatively straightforward and effective regen are a definite possibility. The only option I am aware that you could readily do this is with the Mars 15 HP pancake motor and the Kelly BLDC controller. They are pretty much sized for EV motorbikes and really small cars. Their peak voltage is 72V.

An Italian company called Zapi puts out a controller that will control a series wound DC motor (e.g. an ADC FB-4001 or Netgain Warp9) with regen. The controllers were labelled Zapi H2 and H3. They had a chequered history with a few notable cases of their MOSFETs burning out in regen mode (http://jerryrig.com/convert/step38.html)http://www.evconvert.com. I know of one Zapi in NZ, but it is not current fitted in a vehicle.

Separately Excited DC motors are the third DC option for regen. Basically, your controller has separate circuitry the excite the windings rather than the regen current having to pass through the brushes. A standard DC series wound motor can be used, except the terminals that you normally short together go back to the controller to pick up the excitation current. Shunt motors will work with SepEX as well.

I was driving my electric ute today and thinking that I was getting used to travelling around town without using much heavy braking anyway. I find myself coasting a great deal by anticipating traffic changes ahead of me. There is absolutely no back-pressure with the motor de-energised when your foot's off the accelerator, so you tend to accelerate and glide. I don't think I would get much back from regen to justify much expense in fitting it.

The other benefit of AC is that it is in general thought to be about 5% more efficient than DC, all other things being the same. The stress on the battery pack is thought to be less with AC than the more raw DC systems.


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## Hadleigh Reid (Jul 22, 2008)

Thanks guys.


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## linz (May 18, 2008)

Thanks for all that info. I found two useful articles that helped me understand better also-

excellent article on the various types on motors (insight that a commutator is essentially a mechanical inverter)
http://www.repp.org/discussion/ev/200201/msg00578.html

forum guide explaining problems with dc regen, advance timing is a show stopper.
http://www.diyelectriccar.com/forums/showthread.php?t=8848

From what I have read, high-voltage DC brushed have advance timing that work against regen operation, in addition to the problem of field winding current. But brushless DC is as complex and maybe expensive as an ac controller-motor pair (almost the same thing, as the controller generates an ac waveform). Also brushless DC are not as powerful as series DC (perhaps because its a passive magnet, cannot strengthen the field with more current). 

With smaller vehicles such as bicycles or motorbike conversions brushless dc is fine and regen can be included with a suitable controller such as one from kelly.

This still leaves the question, wellington city has very steep hills. Would regen be very important there to the point of considering going for a small subcompact car to enable a brushless dc solution for modest cost or make a stronger case for a higher cost AC option. Would a standard 120 - 144V (6V or 8V) series dc with curtis or similar ute/pickup work ok in wellington city?


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## Jens Rekker (Oct 26, 2007)

Hi Linz

I don't think so. Driving the electric ute around Dunedin is showing me that you don't want to be limited to a Curtis-style 500A controller. I can tackle steep hills by downshifting. But, one of the easiest ways of killing a bushed DC series motor is by overspeed, so you can't screw the arse end off the motor in low gear to generate the torque that you need to climb hills in the same way a normal car can around Dunedin. It could be be that it is the weight that my flooded lead-acid 700 kg battery pack is hauling around, but performance in accelerating uphill is disappointing from my ute. I leaves me grinding up steep streets at 20 - 30 km. Try to go faster and you are very quickly in the 400A to 500A of current draw with substantial voltage sag (instantaneous pack voltages down around 110V instead of 150V where it should be for a 144V nominal pack). The Curtis is current limited to 500A anyway. Staying in the high currents for any length of time isn't good for the battery pack, range or for the thermal integrity of a medium capacity controller like a 144V/500A Curtis.

So, if you are going to go for a conversion as heavy as a ute, and if you are going to be _routinely_ doing seriously steep hills like Wellington's then I would definitely recommend a 800A to 1000A controller. We forget just how steep some of our cities are compared to continental America, Australia and Europe. I am sometimes worried that the conventional matchings of cars / pickups and electrical kits developed in those places overseas are going to turn out under-powered for New Zealand. Believe it or not, we also drive faster than a lot of those places (OK, not as fast as Italy...). So, the take home message that I have is don't kid yourself that a 500A controller in an even moderately heavy conversion is going whizz around the hills. The higher current controllers were developed more for track performance, but they would be bloody useful in Wellington or Dunedin too.


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## linz (May 18, 2008)

I didnt consider the power to get up hills but of course is more important than regen. So ignoring AC, that pretty much leaves the Zilla 1K, priced about 2K USD. The controller might be able to do 1000A peak but how about the batteries? (say max constant 500A). Configuration would be like a performance EV, looking at 12V and AGM which might source higher A but are more expensive and less cycle life. Or look at buddy pairing batteries, which I am not to sure about because of current loops between pairs and balancing and matching issues. In terms of vehicle size, I think the power to weight ratio is more important, or for a given battery, battery weight to total vehicle weight ratio. Then the overall size of the vehicle would perhaps then determine its range, or at least the total kW.

For a small car, with good power-to-weight ratio, standard components might again be used i.e 500A controller, and fewer units of expensive batteries i.e. AGM or lithium (as in Mike Laba's Mini). With a small enough car, a low V brushless DC system with regen could be considered. 

The other option is multiple battery strings, unfortunately there seems to be no controllers that take more than one battery string (total A/n strings) and combine then internally or use in different motor phases. Unless AC does this?

So for central wellington-
small vehicle with many 12V flooded or AGM's, with short range $$
full-size vehicle with buddy pairs or AGM's with 1K controller, mid-range $$$
small vehicle with amt of lithium determining range $$$$

for flat suburbs, or hutt valley
full-size vehicle with 6V or 8V for cheapest and up-to long-range $$
small vehicle for short-mid range, with cheap components $


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## Jens Rekker (Oct 26, 2007)

If we are still on the subject of AC motors and inverters, I got a message from a kiwi electrician in the South Island who is doing an AC conversion. Just as I was outlining earlier in this thread, he is using the industrial motor variable speed drive approach called VFD. Here's what he sent to me:

_"I am actually converting a Ford Courier Ute at the moment. I have all of the internal combustion gear removed and a 22 kw 4 pole electric motor installed and connected directly to the drive shaft._

_I aim to power this with a modified Variable Speed Drive, that will allow me to apply about 700 volts DC directly on to the DC bus._

_At this stage I haven't designed the connecting and control / protection of the DC circuit, neither have I designed the charging circuit or chosen my batteries, so any information or ideas that I can get from the talk will be most appreciated. I'm also considering about 52 x 12 volt deep cycle 20 to 30 amp /hour batteries. I only require a range of a minimum of about 10 km but preferably up to 25km between charging."_

So, he is using an ordinary industrial-standard three-phase induction motor and an VFD unit for his direct coupled drive. I reckon that this approach has real application for NZ style AC conversions without the usual cost of the Azure / MetricMind equipment configurations. A lot of the gear will be in the country already for industial use and potentialy available second-hand. Regen will be cinch, and the battery current draw effect is substantially less for high voltage AC power systems.


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## Hemon Dey (Jul 31, 2008)

Sounds great Jens, you should get him on the list and post a few pictures ... 

700V DC sounds like a whopping battery bus though, you'd want to be extremely careful to not accidentally short anything???? I saw a schematic for EV somewhere where a 500 VDC bus was split to be +250V - 0V -250V system. This was meant to be a safer way to work with the high voltage as you has separate contactors for the +ve bus as well as the -ve bus. 

I think the University of Canterbury's MR2 conversion used 26x 12V 30 AHr AGM exide batteries which were smaller, gave a 312VDC bus which was then inverted to 3-phase AC (custom design) driving a Solectria motor. They also had a pretty impressive DC-DC converter to buck the voltage down to 48V for high voltage peripheral bus, and then down to 12V as a second stage for low voltage peripheral bus. That was the original plan anyway, not sure if they actually used the 48V or not. It's probably something to consider seeing that it might be hard for find a DC-DC converter for a 700VDC bus. Also he is going to have to find a way to charge the batteries on the 700VDC bus, can you get that high with 3-phase at home? or do you need an industrial 3-phase connection?

Regards,
Hemon


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## locost_bryan (Aug 18, 2008)

What about the practicalities of importing from Blade/Azure in Aussie?

Prices don't look too bad? $AUD3,080 (about $4k) for the AC24LS or $AUD9,037 (about $11k) for the kit (AC24LS, DMOC445 controller, AT1200 fwd gearbox/diff).

Bryan
Swanson


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## Hemon Dey (Jul 31, 2008)

Here are the prices direct from Azure in 1-offs:

US$3495.. .. .. ..DMOC445 motor controler
US$2595.. .. .. ..AC24 motor
US$1695.. .. .. ..AT1200 gearbox 10:1 ratio, no parking pawl
 US$850.. .. .. ..DMOC interface kit
 US$65.. .. .. ..DMOC communications cable
US$945.80 shipping to Chrischurch, including insurance 



Total = US$9648.8 = NZD$13608 + taxes. 



This quote from Azure was obtained on the 18th May 2008. These might be of interest if you wanted to compare pricing.



Regards,
Hemon


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## locost_bryan (Aug 18, 2008)

Hemon Dey said:


> Here are the prices direct from Azure in 1-offs:
> 
> US$3495.. .. .. ..DMOC445 motor controler
> US$2595.. .. .. ..AC24 motor
> ...


Thanks, Hemon.

The Blade price list can be downloaded from here.

Using today's ASB forex rates :-
DMOC445 $US3495 = $NZ4808 - $AU3718 = $NZ4491
AC24 $US2595 = $NZ3570 - $AU2761 = $NZ3335
AT1200 $US1695 = $NZ2332 - $AU1803 = $NZ2178
DMOC int $US850 = $NZ1169 - $AU904 = $NZ1092
DMOC cab $US65 = $NZ89 - $AU69 = $NZ83
Total $US8700 = $NZ11970 - $AU9255 = $NZ11182

Not too much different. Perhaps Blade are passing on their bulk discounts?

Bryan
Swanson


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## Hemon Dey (Jul 31, 2008)

Thanks Bryan, it looks like they are probably trying to price it so as not to encourage others to import it themselves. I didn't ask what their price break was, but as these are expensive items, it may not be very many before you get a bulk order discount (perhaps 5-10?) ... I'm guessing.

Hemon


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## Hemon Dey (Jul 31, 2008)

From what I gather you can reconfigure a 4 pole AC motor to spin at the rated RPM at 1/4 of the voltage by changing the pole windings from series to parallel. This increases the current x4 and the motor still does the same power. 

What this means is that you won't need as high a battery pack as originally thought, and I'm guessing that most smart VSDs are capable of working at lower DC busses. Has anybody contemplated or tried doing this? Would seem to me worth the investigation as it makes the demands from the battery pack much more inline with that of DC conversions.


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