# [EVDL] Available AC drive systems?



## EVDL List (Jul 27, 2007)

Metric Mind offers Brusa and MES AC drives. They're supposed to be pretty 
good stuff, but they're not cheap. 

http://www.metricmind.com/

David Roden
EVDL Administrator
http://www.evdl.org/


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## EVDL List (Jul 27, 2007)

Yes, MM is not known to be cheap. But it seems as if a reasonable setup can
be gotten for around $12k (motor and controller). That's not really so
terrible. An Azure Dynamics AC55 and DMOC445 controller can be gotten for
around 7-8k total though. (That is, if you can find someone to sell you
one.)

However, I had a price quote for a different system (which shall remain
nameless) come in at 21k. I didn't think it was all that special or super
high powered (240Nm peak.) It was 3x the price of an AC55 setup! (Which,
btw, is 280Nm peak torque) For 35k I can purchase an entire Nissan Leaf. I'm
really shocked by the sort of astronomical prices some companies want for
their products. Does anyone really spend $21k on a 45kW motor and
controller? One still needs batteries, a charger, and whole bunch of other
parts. At that rate the parts alone would cost way more than buying a prius,
volt, or leaf. Why bother at that point?

I'll keep MM in mind. I know they are a reputable company.



> EVDL Administrator <[email protected]> wrote:
> 
> > Metric Mind offers Brusa and MES AC drives. They're supposed to be pretty
> > good stuff, but they're not cheap.
> ...


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## EVDL List (Jul 27, 2007)

HPEVS, formerly HPGC, has a line of AC motors using the Curtis 1238
controllers. Voltage limited but an affordable choice for smaller vehicles.
http://hpevs.com/



> Collin Kidder wrote:
> >
> > Alternatively,
> > what other AC systems would be recommended?
> ...


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## EVDL List (Jul 27, 2007)

> On 17 Aug 2011 at 13:49, Collin Kidder wrote:
> 
> > I'm really shocked by the sort of astronomical prices some companies
> > want for their products. Does anyone really spend $21k on a 45kW motor
> ...


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## EVDL List (Jul 27, 2007)

HPEVS, already mentioned is the lowest cost for a motor/controller up to
about 55kW peak power (AC50/Curtis 1238R controller, 115V nominal pack), but
even they are a bit more costly than a good quality equivalent power DC
system. Above that power DC systems are much less costly. Next step would
be systems from http://www.electro-vehicles.eu/, and similar systems from
Metric Mind. This company:
http://www.evo-electric.com/products/electric-motors/, has some very nice
motors. A a diyer in Australia reportedly purchased one for 6k Pounds, and
plans to use it with the very nice Wave Sculptor (Australia) controller for
overall price of around $10k-$12k I would guess. Price goes up from there. 
In addition to small volume production already mentioned, selling to diyers
(depending on the diyer) can entail far more support per unit than selling
to commercial interests. It is generally assumed that most companies would
rather not deal with the headaches, so price their one unit sales very high
to discourage such purchases and to compensate themselves well for the
potential headaches that may follow such sales.

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## EVDL List (Jul 27, 2007)

Thanks for the suggestions.

Evo Electric seems interesting. Their drive solution is a bit out of spec
for what I want to do but it's certainly a nice set up.

6k pounds is about $9900 US. The wave sculptor is about $6k Australian as
far as I remember. $AU is fairly close to $US. That brings the total cost up
to somewhere around $16,000. I wouldn't exactly call that cheap but the Evo
motors are very, very powerful.

I understand that companies don't want to deal with DIY people quite as
much. However, that doesn't perfectly fit my description. I represent a
company, we've already done an electric car that has gotten plenty of
attention, and we're shooting to do at least two more in the next year and
likely more after that. It's not GM levels of production but I'm not a
single guy working in his garage. I've had reasonable luck with a variety of
companies who are willing to sell to smaller manufacturers/conversion shops.
Other companies have platinum plated motors which come with a chauffeur and
a personal masseuse. I can't justify the cost of the really expensive units
as nice as it would be to relieve the tension in my sore back and have
someone drive me around.

I know a lot of the people who sell DC hardware so I don't want to say
anything bad about DC or push hobbyists away from DC. However, I'm really
personally partial to AC (for pretty much all of the reasons you'll see
brought up in AC vs DC fights) despite knowing so many DC vendors.  That
having been said, I'm likely to be doing some DC based conversions at some
point.



> tomw <[email protected]> wrote:
> 
> > HPEVS, already mentioned is the lowest cost for a motor/controller up to
> > about 55kW peak power (AC50/Curtis 1238R controller, 115V nominal pack),
> ...


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## EVDL List (Jul 27, 2007)

I much prefer AC also but can readily see why people go with DC. I'm using
an HPEVS AC50/Curtis 1238-7510 controller in a small car (Suzuki Swift)
which works well. If that option hadn't been available I would have gone
with DC for cost reasons. I just can't see paying the high prices for more
powerful AC systems (as much as I would like to do a conversion with an evo
motor and Tritium controller), especially with the Leaf now becoming
available (still not available in my location).

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## EVDL List (Jul 27, 2007)

I should correct myself here because I was spreading some wrong information.
My memory had failed me and I thought that Azure Dynamics would not sell
directly. It turns out that, at least in some cases, they will. Also, it is
likely that Ford dealerships which have Azure Dynamics certification will be
able to purchase hardware for people. I can provide an update on all of this
later if anyone is interested. Otherwise just let this be my apology for
impugning AD.



> Collin Kidder <[email protected]> wrote:
> 
> >
> > I am trying to get equipment out of my local AD service dealer. I don't
> ...


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## EVDL List (Jul 27, 2007)

> On 19 Aug 2011 at 10:51, Collin Kidder wrote:
> 
> > Other companies have platinum plated motors which come with a chauffeur and a
> > personal masseuse.
> ...


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## EVDL List (Jul 27, 2007)

I'm curious which would perform better if you max'd out allowed voltage.

1. HPEV AC50/Curtis 1238-7510
2. Warp 9/Soliton 1

I chose #2 because my jeep will end up around 3500 lbs and I was told the A=
C50 would
not be the best solution. Also, with #2, I could go to a higher voltage =
which would help performance.

I would have loved to have gone AC, but there was no good economical soluti=
on for me.

Any comments?

-ben


________________________________
From: tomw <[email protected]>
To: [email protected]
Sent: Friday, August 19, 2011 10:07 AM
Subject: Re: [EVDL] Available AC drive systems?

I much prefer AC also but can readily see why people go with DC. I'm usi=
ng
an HPEVS AC50/Curtis 1238-7510 controller in a small car (Suzuki Swift)
which works well. If that option hadn't been available I would have gone
with DC for cost reasons. I just can't see paying the high prices for mo=
re
powerful AC systems (as much as I would like to do a conversion with an evo
motor and Tritium controller), especially with the Leaf now becoming
available (still not available in my location).

--
View this message in context: http://electric-vehicle-discussion-list.41352=
9.n4.nabble.com/Available-AC-drive-systems-tp3750180p3755415.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabb=
le.com.

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## EVDL List (Jul 27, 2007)

> Ben Jarrett <[email protected]>wrote:
> 
> >
> >
> ...


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## EVDL List (Jul 27, 2007)

> Gary Krysztopik wrote:
> > I ordered a 40kW nominal, 80 kW peak BLDC drive from China and it just
> > came in. I think it's taking a detour to a dyno via the Revolt guys,
> > they are making the clutch adapter. It may still be too small for 3500
> ...


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## EVDL List (Jul 27, 2007)

Is that one of the motors Dave Kois is selling though CurrentEVtech?



> gary k wrote:
> >
> > I ordered a 40kW nominal, 80 kW peak BLDC drive from China and it just
> > came in. I think it's taking a detour to a dyno via the Revolt guys,
> ...


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## EVDL List (Jul 27, 2007)

> Collin Kidder wrote:
> >
> > I know a lot of the people who sell DC hardware so I don't want to say
> > anything bad about DC or push hobbyists away from DC. However, I'm really
> ...


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## EVDL List (Jul 27, 2007)

From: Jeffrey Jenkins
> [AC vs. DC] does seem to be the subject of endless and often tiresome
> debate.

Amen to that! It always does seem to create a lot more friction than force.

> The fact of the matter is that an AC inverter will always... be
> more complicated and less efficient than a similarly powerful DC
> converter.

I wouldn't go so far as to say "always"; but it is intrinsically harder to make AC from DC than it is to make DC from DC. An AC inverter requires more parts, which guarantees more complexity, higher cost, and lower reliability. 

Efficiency is more complicated. Consider just the controllers: A DC controller normally has just one power semiconductor between motor and battery (a transistor during the on-time, and a freewheel diode during the off-time). An inverter normally has *two* power semiconductors in series with the motor (a high-side transistor at one end of the winding, and a low-side transistor at the other end). So the inverter's conduction losses are usually twice as high.

But that's only true for the usual 6-transistor bridge. You can get back to a single power semiconductor per winding by center-tapping the motor winding or the battery pack. This is less popular and has problems of it's own; but it makes the basic AC vs. DC controller efficiencies the same.

> you can't ignore the much more complex software to control an AC
> motor in a traction application, whereas the control loop for a DC
> motor can be distilled down to - literally - about a dozen lines
> of C code

Heck; a DC motor controller doesn't even require a micro! Even full featured DC controls with forward/reverse, field weakening, and regenerative braking don't need micros.

> the price penalty paid in the inverter can *theoretically* be
> offset by savings in the motor. AC induction motors (ACIM) can
> not only be much more efficient than an equivalent continuous
> output series DC motor, they can also cost much less to manufacture,
> owing to the greatly simplified rotor construction.

This is where it really gets complicated. I think the theoretical efficiency difference between AC and DC motors is small, and the effects of exactly how you make them are large. Thus, the practical manufacturing differences swamp out any theoretical differences.

A motor that is only built in small quantities will cost more than one made in large quantities.

A motor that costs more will generally have higher efficiency, because they could afford better materials.

> nebulous cost-benefit tradeoffs like regen vs. battery size, etc.

Regen certainly works (adds a little range), and it can improve drive-ability (the car has "engine braking" like an ICE). But the owner's driving pattern will determine whether regen is a "wonderful improvement" or "worthless cost-adder" in his situation. 

--
Those who say it cannot be done should not interrupt the one who is
doing it. -- Chinese proverb
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net

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## EVDL List (Jul 27, 2007)

Jeffery wrote -

>And despite that I make a DC
> motor controller for EVs,

This may be a stupid question, (and I have been known to do stupid things...) but what controller is 
that?

Rush Dougherty
www.TucsonEV.com 

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## EVDL List (Jul 27, 2007)

> Rush-5 wrote:
> >
> > Jeffery wrote -
> >
> ...


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## EVDL List (Jul 27, 2007)

> You won't offend me with your opinions, except insofar as this does seem to
> be the subject of endless and often tiresome debate. My experience is
> mainly
> in power electronics for industrial and, uh... let's just say more esoteric
> applications, so I have a better than average understanding of the
> differences in the hardware for both systems. And despite that I make a DC
> motor controller for EVs, I really am technology-neutral. AC, DC, it all
> requires switching volts and amps to me...
>
<Snipped A lot>

Yes, I didn't want to get into it because the topic has been debated
endlessly on every EV related forum.

I pretty much agree with what you said. However, AC has some advantages that
I don't believe should be overlooked:
1. They tend to be able to spin much faster (upwards of 11,000-12,000 RPM)
which can allow for no transmission or a single gear. This isn't really a
huge advantage if one is doing a conversion as everything in the conversion
will tend to be constructed to handle 0-6000 RPM.
2. Their torque doesn't drop like a stone starting at 0 RPM. Instead the
torque drops like a stone after about 4,000 RPM. So, the starting torque is
less but you get to keep your torque for longer. I think that this makes
them more suited for daily drivers. Now, if you are drag racing then you
would, of course, want DC motors.
3. Much less likely to be able to run away. A stuck inverter will most
likely create a brake not a rocket.
4. Higher voltage and lower amperage allows for smaller wiring
5. It's usually simpler for the end user. AC controller tend to require less
external hardware.

But, there are a million reasons why either AC or DC could better. I see
advantages to both and I think both have their place.
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## EVDL List (Jul 27, 2007)

> Collin Kidder <[email protected]> wrote:
> 
> >
> > I pretty much agree with what you said. However, AC has some advantages that
> ...


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## EVDL List (Jul 27, 2007)

Sort of. I'm running 115V nominal, my AC31 came set to 6500, I reprogrammed
it for 7500, the controller can go to 8000, but I'm not finding much power
left above 7000 because of limited voltage. When talking to HPEVS they said
the motors are good to about 10,000. They are seriously in need of a higher
voltage inverter to push their real potential. There are rumors of Curtis
going to 144V which would be nice.
I've also heard rumors of some other AC systems in the works, can't give
details though.



> Zeke Yewdall wrote:
> >
> >
> > Though, some of the available AC systems are design to be more like DC
> ...


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## EVDL List (Jul 27, 2007)

> Collin Kidder wrote:
> > However, AC has some advantages that I don't believe should be overlooked:
> > 1. They tend to be able to spin much faster (upwards of 11,000-12,000 RPM)
> > which can allow for no transmission or a single gear.
> ...


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## EVDL List (Jul 27, 2007)

> Dan Bentler wrote:
> > For AC induction on VFD all the manuals I read say it is constant torque up to baseline RPM ie 3600 nominal for 2 pole 60Hz. Above baseline HP is constant, the voltage is constant and torque falls off. QUESTION: Above baseline is the decrease in torque solely because of constant voltage or is it caused by this and other factors?
> Torque starts to fall above baseline because that's where the motor
> reaches full voltage. Above this point, the inverter can no longer apply
> ...


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## EVDL List (Jul 27, 2007)

What does your battery voltage under regen get to? I'd be worried that at 115 volts nominal it would get to high when charging quickly. That's why I kept mine at 96volts. But I have not gotten it running yet to test it.

Sent from my iPhone



> AMPhibian <[email protected]> wrote:
> 
> > Sort of. I'm running 115V nominal, my AC31 came set to 6500, I reprogrammed
> > it for 7500, the controller can go to 8000, but I'm not finding much power
> ...


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## EVDL List (Jul 27, 2007)

> Lee wrote:
> >> That's why I say it's the controller's job (and the supply voltage)
> to determine the actual motor torque/speed/horsepower.
> 
> ...


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## EVDL List (Jul 27, 2007)

Most of the people I know running the HPEVS systems use 36 cells, 115V. I
usually don't see more than 126V under regen, though I have gone to 129V
when freshly charged going down hill on a cold day. I usually undercharge
the cells. This is with 100ah CALB cells, larger cells would see less
voltage rise for the same current.



> Zeke Yewdall wrote:
> >
> > What does your battery voltage under regen get to? I'd be worried that
> > at 115 volts nominal it would get to high when charging quickly. That's
> ...


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## EVDL List (Jul 27, 2007)

Regardless of safety features isn't a failed series controller just a
straight path between the pack and the motor, where as a failed AC inverter
is not? 




> Lee Hart wrote:
> >
> >
> >> 3. Much less likely to be able to run away. A stuck inverter will most
> ...


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## EVDL List (Jul 27, 2007)

It has been discussed here several times,
the short answer is that in both cases a failed
controller is typically a direct path between
battery and motor, but the response from the
motor differs:
- DC motor tries to go to max speed (full bore)
- AC motor tries to go to 0 RPM (full stall)

both can be dangerous in a moving vehicle.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of AMPhibian
Sent: Monday, August 22, 2011 8:11 PM
To: [email protected]
Subject: Re: [EVDL] Available AC drive systems?

Regardless of safety features isn't a failed series controller just a
straight path between the pack and the motor, where as a failed AC
inverter
is not? 




> Lee Hart wrote:
> >
> >
> >> 3. Much less likely to be able to run away. A stuck inverter will
> ...


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## EVDL List (Jul 27, 2007)

> On 22 Aug 2011 at 23:46, Lee Hart wrote:
> 
> > There are failure modes in both AC and DC controllers that can cause it to
> > go to full throttle. So, no controller builder would fail to include
> ...


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## EVDL List (Jul 27, 2007)

I was speaking about products we can actually buy and use in an EV, not
vacuum cleaners from Europe and trains.
300+ volts seems to be where most OEM AC systems run, you can get systems
from Metric mind that go up to 600V, until recently the Warps were limited
to less than 200V, now the 11HV goes to 288, so in truth the voltage
difference is getting smaller.



> Lee Hart wrote:
> >
> >
> >> AC motors can go much higher in voltage than series DC from what
> ...


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## EVDL List (Jul 27, 2007)

Doesn't sound like this is what you are looking for, but sometime next year
HPEVS will be offering a system consisting of a nominal 144V Curtis
controller, max about 160 to 170V, with a new 9" motor wound for about 150
ft-lb torque and 100 H.P.

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## EVDL List (Jul 27, 2007)

From: EVDL Administrator <[email protected]>
> I fear you are giving some controller manufacturers credit for more
> ethical health than they possess. Granted, my experience with them
> is years old, but (for example) I am not aware of any such features
> built into Curtis controllers. I'd also be surprised if some of the
> low-end Asian manufacturers weren't also omitting these features.
>
> If I'm wrong about that, please correct me.

I agree that many small low-voltage controllers for scooters etc. do not have any safety features. I guess they figure the power is so low that a full-on failure won't be "that bad". Or if it is, they can't be sued. :-(

But Curtis *does* describe how you are supposd to wire their controllers safely. Their diagrams typically include an emergency-off contactor, precharge resistor to protect it on turn-on, and switch on the potbox to turn it off even if the controller's transistors fail on.

Of course, this leaves it up to the builder to implememnt these features. 

--
Those who say it cannot be done should not interrupt the one who is
doing it. -- Chinese proverb
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net

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