# AC systems



## Joe_L (Sep 17, 2008)

Someone described to me that DC is like carburetor and AC is like Fuel Injection. Both work, but I am leaning more towards the AC setup. 

I have been doing my research and have found that Azure and metric mind offer AC systems (as does ACpropulsion, buy too far out of my price range). I am wondering who all here has done an AC conversion? What is the price difference AC vs DC? Does anyone know what components make up the DMOC445? I am always curious to how the controllers work.

Who has the AC24 and who has an AC55 setup from Azure (Solectria)? What kind of acceleration would one see from the AC24 system vs the AC55 or equivalent DC systems? Are there other variable speed AC motors that people have used? Has anyone built a ground up AC conversion themselves? 

Also, the Azure recommends 312 volts DC (on the AC55). What is the voltage of the AC motor? Does that 312 VDC become 208 or 230 VAC? 

Enough questions for now...


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## JRP3 (Mar 7, 2008)

Have you looked at www.evalbum.com and searched for AC systems? That might give you an idea of performance in different vehicles.


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## Joe_L (Sep 17, 2008)

Yes, I have been doing a searches on evalbum. I am now curious to talk to some of the people who might own those cars on the forum and hear their story.


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## major (Apr 4, 2008)

Joe_L said:


> Also, the Azure recommends 312 volts DC (on the AC55). What is the voltage of the AC motor? Does that 312 VDC become 208 or 230 VAC?


Hi Joe,

The voltage of the motor in AC systems will depend on the particular system. Some forklift trucks are now using induction motor drives at low voltage, like with a 48V battery. Some of the higher power AC drives for commercial vehicles will use 650 VDC sources. I think a few competition vehicles have done 1000 VDC. But I think most AC drives suitable for cars use source voltage in the 300 to 350 VDC range. When inverted to AC, this gives you about 230 VAC, 3 phase to the motor. This is a common voltage in industry for motors and the associated drive components, so the EV drives can use standard parts, like IGBT modules.

Of course, we were speaking of rated voltage. The drive will actually output any voltage below this. It is a VVVF (Variable Voltage Variable Frequency) inverter. The actual motor voltage will depend on the speed.

When buying an AC drive package (motor and controller), you pretty much have to follow the manufacturer's specification for source voltage. This can be a range to allow some customization for your energy storage system. But if you get outside their recommendation, you'll likely have trouble and find them unreceptive to things like warranty claims.

Regards,

major


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## Joe_L (Sep 17, 2008)

Thanks major,

230 VAC makes sense. It was the only way I could get their peak output calculation to work out. I just wanted someone else to verify the AC output voltage.

I have obtained quite a bit of reading material on the digital motor controller (DMOC445) from an Azure representative and have learned quite a bit more about the system. The system is more expensive, however the control box itself has everything built into it already. No need to build your own control box (like the DC system). 

One thing I have found online is the argument that the DC system is not designed for the outdoor environment EV's are put through (i.e. water proof/snow proof). However reading the 34 page manual on the DMOC445 states that it is water resistant, not water proof and should be protected from splashes. So in that regard it is the same deal as the DC controllers.


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## JRP3 (Mar 7, 2008)

Joe_L said:


> One thing I have found online is the argument that the DC system is not designed for the outdoor environment EV's are put through (i.e. water proof/snow proof). However reading the 34 page manual on the DMOC445 states that it is water resistant, not water proof and should be protected from splashes. So in that regard it is the same deal as the DC controllers.


Actually it's the DC motors that are not well protected from water since they are air cooled and have large openings. There are different ways to work around this however and more home conversions are DC and have not had problems with water. Many AC motors are water cooled, or finned for air cooling without large openings. DC controllers are usually fairly waterproof, Alltrax shows theirs being sprayed with water and still functioning.


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