DC v 2pole v 3 phase x voltage x amps

Technical discussion on converting internal combustion to electric
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Nutz
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DC v 2pole v 3 phase x voltage x amps

Post by Nutz » Sun, 26 Apr 2009, 19:12

Being a person that learns from visuals and application rather than comprehending Numbers and theory, (I know i am not alone here) I'll ask if anyone knows of where I can find, or if someone is able to draft a table or graph (or three) that would show the effect of different voltages and ampages on different motor types. It would not need to be comprehensive, just a guide, and only within a range that would suit EVs (light cruiser to heavy performance).
I know this is not a simple question, but I am hoping for a simplified answer. With luck somone will know where to find somthing that already exists and put a link to it here for others to find.
Weather you think you can, or you think you can't, you will usually end up being right.

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woody
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DC v 2pole v 3 phase x voltage x amps

Post by woody » Mon, 27 Apr 2009, 16:38

I gave this a bash for AC:

Image

Sorry it got a bit busy Image

Maybe I should split it in to graphs for Motor / Controller / Battery options?

cheers,
Woody

Edit:
This is for my cortina (800kg starting weight, direct drive)
The long dashed lines are different motors. (the legend doesn't show this)
The solid lines are different batteries.
Last edited by woody on Mon, 27 Apr 2009, 06:42, edited 1 time in total.
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack

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DC v 2pole v 3 phase x voltage x amps

Post by Johny » Mon, 27 Apr 2009, 16:56

Unfortunately a question that takes a paragraph to ask may take many many posts to answer. It is difficult to isolate the motor from the controller's capabilities - unless the controller has massive power. It is difficult to isolate the motor/controller power from the battery capability unless the batteries are "perfect".

Perhaps each one taken alone - motor, controller, batteries without regard to the other, then a final analysis discussing the interactions which inevitably lead to lost performance and range.

If we start with a comparison of various DC, brushless DC and ACIM motors and the power, weight and efficiency of each??? This in itself requires a bit of research to get figures that can be compared.

Is this what you are looking for Nutz?

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DC v 2pole v 3 phase x voltage x amps

Post by woody » Mon, 27 Apr 2009, 18:53

Yes it's messy:
* different components can be "the bottleneck" of performance with a certain combination of components.
* different people give different aspects of performance (range, handling, top speed, acceleration to 60,100,160, standing 400m etc.) more importance.
* each component adds different amounts of weight and space and cost
* different battery types last different number of cycles (LiFePO4: ~2000, AGM: 800) and can be discharged to different depths before sacrificing this (LiFePO4: 70-80%, AGM: 50-60%).

Running components "close to the edge" usually has some side-effects on life, e.g. flogging your batteries and motor to get acceptable performance will lead to early death and is false economy (good time to get better ones :-).

An easy way (probably the best way) to figure out how certain components are going to go together is to see a similar setup in real life. This is easiest if your planned conversion is like a Charade or Swift :-)

Examples of Bottlenecks:
AC Motors have a peak torque which requires a certain current to achieve, and a certain voltage per RPM to maintain it. e.g. ABB 132-316 392Nm @ 141 Amps.

Controllers have a peak input voltage and a peak motor current which will have flow-on effects to the motor. e.g. Curtis 1231C 500Amps, 144V = 72kW.

Batteries have a peak current output and/or their voltage drops when delivering current. (e.g. 42 TS-LFP90s will only put out 57kW : 675 Amps @ 2.0 Volts each = 84 Volts)
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack

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DC v 2pole v 3 phase x voltage x amps

Post by Nutz » Mon, 27 Apr 2009, 23:48

Looks like a flying start Woody,
Having everything overlaped does show that the controller seems to make the biggest difference.(if I read the key right)
Splitting the graphs, as you say, would make things a bit clearer, especialy if the Key was not as abbreviated. You could also label each graph so we can see at a glance what change is being studied(eg. Voltage, Controller, 2phaseAC-3phaseAC-DC etc.)
Like I said, it does not need to be too comprehensive, just enough to give us numericaly challenged an idea of what changeing different components does to the performance of the car, what which components are worth spending the extra dollars on etc.
Weather you think you can, or you think you can't, you will usually end up being right.

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