DIY Electric Car Forums banner

1 - 8 of 8 Posts

·
Registered
Joined
·
32 Posts
Discussion Starter #1 (Edited)
Hey Folks. Has anyone experimented with the Tesla large drive unit at voltages higher than ~400? While I’ve yet to get the wheels to turn under power on my project, I’m coming from a “must make everything faster” background. Increasing voltage would be the first go to idea for higher torque output. I’m wondering if anyone has already started to experiment in this arena? I’m specifically thinking of something in the 550-580v range. Increased cooling capacity would be a natural assumption for supporting this.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
934 Posts
I would say start with 450V and a very stiff battery you will be amazed how hard the voltage sags when drawing the stupid (1200 Amps) one of these drives can soak up.

Also you got a setup that can get that sort of torque down reliably?
 

·
Registered
Joined
·
934 Posts
A stiffer/higher voltage will bump the knee in the torque curve, thus giving you the fixed torque for longer.

Pushing the flat torque up the motor speed, thus making more power.

This will most likely only be accessible if you run an free programmable brainboard in the inverter like Johannes's creation.
 

·
Registered
Joined
·
32 Posts
Discussion Starter #5
A stiffer/higher voltage will bump the knee in the torque curve, thus giving you the fixed torque for longer.



Pushing the flat torque up the motor speed, thus making more power.



This will most likely only be accessible if you run an free programmable brainboard in the inverter like Johannes's creation.


That’s the idea. It’s on Damien’s board so it’s pretty much open for melt down if one chose to do so.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
934 Posts
If you keep the current not too high you can push the voltage in steady steps.

I would strongly recommend get a proper scope to look at the switching behaviour to see if you do not get voltage spikes close to the IGBT ratings.

BTW; Current would melt and Voltage would cause it to blow.
 

·
Registered
Joined
·
32 Posts
Discussion Starter #7
Good info. If I go down this path I’ll certainly be taking things slow.
Crossing over into a performance EV build for the first time after years of turbo V8s.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
367 Posts
I'd ditch Li-Ion and use NiCads for drag racing (I also plan to run mine, when completed at the strip, but can't justify the spend for quickest if it can't "get groceries" regularly as well). Much better at dumping high current.

Current is the game here (as is torque/weight ratio), and as was mentioned by others, battery resistance, not voltage, is the big problem. There's also an argument for using supercaps, which *might* be lower resistance, but those need more bags o money than a "normal" pack does (which includes NiCad).

You also need to fret over every physical connection and its resistance --- every milliohm matters at >1000 amps. Both for voltage sag and heat.

As far as voltage goes, all engineering has safety factors and manufacturing tolerance accounting, built into it, so I'd guess going to 600 might be stressful to breaking insulation down (that includes the kind of coolant you're using...all of which are flammable), but as long as you have a motor with no defects, you might get lucky and not get an arc-initiated meltdown and coolant-initiated fire. Might.

$10k apiece, if you're lucky enough to only toast the motor, is an expensive experiment... but racing was never a cheap endeavor. Having bags o cash is the first order enabler, not brains, IMO.
 
1 - 8 of 8 Posts
Top