VESC Field Weakening Current Question

rg12

100 kW
Joined
Jul 26, 2014
Messages
1,576
A friend flashed a new firmware on a vesc and now has field weakening which is super cool.
The thing is that compared to ASI for example which rates it's FW in percentage, here it's in amps.
Now I have no idea what is considered high and what's low current for FW.

Can someone please explain why is it rated in current?
 

larsb

1 MW
Joined
Dec 10, 2014
Messages
2,790
Location
Gothenburg, Sweden
I think it's complicated to answer easily, this is my understanding.

the current during field weakening is applied with a different angle to the normal (90 degree angled) direction versus the magnetic field of the rotor. The applied total current can then be broken down into the 90deg part (q-axis direction) and the field weakening part (d-axis direction) and the field weakening part can either be expressed as a percentage of the 90deg direction current or as a current value in amperes.

100A field weakening current when your phase current setting is 200A will then mean 50% field weakening current.
 
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