X-File: Understanding VESC: the difference between "battery amps" and "motor amps"
A question was brought up in the "Is my math right?!" thread relating to Understanding VESC: software.

This resulted in some new formulas which seem to enable prediction in advance of all or almost all "motor states."

The question was basically:

1440 W electrical @ %95 duty cycle = xxxx.xxrpm

It turns out you apparently can easily calculate the exact RPM for any W electrical and % duty cycle.

^If you know any 2 of these values, it should be possible to calculate the 3rd value.

To perform these calculations, you only need 4 basic pieces of information about the motor:

- Pack V @ No Load RPM
- No Load RPM
- Ohm Winding Resistance
- Desired W Full Throttle

For example:

devin, post:75, topic:17037 Wrote:Desired Full Throttle Electrical W: 2000W
Pack V = 50V fixed constant
Ohm Resistance = 0.0415ohm
No Load RPM = 4500rpm
Batt Max Setting = 40.00A
Motor Max Setting = 219.52A

~0w electrical @ 100% duty = 4500.00 rpm
1000w electrical @ 100% duty = 4425.29 rpm
2000w electrical @ 100% duty = 4350.60 rpm
2000w electrical @ 95% duty = 4083.92 rpm
2000w electrical @ 50% duty = 1690.37 rpm
2000w electrical @ 43.12% duty = 1324.43 rpm
2000w electrical @ 18.22% duty = 0 rpm

In simple terms to predict all motor states you only need to know Pack V @ No Load RPM, No Load RPM, Ohm Winding Resistance & Desired W Full Throttle.

",0,0,http://www.electric-skateboard.builders/t/understanding-vesc-the-difference-between-battery-amps-and-motor-amps/15995/278,2017-02-04 16:06:50 UTC

Messages In This Thread
RE: Understanding VESC: the difference between "battery amps" and "motor amps" - by devin - 04-22-2017, 01:07 PM

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